TLR DoF DOA

Discussion in 'Medium Format Cameras and Accessories' started by FrankB, May 31, 2006.

  1. FrankB

    FrankB Member

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    I've recently started using a Mamiya C330S TLR for a lot of my shots, and the lack of a depth of field preview facility is really causing me grief.

    The focus scale is (IMHO) next to useless, so even the DOFMaster program I have for my Palm PDA isn't much of a help. Throw in that I'm used to working with 35mm instead of 6x6 (and that a 6x6 80mm 'feels' to me like a 135 50mm, etc.) and time and again I'm finding that the depth of field has tripped me up, even if I attempt to focus hyperfocally. For selective DoF shots the reliability of my cackhandedness nears 100%! :sad:

    All you TLR shooters (especially Mamiya interchangeable lens users) - How do you manage? Any tips you can offer?
     
  2. Lachlan Young

    Lachlan Young Member

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    Make sure you find out whether the distance scale is in feet or metres, then try and get a copy of the Mamiya instruction manual which includes the DOF scales. I have found them to be perfectly adequate for purpose.

    Good luck!

    Lachlan
     
  3. JJC

    JJC Member

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    Hi Frank,

    DOF charts are available from Mamiya's site at http://www.mamiya.com/assets/pdfs/twin_lens/C330_Depth-of-Field.pdf

    For the 80mm lens I've found that I need to stop down 1-2 stops more to get the same dof I was used to from a standard lens on a 35mm camera. The distance scale on my C330f is in meters, and isn't too bad until I get around the last distance mark before infinity. At that point, I find it better to visually estimate, or pace off the distance, and then use the charts. For my photos, I usually am content to have a little more dof if I'm unsure, but it sounds like you are looking for some fairly fine precision. There is a 105mm DS lens for the Mamiya that has dof preview on the viewing lens, if using the charts doesn't allow you to visualize the way you want to.

    I hope I've helped a little.

    JJC
     
  4. Gerald Koch

    Gerald Koch Member

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    I think this explains your problem. MF technique is very different from that for 35mm. Once you are completely familiar with the 330 I think your problems will disappear.
     
  5. Claire Senft

    Claire Senft Member

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    I have no experience with a Mamiya C330. I have considerable experience with an RZ 67. The DOF scales are virtually unusable to me. Of course the camera has depth of field preciew and a very nice viewing system.

    The most common DOF scales have been set using a 4x5 print as a standard.

    Any camera takes a while to use with skill, Perseverance is in order.
     
  6. Dave Miller

    Dave Miller Member

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    D.O.F. scales can be found on grahams site:
    http://www.btinternet.com/~g.a.patterson/mfaq/m_faq-contents.html

    Focus about a third of the way into the scene, which is not always on the subject, and use the tables to estimate front and back focus points. The bigger the planned enlargment the shallower the apparent D.O.F. therefore use a smaller aperture to compensate.
     
  7. FrankB

    FrankB Member

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    I think you've probably nailed it there, Gerald.

    Thanks for all the responses. As I mentioned, I have a program called DOFmaster for the Palm which is the equivalent of DOF tables. I understand about hyperfocal focussing too, and where to place to point of focus within the field.

    I think it's just a lack of familiarity with the format, compounded by the lacknof DOF preview on the TLR. I may look into getting a laser rangefinder (although these are pricey in the UK) but mainly it's probably a case of practice, practice, practice!

    Thanks again.

    Frank
     
  8. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    DOF scales and charts are useful once you get the hang of it and decide what you regard as "sharp" relative to the scale. I usually stop down one or two stops from the recommendation of the scale (any scale, any format).

    I consider f:11 to be a good medium range aperture for medium format, as I would consider f:8 to be for 35mm or f:22 for 4x5", so if you find yourself stopped down to f:11-22 for what you want, don't think it's unusual. That's just normal.

    Meanwhile, experiment with selective focus at wide apertures. That's part of the fun of medium and large format!
     
  9. grahamp

    grahamp Subscriber

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    Ironically, the distance scales used on the C33 and C22 were better than the ones on the C330 bodies. The problem is that the C330 rod measures lens extension directly. Helical mount lenses expand the scale by using a lot of rotational travel for little forward travel.

    Experience is the best thing. If you use a laser rangefinder remember to focus the camera on your chosen point by eye - the scale is nothing like accurate enough.
     
  10. Marco Gilardetti

    Marco Gilardetti Member

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    Frank, what kind of photographs are you taking? You're the first one I met who relies on the DOF preview. I always use it to see if the background is blurred enough, NEVER ABSOLUTELY to check how much something is IN focus. Plus, a roll meter for close ups and guessing for long distances are more than sufficient in most cases! Why do you think you need a laser telemeter?
     
  11. FrankB

    FrankB Member

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    Hi Marco,

    In 35mm terms, I generally work as you suggest.

    However, the depth-of-field in 6x6 with a standard (80mm) lens is considerably shorter than in 35mm with a standard (50mm) lens. With the 180mm Mamiya lens the DoF is *much* shorter than I'm used to! This, and the inability to check, is repeatedly tripping me up.

    For landscape work I am quite often finding that I haven't allowed a wide enough aperture for my composition and either the foreground or the background is soft. In another case I wanted selective DoF for a contre-jour dewy spider-webbed cross in a graveyard. When I check the neg afterwards I find that one side of the cross is sharp as a tack whilst the other is softer than I feel I can get away with, even at 10x8. (I'm currently looking at the possibility of doing this with a paper interneg to give the whole thing a softer, more textured feel... but I may well be in "sow's ear" territory! :sad: )

    I find the distance scales on the C330S very imprecise and (in my inexperienced hands) useless. Others may (and apparently do) find differently. I'm not very good at guessing distances. Others may be (and apparently are) better.

    The idea of a laser rangefinder may well be overkill, but on the other hand may speed my learning process i.e. "The hyperfocal near point for this lens at this aperture is *this* much which makes it about that rock *there*. The hyperfocal focussing distance is *this* much which makes it that mossy patch *there*. Job's a good 'un!"

    I did a quick search online and apparently I'm not the only one who thinks this method may have merit. Unfortunately the products the other chaps are using are only available on the other side of the pond and the ones over here are ridiculously pricey.

    In the meantime I'll keep practicing and bracket my apertures more. If it were easy it wouldn't be fun! :smile:

    All the best

    Frank
     
  12. paul ron

    paul ron Member

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    If you go on the Mamiya forums for TLRs, there are some very knolagable people there, Han and Graham the guys that wrote the book on these TLRs.

    I believe there are focusing aftermarket gizmos you can buy including some gaget that measures the distance the lens has moved off the body. Another I remember being marketed was a special knob with a scale on it like the Yashicas have.

    As many people here have mentioned, it's a matter of practice. Like your 35mm, you will pick up certain tricks to make life easy. If you are doing studio or controlled environment shooting, I sugest you put a ground glass on the film plane, make your focusing adjustments and make reference marks on your camera body so you can repeat the same on demand when you have it loaded with film.
     
  13. grahamp

    grahamp Subscriber

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    Well, Han Verhulst is actually writing the book.

    There were a few devices that attempted to compensate for the poor focus scales (mind you, no scale is as reliable as a good loupe on a large format camera, but I digress).

    One was an odd gadget that fitted in the flash shoe and incorporated something like a dial gauge. The anvil of the gauge pressed against a flange attached to the lens board of the camera. It gave very precise lens extension, provided the infinity point and the correct scale was used. Bear in mind that the extension of infinity focus varies with focal length with these cameras.

    Then there were two replacement focus knobs. One was just oversize, which makes finer adjustments easier. The other was internally geared and used a scale to give measurements.

    Best of luck finding any of these.

    The C33 scale was made up of a plate mounted alongside the bellows with a set of curved lines scribed on it. These lines read off against a vertical scale on the front of the camera body. Because the horizontal motion of extending the lens was enhanced by the vertical scale - more actual travel - it was potentially more accurate.

    The limited maximum apertures of the lenses count against you, too. The 180mm f4.5 has a DOF (from my own tables) of about 3.5 feet wide open at 30 feet. So your visual focus error is likely to be around +/- 1 ft.

    Stop-down depth of field preview on small and medium format has some value down to maybe f8 for me. Anything beyond that and you need a good screen, a darkcloth, and a magnifier.

    Depth of field _in practice_ is a fuzzy issue, more often than not. Experience in applying DoF tables is really useful.
     
  14. DBP

    DBP Member

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    Before you go off and spend real money on double checking focus, why not pick up an old-fashioned rangefinder like item 7623982731 on e*b*a*y. They tend to be really cheap and quite accurate.