Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,276   Posts: 1,534,715   Online: 874
      
Page 1 of 3 123 LastLast
Results 1 to 10 of 22
  1. #1
    Erik Petersson's Avatar
    Join Date
    Jan 2006
    Location
    Stockholm, Sweden
    Shooter
    35mm
    Posts
    634
    Images
    8

    How to use bellows on a 35mm SLR?

    Hello!

    I have a bellows unit from Asahi, that fits to my Zenit ET. My lenses (mainly a Helios 44, 52 mm f1:2) achieve quite some enlargment when attached. The bellows unit can slide back and forth. The unit is marked with f=55 mm on one side and a scale with numbers from 0,7 to 2,3. On the other side it is marked f=58, and a scale with numbers from 0,6 to 2,2.

    The scales probably relates to light loss, but which of them should I use with my 52mm lens, the one on the left side or the one on the right?

    When using the unit, should I leave the lens focused on infinity, on the closest focus, or somewhere in between?

    Anything else to think about? I plan to use negative film in the first try, so exact exposure will not be extremely critical.

    Thanks in ahead for any replies! I hope to catch some of the spring flowers with this setup. The pictures just might be very nice.

    Erik
    Stockholm

  2. #2
    richard ide's Avatar
    Join Date
    Nov 2005
    Location
    Markham, Ontario
    Shooter
    Multi Format
    Posts
    1,215
    Someone correct me if I am wrong, but I think the numbers refer to magnification with both a 55mm and 58mm lens. The bellows is being used for focussing instead of the lens barrel so you can ignore the setting marks on the lens. I am not familiar with your camera so if it has through the lens metering use the meter reading for exposure setting. If not, apply the appropriate correction for the magnification you are using.
    Richard

    Why are there no speaker jacks on a stereo camera?

  3. #3
    Rol_Lei Nut's Avatar
    Join Date
    Jul 2006
    Location
    Hamburg
    Shooter
    Multi Format
    Posts
    1,118
    Those should be the magnification factors.

    If you want to be accurate, the 55mm one would be closest to (but not exactly match) your 52mm.
    Also, leave your lens at infinity, if you want to know the magnification factor as accurately as possible. Otherwise it makes no difference where you have the focusing ring set (exception being lenses with CRC, but does not apply to yours).

    If your camera has through the lenses metering, you don't have to compensate your exposure. If not, you'll have to find a table for exposure compensation according to the magnification factor.
    M6, SL, SL2, R5, P6x7, SL3003, SL35-E, F, F2, FM, FE-2, Varex IIa

  4. #4
    Erik Petersson's Avatar
    Join Date
    Jan 2006
    Location
    Stockholm, Sweden
    Shooter
    35mm
    Posts
    634
    Images
    8
    Richard and Rol Lei Nut,
    thanks for your replies.

    Does exposure compensation relate directly to magnification? Does two times magnification mean that I should open up two stops?

    /Erik

  5. #5
    Rick A's Avatar
    Join Date
    Mar 2009
    Location
    north central Pa
    Shooter
    Multi Format
    Posts
    5,860
    Images
    32
    Exposure compensation does relate to magnification, but not the way you are thinking. If you have TTL metering, do not worry about this. there is a formula for figuring exposure comp, but I dont remember it off-hand. I recommend you find a copy of "The Manual of Close-Up Photography" by Lester Lefkowitz, has all the tables of info and methods of close-up work you could ever want. He even covers DIY gear for macro.
    Rick A
    Argentum aevum

  6. #6

    Join Date
    Jul 2007
    Location
    Netherlands
    Shooter
    Medium Format
    Posts
    5,686
    Quote Originally Posted by Erik Petersson View Post
    Does exposure compensation relate directly to magnification? Does two times magnification mean that I should open up two stops?
    It does. And no.

    Exposure compensation can be calculated using magnification into an aperture factor, a shutterspeed factor and a correction in stops.

    The first, aperture factor, is: 1 / (magnification + 1)

    The second, shutterspeed factor, is: (magnification + 1)^2

    The third, correction in stops, can be derived from either of the two above:

    log(aperture factor) / log(sqr(2)), or
    log(shutterspeed factor) / log(2)


    So a two time magnification needs an aperture correction of 0.33 times the f-number the meter suggests (so set f/2.7 instead of f/8); or a shutterspeed factor of 9 times the shutterspeed the meters suggests (so set 1/15 (actually 1/13.89) instead of 1/125), or a correction of 3.16 stops applied in any way you like.
    Last edited by Q.G.; 04-24-2010 at 10:04 AM. Click to view previous post history.

  7. #7
    Erik Petersson's Avatar
    Join Date
    Jan 2006
    Location
    Stockholm, Sweden
    Shooter
    35mm
    Posts
    634
    Images
    8
    Thanks QG. There is no TTL on this camera.

    Let's see if I get it.

    2 times magnification - f8 adjusted to f2,7
    1 time magnification - f8 adjusted to f4
    1,4 times magnification - f8 adjusted to f3,3

    My lens has one click stop between the standard apertures, so I will probably find acceptable settings.

    the shutterspeed factor, is that (magnification + 1) multiplicated with 2?

    Erik

  8. #8

    Join Date
    Jul 2007
    Location
    Netherlands
    Shooter
    Medium Format
    Posts
    5,686
    No, raised to the power 2.


    I usually take the long route and calculate the correction in stops.

    With the aperture being more important in close up than the shutterspeed, i then put the bulk of the correction into the shutterspeed, and use the aperture only for what then remains.
    That, not just because the aperture is more important, but also because shutterspeeds usually only come in whole stop intervals, apertures in 1/2 stop intervals.

    So, for instance, if a correction of 4.6 stops is called for, 4 stops go into a 4 stops slower shutterspeed, while the remaining 0.6 of a stop is taken care of by opening the lens 0.5 of a stop (the remaining 0.1 cannot be set, but also doesn't matter much).

    When shutterspeeds get long however (i.e. over 1 second), i put everything into a longer shutterspeed. Fractional stops perhaps translate into fractions of seconds. But with reciprocity failure kicking in, it stops being a precise art, and that again doesn't matter much. Just give it something extra, and it'll be fine.

  9. #9
    Erik Petersson's Avatar
    Join Date
    Jan 2006
    Location
    Stockholm, Sweden
    Shooter
    35mm
    Posts
    634
    Images
    8
    Ok, I think I know what I need now to try this out tomorrow. The main problem, now that the exposure compensation is clearer, will be to deal with the shallow depth of field. It will be fun to see what I can achieve with these bellows.

    Thanks everyone!

    Wait, I just realized that the lens will be fixed on f2 as the bellows does not stop down the lens. I will probably have to put a piece of tape on the "pin" on the back of the lens without making it sticky. Hmmm. Thanks anyway!

    Erik

  10. #10
    Rol_Lei Nut's Avatar
    Join Date
    Jul 2006
    Location
    Hamburg
    Shooter
    Multi Format
    Posts
    1,118
    Quote Originally Posted by Q.G. View Post
    It does. And no.

    Exposure compensation can be calculated using magnification into an aperture factor, a shutterspeed factor and a correction in stops.

    The first, aperture factor, is: 1 / (magnification + 1)

    The second, shutterspeed factor, is: (magnification + 1)^2

    The third, correction in stops, can be derived from either of the two above:

    log(aperture factor) / log(sqr(2)), or
    log(shutterspeed factor) / log(2)
    .
    There's a reason I suggested looking for a table...
    M6, SL, SL2, R5, P6x7, SL3003, SL35-E, F, F2, FM, FE-2, Varex IIa

Page 1 of 3 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin