DIY Medium Format camera

Discussion in 'Camera Building, Repairs & Modification' started by wombat2go, Jul 22, 2013.

  1. wombat2go

    wombat2go Subscriber

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    Below is a description of the camera body that I completed in March 2013.
    I call this camera "WomTak1" and I am starting on 'WomTak2" which, if it succeeds, will have an internal electronically timed shutter for use with the wide angle Takumar 6X7 lenses

    "WomTak1"
    The lens is a "Super-Multi-Coated Takumar/6X7 1:2.8/90" with the leaf shutter.

    The camera body is based on an Eddystone die-cast aluminum box.
    These boxes are used in electronics for radio frequency shielding. They are accurately made and the walls are thick enough for machining.
    The box lid has a ridge inside that forms a light tight seal.
    Using the Eddystone box saved a lot of work in this project.

    A square with a groove for light seals was milled in the bottom of the box to form the mount for the lens board.
    The lens board of 2 laminated plates of 6031 aluminum is somewhat based on the Graflex 4x5 lens board.
    A P6X7 bayonet mount was turned in the lens board using the lathe.
    The back is clamped to the lid which is machined with the film gate and a light seal.
    On Graflex cameras, the back is held with quick release clamp slides, but on this camera the clamps are bolted.

    The Graflex (Singer) RH/10 roll-film back contains a truck for 120 film giving 10 exposures of film gate size 57.4 by 67.5 mm.
    Also it will take the truck for an RH/8 back, giving 8 exposures for a total of 18 shots if the spare truck is loaded and taken in the camera bag.

    The published register for Pentax 6X7 is 84.95mm
    The estimated register of this camera is 85.09mm at 25 C and 84.89mm at -10 Celsius
    The TIR of the lens mount parallelism was measured as 0.05mm. However that does not include the Graflex back.
    A 6X7 ground glass was made to fit against the film slides.
    The camera was checked with a loupe at 4 metre and infinity and the lens scales were found to accurate.

    The bottom of the camera contains a tripod mount machined in brass and threaded 1/4_20 into a blind hole.
    The side has a stainless steel industrial handle angled for a personal grip.
    Tho top has 4 bolts for optional viewfinders.

    The present viewfinder is very simple, the lenses were chosen by flipping lens elements in the junk box until an arrangement of 2 meniscus lenses from the front of an old zoom were placed to give about 3+ diopter (focal length 300mm or so).
    The eye cup is much larger than on a normal camera
    The viewfinder has significant barrel distortion which is actually an aid in centering the image.
    The spirit level is easily visible in the bottom of the vf with the help of the lenses.

    The camera with film , back and lens weighs 1.96 kg (4 lb 6 oz)

    There is presently no rangefinder or meter, so the Pentax MX with the SMC Pentax-M 1:2.8~4 40~80mm is taken in a compartment in the camera bag
    The zoom makes a good rangefinder at 80mm and being of wider aperture than an ordinary zoom, has a bright image in the MX viewfinder.

    The roll film back has a dark slide which is not really necessary as the leaf shutter is normally closed.

    photos with the MX alongside

    Front view
    https://app.box.com/s/5iqm4d1co4zbdqbubrdg
    rear view
    https://www.box.com/s/ayxl4s45tpq9as0xtgld
    side view
    https://www.box.com/s/bsf4ca4fy3v149skqxw9
    with AF360 Flash
    https://www.box.com/s/44lzyxxte8c3v1ipj2kj


    Here are some photos taken by the new camera
    https://www.box.com/s/uuoa84o1gawletwfc02g
    https://www.box.com/s/pzzorays1lydomsk9rre
    https://www.box.com/s/c24zem8vrsml7391kiud

    These shots on Fuji 400 were focussed just by estimating distances and using the DOF scales on the lens.
    In use this camera is much easier to use hand held than the Speed Graphic, it is only necessary to remember to wind the film after each shot.
     
  2. Alessandro Serrao

    Alessandro Serrao Member

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    Unbelievable!
     
  3. Dan Fromm

    Dan Fromm Member

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    Ok, so you've made a cute little camera that works with PX 67 lenses in leaf shutter. Its been a long time since I thought about that system, so please enlighten me. How many lenses in shutter does the system have?
     
  4. wombat2go

    wombat2go Subscriber

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    Dan, There were two lenses of the Takumar (Pentax) 6X7 with leaf shutters. - the 90mm and 165mm.
    The next camera i make will be similar, but with an internal shutter. That will allow use of the wide angle Takumars i have.
    I have just purchased a Copal 495, it is a plate shutter with 45mm opening, powered by a solenoid.
    I am about to set the shutter up on a lens bench and measure its performance with a phototransistor and oscilloscope.
    I think I can modify it if necessary to speed it up by adding a closing solenoid. I suppose it will be OK if I can get a top speed of 1/100th to 1/125th out of it.
    The Takumar 90mm leaf shutter has a speed range, with flash sync, from 1/30 to 1/500.
     
  5. zsas

    zsas Member

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    Hi wombat - I can't see your pics of the camera??? The pics you took with it, I can open....any ideas?

    Regardless, congrats on your camera!
     
  6. Matthew Wagg

    Matthew Wagg Member

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    That's fantastic. I guess you zone focus with it and just use the viewfinder for composition?
     
  7. Dan Fromm

    Dan Fromm Member

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    Thanks for the reply. Have you considered making a shorter box (can you shorten an Eddystone box?) with a large, e.g., Compound #3 or larger or Ilex #4 or larger, leaf shutter in front of it with a PX 67 female mount attached to the shutter?

    The obvious step beyond that, given my prejudices, would be to change the rear (stepped plate?) to hold a Mamiya Press "M Frame" (better in some ways, perhaps worse in others) or a 2x3 Graflok (worse in some ways, perhaps better in others) and to use, respectively, an S-shaped Mamiya Press roll holder or a Graflex roll holder. Mamiya Press roll holders are supposed to hold the film flatter than Graflex ones but I don't know where Mamiya ever offered a focusing panel for the M Frame. With a Graflok you'll have a focusing panel, will be able to compose through the lens.

    A question. Why carry several inserts for your roll holder? They're not light tight, can't be carried safely loaded, and have to be in the shell before film can safely be advanced. Using an RH-8 insert in an RH-10 shell wastes film. If you can take an insert out, you can reload it and put it back in.

    I have a little experience with a broad range of lenses (45/9 WA Dagor to 480/9 Apo-Nikkor) mounted in front of a Compur/Copal #1 shutter on 2x3 Graphics, have had no difficulties with vignetting and few difficulties, including one huge embarrassment, with loss of diaphragm control. Diaphragm control can be lost when the shutter's maximum aperture is smaller than the lens' exit pupil.

    To be clear, I'm far from sure that a #1 won't give you vignetting because I don't know how far your lenses' exit pupils will be in front of the shutter. It works for me because my front-mounted lenses are always close to the shutter and the shutter is usually relatively far from the film plane. Not your situation, in general.

    Good luck, keep on having fun,

    Dan
     
  8. wombat2go

    wombat2go Subscriber

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    Thanks Andy
    Sorry that you can view some of the links but not others
    Here is a link to the directory on box.com containing all the photos linked in the op.
    https://app.box.com/s/a5fwaserjsqwwi5r8zjs

    Matt,Thanks and you are correct.
    I have a plan to make a more elaborate viewfinder using an SMC Pentax 1:2 55mm ( a 35mm lens) , a ground glass screen, and a 45 degree erecting prism.
    I have checked the taking lens and that lens with a tape in range 4 ~6 metre and their scales are accurate, so i would transfer the reading from the VF lens on to the taking lens.
    That would allow more accurate focussing close up. Beyonds about 5 metre, my guess is fairly accurate especially above f/11 or so.
     
  9. whowantstoast

    whowantstoast Member

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    Standing ovation for you sir! And I honestly expected it to be ugly, but that is a thing of beauty. You know, another lens option for such a project would be the Koni-Omega lenses. They have shutters, and go down into wide angle.
     
  10. wombat2go

    wombat2go Subscriber

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    Dan, Thanks for the comments and I copied them into a file so I can go through the suggestions.
    I used the RH/10 back mainly due to cost, they are only about $75
    The materials for the camera body are less than $30, and the older Takumar lenses are also available for less than $200 from KEH etc.

    For next, version 2 body I have a big copal "495" shutter, it is on a phenolic plate, does not look like an ordinary shutter, I think it was intended for behind the lens.
    I was happy to find that for $40 . The Takumar 6X7 wide angle lenses are retrofocal and have large diameter rear elements, hence I need a big shutter behind the lens.

    To save loading the holder I have a lens bag that is light tight and wide enough to take the truck, so I can just changeover as necessary..

    I also have a new Prontor shutter. I have ordered a metric screw cutting gear for my lathe.
    The thought there is to do as you suggest and make a mini MF camera with a wide angle lens. For example I have a 50mm Rogonar-S enlarger lens.
    I can machine the metric adaptors, and I was looking at the Crayford focusser for that idea.
    regards !
     
  11. wombat2go

    wombat2go Subscriber

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    Thanks for the comments whowantstoast, the Koni-omega prices look good for this type of project.
    The reason for choosing good quality but lower cost lenses is not only to keep the cost down.
    The lenses have to spend time in the workshop where there is dust and metal chips etc, during the build of the bayonet mounts etc.
    So far I have been careful, and have no damage , but there is a risk that the lens will be damaged.
    So I would not try to use an expensive MF or LF lens on these projects

    By now I am well into the Takumar lenses, i have 3 and also a Computar variable focal 105~150mm out of a 70mm long -roll camera.
     
  12. tkamiya

    tkamiya Member

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    I am IMPRESSED!
     
  13. cramej

    cramej Subscriber

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    Ok, nice machine work and it is a very attractive camera, but why? Can't you just use a P67 with the Tak lenses? How about mounting some LF lenses on it instead of something you can just get off the shelf?
     
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  15. zsas

    zsas Member

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    Thanks Wombat, was able to see the pix better with the full catalog link (think it was some iPhone incompatibility thingy....).

    What a gem that camera is! Look forward to the next one!
     
  16. jjphoto

    jjphoto Member

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    Yeah, nice job etc etc. But why replicate something that you can buy relatively inexpensively?

    Although I understand the concept of doing it 'cos you can, or 'cos it's interesting, fun etc etc.

    You need to be able to focus them. LF, enlarging lenses etc all need a mechanism such as a helicoid or bellows to focus (it's all do-able). The beauty of a fixed register lens, such as that used by the OP, is that it has a helicoid.
     
  17. Dan Fromm

    Dan Fromm Member

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    Oh, the corrupting power of found money! Sorry, found shutter.

    The shutters I suggested have maximum openings no smaller than the 45 mm you say y'r Copal 495 has. Ilex and Compound 5s open to around 65 mm.

    Play is good, so is keeping busy, but enlarging lenses typically cover around 50 degrees and are of normal construction. When a lens of normal construction is focused to infinity, its rear node will be one focal length from the film plane. A 50 mm enlarging lens will cover 24x36 at infinity with a slight margin for movements.

    If you want to use w/a lenses on a box with P67 register, you're pretty well limited to lenses for the P67 and for 6x7 cameras with longer registers.

    Good luck, keep on scheming and plotting,

    Dan
     
  18. Dan Fromm

    Dan Fromm Member

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    I'm not sure you know it, but you've just made an argument for a 2x3 press camera.
     
  19. omaha

    omaha Member

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    The photos aren't coming up for me on my tablet, but I'm still impressed. As for the "why" of this, why not? Sometimes you just have to make something.
     
  20. wombat2go

    wombat2go Subscriber

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    Thanks for all the comments.
    As to why, it is predominantly just a hobby.
    Plus:
    -I read that the while the Pentax 6X7 lenses endure, the bodies can be troublesome, moreover the used bodies still fetch ~ $500 and they are heavier than this one.

    -I wanted a real simple robust camera, the body is such the back balances the lens and forms a robust base. It can be sat on the ground or in the grass etc with the lens and back clear of the ground.The lens has a permanent metal hood with UV filter, and no lens cap. It is carried either by its handle or in an old video bag and does not have to be babied.

    -This camera has no batteries (after my dslr batteries laid down in the Michigan winter) and can be used with gloves on which is not possible for example with a dslr.
    -Having the spirit level in the viewfinder is good feature, more accurate than the grid in the slr and dslr. However I need to work on a better VF than the present one.

    here is a photo of the Medium Format collection so far which puts the DIY body in context.
    https://app.box.com/s/b8di1879qnxjl8h9k1kw

    Next job is to add a body for that 55mm, the lens board is already completed as shown.

    The Computar variable focal telephoto lens can only be used on the Speed Graphic because it needs the bellows. When that lens is set to 135mm, the rangefinder on the Speed is accurate, and I can use it hand held, although it is heavy.
    Note that while there is a smaller Speed Graphic, these medium format lenses will not fit, they need the 4X5 size camera to get a sufficiently large lens board for the bayonet mount.

    Happy MF-ing. There is some thrill in pulling the 120 film out of the tank and seeing 8 big beautiful sharp C41 frames.
    ( Although I haven't got there yet!)
     
  21. Dan Fromm

    Dan Fromm Member

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    So it seems, but there's a way to do it. In essence, attach the female bayonet to a stepped tube that in turn attaches to the lens board. I've done this with several lenses. You might want to take a look at my lens diary, it is at http://www.galerie-photo.com/telechargement/dan-fromm-6x9-lenses-v2-2011-03-29.pdf
     
  22. wombat2go

    wombat2go Subscriber

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    Thanks Dan, I will print your diary and read it.
    I think I had better make a more formal "lens bench", until now I have just been hand holding an old book-end with white paper.
    I might add some vee blocks etc and a 6X9 gg screen and a Slik tripod mount so I can test things more accurately, using what I have here.
     
  23. tkamiya

    tkamiya Member

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    So...

    Do you have an access to a full machine shop? Other than lathe, what was used? A mill? I'm very interested in finding out more about how the back mates the body and how they are held together. It'd be great if you can share that part. I'm very impressed.
     
  24. zsas

    zsas Member

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    Great question T^ I too wanna learn the mechanics Wombat....I dream one day of a little machine shop and a darkroom....gotta plan early:smile:
     
  25. wombat2go

    wombat2go Subscriber

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    Hi TK, and zsas,( and AGX who asked similar by pm)
    Thanks for the queries.
    I see there are more DIY projects of LF in wood. MF in metal is not so common and requires more accuracy.

    Lathe is a South Bend model 9A which was delivered to its original owner in Detroit in 1939.
    I acquired it in 2011 as second owner with a comprehensive set of tooling and attachments.
    That included a small machinist's surface plate which is ideal for camera measurements.
    The lathe was used in the original owner's residence as a hobby lathe and it is in excellent condition.
    On it I have made, from solid Al 6031 billet, lens adaptors from Micro 4/3 up to the Pentax 6X7 bayonet and threaded adaptors too.

    I have just purchased (from Australia, for reasons rather too lengthy to explain here) a compound gear set to allow machining of metric camera threads.
    The Leica M39 mount is actually a 39mm Whitworth thread with 26 Turns Per Inch , so I purchased a set or Whitworth threading tools from UK.

    The "elementary" mill drill is a work in progress.
    It is based on a Delta Shopmaster DP200 pedestal drill purchased new in about 2005.
    I recently added a generic cast iron "Made In China" XY table to convert the drill for limited milling duty.
    There are issues in doing such a conversion, including safety, which are documented in the machinists' fora (forums) perhaps with varying degrees of veracity.
    I have made some weldments (in mild steel by oxy acetylene bronze welding) to bolster the rigidity of the thing and just today (when I got tired of yard work) I spent a couple of hours on what I hope is the final weldment to make the head much more rigid. I reckon I have a few more sessions to go on that project.

    I am aiming for a consistent TIR of 0.05 mm (0.002 inch) on say, a 6X9 frame in aluminum.
    I am using 4 fluted spiral side/end milling cutters in range 4 ~ 7mm, dry on Al.

    To answer your question about the back more specifically:
    The Graflex backs here are an RH/8 and a Singer RH/10. Both at least 30 years old and well used.
    Both have the pin rollers that are documented as necessary for the modern 120 film (I have no experience on this)

    I measured carefully and decided that the distance from the emulsion side of the film (contacting the pin rollers) to the contacting front of the back
    was 5.080 mm , 0.200 inch, considering wear.
    here are my actual measurements in the 4 corners [inch]:
    RH/8 0.180, 0.190, 0.202, 0.200
    RH/10 0.175, 0.191, 0.179, 0.180
    I assumed that the RH/10 was a bit more worn than the RH/8, also my calipers pull the pin rollers to the front of their spindles which the film may not do.

    The Graflex Singer back is bolted to the Eddystone body by 4 clamp plates which were actually quite difficult to make first time. Next time will be easier.
    You can see them on the rear view in the op link.
     
  26. wombat2go

    wombat2go Subscriber

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    I have a question for Dan Fromm, if you are around.
    I finally have my metric thread cutting gears. They are much traveled, made in Australia which metricated in 1966, in my baggage from Australia through South America countries to Michigan.
    Query, As I think Dan can answer - if worthwhile and save me going into a dead end here.
    If I machine an adaptor to orient the Rodenstock Rogonar-S 1:2.8 50mm M39 thread, to the year 1957 Prontor-SVS shutter, the distance from the rear element (lens thread end) to the iris will be approx 15mm.
    Now I can make the shutter face the real world, and the nose of the Rogonar will point to the film; I can adapt that assembly to the Graflex lensboard of my home brew camera. That is, the lens will be inside the camera, and the shutter will be on the outside of the lens board. Of course I can place the longitudinal register for infinity focus.
    What will be the approximate image circle?
    Will the distance to the shutter/iris affect sharpness too much?
    Thanks!

    Edit Oh, I realize I can hold the iris of the shutter open and use the stop in the lens!
    But my queries still stand....
     
    Last edited by a moderator: Sep 12, 2013