DIY Zone plate (help needed)

[radiant]

I was thinking of trying zone plate photography with my 5x7" view finder camera.

However the manufacturing of zone plate starts to become a bit tricky because I didn't first comprehend that the dimensions are really small in zone plate.

I was thinking of making 210mm focal length plate. In that case the first "hole" radius is 0.48mm and last ring radius is 0.96mm. Pretty small, wow.

Then I was thinking of photographing print or computer screen on 35mm film and use that as zone plate. I drawed the circles with cad and framed with 35mm frame size which gave a reference how small the zone plate actually is. And I think it is impossible to photograph this kind of size from any media? Below is a 35mm frame with my design:

Are my calculations correct or what I am missing here? Many sites suggest using film to manufacture the plate but I cannot understand how.

Any ideas or experiences here?

 

[Donald Qualls]

Assuming it's printed (at maximum resolution) on something like 8 1/2 x11 or A4 paper, it shouldn't be a big problem to photograph that to fill a 35mm frame. For my 1970s vintage equipment, the shortest macro ring I own with a 50mm lens ought to be about right. You might save yourself some effort and frustration if you print the zone rings in black on a while background; that way, you can use the negative directly for your zone plate rather than having to make a duplicate positive.

You'll want to use a film that has a very high Dmax and high resolution -- resolution sounds like it points toward microfilm stock or other monodispersed film like CMS 20 II, but high Dmax might put you more in the range of Lomography Babylon 13 or Ilford Ortho 80, both of which should have plenty of resolution. You'll probably also want to use "push" development, to increase Dmax as far as possible.

 

[Dan Fromm]

According to https://web.archive.org/web/20130123085418/http://pinhole.stanford.edu/, the trick is to print the circles @ 25x size needed, photograph and reduce in printing. He gives details and a downloadable set of rings for 200 mm, among others.

 

[radiant]

Thanks @Donald Qualls and @Dan Fromm - now I get it! In the page Dan linked was ready-made 25x PDFs which helps me a lot.

Do you guys think Tmax 400 would be waste of time to use on this? It has quite good resolution and Dmax should be good too? Or should I just wait and order Ortho 80 ?

 

[Donald Qualls]

You could try the TMY you have -- the beauty of having the PDFs and the printed original is that you can make more film copies any time you like. As noted above, you'll get highest contrast with lith film in a lith developer, but that's starting to be a lot of money for a zone plate, even compared to just ordering one.

 

[Jim Jones]

High contrast and high resolution film such as litho film seems like the most practical say to fabricate a zone plate. In the good old days I would have used Kodak Tech Pan film developed in Dektol to photograph a conveniently large template of a zone plate, but my darkroom is long gone. http://www.mrpinhole.com/zp.php has a zone plate generator that I've never tried. Many technical photographic books have large versions that can be copied. I did a quick Yahoo search but didn't find a good image to download. There is a fairly small image of one, but probably good enough, in Pinhole Photography: Rediscovering a Historic Technique, by Eric Renner. The excellent Way Beyond Monochrome by Ralph Lambrecht and Chris Woodhouse has a somewhat larger one. You only have to have one large original that can be scaled down to the right size for any focal length zone plate.

 

[radiant]

Maybe I just attach the PDFs here so they are not lost..

 

[radiant]

The excellent Way Beyond Monochrome by Ralph Lambrecht and Chris Woodhouse has a somewhat larger one.

.. wait what? (reaches this book which is located 50cm from me) - this is not the first time I learn that something is in this book and I haven't noticed it yet!

 

[ic-racer]

And I think it is impossible to photograph this kind of size from any media?

Not sure I understand the issue. Winogrand showed "All things are photographable."

 

[Luckless]

.. wait what? (reaches this book which is located 50cm from me) - this is not the first time I learn that something is in this book and I haven't noticed it yet!

Wait till you 'learn something' from a technical manual... That you wrote...

 

[GRHazelton]

For those like me who didn't know what "zone plate photography" is, here is a link: https://photo.stackexchange.com/questions/11552/what-is-a-zone-plate