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Dougyfresh13

Dougyfresh13

Active member
i am currently making the HD 35mm adapter and i am having a bit of trouble. in the original tutorial it says to focus the lens at infinity and then sand down the pvc until the lens focuses on infinity. it also says that it ends up being around 1-2mm that u have to shave off and the pvc should end up being around 40-42mm in height. the problem is i keep sanding it and sanding it and its not changing anything i was wondering if some one who ahs made this 35mm adapter has any insight into what i am doing wrong thanks.
 
I'm not sure what you are saying. Do you mean that when you sand, the length of the PVC pipe doesn't get smaller? or it does get smaller but you still don't get a sharp image on the Ground glass?

What you are trying to do is space the gg the correct distance back from the 35mm lense flange so that when the 35mm lens is focused at infinity, the image will be in focus on the ground glass. The PVC pipe is used as a spacer to position the gg at the correct distance. The exact distance depends on the type of 35mm lens you are using. Each type of lens (Nikon, Canon, M42 mount) requires a different distance.

You can get a rough idea of that distance by moving the gg back and forth behind the 35mm lens you will be using, and then cutting the pvc a slight bit longer than that distance. Then place the pvc in your extension tube and the gg holder in back of that. If the image on the gg is in focus, great. That's where you want to place the gg holder.

If the gg holder needs to be moved in towards the 35mm lens, then shorten the PVC by sanding the end to make it shorter until it is at the correct distance. If it needs to be moved further out, then you've cut the PVC too short and you either have to start over, or lengthen it slightly using gaskets or some other material.

Remember, the PVC is used as a tool to support the gg holder at the correct distance so you can more easily permanently attach the gg holder to the extension tube (using JB Weld or hot glue). I believe you can take out the PVC and discard it once you have permanently attached the gg holder in your extension tube.
 
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