Hard to get decent lenses for the GH1?
- Thread starter Schmoe
- Start date
cordvision
Well-known member
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.
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.
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cordvision
Well-known member
deleted post because it contained wrong info. See below....
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cordvision
Well-known member
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...)
Schmoe
Member
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
Schmoe
Member
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
Well-known member
Oh well, it happens to all of us :beer:
So AGAIN
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
Well-known member
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....
Schmoe
Member
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"?
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?
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?
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ydgmdlu
Veteran
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
Veteran
That's about four stops... such a huge difference... doesn't seem right....
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
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
Illya Friedman
Well-known member
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
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