Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: 400mm F/10 singlet for my new camera

  1. #1

    400mm F/10 singlet for my new camera

    Finally got my hands on an 8x10 (Seneca View, ca 1925). After a little TLC it is up and running. But no lens (cheap and patient, the only way to use Ebay).

    So how about making a lens? Simple singlet (plano-convex glass lens from Edmund Optics), some PVC, a couple of rubber washers, some 2-part epoxy, plywood, latex caulk and black spray paint. And we gots ourselves a lens! Add some heavy duty tinfoil and you get a custom lens cap!

    Don't have stops cut yet so at f/10 it was way to fast for even photo paper. Added a sheet of ND 0.6 taped to the "back" of the lensboard to drop the speed.

    Overcast day, Arista Edu.Ultra (Foma) photo paper as film, contact print made on second sheet.

    Sombitch, it worked! ;D Attached files

  2. #2
    500+ Posts Daryl's Avatar
    Join Date
    Jun 2004
    Location
    Earth
    Posts
    2,027

    400mm F/10 singlet for my new camera

    Excellent! Can we see a pic of the lens?

  3. #3

    400mm F/10 singlet for my new camera

    put a smaller hole in there (should be easy to calculate the exposure) and you can probably get a much sharper image! It's quite satisfying though, when you get your first image from a home rigged setup, isn't it! 8)

    Yes, I'd like ot see the lens setup as well :-D

  4. #4

    400mm F/10 singlet for my new camera

    Yes, I understand how f/stops work. As I mentioned in the post, I don't have them cut yet. ;P

    It is a wonderful thing when something you make actually works.

    I don't have a digital camera so a quick picture of the lens isn't possible. But then again, it would just be a 4 3/4" square of 1/8" plywood with a 2 1/4" piece of PVC (originally gray electrical conduit) epoxied in the center. The lens is held in the tube (at the rear) by two rubber washers cut to fit and also epoxied. Prior to installing the lens, any gaps between the PVC and the plywood were filled with latex caulk then smoothed. This was followed by two coats of flat-black Krylon. Then the lens installed. The lens cap is made from a double thickness of heavy duty tinfoil molded to fit the outside of the PVC. The ND filter is taped to the backside of the lensboard and so resides inside the camera bellows.

  5. #5

    400mm F/10 singlet for my new camera

    This is great, RW! Stopped down, of course it would be sharper, but what may be especially nice about this lens operated wide open is when you're making 'portraits' - not only of just people, but also of isolated, interesting objects.

    I've used my 7x50 binocular object wide open at F/3 (on a Speed Graphic), and have found the soft edges of the picture, and narrow DOF, give a very nice effect that's a refreshing alternative to pinhole, for instance.

    Well done; let's see some more images posted from this lens.]

    ~Joe

  6. #6

    400mm F/10 singlet for my new camera

    Some back-of-the-envelope calculations and I think that the majority of the abberation is gone by about F/80. So it would be nice to have a set of F/16, 32, 64 and 128. That should really give me a lot of control over the situation.

    And moving this lens to a 4x5, there will be less since the film plane is using much less of the image circle (unless I make some radical shift & swing movements).

  7. #7
    Administrator Tom Persinger's Avatar
    Join Date
    Jun 2004
    Location
    Pittsburgh PA USA
    Posts
    1,810

    400mm F/10 singlet for my new camera

    Quote Originally Posted by Daryl
    Excellent! Can we see a pic of the lens?
    yes yes! post a pic of the lens please!

  8. #8

    400mm F/10 singlet for my new camera

    I'm still not sure why the excitement over seeing a picture of some PVC tube and 1/8 plywood that have been epoxied together and spray painted black... Assembled, you can't really "see" anything.

    The lens lives at the "back", held between two rubber washers that were epoxied into the tube. The washers came from the plumbing department at the hardware store and started out a bit too large diameter to fit in the tube. Used a razor knife to slice out a small section until they fit without distortion. To get the spacing right during epoxy (and to NOT GET EPOXY ON THE LENS) I used a 3rd sacrificial washer of about the same thickness as the lens.

    The lens element came from Edmund Optical, their catalog number NT48-243. I think I wrote before that this was "uncoated". Not quite true, it has their VIS-0 coating which makes it about 2% more efficient in its transmission than an uncoated lens. But I remember now that the only reason I went with this one over an uncoated one was this was in stock! Price difference is minimal.

  9. #9
    500+ Posts Daryl's Avatar
    Join Date
    Jun 2004
    Location
    Earth
    Posts
    2,027

    400mm F/10 singlet for my new camera

    Edmund Optics, Anchor Optics, Freestyle, B & H, and KEH!!

    I can avoid their websites easy enough, but they keep sending me catalogs!!!

    Now I'm looking for something to do with my 700mm f/ 11.7 achromat. ARGH!

  10. #10

    400mm F/10 singlet for my new camera

    Quote Originally Posted by Daryl
    Edmund Optics, Anchor Optics, Freestyle, B & H, and KEH!!

    I can avoid their websites easy enough, but they keep sending me catalogs!!!

    Now I'm looking for something to do with my 700mm f/ 11.7 achromat. ARGH!
    Well, Daryl, you could try fashioning a refractor telescope with that doublet. Or a telephoto lens for LF film.

    I guess I'm gonna hafta get me one of them there catalog thingies, too.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •