Best way to cut holes in body caps?

Discussion in 'Camera Building, Repairs & Modification' started by bhorn, Nov 4, 2008.

  1. bhorn

    bhorn Member

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    I would like to mount some view camera lenses on SLR body caps. What is the best way to cut the holes in them without a drill press. I have a variable speed cordless drill and a dremel tool.

    Thanks,

    Bruce Horn
     
  2. Steve Smith

    Steve Smith Member

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    Get a set of dividers (looks like a pair of compasses but has two points). Inscribe a circle the right diameter on the cap. Use your drill to put a series of closely spaced holes just inside the circle you have marked up. Press out the centre then use a half round file to finish the hole up to the marked edge.

    You may have a problem though with focus as view cameras move the lens relative to the film plane to focus. An SLR lens mount is fixed and the focus mechanism is in the lens.


    Steve.
     
  3. B&Jdude

    B&Jdude Member

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    How about getting one of those bellows units that are (or were) made for most SLR's for close-up or slide copying, putting the lens cap w/view camera lens on it, and using that set-up to focus? :confused:

    EuGene
     
  4. John Koehrer

    John Koehrer Subscriber

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    B&Jdude,
    That works & you can get some very interesting images. I did that once or twice years ago with an uncoated lens & fujichrome.
     
  5. rknewcomb

    rknewcomb Member

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    A power tool is likely to melt the plastic and fill in the cut, so you mostly end up where you started except with a big mess. A jeweler's saw is a small hand saw, like a coping saw except with a blade about the size of thin pencil lead. Many people call a coping saw a jig saw - which they are not. Jeweler's saws and the very fine blades can be found in hobby stores.
    First dill a small hole in the body cap, insert fine jeweler's saw blade through, connect up the other end of the blade to frame of saw and go at it.
     
  6. keithwms

    keithwms Member

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    Which lens do you wish to mount on which SLR?
     
  7. Ian Grant

    Ian Grant Subscriber

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    This links to a post about converting a 9x12cm plate camera to accept interchangeable LF lenses by using a K mount on the camera lens panel & a body cap to mount the lens/shutter.

    Ian
     
  8. B&Jdude

    B&Jdude Member

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    Ian:

    The problem is different with mounting the lens on the 35mm camera. After all, the plate camera has a bellows to allow movement in and out away from the film plane for focusing, but the 35mm doesn't focus that way, instead they rely on a helical mount to move the front lens element in and out.

    That's why I suggested the bellows, as there is no other way to focus with the view camera type of lens except to provide a means to move the whole lens in and out . . . the close-up bellows is an easy way to do that, as they have a lens mount (screw or bayonet) to attach them to the camera for which each type is designed, and a lens mount on the outboard end to which Bruce can attach his body cap mounted lenses for quick changes.

    I use a Minolta mount bellows occasionally with my SRT's so that I can attach body caps that carry different sizes & focal lengths of pinhole lenses.

    EuGene
     
    Last edited by a moderator: Nov 4, 2008
  9. Ian Grant

    Ian Grant Subscriber

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    EuGene, the OP posted a question asking me the same thing a few days ago on another thread, I haven't been online for a week as I was travelling with no Internet access so couldn't reply.

    The idea is to have an SLR camera mount (female) fitted on a lens board or panel on an LF camera then have a lens mount or in this case a body cap (male) fitted to the LF lens.

    Ian
     
  10. bhorn

    bhorn Member

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    Thanks for all the replies.

    Actually I was planning on using a bellows attachment on a Pentax LX and on a Pentax D100Super. I have tried this with a couple of my old view camera lenses just holding the lens against the front of the bellows and focusing and it worked very well. One is an old 90mm, a wollensak f6.8 I think. Another is a 75mm f1.9 off an old Polaroid, may also be a Wollensak. A 135mm off my old busch pressman, an Ektar I think. And I think I have a few old soft lenses from old folders around that I would like to try. I am also planning on trying some old "c" mount lenses on the d100 but that will have to be later as it will probably require a helical mount and a recessed lens board plus some careful calculations to make sure that the mirror does not hit the back. I realize that those lenses will probably not cover the whole aps-c sensor but if I can even get a 4mm to cover the equivalent of a pocket digital sensor I would be happy cropping that much into it as its pixels are much better than my point and shoot.
     
  11. Ian Grant

    Ian Grant Subscriber

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    You may well have problems using the 75mm lens on bellows as it may not have sufficient compression to allow infinity focus. I have an f1.9 75mm Dallmeyer and that won't work on bellows, also the shutter's too large. These are usually oscilloscope lenses designed for macro work.

    I'd assumed incorrectly that you were wanting to do the same as discussed in the other thread :D

    Ian
     
  12. keithwms

    keithwms Member

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    So the idea is to have a 35mm camera, put a body cap with a hole on that, and then attach that to bellows or whatever to then attach to another lens?

    Well one thing you can do is get a cheap 2x3 camera and make lensboard adapters for that. It's easy to mount a 35mm camera to a lensboard, and it's also easy to slap an LF lens on there. Something like a 2x3 Galvin or mini graphic or whatever will give you a (fairly) stable focusing frame and a straightforward way to connect to the camera. You can make that connection as simple or as elegant as you wish. E.g. just get an extension tube for your 35mm camera and attach it to a lensboard and off you go. You could also use a body cap but I think you will find that you want more space between the camera and the (rear) lens board. an extension tube would give you more stability and all the space you need.

    Incidentally the Chinese company "shelro" used to have something like this. You might look at their solution, it might inspire you.
     
  13. B&Jdude

    B&Jdude Member

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    Ian & bhorn:

    Sorry if I muddied the waters, as I thought we were talking about using some view camera lenses on a 35mm body. Apparently I am getting too senile or something, 'cuz I went off on a tangent back there! :tongue:

    EuGene
     
  14. bhorn

    bhorn Member

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    Thanks for all the comments. Sorry for posting this twice. I didn't know if that other thread was fallow at this point.

    Yes, I plan to use my 35mm bellows for focusing. I am aware that some of my lenses wont focus to infinity with this and am fine just using those for close focus work.

    I had thought at one point of making a plate for the back of my Busch Pressman but I want something smaller and lighter.

    If this works I may try making a tilt-shift bellows to do this with as well. I've seen some on eBay but they usually go for more than I want to spend.

    I may also try making a short helical focus attachment for shorter lenses, adapting a Lensbaby or making something similar to one.

    Cheers,

    Bruce Horn
     
  15. bhorn

    bhorn Member

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    First attempt moderately successful

    I made the first of these body cap mounts last weekend and it worked moderately well.

    One question though, how do you all mark the exact center of a circle. I read advice somewhere to draw an "X" on it and mark the intersection but I am skeptical as to how precise that was. Is there a better way?

    Thanks,

    Bruce
     
  16. bhorn

    bhorn Member

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    Hole saw worked tolerably well. I drilled at slow speed in short bursts of about 1/2 a second each and it didn't melt. A bit with less surface area in contact with the plastic would have been better, a forstner or a variable size bit.
     
  17. bhorn

    bhorn Member

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    You were right by the way Ian, the 75mm would not focus with the bellows. The front and back standards of the bellows combined were too deep. However, the the lens does focus to infinity about 50-100mm in front of the lens mount so I am thinking of building a little bag bellows for it.
     
  18. keithwms

    keithwms Member

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    I don't fuss over dead center of the cap. I just drill a big hole right through, then mount a thin copper sheet with a pinhole on that, with tape, and move it around until I get what I want.

    I make my pinhole in the copper by finger drilling it with a pin. The results are perfectly acceptable to me.
     
  19. bhorn

    bhorn Member

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    Thanks Keith,
    As well as the question of whether the hole is truly dead center, it also turns out that the hole is a little too big because the kerf of the hole saw is slightly wider than the thread of the shutter. If I decide to continue using this I may try putting a triangular cross-section washer in between the flange and the shutter to center it better.

    The only problem that I have had with the images from this lens are that any images with a light background have a large circle of what looks like flare to me slightly off-center covering perhaps 1/8 of the image. It is washed out and soft. The fact that it is slightly off center is what made me think that the lens might not be exactly centered. I'll try it with a lens hood next time but I think the flare might me inherent in this lens when using it with a digital sensor. I only had time for a few shots before it got too dark but I think stopping it down might have improved that a bit.

    Next attempt will be a Xenotar 80mm f2.8 but I think that might have the same problem as the 75mm focusing to infinity. Oh well, even for close-ups it will be fun. If I can get it to work reasonably well I may buy some longer lenses as those actually should be fairly useful with this setup.

    Thanks,

    Bruce Horn
     
  20. keithwms

    keithwms Member

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    Could you post an image of your project? I think I am still not quite clear on what you've made, sorry!
     
  21. bhorn

    bhorn Member

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    Sure, Some time on the weekend when they actually let me out during daylight hours. :smile:

    Right now it is simply a plastic k-mount body cap with a hole cut in it to allow me to mount my view camera lenses on it. This one will fit a #0 shutter and currently has a Wollensak 90mm f6.8 lens on it. I then mount that body cap on a bellows made for a 35mm camera for focusing and can attach it to my digital or film SLR. So far I have only tried it on the digital as that makes it easier to try out different things with it.

    Once I have this basic setup all worked out I plan to try making a few tilt-shift bellows or sort of Lensbabies type mounts to see if I can apply the same moves to the smaller formats that I used to use one a large format camera. That part of it may not work for anything other than Lensbaby type special effects however as I understand that the movements need to be quite precise when you are working with that smaller scale.

    --Bruce Horn