35mm optical adapter (No GG)

[Shaw]

Greetings all,

I've been pondering the possibilities of creating an adapter for the DVX that would allow the use of 35mm lenses which would neutralize the magnification factor (without GG and as much light loss). I have access to lens design software and have expert help (My father has a PHD in optics).

I know I can make an adapter that would compress the outcoming light from a 35mm lense so that it fit fully onto the 1/3" CCD. No problems there really. My only hesitation, however, is that I am unsure of whether this would retain a 35mm depth of field... I can see arguements both for and against this assumption. Anyone know?

[J_Barnes]

I would assume that if there were a simple lens solution that allowed for the full retention of light and DoF on a smaller imaging space, someone would have developed an equally simple solution to implement it by now.

[Shaw]

So would I but from recent discussions I'm beginning to wonder...

At the very least such an adapter would allow the use of quality 35mm lenses without that darn magnification factor.

[disjecta]

I would assume that if there were a simple lens solution that allowed for the full retention of light and DoF on a smaller imaging space, someone would have developed an equally simple solution to implement it by now.



That's what the guy who was going to invent the wheel but decided not to said. :D

[taubkin]

LOL

[J_Barnes]

That's what the guy who was going to invent the wheel but decided not to said. * :D


Yeah, but what'd he invent instead? If it was the club, or the interest based loan system, it's a fair trade.

[glassblowerscat]

As far as I understand it, the DOF problem is solved by, say: The mini35, by the recording of an already flattened image.

In other words, with the mini35, the 35mm lens "projects" its image on the GG, using its own DOF. The DV camera's lens then simply picks up this already created image (and its accompanying DOF) and records it to its own CCD. So it's a similar concept to taking a picture of a picture—just re-recording an already existing image.

Of course, I'm sure you all knew this.

But what that says to me is that the problem is solved by the fact that the image is being initially recorded, not by the camera, but by the GG. Thus having an adapter connect a 35mm lens to would not accomplish the same thing.

Of course, I am always quite willing to be proved completely wrong by someone with a degree in optics.

Ryan

[Shaw]

glassblowerscat:

You may indeed be correct. I never got around to discussing this aspect with my Father very much. I'll keep looking into it and see what I can come up with though. Maybe work through the math and see if I am missing something big (probably am). If such a solution were possible it could be created for much cheaper, and theoretically produce better results, than the Mini35.

[Barry_Green]

I believe the term you're looking for is aerial image focusing -- where the 35mm lens would still focus its image to the same plane, and then the camera would focus where that plane is and somehow be able to capture that image even though it's not being projected on something.

I do not, by any stretch of the imagination, know what I'm talking about here, but the theory sounded interesting. I tried it and got nowhere. But perhaps with your resources you could find a way to make this happen, and if it's possible, it sure would be sweet!

[Shaw]

Now that is an interesting idea... wasn't thinking of that specifically though. I'll have to think about that too now!

The idea I have been working with does indeed sound far too simple... but from my (granted, limited) optics knowledge it seems as though it would work fine if designed with some real software. Please note though that I may be barking up the entirely wrong tree here :)

What I was meaning though:

All 35mm lenses have a focus plane at the same place (well at least all lenses of a certain manufacturer. Not sure about how/if this differs from lens maker to lens maker). The following diagram shows somewhat of what I was thinking (the optic lens shapes are not in correct form. I am merely demonstrating the rough idea here):

http://www.weet.us/adapter.jpg

The only problem with designing a relay lens of this type is that you have to correct for various abberations introduced by the compression process so the final relay lens will probably end up being multi-element.

Again, not sure if the math will work though...

[Mike_Donis]

It seems to make sense on paper!

[glassblowerscat]

No kidding, man. If that was possible (and by your explanation, it sounds worth looking into), it would not only be a cheaper solution, it would be much better for us run 'n' gun guys to use than the monster mini35 and its accompanying rods.

The only thing that troubles me is, as you said above, that it seems too simple. I always wondered why no one used glass that didn't require being spun to project a grainless image. But my knowledge of optics is limited, to understate things to a laughable degree.

And then again, you don't want to be the guy who thought about inventing the wheel, but didn't. ;)

[J_Barnes]

hold on there...since when are multi element aspherical lens assemblys cheap? And you better believe that you'd have a rod assembly after attaching two lenses to the front of a DVX.

Lens glass is heavy.

[Neil Rowe]

if you shift the focal plane back, and condens the image to a 1/3 ccd size it should work.. while your at it, you should flip the image back right side up ;)

..ive actually thought about trying to do this many times, but didnt have time or energy to spened on it. but in all my theory, and knowledge (uh.. yeah.. all 2 cents of it.. ) it should work fine.. i think of it like a focusing lense for a projector. you can resize the image optically , and it retains all the same imagery of course and you can shift the focal plane to focus further away, or closer. and its the same image. so doing the same thing in reverse with light coming in instead of going out ..by all practical purposes should work as well, and the image should be the same as before you adjusted those things. so youd be getting that sought after 35mm DOF.

i always thought that using a simple magnifying lense right behind the 35mm lense would cause the image to be projected larger, and make you not have to zoom in as much. ..astoundingly as i now notice, ive never tried it. :P then thoeretically if you could shift the focal point back your gold.

who knows.. im not a lense guru by any means..lol

[Barry_Green]

I can't see how that would work on a camera like the DVX. You'd have to pry the camera's lens off first. Might work for an XL2, where you have the ability to get a clear path to the CCD's, but for the DVX the only way to get an image to the CCD's is to go through the camera's lens, and the camera's lens will always need a certain focal plane in front of it for it to be able to resolve the image.

[Guest]

Damn I hate to be the bringer of bad news here but due to real world laws of optics it just isnt possible to maintain the DOF thru this method.

This exact method has not only been brought up, tested and proven to not be true for many years now in forums but major lens manufactures like Zeiss have long joined forces on this venture. The result was a adapter made commercially available in the mid 90's. The adapter lets you use 35mm lens on a 2/3 CCD camera. It works the same as whats being proposed on this thread. The 35mm image is optically reduced in size thru a very complex precision set of lenses to finally be able to fit on 2/3" CCD. While the field of view maintained THE DOF IS NOT. Law of optics. You need to have a physical intermediate image plane.

Sorry guys. I wish it was possible too.

[Shaw]

You bring up a good point Barry. It is something I'll have to seriously think about. I *believe* a system could be designed to work with the panasonic lens but at this point it's all speculation. The only trouble would be getting my hands on detailed specs of the lens design and precise location of the CCDs... and I would rather not tear the lense off my new DVX!

[Shaw]

Looks like you posted while I was typing a response Brett.

Could you explain why it doesn't work?

[Guest]

Its very hard to type out a explaination but heres a basic visual you can use to understand why it doesnt work.

Imagine the light coming out of the back of any given photo lens as a 3D cone. The diameter of that cone represents the CCD or film plane size and the length of the cone represents the focus/DOF. The point of the cone is the point where the image comes in focus. Anything farther before or after that point will be progressively more out of focus.

With that idea in your mind imagine the cone of light coming off a 35mm lens. We know the "diameter" of that cone is going to be relatively large compaired to a 1/3'' CCD cameras lens because the 35mm film area is so much larger that a 1/3" CCD. So if we take the idea of shrinking down the light rays (or "cone") of a 35mm lens to make it fit on a 1/3" CCD we are both making the cone smaller in diameter and also not as long. The basic ratio between the diameter of the cone and its length stays the same as we make the cone smaller.

By doing so you get the image (cone) to fit on a 1/3" CCD and thus maintain the FOV. BUT the 35mm DOF is changed and in fact will be the same as if it were shot with a 1/3" chip lens.

To understand why think back to the fact that the point of the cone represents the image in focus at the point of the CCD (or film plane). Because we have shunk the cone we have made the length of the cone less substatual. And if its shorter more rays are closer to the focus point (point of the cone) than before. In other words more things are in focus - thus the DOF isnt nearly as shallow as a 35mm lens.

Thats basically whats happening. Hope that helps and wasnt too abstract.

Brett Erskine
www.CinematographerReels.com

[Guest]

But not all is lost. You wont be able to have 35mm DOF but if you do end up making one of these image plane reducing adapters you will notice three different benifits.

1)FOV is the same,
2)Use of all film lens accessories, follow focus, slower powered zooms, etc.
3)Increase in low light capablity. (Yes you heard right)

[Shaw]

Thanks for the explanation Brett :). Very helpful!

I did realize that the adapter would allow the full field of view for the lens - I was just hoping that it would also (magically) retain the depth of field. Ah well!

One thing I don't understand is how you would increase your low light sensitivity. Is it just due to the better light gathering capabilities of 35mm lenses?

Maybe I'll set to work on my other idea - designing a 2.35:1 anamorphic adapter ;). Though that brings up problems too... darn!

Thanks for the explanation!

[TC]

Geez, DIY lenses. Shaw just kicked it up a notch. ;)

[Guest]

It gives your better low light capability because you CCD is getting more light than before. This is happening not so much because of the 35mm lens but the fact that your taking the 35mm image area and squeezing it down to 1/3" size.

You can see the same thing happen when you take a video projector and use the lens to squeeze down the projected image. As the image gets smaller it also gets brighter. Focusing a mag light is another basic example.

To make your anamorphic adapter you'll need whats called a two element cylindrical lens and if you want it to give you a 2:35 image for a DV camera it will need to be aprox. 1.78X horizontal power. Thats it. Let us know how it goes.

Brett Erskine
www.CinematographerReels.com

[Shaw]

Geez, DIY lenses. Shaw just kicked it up a notch.

:D I'm actually not all that skilled in this area - I just know I have the resources to attempt it! We'll see how my attempts turn out ;)

Again, thanks for the info Brett - and thanks for the encouragement. I think I'm going to give both lenses a shot and see how they turn out. I'll be sure to post my progress and results!

[Neil Rowe]

hillarious! yeatserday i took out a few 35mm lenses, and started experimenting with a bright light trying to focus an image on a wall at the correct distance, then i took some various lenses i have around and tried to shift the focal plane back to see if this was possible. it went out of alignment, and i ended up looking into the darn thing to line it up, and blinded myself for a sec in that eye from the light.. :o what a dope! then i put the stuff away. i started laughing and asked myself "what the heck are you doing" ..then i decided i would leave the optics testing to the people who actually know something about it. it was a moment of laughable stupidity.

im glad this was resolved by people who actually knew about this issue with lense optics right away before any more people started frying their eyes. :P

[TC]

:D

[kplo]

Barry,
Interesting that you should mention aerial image...ever since
I read about the home-built Mini35 thing, I wondered why no one (apparently) has tried an aerial image design. The best "slide to video" transfers I ever had were done using this design...I built one years ago with parts from a surplus store.
A rail assembly would certainly be needed because of the weight, but it seems a viable solution...at least on paper.
Ken

[Guest]

Read above for why it doesnt work for DOF.

[kplo]

Brett,
If you're simply "rephotographing" a projected image, whether it's on ground glass, the wall, or existing in an aerial plane of 35mm film size, the DOF effect of the 35mm lens will be recorded.
Ken

[Guest]

Ken-
I'd love to be proven wrong for this project so please share your source that makes you believe that the DOF will also be maintained. From the real world tests over the years both mine and coutless others this has been unfortunately shown not to be true - unfortunately.

[kplo]

Brett,
DOH! Sorry about that...my old brain was transposing FOV with DOF.
The knees are definitely NOT the first to go. :)
Ken

[cardmaverick]

I know, I know... I'm raising this thread from the dead but...

http://www.abelcine.com/articles/index.php?option=com_content&task=view&id=170&Itemid=45

http://www.abelcine.com/store/product.php?productid=1000394&cat=354&page=1

Apparently this IS possible, DOF, and FOV both retained :)

With that said, I'd like to start up a big discussion on how to actually make one of these.

From what I understand, the majority of this adapter is essentially just a lens to relay the resized aerial image to the cameras CCD's. With conventional ground glass adapters, this relay lens would be the cameras built in lens. According to these sources there are 11 optical elements total, most of which are probably used for resizing the image. So I'm willing to bet that only a few optical elements would be needed if you tried making something like this for a camera with a built in lens.

Anyone wanna experiment and report back?

I recently put a negative magnifying glass up to my eye and then held a 50 mm lens up in front of it. The lens was set to 1ft focus. I positioned my eye about 1 foot away from an object. I then put the lens in front of the magnifying glass and moved it back and fort till the object came into focus. I was then able to successfully pull focus. I don't know how accurate the DOF is yet. At any rate, it looked promising enough to keep on messing around with it.

[Tim Naylor]

I've read that review about the JVC adaptor a while ago. I thought it's too good to be true then two items struck me: it only maintains S-16mm FOV and has a minimum effective aperture of 2.8 (even when your PL lens is wide open). This is hardly the DOF characteristics of a 35mm size imager. Whenever I shoot S-16, I routinely shoot at 2.0 or lower just to get a "cinematic" DOF. 2.8 doesn't cut it. But the JVC shows that an adaptor without a GG is possible. To use the built in lens as part of the relay would be the solution.

quote from review:

"Transmittance

I was slightly disappointed when I determined that the maximum usable aperture of the HZ-CA13U seemed to be T2.8. The documentation states an exit aperture of f/1.4, and after a day of research, I realized that my findings of T2.8 on the lens side are a result of a basic optical imaging law known as the Lagrange invariant. This affects all lens systems in the same way. Using the horizontal frame size values of 16mm (9.35mm), 1/3” CCD (4.8mm), and the exit aperture of f/1.4, I determined mathematically that the max lens aperture is f/2.73.

The bottom line is that using high-speed lenses will have no benefit to exposure or depth of field once they are opened past T2.8. However, if you are used to shooting at open apertures in low-light on your video lens, you will be surprised to find that the equivalent T-stops marked on the ciné lenses all seem to be about 1-1/2 stops brighter than the same video zoom F-stop values. This means that T2.8 on a PL prime lens has an equivalent exposure to about f/1.7 on the video zoom lens. This phenomenon seems to be an added benefit of the optical invariant. The easiest way to manage this is to rate the camera 1-1/2 stops more sensitive than usual. "

[cardmaverick]

Interesting catch there Tim, but I think I remember reading in the review that it wasn't a production model he was testing, but rather a prototype model. Also, this is older material... for what its worth.

I did catch this though..

"We found that the HZ-CA13U has an equivalent angle of view of standard 16mm. The fact that JVC chose a 16mm frame size aerial image will come as a surprise to most because the trend tends to be 35mm for all of the other ciné lens adapters. I was also disappointed when I first read the spec. However, I now realize that this was a calculated move on JVC’s part. There is an abundance of standard PL 16mm lenses available around the world. From film schools to rental houses, it won’t be hard to find a half-decent set of 16mm format primes somewhere in your part of the world. Of course, any PL prime or accessory (35mm or 16mm format) will work with the adapter. "

Apparently this prototype at that time was made for 16mm FOV DOF, but because the mounts are the same, can take 35mm (but not have 35mm FOV and DOF when using 35mm lenses) as well. At least thats how I read it.

Now my big question is this...

Can you make one of these devices designed with a 35mm aerial image instead?

[cardmaverick]

I'm not surprised this adapter makes the camera more sensitive at all... It kinda makes sense really. Ever mess with a magnifying glass and ants on a summer day?

:P

Probably the same general idea going on here.

[Coco Bermudez]

I've been making my own adapters for the longest time...actually they work pretty awesome. I've used them in a couple of commercials and lately in two 48 Hour Film Project films. A couple of my colleagues have the LetUs and the Brevis and Redrock and they are always begging me to make them one...I actually have a LetUs Extreme which I love...but I still think mine rocks.....

Regardless...all this munble just to say one day I was building a couple of prototypes when I had a little revelation that blew me away. While building one i attached the lens to the tube and I looked in the camera and i had the most beautiful clear image. I was so excited because I had been experimenting with GG's. SO I thought I had come up with the Holy Grail of static adapters....the grainless one.

So i get my pencil and notebook just to make notes on the GG I had used. i open the adapter and violá! I had forgotten to put the GG...yet I was getting an image! WHat the heck.

To make the long story short...Somehow I was getting a crystal clear image. I was BLOWN away! Upon further testing of this new adapter I started noticing that the DOF was not as radical as the ones you get with the regular DOF adapters out there...but it is a pretty subtle one.

While looking at the pics on the JVC article the DOF of eminds me of the one I was getting. i assure you that if they had also tested a Redrock or a Bravis the DOF would have been more noticeable. But...hey grainless, motorless, and light loss none existent? Can't beat that.

I do not undesrtand the why's of what is happening...but it does work. I still have it somewhere...maybe I should pull it out and see what the heck is going on...oh yeah and mine has no 11 elements

[cardmaverick]

Nice info Super8. I think all optical 35mm adapters are the wave of the future as long as sub 35mm size chip cameras are around...

FOOTAGE:

http://web.mac.com/timdashwood/iWeb/sundance/HZ-CA13U_Test.html

Yeah, it looks like nice 16mm because thats what the adapter was made to give, and its grain free ;)

I wonder if you can't get more shallow than 16mm though? Just a though. Even if that turns out to be the case, I wouldn't mind 16mm DOF, its better than the cameras native lens and DOF combo... and that whole EXTRA light characteristic is mighty nice too :)

[Dan Vance]

Super8: All GG adapters will pick up an aerial image if the GG is removed. The DOF will be the same as the equivalent focal length of the system. That is, you do not get the benefit of the shallow DOF without the GG.

Other notes:
JVC didn't really "pick" 16mm FOV for their adapter--that's the best that can be done with that technique. There are only two variables that you have to work with when trying to reduce DOF: focal length and f-stop. We already know that no combination of focal lengths gets us anywhere in the DOF battle. So...the way it works, as explained to me by an optical engineer, is that the JVC adapter increases the light thruput by 2.5 stops. The DOF difference between 16mm and 1/3" is 2.5 stops. But of course the hitch is as was mentioned about the JVC--maximum aperture is T2.8! So there goes a lot of shallow DOF capability.

The Angenieux CLA35 works the same way. It gains 2.5 stops. The DOF difference from 35mm to 2/3" is, not coincidentally, 2.5 stops. But of course it also has a maximum aperture limit that also limiits the shallowness of the DOF.

Using this same technique to go from 35mm Cine to 1/3", you would need to gain 4.6 stops, which is pretty much impossible, plus the maximum aperture would come into play again, so the useful DOF would still be limited.

(And the damn image would STILL be upside-down!)

GG is better.

[Coco Bermudez]

Super8: All GG adapters will pick up an aerial image if the GG is removed. The DOF will be the same as the equivalent focal length of the system. That is, you do not get the benefit of the shallow DOF without the GG.



Dan:

I did get DOF...if i had to rate the different DOF's I was getting (and I did the comparisons) with 10 stars being the best and 1 star being the crappiest DOF I would say:

Adapter with GG = 10 stars for DOF
Adapter with no GG = 6 stars for DOF
Stock Lens = 1 Star for DOF

[cardmaverick]

The DOF difference between 16mm and 1/3" is 2.5 stops. But of course the hitch is as was mentioned about the JVC--maximum aperture is T2.8! So there goes a lot of shallow DOF capability.

The Angenieux CLA35 works the same way. It gains 2.5 stops. The DOF difference from 35mm to 2/3" is, not coincidentally, 2.5 stops. But of course it also has a maximum aperture limit that also limiits the shallowness of the DOF.

Using this same technique to go from 35mm Cine to 1/3", you would need to gain 4.6 stops, which is pretty much impossible, plus the maximum aperture would come into play again, so the useful DOF would still be limited.


Just out of curiosity, why are you using the term stop in your explanation. Do you simply mean doubling of sensor size or something to that effect? Sorry, I just don't hear that term outside of the exposure world very often.

Could you elaborate more on this maximum aperture limit? What happens if you open the lens wider than 2.8?

You know, a cool feature for some of the GG adapters could be an easy and fast way to pull the GG out of the optical path inside the adapter. Now you could have two options: 16mm grain free look, or a grainy looking 35mm look. That would be really cool actually.

Thanks

[Luis Caffesse]

Dan:

I did get DOF...if i had to rate the different DOF's I was getting (and I did the comparisons) with 10 stars being the best and 1 star being the crappiest DOF I would say:

Adapter with GG = 10 stars for DOF
Adapter with no GG = 6 stars for DOF
Stock Lens = 1 Star for DOF

When you compared the stock lens to your adapter with no GG did you make certain the stock lens was at an equivalent focal length and field of view?
If so - you shouldn't see any difference in the DOF.

[Car3o]

i brought this up months ago over at dvinfo and here about the GGless solution which i came across with i just attached a lens onto the front of my camera with a achromat.

http://www.dvxuser.com/V6/showthread.php?t=110687

the thread is there with a video you can check out. there's also an optical taper but i can't find the link he provided. the thread is over here

http://dvinfo.net/conf/showthread.php?t=87243&page=2

you quickly find out the dof is there, but on medium close ups which is still nice considering no grain. the bokeh isn't as good as you want it to be or could be with a 35mm adapter.



edit: it only had a link to one of the videos. the first link is my fav of the 2
right click and save as for these please:

http://www.fileden.com/files/2007/1/8/612706/Optical%20Video1.mov
http://www.fileden.com/files/2007/1/8/612706/Optical2.mov

[davide]

Does anyone know how this is supposed to work: http://www.zacuto.com/Zacuto_DOF_Adapter.htm

[cardmaverick]

I've been thinking about this some more... I don't have an adapter to mess with so I can't really even try this but, I wonder what would happen if you switched the GG for just plain old NON ground glass.

It might not do a single thing, but you never know till you try it right?

[cardmaverick]

"Estimated cost of Zacuto DOF system: $12-$15K including 4 Zeiss prime lenses (25, 35, 50 & 85mm), 4 Zacuto Zip gears, 4 Zacuto ZLA's (20, 35,50 & 85mm), 1 Zacuto ZCA (pick camera), 1 Zacuto Lens Support (ZLS), 1 set of 10" rod extensions, Zacuto custom cut foam insert & case. In development."

Just keep saving up for that Red One.....

[thekreative]

I messed with this a while ago when the motor died on my Letus Flip. I thought it was doing something but I got a new motor and forgot about it. Today I pulled the GG again and tested it with a FD 50 1.4 and 28 2.8 and the DOF is less than the GG but still better than the HVX alone. With the plus of no grain at all and the fact that I try to avoid extreme DOF other than FX shots, this might be the way to go. I'll get outside tomorrow and shoot some more. It looks really good in the basement with 2k of light. Seems too simple, am I missing something? I've spend 100's of hours looking at plastics for a static adapter (movie tube) but this seems promising.

I hope there is no math in this class.

[Dan Vance]

Just out of curiosity, why are you using the term stop in your explanation. Do you simply mean doubling of sensor size or something to that effect? Sorry, I just don't hear that term outside of the exposure world very often.

Thanks

I was using the term 'stop' in reference to use in the equations for DOF calculations. For example, a lens set at F4 on a 2/3" camera has a certain DOF. If you have a 1/3" camera and you use a lens that gives the same FOV, then the DOF will be the same as the 2/3" at about F2.4 (2.5 stops open from F4).

To clarify a little more on the No-GG adapters, think of them as a "black box" system. Say for example you put a 20mm lens from a 16mm film camera on the JVC device, set at F2.8. According to the specs, on your 1/3" camera, you see the same FOV that you would see on the 16mm camera, and you have the same DOF as the 16mm camera with that lens.

If that is true (and I'm sure it is, or reasonably close), then you can work backwards from the FOV and DOF and establish exactly what is going on. If the FOV is the same on the 1/3" camera as it was on the 16mm camera, that DEFINES the effective focal length of the black box. In this example, the focal length of the black box is 20/2.5 = 8mm. That is an absolute--it is a function of the imager size and FOV--you can't change it. Now, for this 8mm black box to have the same DOF as the original 20mm lens, the f-number of the SYSTEM has to be 2.5 STOPs wider than the original f-stop, in this case F1.0.

I think maybe that's why no one goes beyond a 2.5 stop conversion, because the limit of any system may well be F1.0. If that's true, then the maximum usable aperture for a 35mm cine to 1/3" camera would be F4.6, which would not be very helpful to achieve shallow DOF.

Regarding "apparent" shallow DOF without GG, careful testing will reveal what we already know from the laws of optics--unless the overall F-number of the system is decreasing as with the JVC and Angenieux, you don't get shallower DOF.

[Bob Gruen]

Brett,
If you're simply rephotographing a projected image, whether it's on ground glass, the wall, or existing in an aerial plane of 35mm film size, the DOF effect of the 35mm lens will be recorded.
Ken


I think what the posters on this thread are missing is the overall purpose of the ground glass: to collapse the many vectors of photons onto a single focal plane.

If you envision the light vectors that go through the center of a lens they tend to be very straight through the lens. If you envision the vector through the edge of a lens the glass does a good bit of bending to get the vector to strike the focal plane in the right place. There are some errors in this bending that can limit the depth of focus, causing bokeh. The more you open the iris the more edge glass you use, the more bending errors are introduced, the more bokeh you get. But until you introduce a focus plane to collapse the vectors to a plane, you are dealing with VECTORS.

The question becomes: what happens to a *desired errant vector* (a photon that adds to bokeh) that is sent through a second lens before being collapsed onto an imager? From the JVC review it would seem that these vectors are further bent (or even refracted away) by the camera's lens to the point of missing the imager entirely. If this were not true than opening the iris on the mounted lens would create a softness on the entire image.

Ground glass lens adapters are a stopgap technology that will be around until larger imager-ed cameras with lens mounts (like the Red One) become more affordable. I am very curious to see what Canon brings out next in its XL line as they have a lens adapter for their SLR lenses that adapts the EOS to the XL mount, replacing the delivered lens.

As far as removing grain, why would you want to? We have been viewing film for 80 years now and grain has always been present. When using the HVX, my personal obsession is reducing noise (color and luma errors) because I know my Micro35 will bring a certain amount of grain (luma deltas) to the image. If I *swing for the fences* in making a feature length film that does not make it to theaters but does make it to DVD retail and rental, I don't want to have to pay to scan in my film print when my computer can output the proper format, complete with film grain a-la Micro35...

Bob

[thekreative]

oh well, tried some more and then put a GG in half the image and you really do need the gg. there is some increase in DOF but the comparison between GG and no GG is huge.
oh well now for my hangover.

[cardmaverick]

As far as removing grain, why would you want to? We have been viewing film for 80 years now and grain has always been present.
Bob

I should be more clear, its both the grain and the sharpness of the image. Projecting onto a GG will always soften the image. You are essentially shooting threw a promist filter really, and I just don't want my image to constantly look soft focus. As for grain, my camera (Andromeda) producers a very very tight low noise (some would say grain free) image, and I want to keep it that way.

[ESTEBEVERDE]

Grain will go the way of the Dodo.

When the average person has 60"1080 120p+ monitors at home (probably within the next 5 years) they will indeed be turned off by the grain. They will be use to Discovery HD et al.

[cardmaverick]

Does anyone know what would or could happen if you tried making an all optical adapter using MEDIUM format lenses instead? Or does it not make any difference?

[ESTEBEVERDE]

I don't have any specifics off hand but I have read on the "internets" there are indeed peoples working on them.

[Ted Ramasola]

This portion of a chart test didnt come from a straight optical but from a gg based adapter. The gg image size were bigger on the mid format at 42mm x24mm compared to the 35mm lens at 29.6mm x 16.6mm.

My point in the test was to campare grain.

I found the difference minimal. I dont know if this would still be the case in a straight optical path.


Ted


http://www.dvxuser6.com/uploaded/6699/1199258371.jpg

[cardmaverick]

The medium format looks much more sharp. Are you sure the FOV is correct? Thats one thing I don't like about these adapter tests... how far should you really be zooming in on the ground glass? Anyhow, I'm sure this affects every adapter test out there in some way or another.

[Ted Ramasola]

I try to capture as much FOV as i could based on the original film image from each lens category, 6 x 4.5cm for the mid format and 36 x 24mm for 35mm. But doing so produces light falloff and corner softness. This is the case with an image travelling from still cam lens to GG to achromat then to cam lens.


The zoom recommended in most adapters is even slightly smaller in image width than what i did. for the 35mm gg image, its wider than the crop factor of a digital SLR. The benefit of the med format is outweight by flexibility and economy.
If grain is compared, at first I was expecting a dramatic difference. But it wasnt the case in my tests.

But then again its an observation based on GG based adapter's image. I dont know about the straight optical path proposition, I read somewhere here that the attached still lenses, wether 35mm or others lose there DOF and the FOV is smaller without GG but it must be clearer and cleaner.

Ted

[cardmaverick]

Do you have two adapters? If so, what are you using for the medium format lenses?

[Ted Ramasola]

Yes, I have two adapters. The mid format lens adapter and one for 35mm.
The one for mid format has a bigger housing due to a bigger gg.
Heres a side by side pic for size comparison.

http://www.dvinfo.net/conf/attachment.php?attachmentid=5329&d=1196749982

[ESTEBEVERDE]

Hoy! Pare!

Kumasta ka na Ted!

Paumahin na ako ay huli sa ibang sinulid.


Your grab from the adapters look nice.

I hope we can get some footage of some of your comparison shots!

[ESTEBEVERDE]

Ted has engineered some pretty nice adapters.

They are really nicely done.

Maybe he has to much hiya (humility) to share so here's the link:

http://www.dvxuser.com/V6/showthread.php?t=118399

[Ted Ramasola]

Great ESTEBEVERDE.

Maligayang bagong taon sa yo at sa iyong pamilya.
(Happy new year to you and your family)

Other than charts theres not much side by side footage between the two. I just posted it here when you and chris were discussin if it would make a difference on grain using mid format lens.

Ive been using the mid format adapter for just around 2 years until its limitation has become apparent to me.

Aside from cost and bulkier in housing size, and less options for different lenses.
Its obvious advantage, bigger gg image thus less grain is not dramatically significant, based in my set up though, so the pros of using the 35mm adapter outweighs the use of mid format.

But for some where the resolution is priority then mid format is an option. The portion of the charts i posted is 100% crop. these are the trumpets near the center bullseye. The mid format resolves the lines up to 600 while the 35 already exhibit aliasing and fusing of lines at a little more than a quarter past 500.

But then in the end, as shooters we look at the overall aesthetic. Composition, balance, lighting, movement. Grain becomes less apparent when the viewer is absorbed by the moving images in its entirety.

[ESTEBEVERDE]

Nice work!


Maraming Salamt for posting those and the accompanying info.
(Thank You Very Much)


Maligayang bagong taon sa yo at sa iyong pamilya rin!
(Happy new year to you and your family too!)