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Schmoe
05-30-2009, 06:53 PM
Complete newb to all this stuff, so go easy on me :beer:

I've been reading a bit, and from what I understand, a 25mm f1.2 lens placed on a GH1 is equal to a 50mm f2.4 on a full frame camera, as far as field of view and DOF.

So is it possible to get decent DOF on a GH1 without breaking the bank on a superfast wide? It seems that buying a superfast wide would cost as much as the camera itself...

And I don't suppose that there is ANY chance of getting decent DOF with the kit lens, since it only goes as high as F4. Or am I wrong here?

squig
05-30-2009, 07:14 PM
A superfast wide will cost an arm and a leg for any camera. There's some less expensive options like the sigma 14mm f/2.8 aspherical and the zenitar 16mm f/2.8 fisheye. There's also a sigma 20mm f/1.8.

Schmoe
05-30-2009, 07:44 PM
Yes, but my point was that with the GH1, a superfast wide is a REQUIREMENT just to get the equivalent of a basic 50mm. So you may be paying the price for a superfast wide, but you're only getting the performance of a slower standard lens.

For example, that $570 Sigma 20mm f1.8 is only going to be a 40mm f3.6 on a GH1.

Can you even get decent shallow DOF with a 40mm f3.6?

squig
05-30-2009, 08:00 PM
well unless you're in a confined space you can stand back and your 20mm will look like a 20mm. the angle of view is the same it's just that the edges of the frame are cropped. full frame camera's have much a shallower depth of field than a 35mm movie camera does. there's plenty of shallow DOF examples on vimeo from the GH1, it's not a major issue.

MatzeB
05-30-2009, 08:18 PM
For example, that $570 Sigma 20mm f1.8 is only going to be a 40mm f3.6 on a GH1.

that's wrong - or at least missleading.

Schmoe
05-30-2009, 08:20 PM
That's true. And standing back is fine for outdoors shots, but what about stuff done inside? You can only move back so far until you back into a wall.

The shallow depth of field shots on Vimeo are all either taken outside, in long rooms, or they are close-up shots. The few that aren't are shot on an $1100 Summilux 25mm f1.4 lens, which in GH1 math means that you are paying $1100 for a 50mm f2.8 equivalent.

I'm not bashing the GH1 btw. It's an excellent camera and I would really like it to be MY next camera. But it's beginning to look like a decent 50mm equivalent for this camera will cost as much as the camera itself. Something to consider when making a purchase if someone doesn't already have a superfast wide.

Schmoe
05-30-2009, 08:27 PM
that's wrong - or at least missleading.
If I am being misleading, please tell me how.

It is my understanding that for DOF PURPOSES(as I mentioned in my first post) a 20mm lens on the GH1 gives the equivalent FOV of a 40mm lens on a full frame camera. I mean, if the edges are cropped...then they're not there for me to use regardless of what the "true angle of view" might be. And an f1.8 aperture gives the equivalent of an f3.6 aperture(as far as DOF is concerned.)

As I mentioned in my first post, I am a newbie to all this 4/3 stuff, so I may be completely mistaken on any/all of it. I'm not here to argue, only to get information. I'm more than happy for someone to point out where I am wrong and explain things correctly for me.

ydgmdlu
05-30-2009, 09:25 PM
Well, the answer is that it really depends on what you're looking to get DOF-wise. Not everyone is looking to get the DOF that full-frame imaging solutions provide. So what one might consider to be "decent DOF" is highly subjective.

Consider this: The GH1's sensor in video mode provides a very similar horizontal field of view compared to the Academy film frame, which is the format in which most studio productions are shot. And the most common F-stops used in studio productions also happen to be F4.0 and F5.6, something that I read years ago (but correct me if I'm wrong). So with the stock lens wide open, the kind of DOF that you get should be close to what you see in the movies that you commonly see in theaters.

Movies are rarely shot with apertures larger than F2.8. For instance, The Godfather was shot at around F2.8. Ultra-wide lenses are hard to find at that aperture, but you can find a few inexpensive ones at F3.5 (half stop difference). For instance, Tamron made a very good Adaptall-2 17mm F3.5 lens that appears on eBay every once in a while.

The DOF question only matters if you're used to shooting full frame, either in still photography, or with 35mm adapters. If you don't have that kind of background or experience, then don't sweat it. The crop factor won't matter much to you at all.

squig
05-30-2009, 09:36 PM
there's a lot of fast/wide c-mount lenses around but it's hard to say if they will vignette on the 4/3 sensor but sometimes you can find them so cheap that it may be worth trying some out.

ydgmdlu
05-30-2009, 09:38 PM
there's a lot of fast/wide c-mount lenses around but it's hard to say if they will vignette on the 4/3 sensor but sometimes you can find them so cheap that it may be worth trying some out.
Actually, users have found that pretty much any C-mount lens wider than 25mm will vignette.

DrBlaz
05-30-2009, 09:40 PM
as far I know the DOF depends on lens aperture, not the crop factor, this is, the sigma 20mm f1.8 gives 40mm f1.8 on a GH1, so you get a f1.8 DOF

Ian-T
05-30-2009, 09:48 PM
That's exactly as I understand it also.

ydgmdlu
05-30-2009, 09:55 PM
No, DOF depends precisely on focal length and aperture. Image size or crop factor is an informal factor, since it alters field of view, which then affects the other two (real) factors.

ydgmdlu
05-30-2009, 10:05 PM
Come to think of it, the ideal wide lens is the Tokina AT-X 116 PRO DX (11-16mm F2.8), which Kholi keeps pimping around here. It really is a fabulous lens, nothing else like it on the market from any other manufacturer. It's a must-have, IMO, if you're really serious about wide angles. Only $600.

Do you really need anything faster than F2.8? Nothing else exists that will work (since the wider C-mounts will vignette), AFAIK.

cordvision
05-30-2009, 10:08 PM
There is so much false information in this thread. First of all a 50mm lens is always a 50mm lens, no matter what camera it is used with, what changes is the FOV and not the focal length. The smaller the sensor the narrower the FOV (with a given lens).


No, DOF depends precisely on focal length and aperture. Image size or crop factor is an informal factor, since it alters field of view, which then affects the other two (real) factors.

No, the aperture, the focal length, and lens to subject distance are the factors that influence DOF. A 50mm lens at f1.4 will give you about the same DOF on a GH1 as it does on a FF SLR Camera. (I use the word "about" because the enlargement factors when projecting the image are different, therefore, you might use a different value for the "circle confusion diameter limit".)

DrBlaz
05-30-2009, 10:09 PM
sure 1.8 DOF but 25mm angle

ydgmdlu
05-30-2009, 10:16 PM
There is so much false information in this thread. First of all a 50mm lens is always a 50mm lens, no matter what camera it is used with, what changes is the FOV and not the focal length.



No, the aperture, the focal length, and lens to subject distance are the factors that influence DOF. A 50mm lens at f1.4 will give you about the same DOF on a GH1 as it does on a FF SLR Camera. (I use the word "about" because the enlargement factors when projecting the image are different, therefore, you might use a different value for the "circle confusion diameter limit".)
I never said that crop factor "changes" focal length. I said that it "affects" the other two factors, and I apologize for not being clear about what I meant. The change in FOV "affects" focal length insofar as shorter focal lengths are required in order to achieve the same FOV. That's why I called the crop factor a "secondary factor." The aperture is affected insofar as its relation to focal length and lens choice. A shorter focal length means greater DOF for a given F-number, and wider lenses tend to be slower as well, limiting the aperture options.

Yes, actually there is the third factor of subject-to-camera distance that I can't believe I forgot.

Schmoe
05-30-2009, 10:29 PM
A 50mm lens at f1.4 will give you about the same DOF on a GH1 as it does on a FF SLR Camera.

Thanks for the clarification. Just to make sure I understand-
For the same distance to shooting subject: A 25mm f1.8 lens on a GH1 will give the equivalent FOV and DOF as a 50mm f1.8 on a full frame. Is that correct?

ydgmdlu
05-30-2009, 10:43 PM
No, the DOF will not be the same because the shorter focal is responsible for greater DOF. As I've been saying, aperture is not the only factor.

A 25mm lens on Four Thirds will give the same FOV as a 50mm lens. That's all.

cordvision
05-30-2009, 10:59 PM
No, the DOF will not be the same because the shorter focal is responsible for greater DOF. As I've been saying, aperture is not the only factor.

A 25mm lens on Four Thirds will give the same FOV as a 50mm lens. That's all.

I agree.
Sorry for misunderstanding you in the post above.

Schmoe
05-30-2009, 11:00 PM
grr oh well cordvision's "corrections" really did nothing more than to confuse the matter then.

So we're back to the original discussion, to get the same FOV and DOF of a 50mm f2.8 on a full frame camera, you have to buy a 3x more expensive 25mm f1.4 for the GH1

cordvision
05-30-2009, 11:03 PM
To summarize:

Longer Focal length = shallower DOF
Shorter Distance from subject to lens = shallower DOF
Larger Aperture (smaller f number) = shallower DOF

About FOV: The smaller the sensor the wider the lens needs to be to maintain the same FOV. This means, consumer cameras with a very small sensor need a very wide lens to get a "normal FOV", and as you know, shorter focal length = deeper DOV.

About crop factor: The crop factor is always comparing one sensor size to an other in therms of the focal length you need to use in order to get the same FOV. Ex. Between the GH1 and a FF SLR Camera we have a crop factor of about x2. This means that if you want to get the same FOV view with booth cameras, you need for example to use a 50mm lens on the FF SLR but a 25mm lens on the GH1.

cordvision
05-30-2009, 11:12 PM
deleted post because it contained wrong info. See below....

Schmoe
05-30-2009, 11:17 PM
also deleted for wrong info, so as not to confuse

cordvision
05-30-2009, 11:25 PM
okay, so just to make sure I(finally) have this straight.

For the SAME distance from camera to subject:
*a 50mm f2.8 lens on a full frame camera
is equal in FOV and DOF to
*a 25mm f2.8 lens on a GH1

?
Sorry, no I messed up completely. You were right with the f1.4. I need to get some sleep. I was mixing to issues together that you shouldn't mix in this case. My bad. A 25mm f1.4 on a GH1 should give you the same FOV and DOF than a 50mm f2.8 on a full frame SLR. I apologize for the confusion.... (everything else up to my last post was correct though...)

Nighthawk
05-30-2009, 11:26 PM
Just read this thread. Somebody want to pass the Tylenol.

Schmoe
05-30-2009, 11:29 PM
Sorry, no I messed up completely. You were right with the f1.4. I need to get some sleep. I was mixing to issues together that you shouldn't mix in this case. My bad. A 25mm f1.4 on a GH1 should give you the same FOV and DOF than a 50mm f2.8 on a full frame SLR. I apologize for the confusion....
Oh well, it happens to all of us :beer:

So AGAIN ;) we're back to the original discussion, to get the same FOV and DOF of a 50mm f2.8 on a full frame camera, you have to buy a 3x more expensive 25mm f1.4 for the GH1

ydgmdlu
05-30-2009, 11:32 PM
Yes, you have the right idea, but do you really need that sort of DOF? If you do, then you might as well get the 5D Mark II. It should make your life easier, as far as lenses is concerned. The cost would be the same, by your estimates.

Schmoe
05-30-2009, 11:35 PM
as far I know the DOF depends on lens aperture, not the crop factor, this is, the sigma 20mm f1.8 gives 40mm f1.8 on a GH1, so you get a f1.8 DOF

No, that's just my point. I think it would actually be IMPOSSIBLE to get 40mm f1.8 on a GH1. That would require a 20mm f0.9 and I don't think you could even find such a thing.

Even to get the same FOV and DOF as a 40mm f2.8, you would have to buy a MUCH more expensive 20mm f1.4.

As you can see, this could be a serious price consideration for someone choosing between a GH1 and a 5DMK2, if they want to shoot in anything less than 100mm...

cordvision
05-30-2009, 11:37 PM
Oh well, it happens to all of us :beer:

So AGAIN ;) we're back to the original discussion, to get the same FOV and DOF of a 50mm f2.8 on a full frame camera, you have to buy a 3x more expensive 25mm f1.4 for the GH1

You are correct.... :) This is actually exactly the same point I don't like about the GH1. If you want to have a wide lens on the GH1, it needs to be arround 12mm. The problem is that there are almost no affordable fully manual, fast lenses with that focal length (and if you find one, it probably has a very short focus throw). On top of that, you get relatively deep DOF because the lens is so wide....

cordvision
05-30-2009, 11:40 PM
The tokina 11-16 2.8 isn't too bad, but it doesn't compare to the zeiss contax lenses I have in terms of the mechanics. I wish panasonic would release a camera with a DX sized sensor....

dcloud
05-30-2009, 11:55 PM
if you want a wide lens for the gh1, get the wide DX or EFS lenses
its only x1.25 for gh1 not x2 which would give you a wide FOV

controlling apperture would be another thing though.

Schmoe
05-31-2009, 12:02 AM
Yes, you have the right idea, but do you really need that sort of DOF? If you do, then you might as well get the 5D Mark II. It should make your life easier, as far as lenses is concerned. The cost would be the same, by your estimates.

I'm a newbie to video, having only shot stills. I'm looking at the GH1 as a good option to jump into some live-action. So... I don't know that I necessarily NEED that sort of DOF, but it would be nice to have it as an option and I've certainly seen some amazing footage shot with a very shallow depth of field.

As you mentioned in a previous post, some movies are shot at full frame f2.8, so it seems like I would at least want to have that level of DOF.

Or am I completely turned around on all this? Would love to hear any advice about this from someone who's been shooting video for a while. What's the DOF required for a "film look"?

DrBlaz
05-31-2009, 12:08 AM
ok, then to get 50mm f1.8 on a GH1 you need a 25mm f1.8 lens, and the DOF will be bigger :

SSubject distance 3 meters
--------------------------------- 50mm f1.8 full frame
Depth of field
Near limit 2.82 m
Far limit 3.2 m
Total 0.38 m
--------------------------------- 25 mm f1.8 , equivalent to 50mm on a GH1
Near limit 2.66 m
Far limit 3.44 m
Total 0.78 m


to get a DOF similar to GH1 in a full frame you need to stop down to f3.6:

--------------------------------- 50mm f3.6 full frame
Depth of field
Near limit 2.66 m
Far limit 3.43 m
Total 0.77 m


so... it seems the GH1 DOF of a 25mm 1.8 is equivalent to a 50mm f3.6 full frame?

ydgmdlu
05-31-2009, 12:10 AM
As you mentioned in a previous post, some movies are shot at full frame f2.8, so it seems like I would at least want to have that level of DOF.

Or am I completely turned around on all this? Would love to hear any advice about this from someone who's been shooting video for a while. What's the DOF required for a "film look"?
I never said that some movies are shot at "full frame F2.8," although that's probably true. What I said was that most movies are shot with the Academy frame size, which is 21.95mm wide. Super 35 is 24.89mm wide, but it's not commonly used. Full frame is the VistaVision format, which was used on a handful of studio features a few decades ago. AFAIK, most movies are shot with apertures smaller than F2.8. I used The Godfather as an example of a movie that used an aperture around F2.8. But The Godfather was neither shot with Super 35 nor VistaVision.

So, in short, the GH1 is certainly enough to give you the "film look" in terms of the most commonly seen DOF, whether you're using lenses with maximum apertures of F2.8, F4.0, or F5.6.

ydgmdlu
05-31-2009, 12:22 AM
ok, then to get 50mm f1.8 on a GH1 you need a 25mm f1.8 lens, and the DOF will be bigger :

Subject distance 3 meters
---------------------------------50mm f1.8 full frame
Depth of field
Near limit 2.82 m
Far limit 3.2 m
Total 0.38 m
---------------------------------25 mm f1.8 , equivalent to 50mm on a GH1
Depth of field
Near limit 2.39 m
Far limit 4.02 m
Total 1.63 m


to get a DOF similar to GH1 in a full frame you need to stop down to f7:
---------------------------------50mm f7 full frame
Depth of field
Near limit 2.4 m
Far limit 4.01 m
Total 1.62 m


so... it seems the GH1 DOF of a 25mm 1.8 is equivalent to a 50mm f7 full frame?
That's about four stops... such a huge difference... doesn't seem right....

DrBlaz
05-31-2009, 12:33 AM
sure, too late!, recalculating...

Subject distance 3 meters
---------------------------------50mm f1.8 full frame
Depth of field
Near limit 2.82 m
Far limit 3.2 m
Total 0.38 m
---------------------------------25 mm f1.8 , equivalent to 50mm on a GH1
Near limit 2.66 m
Far limit 3.44 m
Total 0.78 m


to get a DOF similar to GH1 in a full frame you need to stop down to f3.6:

---------------------------------50mm f3.6 full frame
Depth of field
Near limit 2.66 m
Far limit 3.43 m
Total 0.77 m


now its right

ydgmdlu
05-31-2009, 12:37 AM
OK, so it's two stops, as we've been thinking all along. :smile: :beer:

Illya Friedman
05-31-2009, 01:46 AM
I'm a newbie to video, having only shot stills....

....What's the DOF required for a "film look"?

Good question. There seems to be a lot of confusion around this. Technically, one could argue that a film look could be achieved with 2/3" HD/video- plenty of features and TV have been shot in this format. The filmmakers don't complain, and neither do the audiences. The 2/3" HD format has a deeper DoF than 16mm film.

4/3 has an even shallower DoF than 16mm (by a wide margin), and is only a little deeper DoF than Super 35mm / APC sized sensors (like Red). Really 4/3 DoF is "filmic"; and it's very easy to control.

There's lot's of really fast PL mount lenses out there, and very soon anyone will be able to put those on a GH1. The entire set of Mk.III Super Speeds open up to T1.3, and those can be rented for a weekend most places in LA for about $300. Cooke S4 lenses are T1.9 or T2 and start at 12mm. Storraro loves Cooke lenses and it's no wonder why- they are fantastic.

I see people on message boards talking about a 4/3 having a 2x crop factor--- that is incorrect; unless you are comparing shooting stills, 30p video on a Canon 5DmkII or VistaVision. It's incorrect to be comparing DoF/FoV to 135 sized 35mm still cameras/VistaVision to 4/3, as if this is "the standard" because it's not- people don't usually make movies in the 135 format.

My quick and dirty (unscientific) figuring pegged the difference between the 4/3 and S35/APC-size at roughly 17%. I can figure out exactly what the difference but I haven't put for the effort as I've been too busy. Panasonic doesn't make it easy as they don't give sensor dimensions for shooting in 16:9 mode, so I can only figure it out based on the 4/3 4:3 dimensions.

There's a lot written about DoF and FoV in the ASC Manual, it's a pricey book but I'm pretty sure they are easy to find used on Amazon. The book also includes tables, so for those hellbent on trying to match two different format cameras 100% EXACTLY (somewhat of a rareity, but done) you can do it. The book finally went hardbound with the 8th edition, and you shouldn't buy anything older than that. The 7th edition got damaged way to easily.


I.

Illya Friedman
Hot Rod Cameras

AdrianF
05-31-2009, 02:16 AM
My quick and dirty (unscientific) figuring pegged the difference between the 4/3 and S35/APC-size at roughly 17%. I can figure out exactly what the difference but I haven't put for the effort as I've been too busy. Panasonic doesn't make it easy as they don't give sensor dimensions for shooting in 16:9 mode, so I can only figure it out based on the 4/3 4:3 dimensions.

Have you seen this article over at fourthirds-user? It has some info on the GH1 sensor and how the 16:9 aspect is achieved, thought you might be interested if you haven't seen it already..
http://fourthirds-user.com/2009/04/the_biggest_four_thirds_sensor_yet.php


For the OP, if you're looking for a fast 50mm equivalent, the Leica D 25mm 1.4 should be plenty, if you can get your hands on one:
http://www.dpreview.com/news/0703/07030703leica50mmsumm.asp

ydgmdlu
05-31-2009, 07:04 AM
Once upon a time, a nice French dude who called himself "divide" created a field-of-view chart comparing the popular motion picture image formats. You can find it here: http://www.dvxuser.com/V6/showthread.php?t=169831

vip77
05-31-2009, 09:39 AM
sure, too late!, recalculating...

Subject distance 3 meters
---------------------------------50mm f1.8 full frame
Depth of field
Near limit 2.82 m
Far limit 3.2 m
Total 0.38 m
---------------------------------25 mm f1.8 , equivalent to 50mm on a GH1
Near limit 2.66 m
Far limit 3.44 m
Total 0.78 m


to get a DOF similar to GH1 in a full frame you need to stop down to f3.6:

---------------------------------50mm f3.6 full frame
Depth of field
Near limit 2.66 m
Far limit 3.43 m
Total 0.77 m


now its right


So, just to clarify, the effective speed of the lens when mounted to a GH1 is what?

DrBlaz
05-31-2009, 09:48 AM
you only lose "two f-stops of DOF", not two f-stops of light, relating to light, the 20mm 1.8 is equivalent to 40mm 1.8

Martti Ekstrand
05-31-2009, 10:45 AM
Panasonic doesn't make it easy as they don't give sensor dimensions for shooting in 16:9 mode, so I can only figure it out based on the 4/3 4:3 dimensions.

According to a article on Four Thirds User the sensor width used for 16:9 on GH-1 is 22.5 mm which would make it nearly identical to the width of widescreen 35mm 1:85: http://fourthirds-user.com/2009/04/the_biggest_four_thirds_sensor_yet.php

Compare with illustration here: http://en.wikipedia.org/wiki/Super_35_film

Anybody have a opinion on this Sigma 30mm/1.4 lens that's available with a standard 4/3s mount? Looks like a good close-up lens to me but I don't know much about Sigma at all. http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3300&navigator=6

mkeep
05-31-2009, 11:38 AM
Don't forget, Panasonic is supposed to be coming out with a 20mm 1.7 pancake lens.

anthonybsd
05-31-2009, 01:49 PM
No, that's just my point. I think it would actually be IMPOSSIBLE to get 40mm f1.8 on a GH1. That would require a 20mm f0.9 and I don't think you could even find such a thing.

Even to get the same FOV and DOF as a 40mm f2.8, you would have to buy a MUCH more expensive 20mm f1.4.

As you can see, this could be a serious price consideration for someone choosing between a GH1 and a 5DMK2, if they want to shoot in anything less than 100mm...

This whole discussion is confusing to no end to me as a photographer. A 1.4 aperture, is a 1.4 aperture, regardless of the FOV. In other words GH1 with a 50mm lens at fully open will give you the same exact dept of field, but at 2x multiplication. In other words, I'm not sure where you are getting the whole 2.8f. Want the same exact depth of field with 50mm 1.4 with GH1 as on MK2? Stand back a bit - that's all there's to it. Two lenses at the same aperture covering the same frame will have the same exact depth of field, whether you have 25 mm lenses, 50 mm lenses, 100mm lenses or 400mm. The 400 mm would have to be standing quite a bit further away from the subject to have the same FOV as opposed to the 25mm, but that's not the point.

In other words, is the problem here the fact that people are used to a certain style of shooting and don't want to move around?

Schmoe
05-31-2009, 03:20 PM
Want the same exact depth of field with 50mm 1.4 with GH1 as on MK2? Stand back a bit - that's all there's to it.
And that's the point, if you are shooting inside, there are WALLS that might prevent backing up ;) Can't speak for everyone, but for video, I will likely be using this for 90% indoor shots. I honestly can't imagine anyone shooting a short that takes place entirely outside, and I don't think most of us would be looking at the GH1 if we did most of our shooting on actual SETS. Personally, I'll be shooting video in houses, apartments, hallways... places where I can't always simply "stand back a bit".


In other words GH1 with a 50mm lens at fully open will give you the same exact dept of field, but at 2x multiplication. In other words, I'm not sure where you are getting the whole 2.8f.

I'm comparing how the lenses will behave on the GH1 compared to a full frame camera at the same distance, field of view, and depth of field.

For example, if I were shooting with a full frame camera with a 50mm f2.8 lens: I'm shooting at a distance of 7 feet from my subject. This gives me roughly a 5 ft wide by 3.5 ft high FOV. I would get a 1ft depth of field.

Now I switch to the GH1 with a 25mm f1.4 lens:
I'm shooting at the SAME distance of 7 feet from my subject. This gives me the SAME 5 ft wide by 3.5 ft high FOV. I would also get the SAME 1ft depth of field.

So for this VERY practical purpose,
25mm f1.4 lens on a GH1 = 50mm f2.8 on a full frame

And the problem is that the 25mm f1.4 lens is gonna be MUCH more expensive than that 50mm f2.8 lens. That's why I think this could be an important price consideration for those choosing between the GH1 and a full frame camera like the 5DMK2.

anthonybsd
05-31-2009, 03:47 PM
I see the dilemma(I think). You see my film making knowledge is minus one, i.e. less than zero. In photography I wouldn't have considered this a limitation, just as I never really thought of 1.6x crop on my first APS-C DSLR as a limitation since I could simply move around and achieve the same DOF for portraits (case in point: http://www.film-and-video.com/dofmyth.htm). Except of course when the subject is your entire frame i.e. focus is infinity - in which case I really never concerned myself about how much foreground is blurred.

What you are saying is logistical consideration is of enormous importance?

From my totally amateuristic point of view I'll use all my bright FD lenses on this and get the 1.4 of the low light sitations - and work around different FOV. I mean I'm still getting tons of light on the sensor, right?

puredrifting
05-31-2009, 06:17 PM
50mm 2.8? Haven't seen one of those.

You do know that the GH1s crop mode with non 4:3 Micro lenses has nothing to do with lens speed, only field of view, correct?

Dan

DrBlaz
05-31-2009, 06:35 PM
we were talking about how the 2x crop factor affects to DOF compared to 35mm full frame.

the results are about two f-stops more, but only related to DOF. To get the same image with the same DOF with a GH1 and a 35mm full frame you need :

GH1----> 25mm f1.8
35mm-> 50mm f3.6

of course, the 25mm f1.8 on the GH1 remains f1.8, allowing low light filming, but the DOF is equivalent to a 50mm stopped down to f3.6

puredrifting
05-31-2009, 07:34 PM
Okay, now I get it. Thanks for clarifying that. Stupid me, jumping on the conversation without reading the whole thread. Carry on!

Dan

AdrianF
06-01-2009, 01:24 AM
we were talking about how the 2x crop factor affects to DOF compared to 35mm full frame.

the results are about two f-stops more, but only related to DOF. To get the same image with the same DOF with a GH1 and a 35mm full frame you need :

GH1----> 25mm f1.8
35mm-> 50mm f3.6

of course, the 25mm f1.8 on the GH1 remains f1.8, allowing low light filming, but the DOF is equivalent to a 50mm stopped down to f3.6

Is this based on actual camera tests you've carried out with both formats?

Kholi
06-01-2009, 01:35 AM
It's odd to me that the Original Posts in this thread somehow manage to pain the MKii as a cheaper option in ANY way SHAPE or form. No matter if you're going for ultra shallow DOF or not.

Price doesn't matter, you're going to spend more money no matter which way you go if you're trying to do what you're outlining.

MKii body - 2800 after tax w/NO lens. 50/1.4 - 300 for a Contax Zeiss. CF card fast enough to handle data - 60. A Lens adapter to EOS - 10 for one that doesn't even work right.

Rounded DOWN to about 3100.00

GH-1 Body w/Kit Lens - 1500.00. 20/1.8 SIgma (I have this lens) - 500.00. SDHC Card fast enough to handle data - 60. Micro Four Thirds to Four Thirds to Your Choice Adapter - 100.00

Rounded up to about 2200.00

No matter which way you want to slice yoru bread, the MKii is a more expensive purchase then the GH-1. You buy an MKii body and you spend even more money trying to do the same thing that you can with a GH-1 for less.

A 20/1.8 on the GH-1 is pretty damned shallow, especially the SIGMA 20/1.8 which has insane close focus.

oi

Illya Friedman
06-01-2009, 02:01 AM
According to a article on Four Thirds User the sensor width used for 16:9 on GH-1 is 22.5 mm which would make it nearly identical to the width of widescreen 35mm 1:85: http://fourthirds-user.com/2009/04/the_biggest_four_thirds_sensor_yet.php

Hi Martti,

That's actually a 22.5mm hypotenuse (not width) from the 4:3 mode; if you look again you'll see that they don't actually know the size of the width in 16:9, but I'm willing to guess that the methodology they propose is correct.

Pythagorean theorem puts Super 35 hypotenuses at about 28.8mm which is about 22% greater than 4:3 in 4/3. Regardless that point is moot, because you're not shooting in 4:3 with the GH1 in HD (16:9 only) and you get to take advantage of that extra horizontal resolution.

There's a couple ways to solve the hypotenuse question beyond a doubt; and it's likely someone will have need of knowing exactly and solve the distance before I do (next month)- it will save me the effort.

Again- just to repeat myself (paraprasing) it's deliberately misleading to say "2x crop factor" when "compared to 35mm" is a problem when shooting indoors. That's like saying that 16mm and HD can't be shot in a car, becuase it's a confined space. But that happens every day- and it can look very, very good.

Before the advent of HD video, one of the big pushes by DPs was to convince Kodak/Fuji/Agfa to make tighter grained high speed stocks so DPs could work at a higher T-stop to get more DoF, not less. Then after HD comes along, some of those same film purists who wanted more DoF now say that additional DoF is a liability. DoF (or lack there of) is a fad like many of the other tools of the trade. Best case cenario is you can have it when you want it, and take it away when you don't. IMO 4/3 may be the best format for that kind of flexibility and control.

Use the tool that's right for the job, if VistaVision for A camera was the right choice for most productions, a heck of a lot more projects would have shot that way- and they didn't. There's plenty of reasons not too beyond cost.

I.

Illya Friedman
Hot Rod Cameras

Martti Ekstrand
06-01-2009, 03:49 AM
Oh yes, now I see, I misread that figure. Calculating from the 18 mm measure in their diagram it seems then like the width is 19.5 mm which still is pretty close to Academy 1:1.85 negative width. And I definitely concur with your conclusion that 4/3 sensor size may be the best option for flexibility. I can understand that coming from still photography on horizontal 35mm format one can worry about '2x crop factor'. However coming like me from vertical 35mm & 16mm film and 2/3 video cameras the DoF on GH-1 is not a concern, quite the contrary; to me the crop factor is roughly 1x.

I don't know how many of you who fear that the DoF on GH-1 wouldn't be enough have actually shoot scenes with actors moving about and tried to follow focus on them. Even at f4.0 is pretty darn hard for a dedicated focus puller, step up aperture to 2.8 and he has to be very good - it's a job position that can take a couple of years to master. Do it as a lone operator without assistance and you'd have to be pretty frakkin ninja to pull it off. Especially without a follow focus rig.

Not only that, in narrative film context a very shallow DoF is not used that much, because it tends to isolate the character from the place and give a claustrophobic/alienated feel. One wants the background to be there but a bit off-focus as not to pull attention to it - a super soft background that looks beautiful on a still often feels 'unreal' in motion throwing the viewer out of the narrative. And it's hard to get a good flow in the edit when having a bunch of such shots following each other, also disrupting the viewer. Look at some features on DVD, freeze-frame here and there and pay attention to the DoF and you'll see that cuts with very shallow DoF are rare. Most features are shoot around f4 with 5.6 for wider shoots and 2.8 for close-ups. 2.0 is used mostly when running out of daylight on location or for that super-dramatic close-up - "Dammit Chloe, should I cut the blue or the pink wire?" - pulling from the hero's eye to the ticking bomb.

As for super wide angles again they are not that useful in a narrative context, make a pan and the whole world bends, have somebody walk across the frame and he/she bends with the world and this also will risk throwing the viewer out of the suspension of disbelief (plus few actors enjoy having their faces and bodies distorted). And if Hype Williams managed to make all his crazy super-wide boot-shaking hip-hop videos on 35mm film cameras I'm pretty certain the GH-1 will suffice as well.

Side note Illya: a friend of mine is sitting on a bunch of old lenses with Arri mounts. Do you have any plans for a GH-1 / Arri adapter? I mean, speaking of getting decent lenses :Drogar-BigGrin(DBG)

BrianMurphy
06-01-2009, 04:12 AM
On the BH specs page it lists the sensor as "17.3 x 13.0mm".

Martti Ekstrand
06-01-2009, 06:50 AM
Yes, but that's the same spec as given for G-1 and according to the Four Thirds User article Panasonic has said that the active area for 16:9 is bigger on GH-1.

Illya Friedman
06-01-2009, 01:23 PM
Side note Illya: a friend of mine is sitting on a bunch of old lenses with Arri mounts. Do you have any plans for a GH-1 / Arri adapter? I mean, speaking of getting decent lenses :Drogar-BigGrin(DBG)

Sweet! That's a good friend to have. Some Arri mount lenses can also be converted to PL, then you get more flexibility.

There's a couple different Arri mounts, Arri B and Arri Std. Let me know which on it is, if there's enough demand, I could do a run of these (probably need at least 9-more people to make it worth while.) I hadn't planned on building those initially.

I can also always do a custom '1 of' job Arri to m4/3. If you're interested, contact me by PM.

I.

Illya Friedman
Hot Rod Cameras

Schmoe
06-01-2009, 05:00 PM
I don't know how many of you who fear that the DoF on GH-1 wouldn't be enough have actually shoot scenes with actors moving about and tried to follow focus on them.
I have shot approximately NONE. As in not a single one. If you've shot even as much as a well-produced wedding video, you have more video experience than I do. :)

I've only shot stills and was coming from the perspective that I'd hate to have such limits there. But I'm buying this camera for video, so it's video performance is really my concern.



Not only that, in narrative film context a very shallow DoF is not used that much, because it tends to isolate the character from the place and give a claustrophobic/alienated feel.
[SNIP]
Most features are shoot around f4 with 5.6 for wider shoots and 2.8 for close-ups. 2.0 is used mostly when running out of daylight on location or for that super-dramatic close-up

This is exactly the kind of advice I'm looking for from you guys with video/film experience. To be specific-
About how many feet(near focus limit to far limit) of DOF will I need for a "film-like" look? Just for average narrative storytelling, nothing fancy/artsy. And what focal length and aperture would you recommend for achieving it on the GH1?

How many feet of DOF for good "film-like" close ups and "attention focussing" shots? And what focal length and aperture would you recommend for achieving it on the GH1?

Would love to hear comments from anyone with some proper video/film experience. Even guesses are welcome :beer:

Nighthawk
06-01-2009, 05:52 PM
Oh yes, now I see, I misread that figure. Calculating from the 18 mm measure in their diagram it seems then like the width is 19.5 mm which still is pretty close to Academy 1:1.85 negative width. And I definitely concur with your conclusion that 4/3 sensor size may be the best option for flexibility. I can understand that coming from still photography on horizontal 35mm format one can worry about '2x crop factor'. However coming like me from vertical 35mm & 16mm film and 2/3 video cameras the DoF on GH-1 is not a concern, quite the contrary; to me the crop factor is roughly 1x.

I don't know how many of you who fear that the DoF on GH-1 wouldn't be enough have actually shoot scenes with actors moving about and tried to follow focus on them. Even at f4.0 is pretty darn hard for a dedicated focus puller, step up aperture to 2.8 and he has to be very good - it's a job position that can take a couple of years to master. Do it as a lone operator without assistance and you'd have to be pretty frakkin ninja to pull it off. Especially without a follow focus rig.

Not only that, in narrative film context a very shallow DoF is not used that much, because it tends to isolate the character from the place and give a claustrophobic/alienated feel. One wants the background to be there but a bit off-focus as not to pull attention to it - a super soft background that looks beautiful on a still often feels 'unreal' in motion throwing the viewer out of the narrative. And it's hard to get a good flow in the edit when having a bunch of such shots following each other, also disrupting the viewer. Look at some features on DVD, freeze-frame here and there and pay attention to the DoF and you'll see that cuts with very shallow DoF are rare. Most features are shoot around f4 with 5.6 for wider shoots and 2.8 for close-ups. 2.0 is used mostly when running out of daylight on location or for that super-dramatic close-up - "Dammit Chloe, should I cut the blue or the pink wire?" - pulling from the hero's eye to the ticking bomb.

As for super wide angles again they are not that useful in a narrative context, make a pan and the whole world bends, have somebody walk across the frame and he/she bends with the world and this also will risk throwing the viewer out of the suspension of disbelief (plus few actors enjoy having their faces and bodies distorted). And if Hype Williams managed to make all his crazy super-wide boot-shaking hip-hop videos on 35mm film cameras I'm pretty certain the GH-1 will suffice as well.

Side note Illya: a friend of mine is sitting on a bunch of old lenses with Arri mounts. Do you have any plans for a GH-1 / Arri adapter? I mean, speaking of getting decent lenses :Drogar-BigGrin(DBG)

Martti, I agree with everything you say but, as a director, I'd like to have as many tools available in my shot list toolbox. We all know that composition/ framing, camera movement and, yes, DOF can strike an emotional chord with the audience. Having the option to shoot that claustrophobic/alienated feel if it fits the context of the the story is an option I'd like to have at hand. I freely admit with this camera, or any other DSLR format cam, it's going to be a bitch for all the reasons you mention but, hey, no pain no gain. Know your cam, you'll know your shot list.

ydgmdlu
06-01-2009, 09:02 PM
About how many feet(near focus limit to far limit) of DOF will I need for a "film-like" look? Just for average narrative storytelling, nothing fancy/artsy. And what focal length and aperture would you recommend for achieving it on the GH1?

How many feet of DOF for good "film-like" close ups and "attention focussing" shots? And what focal length and aperture would you recommend for achieving it on the GH1?
As I said earlier in this thread, the GH1's sensor has an active image area in video mode that is only slightly smaller than the Academy frame size. I don't think that you understood what that meant.

1) Motion picture film is run vertically rather than horizontally (as it is in still photography). There is a motion picture format in which the film is run horizontally, and it's called VistaVision. VistaVision was used in a handful of studio productions a few decades ago and found a champion in Alfred Hitchcock, but it never got mainstream acceptance and soon went out of fashion completely. So you shouldn't think of full frame as a "standard" in cinema because it's almost never used.

2) Since the film is normally run vertically, the maximum frame width is 24.89mm, which is the width for the Super 35 format. However, for a number of reasons, Super 35 (or "S35") is not the dominant format. One reason is that in order to achieve that width, the small area of celluloid to left of the image frame that is normally reserved for the audio track is instead used for the image as well. (This has numerous implications on workflow, delivery, and exhibition.)

3) So because there's an area on the celluloid that's normally reserved for the audio track, the image area in most productions is not as wide as the full 24.89mm. It's actually 20.95mm wide (for 1.85 matted widescreen, which is the the most common format). This is what's known as the Academy film gate (or frame) size. The GH1's sensor in video mode is estimated to be 18.8mm wide. As a result, the field of view that you get from it is barely distinguishable from that of the most common motion picture film format.

If you go to a cinematography resource like American Cinematographer magazine (the trade publication of the American Society of Cinematographers, of which all professional American cinematographers working in Hollywood are members), you can read all about what lenses and apertures were used on high profile productions.

Most movies seem to be shot between T2.8 and T4.0, although T5.6 is not uncommon either. In case you don't know, there's a small technical difference between T-stops and F-stops, but for simplicity's sake, you can consider them the same. Most Hollywood cinematographers on most productions like to keep the aperture more or less constant on all shots. In fact, I read in an IMDb interview some years ago that choosing the aperture value is the first step that many/most cinematographers take in establishing the look for a movie.

Because the aperture is decided early in pre-production or production by a cinematographer, then focal lengths matter primarily for field of view and object proportion within the image. They don't matter so much for depth-of-field considerations. However, there are certain conventions for certain kinds of shots, like longer lenses for close-ups of people. You can read about what the conventions are from cinematography books that you can borrow from the public library.

But ultimately, the point is that you don't have to worry so much about what lenses to use on the GH1 to get a "film look." Because the image size is so similar to the Academy frame, you can just use the same focal lengths and apertures that Hollywood cinematographers use without any worries about crop factor. Even the kit lens is fine for getting a "filmic" DOF. I recommend paying close attention to the movies that you commonly find in theaters to get a good feel for the conventions. Really, these conventions are not all that different from the ones in the still photo world.

Martti Ekstrand
06-01-2009, 11:42 PM
as a director, I'd like to have as many tools available in my shot list toolbox ... Having the option to shoot that claustrophobic/alienated feel if it fits the context of the the story is an option I'd like to have at hand.
As a fellow director and editor/amateur camera man I get ya. For those shots I present to you this 50mm/f1.1 baby

http://www.voigtlaender.de/cms/voigtlaender/voigtlaender_cms.nsf/id/pa_fdih7s8jbr.html

You need a Leica to 4/3 adapter, Voigtlaender recommends one from Novoflex.

If you need a wider lens Sigma has a 30mm/f1.4, a 24/f1.8 and Leica makes a 24/f1.4 which is a bit pricey.

http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3300&navigator=6

http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3281&navigator=4

http://panasonic.net/avc/lumix/systemcamera/dslr/lens/fixed_focal_length_lens.html

For all these you'll need a 4/3 to 4/3 adapter.

I'm sure there are more options out there, this is what I've found while lazily surfing the intratubes for some hours.

Nighthawk
06-02-2009, 12:09 AM
Awesome links Martti, thanks. There goes the Xmas funds.

MatzeB
06-02-2009, 12:27 AM
There's enough 'shallowness' for all of you in this camera.