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Thread: Nikkor shutters

  1. #1

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    Nikkor shutters

    I went digging through the archives on this but couldn't find the answer...

    I prefer to travel really light. As such, I'm wanting to leave some shutters and lensboards at home. I am thinking of carrying a bunch of lenses but only a couple of shutters. But, in comparing shutters that were specifically made for Nikkor lenses, it looks like I can't swap lenses around to use one shutter for a couple of lenses.

    With the lenses off, the size of aperture of two Nikkor shutters at the same f-stop are different. So, while the lenses and the shutters are interchangable with regards to the threads, the aperture and aperture scale will be incorrect.

    Can someone confirm this for me? Has anyone developed a fudge factor such that f/22 on the correct shutter is f/xx on a different Nikkor shutter? Do I need to be concerned that the spacing between the rear elements of the lenses are incorrect when using a different shutter?

    And, what about putting Nikkor lenses on generic Copal shutters?

    Thanks for any input.

    Cheers,
    -bob

  2. #2

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    Re: Nikkor shutters

    You could have a scale made similar to those on a convertable lens, with each lens' elements f-stop indicated. Grimes could probably do that.
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.
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  3. #3

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    Re: Nikkor shutters

    I would sure be worried about taking lenses apart in the field. I am not sure this the best way to save weight. You could put them on smaller boards and get an adapter for your camera. If you go with small lenses, the copal #0 and 1s do not weigh much.
    Last edited by Ed Richards; 15-Jul-2006 at 19:55.

  4. #4

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    Re: Nikkor shutters

    Bob,

    When I was looking into having an aperture scale engraved onto a Copal 3 shutter for my Symmar 360 f/6.8, S.K. Grimes insisted that the lens be sent in with the shutter. I asked why they required the lens and they explained that it was necessary for calibrating the shutter openings to the markings on the shutter.

    In general, if the f-stops are the same for both lenses, I wouldn't think there's that much of an issue for using different sets of lenses in the same shutter. I've done this on occasion and have not seen any detrimental effects.

    However, I would be a bit more concerned about swapping lenses in the field. IMHO, it wouldn't be that difficult to cross-thread a lens especially if one were in a hurry...

    In order to lighten the weight, have you thought about mounting your lenses on to smaller lens boards and using adapter boards? For example, I have 5.25 x 5.25 inch square boards for the Sinar, Technika boards for the Dorff 5x7, and 6x6 boards for a Dorff 8x10. What I've done is to mount all of my lenses onto the smaller Linhof Technika boards and bought adapter boards to accept them for use on the other cameras. That way, I don't have to constantly swap lenses between camera systems. The down-side is that there IS an initial investment for the adapter board...

    Just my 2 cents worth!

    Cheers
    Life in the fast lane!

  5. #5

    Re: Nikkor shutters

    Quote Originally Posted by bobc

    ...............

    With the lenses off, the size of aperture of two Nikkor shutters at the same f-stop are different. So, while the lenses and the shutters are interchangable with regards to the threads, the aperture and aperture scale will be incorrect.

    ...........

    This isn't some special property of Nikon shutters, nor should it be unexpected. The equation for the f-stop N is N = focal length / aperture diameter. So two lenses of different focal lengths will need different aperture diameters to achieve the same f-stop. You could use the equation to develop "joint" scales to use several lenses on shutter.

    There is a further consideration. With a complex lens, the aperture diameter should really be measured as the entrance pupil, i.e., by viewing the aperture through the lens, which might magnify the aperture and change its apparent diameter. So it is even possible for two lenses of the same focal length to have different mechanical diameters of the shutter diaphragm for the same f-number.

    As the others have said, I'm not sure that swapping lens cells in the field is such a good idea. The threads are fine, and Copal 0 and 1 shutters don't weight that much. If you have a Nikkor-SW lens, you have to be very careful with the thin shim washer used between the front cell and the shutter.

  6. #6

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    Re: Nikkor shutters

    Nikon, to my knowledge have never manufactured shutters. If you are talking about the Copal shutters that come with MOST Nikkor large format lenses (assumption again here), then there is nothing mystical nor magical - nor anything that might require the likes of Grimes Co. The major thing you have to be careful of is to transport the shims (if applicable) WITH the lens cells - and don't get them mixed up (!!). That could be deadly.

    I would assume that even the most novice of LF photographers wouldn't be put off by aperture scales. You already know that the f-number corresponds to a fraction of the focal length, right? Well, Let's say we're going to use a 150mm cell set on a shutter made for a 75. Well, now what is f/11 on the 75 scale becomes f/22, since the absolute size is exactly HALF what it needs to be. This would be the opposite case, were you to use the 150 shutter/scale on a 75. At any rate - I'd say it's all quite do-able. But I'd personally rather just carry the lenses and their respective shutters with me. Less mental gymnastics that way.

    Jonathan

  7. #7

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    Re: Nikkor shutters

    Quote Originally Posted by Michael S. Briggs
    There is a further consideration. With a complex lens, the aperture diameter should really be measured as the entrance pupil, i.e., by viewing the aperture through the lens, which might magnify the aperture and change its apparent diameter. So it is even possible for two lenses of the same focal length to have different mechanical diameters of the shutter diaphragm for the same f-number.
    Michael - I generally agree with everything else you've said, but not this. The 'apparent' magnification of the aperture does not make it admit more or less light. It has only to do with the physical (actual) size of the diaphragm. IF you had noticed that different lenses of the same focal length have different size diaphragm diameters for the same f-number - I would suspect it is either because a) there's been some hanky panky with that lens/shutter or b) just because it might be, let's say, a "240mm" lens - the actual measured focal length may in fact be 228.5mm or 255.4mm. Many measured FLs DO tend to be out by this much - most often by design, but sometimes simply due to variability in manufacturing. Of course - feel free to take this as opinion if you like. I just thought you might be overcomplicating the issue in your head a bit.

  8. #8
    All metric sizes to 24x30 Ole Tjugen's Avatar
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    Re: Nikkor shutters

    Quote Originally Posted by JW Dewdney
    ... The 'apparent' magnification of the aperture does not make it admit more or less light. It has only to do with the physical (actual) size of the diaphragm. ...
    Michael is absolutely correct. The "aperture diameter" in the equation is the diameter of the entrance pupil, not the physical opening of the aperture.

    The difference is often slight between lenses of similar design, but the difference between a Tessar-type and a plasmat can be large enough to be significant.

    Telephoto lenses are even more extreme, with a strong positive group in front and a negative group behind.

    The lens doesn't have to be very complex either (that's where I disagree), a simple meniscus lens or single cell of a convertible lens is far simpler than most LF lenses, yet show the difference in effective aperture very clearly.

  9. #9

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    Re: Nikkor shutters

    Quote Originally Posted by Ole Tjugen
    Michael is absolutely correct. The "aperture diameter" in the equation is the diameter of the entrance pupil, not the physical opening of the aperture.
    Ole - I BELIEVE Michael is saying the exact OPPOSITE - he's saying that the physical APERTURE itself "should be taken AS the entrance pupil" - but in addition to this - he's suggesting that because viewing it through the front element will alter the apparent size of it (based on it's magnification factor) that this would affect it's light gathering ability. This APPEARS to be what he's saying. And this is what I'm objecting to.

  10. #10

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    Re: Nikkor shutters

    I don't think lens designers EVER consider the actual aperture mechanism in developing an optical formula - only for determining where the blades should sit and how it will affect the housing design. There wouldn't be any need to. It could easily be treated as an afterthought except in very few, very special applications which are limited by aperture placement.

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