Hi Bert and everyone,
I've finished building a prototype of a new 5x7" camera ( 114mm focal length ), and learned quite a lot in the process. However, it is a convertible lensed and/or pinhole camera, so I'm not sure this is the place to talk about it. Much of what I learned so far had to do with the lens and getting it focused properly. I'll post some thoughts about it here if people are interested.
One of the things that happened along the way was that it is faster than I expected, even with a 2mm aperture. This got me to thinking about how small the aperture can get before it's something like a pinhole camera with a lens stuck over the pinhole. If I go down to 1mm, which should bring it into "hat trick" speed range, then it's just over twice the diameter of an "optimal" pinhole! I've designed the camera so that the apertures and/or pinhole slips behind the lens on a removable lens board... the idea was to remove the lens when using a pinhole, but there's nothing to prevent it being used in "lensed pinhole" mode, whatever that means!
Next step for me is to build a sliding shutter like I use for pinhole cameras, so that I can even do the "hat trick"... I'm not nimble enough to take the lens cap on and off without shaking the camera too much!
Do you have pictures of your design?
I don't have any pictures yet, but I'll make some. Building the prototype out of cardboard was a good idea because I've discovered several things to do differently! I should have realized the aperture situation would be a problem. When I use my old cameras for paper negatives, I use a yellow filter ( w/ pre-flashed MGIV ) and then stop down to get to exposures of 1 to 3 seconds ( iso about 3 ). If I don't use the yellow filter, then I open up to shoot at 1/25 ( iso around 12 ). Without a shutter, I don't have the same flexibility.
I spent most of today working on a new but still "prototype" version of the same camera made out of cut double-black mat board. The paper holder is a sandwich of two mat boards with a window cut out of one.. like you would make for a frame -- I made the window 4 x 6.5 inches centered on the 5x7 paper, which is a format I like. That part is working great, and it seems to be a good idea. The back area sticks up 1 inch and the lid fits over that and there is a baffle for light. There is a storage area behind the window for exposed and unexposed paper, and there is a fitted lid to access and change paper. The back is lower than the piece with the window, which makes putting the paper in easy and smooth and I think it could be done in my changing bag easily enough. BUT... I've gotten very frustrated with the rest of it... I think my design is too complicated. I have a bunch of 4x4" pieces of mat board cut and was going to fashion a lens board, with aperture stops behind that and a simple shutter ( like I use on some other pinhole cameras ) behind that. All of them were to be held in place by four bolts and wing nuts... I got as far as drilling the holes for the bolts on my drill press when I realized I can't reach inside the box to hold the bolts fast. Yes I can work around this, maybe by epoxying the bolts in place... but it would be better to make then entire front of the camera removable.... so now it's almost turning into a sliding box camera! And I don't like the idea of epoxying the bolts to mat paper. And I'm spending so much time that I'm wishing it was made with something more permanent like wood. It looks really nice, but if I'm going to put this much effort and time into something, maybe it should be the larger format camera that I can use my rapid rectilinear lens/shutter on. I wanted this one to be simpler, more like just a box with a removable lens board, and it is turning into a bigger project than I imagined. But it has served the purpose of learning. I'll probably use the paper holder idea in my future cameras, but now I wish I'd just used a flat back with tape since this is supposed to be a test camera.
Anyway... a lot of hours into this and I'm not sure if I will finish it. I now wish I'd made a simple wooden box first and then added the mat board parts to the front and back of that. I might still do that. I wish I'd just hammered together some pine into roughly a 5x7 box without a front and back... that would have made a sturdy frame to attach to, and I could have made custom pieces for the the back and the front from the black mat board. Some lessons I've learned so far:
1. A simple shutter is a good idea, even if you plan to use a "hat shutter" or a "Jim Galli" shutter. A lens cap really isn't enough. This way you can get the hat or black card in front, slide the shutter open, and then make the exposure without jiggling the camera. I was able to make reasonable exposures in my cardboard box version by using this approach ( I inserted a "paddle of black card, with a little light trap...it worked fine for blocking the lens long enough to get ready for the hat trick. )
2. I got 1/4 -20 T-fittings to make the tripod mount. Mine is just a pine wood platform with the fitting and some rubber bands to hold the camera on it. I was so happy to find them right away at the hardware store! But when I installed the first one, I thought it went in a bit too easy and it didn't bother me when I used a 1/4" drill bit.... oops. It turned out that some T-fittings the wrong size were mixed in with the right ones at the hardware store... and I installed one that was too small. They *are not* easy to remove! So double check that they are the right size before installing. I had only one that was the wrong size and Murphy's Law made that the one I installed first!
3. Finding the infinity focus point on the lens was pretty easy by taking it outside at night and focusing on a distant light... and my initial guess was very wrong. On this lens the 144mm is measured almost from the front of the lens... and my original carboard box was too long by almost 3/4 of an inch. A small movement of the lens changes the focus *a lot*. So making some kind of contraption to get close to the focal length first will be a good idea if the camera will be fixed focus... if the camera can be focused, it's still probably a good idea to do this to make sure the focal length is well covered.
We'll see where this all goes. I will sleep on it before I junk this design, but it's gotten a lot more complicated than I intended for this quick fixed focus experiment with the 114mm lens. What I'm aiming for eventually is a camera that can use my RR at 170mm or about 300mm with the front lens removed. I want the back to be replaceable to use 5x7 or 8x10 paper with these cut mat windows to use variable aspect ratios... and some kind of focusing screen. With the amount of work and time I put in today, I think it would be better spent working on parts of what I really want rather than fooling around with making a super nice mat board box. I could have spent the same time working with wood and had something more permanent and sturdy at the end of the day instead of a cool-looking but not very practical fitted black box!
So after thinking it over, I decided to finish the camera. I put on a removable front and attached the lens boards. I realized that it is still worth testing the lens board design and also taking it out and making some pictures to see if there is anything I might want to change. The lens board has a sliding shutter and a sliding removable aperture, so that you can easily change the aperture or put in a pinhole. It's all done. Now that it's got a kludged front, it's sort of an ugly duck, but I'll take some photos of it and with it. ( hmm.. this being APUG I might have to use my film camera for this.... and wait until I develop the film and wait until I have time to print them! )
Quite an experiment you've got there! And thank you for the detail report: I'm learning also ;-)
I'm planning on building something like this also (suitable for lens and pinhole) this sumer. I was thinking about removing the lens and placing a pinhole as an option. But I wonder what the differences you'll see in an image made with a pinhole and one made with a pinhole diaphragm in a lens (besides for differences in angle of view maybe). Will the glass have (much) effect while using photographic paper as a negative?
I'm thinking of using plywood and Duckt tape for making a simple test mock up. In an other forum I got some advise on the focal distance, etc.
See: http://www.apug.org/forums/forum147/...amera-p-s.html (we met there too).
Initially I wanted to make a 4x5" Point & Shoot camera, but I'm up for a 5x7" now. I have several 5x7" filmholders lying around I want to use.
Do you know the Afghanistan box street camera? See: http://www.afghanboxcamera.com/
It is a simple camera and darkroom in one. You can see a 8 minute Youtube film of a street photographer from Afghanistan using it and there are building plans
on the site. Maybe it will help you to get some ideas for redesigning your camera.
Have fun and keep us posted!
Greetings from Bert
Yes those Afghani street cameras are neat!
A few minutes ago I actually made a photograph with my matboard camera. The lens is from an old polaroid camera that I made into a pinhole camera. It looked like it would cover 5x7 wide open, but it was obvious as I stopped down the lens that it was going to lose the coverage. Right now I'm using a 1mm aperture in order to keep the exposure times reasonable, and it did not cover very well at all. I'm not even sure it would cover 4x5, much less 5x7.
The exposure is a little interesting. I calculated that with my pre-flashed Adorama VC paper and f/114, the exposure in full sun should be about 4 seconds. I put a test strip in and tried 5 seconds... it was just a little overexposed so I went with 4 seconds on a full sheet of 5x7 and it looks about perfect. It's hanging to dry right now and I'll post it here after I scan it.
This looks like it won't make a great lensed camera, but it ought to make a fine and convenient 5x7 pinhole camera! Also I have found that my shutter and removable aperture ideas work, and that there are no light leaks even though the fit of the front and lid are not super tight. In theory, these should be fine, since light would have to make a 180 degree turn, and then another 90 degree turn to the side to get to the paper... but it's nice to see that's actually true!!
The other thing this project has done is make me think very hard about what I actually want in a larger camera, and I have come to some firm ideas... so that was extremely useful. I also know that when I build the 8x10 prototype, it will be simple plywood first so I don't hit the same frustrations.
PS I think plywood and duct tape is a great way to do a mock-up. And I will try a pinhole instead of an aperture with this lens... I'm curious about that too!
Sounds like you are on the right track. I have used a somewhat similar arrangement for aperture stops with my experimental lenses, but have been able to get by mostly with a lens cap. (one which completely covers the lens and slips off easily without inducing a great deal of shake) I'm a little unclear of how your paper holder will work, or rather, how you will be able to load and unload it in the camera.
Keep it up, I want to see what this comes out like.
Hi Tom and Bert and everyone,
Well I uploaded that test picture to the gallery. It's not a pinhole photo, but it's from a "pinhole convertible" camera that almost certainly will end up being used as a pinhole. I'll upload some photos of the camera soon... there are some things about the design that did work very well. Mostly I copied ideas I saw in Joe Van Cleave's posts over at F295.org. There is a paper storage compartment in the back of the camera, with a little lid on top so that the paper can be changed in a changing bag. The front of this compartment serves as the back of the actual camera section and there is a mat window in front of that to hold the paper in place. In the test image, I did not realize the paper was not all the way in, and my sliding aperture stop was not pushed all the way in, so it wasn't centered behind the lens.
When I went to walk the dog this afternoon, I took it with me and made another photo along the way that corrects those problems. Nothing is going to correct the coverage problem... to use the lens wide open would require a shutter, and you can see how far off the coverage is stopped down to f114.
When I was getting the camera ready for the second shot, the tape that holds the back of the camera failed, and an entire edge opened up. I thought the paper would have been exposed for sure, but it wasn't. ( If there had been paper in the storage area, it would have been fogged. ) But that was another sign that the overall design is reasonable for minimizing light leaks. I'll post the second image after it dries and I can scan it. Both images are made from pre-flashed Adorama VC paper with no filtering. Normally when I use VC paper in one of my antique cameras, I use a yellow filter and rate the paper at ISO 3. I sometimes use it the way you see it here unfiltered for dramatic skies at about ISO 12. This 1st test image does not have as much contrast as I would expect, so maybe there's a little light bouncing somewhere or maybe it is a feature of this cheap lens-- not sure.
I think this will make a nice pinhole camera, and I will probably add some more glue for stability and use it as it is. I still would like to have a fixed focus 5x7 camera, but I don't have another lens, except a B&L RR from an old Kodak 3A that I specifically want to use in a larger camera that can focus.
It's all fun and that was my first picture ever from a homemade camera with a lens... so that's something!
Tom, I shouldn't have called it a "paper holder" really. It's not separate from the camera... it's basically a back mat with a window mat installed in the camera, with access from above so the paper can be slid into it. This is part of the camera design that seems to work well!
2nd image is in the gallery. I was wrong, there was some light leak ( lower left corner ) from the tape coming undone. Next will be a pinhole image!
I discovered today that my 170mm B&L Rapid Rectilinear lens does actually cover 5x7 even stopped down all the way. So there will be a "prototype mark III" version of this camera, and I will eventually have the fixed focus 5x7 I was hoping for. 1st version was cardboard, 2nd was mat board, the third will be made from pine... if it's good then I'll make it out of nicer wood.
Thank you for keeping us posted of your progress. It helps me to determine how to approach my project this summer. It's gonna be a 5x7" pinhole camera for Ilford Direct Positive paper. But I will also try to fit my Kodak 12 inch Commercial Ektar f6.3 (for 8x10") someway, or an other lens, like mine Schneider-Kreuznach Super-Angulon 1:8/121 (both not very wide, I know).
I also have a Russian Industar 210 mm lens lying arond, but that might only cover 4x5". I also have a Industar 300 mm lens (almost 8x10") which both use a simple lensmounting ring screwed unto a lensboard.
I'm thinking of a kind of "screw-on-lensboard" so I can change lens/pinhole in the field easily.
I'm gonna use it for landscape photography.
This has been an interesting topic. You gain insight into some 150 years of camera building when you try your own innovations. Some of our modifications are brilliant, some are brilliant, but useless, (for example, my ground-breaking innovation to add a slot to exchange pinholes... great, but on a fixed-focal length box, there is virtually no need for more than a single pinhole) and some are brilliant, but make it difficult or impossible to get a good photo where a simple box would suffice. (fill in your own blanks here)
At least we are consistently brilliant.
Some inventions take time and a second inventor to find a useful practice. In your case: swapping pinholes doesn't seem useful maybe, but being able to swap a pinhole and zone plate would be more interesting ;-)
"Have fun and catch that light beam!"
Bert from Holland
I agree and it's been fun... it's a bit addictive too, I keep thinking of new little things. I cut the wood for the next version but was pretty busy this weekend. I was pretty happy to learn that my 170mm lens will work. I want to make a mask so that the image will be 4 x 6.75 inches, which is close to the "postcard" format which I really like and especially like the look of paper negatives for. These could be contact printed nicely on 5 x 8 paper, I think.
I've made lots of pinholes but I was thinking of trying something a little different: pounding the metal thin with a ball peen hammer before making the "dimple". We'll see how that works...I didn't get to it this weekend but the next image really will be a pinhole image!
I don't know if you all saw this 5x7" and 8x10" homebuild pinhole camera?
Some nice images and tips there too.
I've decided to remove those two images from the group gallery because they were scanned and inverted rather than contact prints. I'm pretty new to APUG and I think I inadvertently broke the rules, which try to be very pure. I do make contact prints often from my paper negatives, so in future results from these prototype cameras, I'll make contact prints and upload them instead! It didn't seem worth the effort since these were test shots and only served to show that the coverage was insufficient ... and that I need a different lens!
This weekend I have two goals:
1) make a little more progress on fixed-focus 5x7 mark III. ( I decided the cuts I made with a handheld jigsaw are not square enough. )
2) make a pinhole to go onto the mat board "mark II" version and turn it into a nice 5x7 pinhole camera.
I tend not to make a big deal about it, but I think negative scans are acceptable anyway.
Keep us informed of your progress.
Hi Tom, Yeah... I thought about it last night and decided that I can hold myself to a "pure" standard here even if I might be going overboard a little. One of the reasons I'm interested in making these cameras is to have negatives large enough to make nice contact prints, so it keeps things in that same spirit of having a physical print be the "goal". But I promise I won't become fanatic about it... I've convinced myself that scans of negatives and scans of prints both are about equally bad at showing what things really look like.
I'm eyeing a "Hello Kitty" popcorn can in the garage and imagining what an 11x14 pinhole paper negative would look like... I'm starting to think *that* will be my goal for WPPD this year! 5x7 paper negatives are amazing... I'd really like to see an 11x14 one.