8x10 pinhole diameter formula, esp. for closeup?

[hendrik faure]

for lensboard- pinhole on 8x10 camera: is there a formula showing best pinhole diameter for closeup- pictures with variabel bellow extension?
My photographs are very unsharp at low distance (1 to 10 inch). Do I touch there optical borders?
who drills or lasers pinholes in metal plates on order?
thank you very much
hendrik

[Tin Can]

Try this site. http://www.mrpinhole.com/

I buy laser cut metal pinholes on eBay.

[Dan Fromm]

What magnifications are you working at? What extensions? What size is your pinhole? How are you lighting our subjects? How long are your exposures?

[Greg]

From Micro Mark or at a good hobby store, you can pick up a set of 20 bits in a plastic index case for under $20.00.Bit sizes are from #61 (0.039") down to #80 (0.0135"). Also pick up a swivel head pin vice for around $10.00. For metal I used 1"x1" pieces of aluminum from a soda can. Believe it or not but some makes of soda cans make better pinholes than others. I would drill my pinholes with the 1"x1" piece of aluminum taped to a piece of foam core. Also drill the pinholes on a clean desk... If you drop one of the bits onto a rug, you will most probably never find the bit, trust me on that one. I have drilled and donated hundreds of pinholes to local Photo classes over the years. Once you get the set of bits and the pin vice, from then on the pinholes will cost you way less than a penny each. A few times I was able to compare laser drilled pinholes to pinholes I had made as per the above instructions and there was no difference in the resulting imagery. You can easily find a chart of ideal pinhole sizes on the WEB.

[Jim Jones]

Page 3 of this link http://www.huecandela.com/hue-x/pin-...%20Wellman.pdf gives a formula for macro pinhole photography. A calculator for determining macro pinhole size is at http://pinhole.stanford.edu/phcalc3.htm.

[Barry Kirsten]

Sorry Hendrik, I offered you this answer earlier, but on the wrong thread:

There is a book by Renner referenced in this excellent article by Brian Young here: http://www.alternativephotography.co...h-really-said/ I haven't read it, but it, but it might be helpful. I find the web a great place for finding pinhole info. In general for close up work you need a small pinhole because each diameter of pinhole has a limit for close focus at a given film-pinhole distance. There are no hard and fast rules, so you might like to start experimenting with a pinhole of 0.2mm at a lens-pinhole distance depending on your camera. This should provide very close focus. For pinhole supplies there is Lennox Laser, https://lenoxlaser.com/ Also a man named Earl who used to be on f295, but I don't have contact details for him at present. He sold laser drilled electron microscope apertures which are just perfect for pinhole. James at http://www.aupremierplan.fr/ sells Earl's apertures already mounted.

[hendrik faure]

thank you all for valuable advice, saving a lot of time!
I posed an example of closeup pinhole in alternative technik
Dan, I never note anything (except when etching copperplates). So I cannot answer questions, but I posted examples in "pictures of mistake". They were made with an industrial ("Ilford") 8x10 inch pinhole camera
hendrik