Pinhole Pentax

[pbromaghin]

My dear old Pentax ME Super has lost it's light meter and has been sitting on the shelf looking forlorn and lost for a couple of years. But today I came across this:

http://www.pinholeresource.com/shop/shop?page=shop.browse&category_id=14

Toward the bottom there's one for Pentax K mount. I've never done pinhole photography, but it looks fun. Does anybody know how these caps work? It sure would be nice to use to start using the Super again.

 

[lxdude]

Sounds like fun! They drill a hole in a standard body cap, then cover the hole with a piece of thin metal with a pinhole drilled in it. No lens needed- the pinhole forms the image.

45mm focal length, f/181.
I'd say the winder won't be needed.

 

[average-guy]

about a year ago I took a spare body cap and drilled a hole in it, then used foil/electrical tape and experimented with different sized holes and ended up with some neat pic's. It was a lot cheaper than 45 bucks. I did this with a Pentax digital SLR which was nice because I got immediate feedback on the effect I got with different sized holes and shutter speeds. I misplaced that particular body cap earlier this year, but it can be made form any body cap as long as it's designed for your particular lens mount, It's cheap fun.

Edit: Since this is an analog forum, I used the digital with my homemade body cap to get approximate hole size/shutter speeds at different iso values so I could use them as a starting point on my Pentax film pinhole photography (wink, wink).

 

[pbromaghin]

Hmm. Home built... I don't really like a lot of home built pictures I've seen - the main problem probably being imprecision in the hole causing excessive softness. I thought this product might get around that. But then again, Denver Camera Exchange has a whole bin full of spare caps. It shouldn't be too hard to find somebody to laser drill a hole in a piece of soda can. Average, you might be on to something. Either that or your on something.

My original question was meant more along the lines of "I'm thinking that to use this I would replace the existing cap, put it on bulb setting with a cable release and use the mirror as the shutter." Does that sound right?

 

[nhemann]

its really not hard to make a nice sharp pinhole if you have one of these start the hole with a pin over something sort of soft - like phone book so that you can get an actual depression or even small hole - and then start to rub it on the plate (wet to lubricate it)you can start to widen the hole up with the needle, a little more pressure and the plate. when you are done, burnish the edges of the hole by just twisting the metal on the end of the needle.

I have one those caps for my Minolta and its decent - the price a little hi but not that bad and it gets you going immediately - though I found I can get sharper stuff with my own if I take the time with it.

In fact, I took (there was a url link here which no longer exists), (there was a url link here which no longer exists) [/URL], this and this with that pre-made cap.

 

[Klainmeister]

I took an old beer can, cut out a piece, sanded it thin, used a needle to poke the whole, and finally used my scanner to derive the actual hole size and therefore the f#.

Sharp as a tack. Homebuilt stuff can be just as good.

 

[pbromaghin]

This is getting good.

nhemann - I have one of these: http://www.amazon.com/Japanese-Professional-Knife-Sharpening-Sharpener/dp/B000UZET0M It would probably work.

 

[nhemann]

oh yeah - just as good. I mentioned the small ones only because most people don't have such nice stones.

also that avatar pic of me over to the left was taken with that ready-made cap.

 

[pbromaghin]

Klainmeister - how did you measure the hole once you scanned it? I would assume you knew the enlargement and did some arithmetic, but how did you know the enlargement factor?

 

[nhemann]

scan it at the highest possible resolution you can (mine is like 2000 dpi) enlarge that image in a graphics program - Gimp is free - and then select it with a circle tool to tell you how many pixels wide it is. Multiply: number of pixels * inches-per-pixel and voila - pinhole diameter!

I remeasured mine with a microscope once and the method was pretty damned accurate.

 

[Klainmeister]

scan it at the highest possible resolution you can (mine is like 2000 dpi) enlarge that image in a graphics program - Gimp is free - and then select it with a circle tool to tell you how many pixels wide it is. Multiply: number of pixels * inches-per-pixel and voila - pinhole diameter!

I remeasured mine with a microscope once and the method was pretty damned accurate.

What he said!

 

[pbromaghin]

Hey, thank you guys. This is going to be a cool little project. Cheap, and even easy with your help. This camera was the first luxury purchase my wife and I made in 1982 after I got my first real job out of college. It pains me to see it doing nothing on the shelf and using it this way makes a virtue of the dead light meter.

 

[pbromaghin]

One more thing.

To get the focal length, do I just measure from the film pressure plate to the outside-front edge of the body where the cap will be?

 

[Klainmeister]

Yes.

 

[RalphLambrecht]

My dear old Pentax ME Super has lost it's light meter and has been sitting on the shelf looking forlorn and lost for a couple of years. But today I came across this:

http://www.pinholeresource.com/shop/shop?page=shop.browse&category_id=14

Toward the bottom there's one for Pentax K mount. I've never done pinhole photography, but it looks fun. Does anybody know how these caps work? It sure would be nice to use to start using the Super again.

i made one ,yself for my nikons.yes, they work

 

[Jim Jones]

This is getting good.

nhemann - I have one of these: http://www.amazon.com/Japanese-Professional-Knife-Sharpening-Sharpener/dp/B000UZET0M It would probably work.

I brought a similar, but much smaller (and cheaper) stone back from Japan years ago. It's the best of many methods I've tried for making pinholes.

 

[RalphLambrecht]

scan it at the highest possible resolution you can (mine is like 2000 dpi) enlarge that image in a graphics program - Gimp is free - and then select it with a circle tool to tell you how many pixels wide it is. Multiply: number of pixels * inches-per-pixel and voila - pinhole diameter!

I remeasured mine with a microscope once and the method was pretty damned accurate.

this is my take on it;

 

[RalphLambrecht]

would a slide projector or an enlarger work?

 

[Peltigera]

I have been practising this with my Canon EOS. I tried using my extension tubes with the body cap on the end and it works like a telephoto pinhole.

 

[Lowenburg]

I've made a pinhole from a Nikon 35mm body by taking the backing paper from 120 film, taping it over the lens opening in the body and punching a hole in it with a pin. I used 400 speed film and made exposures of 2-5 seconds in sunlight and it worked. Body caps work fine too if you happen to have one, but if not, improvise -- it's more fun experimenting anyway. Have a good time!