Plans for a DOF adapter

[Jesse Haycraft]

Hello all, this is my first post here at dvinfo.com

I am working out plans for a dof adapter. I'm basing it on this: http://hishamkhalifa.com/?p=75
That last comment on the bottom is me!

The idea is:
1 x 2″ stackable lens tube for 2″/50mm optics (PN: SM2L20)
2 x retaining rings for stackable lens tube (PN: SM2RR)
1 x 50mm ground glass (1500 grit) (PN: DG20-1500)
1 x 50mm plano convex lens (PN: LA1401)
1 x step-up ring 37mm-52mm
1 x 52mm 10x macro close up lens
1 x reverse macro adapter for Pentax lenses

Order of parts from camcorder's lens:
37mm-52mm step-up -> macro close up lens -> lens tube (inside lens tube: ground glass -> plano convex lens, both held by retaining rings on each end) -> reverse macro adapter -> SLR Lens

I have thought, however, that it would be better to use Canon Ee-a/s as the GG. Thorlabs isn't the highest quality. Would I need to put two UV filters on either side to keep out dust? What do you all think?

[Paul Nixon]

I am constantly having a problem not with dust per se, but with flakes of paint from the el cheapo extension tubes. The Canon Ee-A GG is also a dust magnet - it is surprising just how well those little bits of paint and other assorted bits stick to that thing. I am planning on wiping the interior of the tubes with oil or something.

Also, you mention adding a 10x macro lens. I experimented with the macro lens idea (Lensbabies 10x, 37mm) and it was terrible due to color aberration. Perhaps you have a different macro in mind.

I've been posting a lot of various pics of my results - it's been fun and educational, but I'm still not quite "there" yet. Good luck with your project!

[Jesse Haycraft]

Thanks Paul

Are the cheapo extension tubes you are using the Thorlabs tubes I listed? If so, perhaps I could encase the Ee-A in the UV filters before sticking them inside the tube, so the screen itself is always protected from the flecks of paint you spoke of. Then I would screw in the retaining rings on either side to keep it all together.

Whadaya think?

[Paul Nixon]

Originally Posted by Jesse Haycraft

Thanks Paul

Are the cheapo extension tubes you are using the Thorlabs tubes I listed? If so, perhaps I could encase the Ee-A in the UV filters before sticking them inside the tube, so the screen itself is always protected from the flecks of paint you spoke of. Then I would screw in the retaining rings on either side to keep it all together.

Whadaya think?

My tubes are the bargain basement "Asian" Canon-type from Ebay.

Encasing the GG between UV filters is highly recommended for a number of reasons.

Be very sure of controlling the distance from the lens back to the focus screen and the squareness. It has to be as exact as possible.

Also, if you haven't already, take a look at: http://www.jetsetmodels.info/tutorials.htm

There is loads of information there that even if it doesn't directly apply, it is likely to be useful/helpful in some way. Good luck.

[Jesse Haycraft]

Thanks Paul!

Now... On to 35mm goodness...

[Stephen King]

How do you determine the correct/optimum distance between the GG and the camcorder lens? what is the procedure taking into account changing the distance vs. ability to zoom in on the gg?

[Chris Barcellos]

Originally Posted by Stephen King

How do you determine the correct/optimum distance between the GG and the camcorder lens? what is the procedure taking into account changing the distance vs. ability to zoom in on the gg?

Trial and error. Start by trying to focus your camera inside the frame of a 35mm negative. If you can do that, you are almost there, but will even have to so a little more zooming andfocusing to avoid vignetting. You do that by adding achromats, and adjusting distance between the target and the camera/achromat combination. If you are lucky you camera will not need achromat.