Confused about lensless photography and 4x5 camera

[SMBooth]

Q1 Almost
Q2 I have a swappable pinhole with a 4mm hole, i use that to see on ground glass
Q3 Focus is constant, everything in view is in focus, just soft.

[Andrew Plume]

check out any stuff written (or on) Tom Persinger

and also

http://phototechmag.com/tom-persinge...cess-workbook/

andrew

[xkaes]

I've got some info on my pinholes at www.subclub.org/fujinon or www.subclub.org/fujinon/index.htm

Check out the bottom of the MY GEAR page. You might be surprised at how small the pinholes are and how long an exposure you need!

There is also some info on how to attach the pinholes to your shutter. I'm still working out how to get my filters attached at the same time.

[xkaes]

There are "companies" that make pinholes cut with lasers in flat aluminum sheets. They tell you what the size of the hole is, such as .025". Then you can figure out the optimal focal length and the f-stop. Then all you need is a ruler to measure the bellows extension. You can use a hand-held meter but you will have to do some calculating since most meters don't go to f455. I have a set of about eight but I don't recall the name of the place where I got them. I'm sure an internet search would reveal it. Still you have to figure out a way to attached these to your shutter.

[pdh]

If you're the sort of person who likes reading books rather than internetting, http://www.amazon.com/Pinhole-Photog.../dp/0240810473 is a bit of a "classic" resource. Some of examples of the inventiveness of lensless photography are rather breathtaking.

[photonsoup]

Sadly f295 is no longer being maintained and presumably will die away, however people are still managing to post there. It is still possible to access the site and its marvelous archive.

If you go to archive.org you can use the " wayback machine" function to view a website how looked at a particular time. Thus the archive should still be viewable even after the actual site is long gone.

[StoneNYC]

There are "companies" that make pinholes cut with lasers in flat aluminum sheets. They tell you what the size of the hole is, such as .025". Then you can figure out the optimal focal length and the f-stop. Then all you need is a ruler to measure the bellows extension. You can use a hand-held meter but you will have to do some calculating since most meters don't go to f455. I have a set of about eight but I don't recall the name of the place where I got them. I'm sure an internet search would reveal it. Still you have to figure out a way to attached these to your shutter.

+1

In addition, you have to understand "pinhole" is often smaller than a pinhole, the two holes you made were too big for 4x5.

I built an 11x14 pinhole with a 400mm bellows draw using the optimal pinhole size which was the smallest regularly available needle.

Most people don't know that the needle sizes for sewing needles are usually actually the mm of the needle, I think they call it mn for "Metric Number" or something, it goes back to when they were sorting out Singer's use of the American sizing from the European sizing. But that's how you find the needle size if you don't own a laser...

Anyway, at 4x5 the hole you need is MUCH smaller than any regularly available needle diameters, so getting a laser cut one would make a lot of sense.

You can essentially use any size pinhole but you're going to get the best results by using the appropriate bellows draw with the appropriate pinhole size for best sharpness. The light waves have to all line up properly.

There are a few sites that help you calculate it, and some that probably have a "calculator" for it. There doesn't seem to be an app for actually calculating the bellows draw/pinhole ratio but once it's built there are a few apps for exposure calculation but before you buy into those, look at the "reciprocity timer" app, it's really good and the basic package before the upgrades is pretty much all you need. It's a great app and a member here created it.

That's what I use for all my long exposure work.

That's the other thing, these are long exposures if you're using the proper pinhole size for optimal sharpness you shouldn't need a "shutter" except a piece of tape, your exposures are going to be in the 30 seconds to 30 minute range. Not like 2 seconds where you have to worry about a shutter.

You CAN use wider aperture sizes that would expose faster, but then the image wouldn't be very sharp.

Again don't forget about the reciprocity factor, a 30 second metered exposure on most films would be a lot more when you add in reciprocity, hence using that app I mentioned.

Anyway good luck, hope that helped a bit.

~Stone

[vinny]

Stone means "a lot more"

[StoneNYC]

Stone means "a lot more"

Thanks, I edited that, glad you caught it, yes a lot more.

[tonyowen]

Still you have to figure out a way to attached these to your shutter.

Pin hole photography means exposure of many seconds BEFORE taking into account reciprocal failure.
[exposure meter reading of 1/15s @ f16 - equates to 16s exposure for a f254 pin hole, plus a (circa) 10x addition for reciprocal failure -> totals 2m 8s exposure]
So why do you need a shutter and hence the problems of attaching the pin hole to the shutter?
Simplicity means a blank lens panel with suitable sized central hole over which, or into which, the pin hole (plate) is secured.
Exposure is by withdrawing and replacing the DDS, and/or using a cloth over the entire front standard, before and after exposure takes place.
regards

Tony