Pinhole macro (does this count as a "Lens" question?!)

[Sharon]

Hi all,

Thanks very much for your replies--a lot to think about . I've seen some information that talks about optimising pinholes for a particular focal length and also some different information that talks about optimising pinholes for the pinhole-to-subject distance, which is why I was asking real people with real experience if it is possible, or rather perhaps scientifically meaningful, to optimise a pinhole for a particular distance (either as a stand-alone question or in addition to being optimised for a focal length). Light will of course be an issue, but my plan is to bring along a sketch pad and pencils, or a good book, or some music to practice, to pass the time during hour-long exposures .

In the meantime, thank you for links to websites and calculators, and I have a plan brewing to see if I can do some experimentation digitally.

Thanks again,
Sharon

[mdarnton]

You might find this site more useful:
http://www.f295.org/main/forum.php

[Sharon]

Hi again all,

Thanks again for your suggestions and pointing me toward some very useful links. I've surprised myself with some success! I bought a set of pinholes from pinholeresource.com and mounted a couple of them on lensboards, then used them with our 4x5 Arca. I tried two setups, one at a focal length of about 200mm and one at about 400mm. In bright sunlight (through the window) I got reasonable exposure times (5-30 min, though as you can see, if I've attached the files correctly, I still had some under-exposure with one setup). Particularly with the 400mm focal length, I was getting good magnification of around 5x--not pin-sharp, of course, but I'm really interested in being able to see detail (which I can) rather than maximising sharpness.



I'm keen to try getting closer in with the 400mm focal length, but I'm finding that as I move it closer to the subject, the large camera throws a lot of shadow on the subject, pushing the exposure times to the ridiculous. We have some ideas about how to combat this--namely, constructing a tapered camera (we're thinking of adapting a traffic cone, for starters ) and learning how to use a flash.

Anyway, thanks again--I'm pleasantly surprised that I seem to be getting somewhere! If anyone is interested in updates, let me know and I can keep posting .

Best wishes,
Sharon

[Tin Can]

Cool keep posting results!

Your posts sent me to strange pinhole lands. Such as Electron Microscopes that use Pinhole, LF film and Gas Burst Development.

[stawastawa]

Yes keep updating!

[Sharon]

Well, I've built myself a camera out of our old Arca 4x5 rear standard and a traffic cone...photos attached. I'm getting upwards of 20x magnification with good detail, I think (using FP4 and a flash).



Next steps are getting rid of internal reflection in the camera and seeing how far back I can move it from my subject while still getting good detail (because the fewer times I need to change the pinhole size, probably the better). Also probably moving to HP5 rather than FP4 so I don't need quite so many passes with the flash, but we'll see...

Thanks for your interest !

Sharon