My Adapter TEST and A Couple of Questions.

Polanski

Polanski

Well-known member
I put together some time ago an adapter whose result I'm not satisified with yet.
Here the result:

Frame.jpg


I'm using a mamiya 50mm lens and the frosted back of a CD box as a spinning GG.

Here is a diagram with the questions that I want to ask.

35MM.jpg


Any comment will be highly appreciated...
 
You may want to try actually using true Ground Glass. Glass is the only way really. I dunno how well plastic frosted CD casing will work. That's probably where the problem is.
 
Yes, I have a GG that I bought from Redmicro which is the one I'm going to use in the final project.
 
I think that might work better for you. It seems like nowadays the achromat buts right up to the Camera. So I dunno about spacing there my friend.
 
Have you focused to infinity? It really depends on your lens on how far you need to set your GG from lens.

Here is a website I dug out to find out how far your lens mount has to be from the GG.

http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html

Also, the question about your Achromat depends on the FL of the achromat. You have to have it practically against your camera lens and a certain distance from your GG as well. Say a +7 Achromat should be at least 5inches from the GG. Give or take. Should be the sharpest around there.
 
Hi, the distance from the distance to the GG is called Flange Focal Distance, if is off you will notice it for example because you will have to re-focus everytime you change, let´s say from 80mm to 200mm with a zoom lens. Every manufacturer of lenses has a different FFD "published"... With a spinner adapter like yours, you will have to open it, change the distance and see if it is better or worse, and then doing it again carefully until u get it right. Or you could try to buy one of the lens mounts with backfocus adjustment like Letus has, and try to make it work.

About the achromat, yes, the closer the better. You want to get the center of the achromat, not the edges where most of the distortion is. And the distance to the GG depends on the achromat you have, do some tests and try to get the sharpest and rid of the vignette.

My 2 cents.

Cheers...
 
I'm planning to use Nikon lenses. I measured the distance between the lens and the film in a Nikon 35mm film camera and is approximately 46mm. Then if I place the GG at that distance from the lens I'll have everything in focus when I set the lens to infinite. Is that right?
 
Thank you Ted.
0.5 is half of a millimeter? that's really hard to do.

BTW, how's your new adapter working?
 
Last edited:
yes, it half a millimeter.

The second version adapter works fine polanski, heres a finished job:

http://www.vimeo.com/1229221

All nikon lens and nikon compatible sigmas.

Are you still using the mamiya lens you mentioned? or will you go with 35mm nikon. The mamiya mid format has a different flange distance. its longer at 63.3mm.

This is a sample of a work i did combining mamiya and 35mm. The shots with mamiya are those with excessive CA. NOT caused by the lens though but by the wrong achromat combination.

http://www.vimeo.com/1142585


Good luck in your project. feel free to PM me or email if you need more information.

Ted
 
Great job, Ted. You're a professional DP. I love all the takes and the editing is excellent.
When I start putting things together I'll PM you.
I'm not going to use the mamiya lens any longer. I'll buy some nikon and compatible sigmas lenses.
I'll be in touch.
 
No. but if you intend to make a hybrid, you can have a mamiya mount made to go on the nikon mount.

The flange depth of the mamiya at 63.3mm will allow you a play distance of 16.8 mm. this is the add on distance or depth for your mamiya to nikon adapter.
 
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