Question about being able to use 6x7 carrier, 135mm lens on bessler 45

Discussion in 'Darkroom Equipment' started by ke6igz, Mar 21, 2011.

  1. ke6igz

    ke6igz Member

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    I currently have a Beseler 45 with a 135mm lens that I use to make prints from 4x5 negatives. I am in the process of purchasing a 6x7 negative carrier. Will I be able to use the 135mm lens for making prints from 6x7 negatives or will I need to get a 90mm lens like the Beseler manual says. I would like to make 8x10 to 16x20 enlargements.


    Thanks
     
  2. markbarendt

    markbarendt Subscriber

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    You betcha by golly!
     
  3. MattKing

    MattKing Subscriber

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    You may have trouble making a 16 x 20 enlargement. The 135mm lens doesn't magnify as much as a 90mm lens, so you may run out of column height before your projected image is large enough to fill a 16 x 20 sheet of paper.
     
  4. ke6igz

    ke6igz Member

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    Thanks that answered my question.
     
  5. Ian C

    Ian C Member

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    Comparison of magnifications of enlarging lenses of different focal lengths

    The shortest lens that is specifically designed to fully cover the format will give the greatest magnification.

    The usual 6 x 7cm-specific lenses are 90mm—the so-called “normal” focal length.

    Too, most modern 80mm lenses are designed to fully cover the 6 x 7cm format.

    The 60mm f/4 Rodagon WA is a wide-angle enlarging lens designed to cover 6 x 7cm.

    With a 1000mm negative-to-print distance, for the stated focal lengths we get the following magnifications:

    135mm, 5.2X

    90mm, 9X

    80mm, 10.4X

    60mm, 14.6X


    The 16” x 20” print has aspect ratio length/width = 5/4 = 1.25

    At a 1000mm negative-to-print distance, the largest 5/4 projection cropped from a 6 x 7 cm negative using each focal lenght lens is:

    135mm, 11.3” x 14.1”

    90mm, 19.6” x 24.5”

    80mm, 22.7” x 28.4”

    60mm, 31.8” x 39.8”
     
  6. ke6igz

    ke6igz Member

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    with the 135mm lens I run out of column before I get to 11x14

    Just got my 6x7 negative carrier. 8x10 covers fine with my 135mm lens. I run out of column height before I get full coverage on 11x14.

    Now I need a Beseler 45 lens board and a 90mm lens with a 39mm diameter mount. Where can I find one? I checked Ebay and there is only one 90mm enlarger lens listed.
     
  7. 2F/2F

    2F/2F Member

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    It will work in general, because it covers the film, but you will not be able to print 16x20's. I'd try a 90 or 100/105. Enlarger lenses are cheap on the used market. I would lurk in the classified section here for a while. They come up pretty frequently. E-Bay is an option as well, of course. Just follow the normal precautions. Ask lots of questions, and get lots of good photos until you are satisfied, then make sure that you have a good return contract with the seller.
     
    Last edited by a moderator: Mar 25, 2011
  8. MattKing

    MattKing Subscriber

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    Many high quality 80mm lenses will cover 6x7. 105mm lenses will probably give you 11x14.

    I'd start a thread here on APUG asking who successfully uses which 80mm lenses for 6x7.
     
  9. 2F/2F

    2F/2F Member

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    There is another trick with that enlarger that you can use so you do not have to buy another lens. It is a bit of a process, but it works. You can raise the enlarger by putting blocks underneath each side of the base rails. Then remove the baseboard and print on the table. The problem, if this is a temporary setup done with imprecise blocks such as 2x4s, is alignment. After you rig it up on the blocks and test to make sure you have enough enlargement, you might need to use some shims for the blocks – strips of card stock will work fine – and a way to test your alignment. I use a grainy negative to fix my B22 when it inevitably slips out of alignment every now and then. (They are cheap enlargers. Yours is much better; once set up properly, it will rarely, if ever, go out of alignment, and if it does, it is easy to adjust.)

    With this enlarger, you can also very easily tilt it backward for horizontals. If you have a rolling metal filing cabinet, you can use magnets to hold your paper in place there. Again, with a temporary setup, alignment is a pain, but it can be done.

    Ideally, you have a special table with two shelves (top one removable) set up permanently. When using the top for normal printing, the bottom serves as a storage shelf for your paper, proofer, etc. When printing big, take the top shelf off and the bottom shelf serves as your baseboard.
     
  10. ke6igz

    ke6igz Member

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    measured distance from neg carrier to enlarger baseboard at full column height

    Measured the distance from neg carrier to enlarger baseboard at full column height and its about 35 inches or 890 mm. So that explains why I can't get to 11x14 with a 135mm lens. What is the formula used to calculate the magnification factors? I could then figure out what focal length lens I would need to get me to 16x20 size enlargements. Of course a 90mm would be ideal but they seem to be hard to find in the used market.
     
    Last edited by a moderator: Mar 25, 2011
  11. hpulley

    hpulley Member

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    I use a 90mm f/5.6 Omicron EL for my 6x7 negatives. It's a 6-element design, f/5.6-f/32, 39mm. I find it works very well, sharp, good coverage, smooth aperture stops. There is one on eBay from the same seller I got mine from, KHB Photo. They are not a fly by night place, they repair large format lenses/shutters and stuff as a business along with supplying enlargers, lighting, etc. and parts. Just a satisfied customer...

    http://cgi.ebay.ca/Omicron-EL-90mm-...762?pt=LH_DefaultDomain_2&hash=item588c57a372
     
    Last edited by a moderator: Mar 25, 2011
  12. Rick A

    Rick A Subscriber

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    If you can use 25mm lens mount, I have a Wollensak 90mm that covers 6x9 I'll let you have on the cheap.