Cinemascope for DVX

Re: Cinemascope for DVX

Good point about the grain size limiting resolution. I had not thought of that.

Yeah but you wouldn't need to go through and edit every frame individually (static adapter design). You could attach the adapter to your camera and then point the whole system at a light source (or perhaps a light source reflected off of flat white surface?) so the only thing visible is the glass and its imperfections (to the video camera). Shoot a few seconds then pull out a single frame (would work best with a progressive scan camera), invert it, desaturate it and subtract it from the main footage. Since the grain is static this could be applied to entire clips.

Is this what you were thinking of? I wasn't meaning to suggest we shoud go through and manually edit every single frame!
 
Re: Cinemascope for DVX

Shaw-
I understand what your saying but I dont think this process will work very well. GG, static, diffuses light and the grain in the glass will appear different under each lighting condition.

As far as the medium format lens thing. Thats what my DOF adapter design is based on. Yes the medium format lenses are slower but in my opinion you make that up in the fact that you dont have to zoom in on the DVX lens and loose stops on that side. Not to mention the increase in quality due to much smaller grain and diffused characteristics. Not to mention the quality loss you get from using most diopters. You wouldnt need one with a medium format adapter and hey you can always make it work with 35mm lens as well. The GG is more than big enough to except it.

-Brett Erskine
 
Re: Cinemascope for DVX

Excellent point about the lighting conditions. I'm going to give it a try though and see what I come up with. Can't hurt to give it a shot I suppose.

That does bring up an entirely different question though about noise. Do prosumer cameras do anything to filter out dark noise etc? I'm just curious as to the cause of so much grain in the DVX. If there were a way to remove this intelligently...

Are you saying that you don't have to zoom in at all with your medium format lens?! Do you have more specifics on your design that you could provide (unless you are in the manufacturing and selling business). What are you using as your diffusion surface? GG? focus screen? Wax disc? I'd love to see some footage or screen grabs if you have a completed system!

On a related note: if, by chance, I just happened to run across a Carl Zeiss f2 80mm lens for several hundred dollars would I be an idiot not to buy it?
 
Re: Cinemascope for DVX

One more question if I may :)

How fast of lenses are you using and what specific medium format? 6x4.5, 6x6, 6x7? That would, of course, make a rather significant difference in image size.
 
Re: Cinemascope for DVX

I would think that 645 lenses would be best for this situation. The aspect ratio is very similar and there are lots of Pentax 645 lenses available that are quite reasonable in price. Check out http://www.keh.com for some great prices on older manual focus lenses.
 
Re: Cinemascope for DVX

Thanks a bunch scharky. I've never dealt with medium format photography before so these tips are all great :)
 
Re: Cinemascope for DVX

Yep. I also recomend using 645 lenses for the same reasons.

When it comes to what lens to buy the question to ask yourself is what kind of videography do yo usually do. If its alittle of everything, do run and gun shooting and dont run into low light situations too often then get a zoom for sure but if are always fighting low light or doing multi take work where you have time to change lenses for each shot then get a small set of primes. At minimum a wide, medium and portrait lens would be nice to have. Have these three primes and the zoom would be the best though. Its all about what you want to shoot.

Well as far as GG I was originally using a special focusing screen that I had custom made for me but it ended up not working for a oscillating movement because the lens and GG were one piece. I'm now trying to do the same thing but with three pieces. Two field lenses that are static and the GG which moves. If we decide to go down the same design path then perhaps we can work together. It would definately help if you used that software on this project. I can give you all of the specs and hopefully the software will be able to give us the right focal lengths for the two field lenses. Does it do multiple elements and achromats? Let me know if your interested.
 
Re: Cinemascope for DVX

I'm mostly going to be needing the best low light performance possible. I'm doing stuff where I have a decent amount of time to set up but I'm mostly shooting out doors under forested canopy which makes the situation quite variable and high contrast. So I'm probably going to buy a 50mm and possibly an 80mm. The only reason I ask about the 80mm is because it's faster than any other lens I have seen at this price point.

The custom GG job you had done sounds interesting. How did it work exactly? What type of lens was it built into?

What is your current design looking like? I'm not sure if I am going to go for an oscillating adapter but in either case I will need to do precisely everything you mention with regard to the lenses so I'd be most happy to work with you. The software can do most anything - the limiting factor is me at the moment. What you describe sounds easy enough though and I have several experienced users I can ask if I need to do something that's beyond me.

You can e-mail me specs if you would like.
 
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Re: Cinemascope for DVX

Oh, Brett,

Where do you find medium format mounts for use in these sorts of systems? Do t-mounts work with medium format lenses? I'm just not sure how I would go about connecting this lens to anything I build. With 35mm it was easy - just use a nikon f-mount (for me at least).
 
Re: Cinemascope for DVX

Pull it from a extension tube or junk camera body.

The GG was focusing screen with a custom focal length. As far as all the details of my current design I think we should exchange phone numbers via email rather than write a book here. When its done I'll post pics and details for everyone.
 
Re: Cinemascope for DVX

Brett,

Sounds good to me. Your email is hidden though so I cannot send you an email.
 
Re: Cinemascope for DVX

Does anyone here know the exact dimensions of the image produced by a 645 lens? I need the information to help me design my adapter as I want to anamorphically squeeze the image. I'm just not sure if that will make the image small enough that I will have to zoom in and/or use a diopter.
 
Re: Cinemascope for DVX

Shaw, do you mean that 6cm x 4.5cm is not accurate enough for your purposes? I would suspect that the aperture in the camera is quite close and that and all the lenses produce an image at least equal to that diagonal-- if fact some of the longer lenses used to be the same as their 6x7 lenses but mounted for the 645 camera.

Bill Turner
Century Division
Schneider Optics
 
Re: Cinemascope for DVX

Bill,

Thanks for the info. I just wasn't sure if the numbers refered to mm or cm.
 
Re: Cinemascope for DVX

And yet another question!

Am I correct in assuming that the ratio is to be read with height then width? If so would it be possible to mount this lens sideways and get a larger image horizontally? I'm curious because the adapter I want to make needs to compress the image horizontally by at least a factor of 1.5 and to do that with the 4.5 side would make the use of MF lenses pointless for my purposes.
 
Re: Cinemascope for DVX

Shaw-
6 wide 4.5 high. But it could be the other way as well. You know it doesnt really matter because just about all lenses produce a image on the GG that is round. Its within that circle that the camera crops its 35mm or 645 aspect ratio square image.
 
Re: Cinemascope for DVX

how long do you think it's gonna take you to come up with a working resolution chart tested prototype? I'm interested to see where this goes.
 
Re: Cinemascope for DVX

Brett, Thank you! I feel like an idiot! It seems I have been thinking too hard and not stepping back to see the whole picture!

So what is the diameter of the image from a 645 lens? That would be most helpful to me at the moment.

Nick, I'm not entirely sure. It depends on how quickly I can get all the parts together so building can begin.
 
Re: Cinemascope for DVX

Oh a few more things :)

Nick - should have a working version done around new years.

does anyone know of a relatively easy test to measure the light tranmittance of the completed system? I need to know exactly how much light I am loosing and whether it conforms to my design expectations.
 
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