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Thread: Polaroid Shutters - What's the Catch

  1. #1

    Polaroid Shutters - What's the Catch

    I just purchased a 150mm f9 Computar off eBay. My goal is to test this lens as a possible wide angle on 4x10. I also have a 150mm f9 Graphic-Kowa that is supposed to be the same, but maybe not (there have been conflicting reports on the coverage of these two similar lenses). I plan to tset both and keep the one I like best (if there is any difference).

    In any case, unlike my 150mm Graphic Kowa that came in a barrel, this Computar came in an obviously non-original Polaroid Copal shutter. This shutter has a couple limitations compared to a standard Copal No. 1 shutter, but those may prove irrelevent in this case. First, since it is a self-cocking shutter, the top speed is "only" 1/125 sec. compared to the 1/400 sec of the standard Copal No. 1. Not an issue for me personally as I can never recall taking a single large format image at a shutter speed faster than 1/125. Second, the maximum opening of the aperture blades isn't nearly as large as a standard Copal No. 1 shutter. This might be an issue if attempting to use this shutter with a faster 150, or longer lens. However, in this case, the maximum aperture opening is a hair larger than the internal field stops of the lens cells (in other words, the diaphram does not limit the maximum aperture, the cells do). In fact, I'm told by the seller that this shutter is originally from a 75mm f4.5 Polaroid Tominon lens. In that case, it would seem I can just double the marked aperture setting to get the true aperture of my 150mm lens. In other words the f4.5 setting = f9, f5.6 = f11, f8 = f16, etc. all the way down to f45 = f90. As long as I can remember to mentally multiply by two, I don't even have to go to the expense of getting a new aperture scale engraved.

    And much to my pleasant surprise, this Polaroid Copal shutter is significantly lighther than a standard Copal No. 1 shutter (115g vs. 160g). The shutter speeds all work properly and seem every bit as crisp and snappy as any other Copal shutter I own. There is no press focus lever, but the shutter has a T setting that can be used for focusing.

    So, what's the catch? Is there one? The smaller max. diaphram opening (about 15 or 16mm) would limit the usefulness of this shutter for faster or longer lenses, but in this case it seems to be a good match. Am I missing something here, or did I just get a good deal on a shutter mounted lens that will cover 4x10 and weigh less than 200g?

    Kerry

  2. #2
    Scott Rosenberg's Avatar
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    Polaroid Shutters - What's the Catch

    kerry... i don't know how much help my response will be, but i use a 75mm f4.5 Polaroid Tominon lens mounted in the same shutter you have for macro work on my technika. it's been working wonderfully for me. the only differences in function between it and a copal shutter, as you have already discovered, is you use the 't' setting to focus and the aperature scale isn't marked in 1/3 increments, so there's a bit of estimating there. other than that, it works brilliantly... quite crisp and snappy.

  3. #3

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    Polaroid Shutters - What's the Catch

    Kerry, there are other Polaroid Copal 1 press shutters that can be used with longer/faster lenses. The Tominon 127mm and 135mm came in those. They can be had for less than $100 with the lens in (in new condition). The Tominon 105mm comes in a Copal 0 if the shutter is between the lens and a Copal 1 if the lens is entirely in front of the shutter. I enjoy using press shutters because I don't have to remember to cock them. Jim Galli buys G Clarons and mounts them in these shutters for resale. He would be a good person to ask about limitations. I have a 210mm Sinaron S mounted in the same shutter (it was conienient). It is diaphram limited to ~f/11. I will replace the shutter when another comes along but for now it works fine.

  4. #4

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    Polaroid Shutters - What's the Catch

    Kerry, there's one tiny catch, but I don't think it applies to you. For flash photography out-of-doors, 1/125 can be a little on the slow side.

    I front mount a variety of lenses on ex-MP-4 (badged "Polaroid MP-4") #1 Copal Press shutters. The ex-MP-4 #1s have two tiny advantages over ones like yours and one large disadvantage. The large disadvantage is no diaphragm. The tiny advantages are a large fixed aperture, 30 mm to be exact, and "open shutter" lever/cable socket. So for front mounting an MP-4 shutter is the one to get.

    IMO, the most useful of the ex-CU-5/DS-34/DS-39/who knows which other Polaroid cameras Copal #1 shutters is probably the one used for 127/4.7 Tominons. Its diaphragm opens to 30 mm. This is the shutter that that vandal Jim Galli puts most of the recycled process lenses he sells on eBay into. Lenses for the Polaroid MP-3 were mainly in #1 Prontor Press shutters. Much the same in use as the MP-4 Copal #1 Press PLUS with a diaphragm (most of 'em) but with only an "open shutter" socket, no lever.

    Cheers,

    Dan

  5. #5

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    Polaroid Shutters - What's the Catch

    Personally, I prefer self-cocking shutters. Unfortunately, usually you have no choice.

  6. #6

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    Polaroid Shutters - What's the Catch

    As the others have said, no catch at all. Especially with the 127 f4.7 version that has a max aperture almost as large as standard Copal 1. It is a little smaller. A 5.6 210 becomes an f8 210 in one. The only catch is threads like this will drive the price up on Ebay and I need a couple for lenses on their way from Chermany. MP4 shutters are no good as they have no aperture at all.
    He is no fool who gives what he cannot keep..to gain that which he cannot lose. Jim Elliot, 1949

  7. #7

    Polaroid Shutters - What's the Catch

    Kerry,

    There is one difference that nobody has mentioned, and it may not be terribly significant on normal lenses, but it may affect sharpness and aperture calculations on wide angle lenses.

    The press shutters have the iris about 1mm further back from the front threads compared to the normal shutters. I don't know if the Polaroid shutters do also, but it's worth a check, and also a consult with someone knowledgeable as to whether the difference will be a problem that will affect sharpness or other performance issues.

    For the sake of having complete information, I think it's worth mentioning this.

    ---Michael

  8. #8

    Polaroid Shutters - What's the Catch

    Gentlemen,

    Thanks for all the responses. They have been very enlightening. It sounds like the Polaroid Copal shutter from the 75mm Tominon will be usable for my application. As I have two 150mm f9 lenses to test, I just picked up another 75mm Tominon in a Copal shutter off eBay for $25. I could have just swapped the cells back and forth between one shutter, but for 25 bucks it didn't seem worth the hassle or the risk of dropping a lens cell or cross-threading it in the shutter when working outside with cold fingers. Besides, when I decide which lens to keep and which to sell, I'll be able to offer a complete lens/shutter rather than just a barrel mounted lens.

    I did find one additional difference... The Copal press shutters, both No. 0 and No. 1 have a larger min. diaphram opening. This means they won't stop down quite as far as a regular Copal shutter. For the Copal No. 1 Press, the min. diaphram opening is 2.5mm compared to 2.0mm for the regular Copal No. 1. Again, not an issue for me as I won't be shooting beyond f64 with my 150mm lens anyway.

    I found a handy table of specs for all current Copal shutters on the RTS (official Copal distributor) web site at:


    http://www.rtsphoto.com/html/copal2.html


    This table confirmed my finding concerning weight (when I first picked it up, I was amazed how light the 150mm f9 Computar felt in this shutter) - the No. 1 Copal Press shutter at 115g is indeed 45g lighter than the standard Copal No. 1 shutter (160g). In fact, at 115g the Copal No. 1 Press weighs exactly the same as a standard Copal No. 0 shutter. So, you get Copal 1 size at Copal 0 weight (I tend to obsess about these things). The weight savings are less significant with the Copal No. 0 press shutter. At 100g, it's only 15g lighter than a standard Copal No. 0, and heavier than both the recent all-black Compur 0 and the Seiko 0 shutters.

    Jim,

    Sorry, it was not my intent to drive up prices. Due to the small max. disphram opening on the 75mm Tominon shutters, it doesn't sound like there will be much demand for these. They just happen to be a good match for this one particular application. It sounds like the shutter from the 127mm is a much better "general-purpose" replacement.

    Michael,

    Yes, you are correct, the iris diaphram is placed further back in the Copal Press shutters. In theory, this could cause some performance issues for certain types of lenses. However, (and I could be wrong here, as this is based on assumption) I don't think this will be an issue for most modern lenses. Most manufacturers offer press shutter as an option for their lenses. So, the spacing either isn't an issue, or they have to manufacture two different versions of their lens cells for the different shutter types. I don't believe they do this. Simple shims would not work since moving the rear cell back with a spacer would require setting the front cell deeper into the shutter to maintain the proper cell:cell spacing. However, the iris location can present a mechanical mounting problem with some lens cells. From what I've read online, this is a common problem when attempting to mount Fujinon lenses in Copal Press shutters.

    Kerry

  9. #9

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    Polaroid Shutters - What's the Catch

    Jim's concern that WE will drive up the prices he has to pay is self-serving and unworthy of him. HE drives up the prices we pay. Who bids highest gets the item, end of discussion.

  10. #10
    tim atherton's Avatar
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    Polaroid Shutters - What's the Catch

    Dan - so serious - and it's almost Xmas too. Could it just be Jim was being a little tongue in cheek... avid ebayer that he is?
    You'd be amazed how small the demand is for pictures of trees... - Fred Astaire to Audrey Hepburn

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