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Thread: Grafmatic light leaks

  1. #11

    Grafmatic light leaks

    Paul, you may not care about, or consider the registration and parallelism of the film to be of much consequence in LF, but to say that a Grafmatic doesn't rely on plastic for it's dimensional stability is just plain wrong.The whole front face of the thing is plastic, and this is the bit that mates with the camera and forms a major part of the light seal. The steel back is merely a cover screwed to that plastic, and carried by it, as anyone can see.The moveable septum carrier is made of a metal alloy, but this simply slides behind the plastic front, and that plastic front most definitely plays a large part in governing the distance of the film from the camera back. If the plastic gets warped, then that distance won't be correct, no matter how flat the septums are.

    Consider that just the thickness of a sheet of film, a 0.2mm shift in focal plane, gives a 10% focusing error at 10 meters with a 150mm lens, regardless of aperture.Now, I'm measuring close to 0.5mm error in all my Grafmatics, and that's a 20% focus error.So what's the point of carefully focusing with a loupe on the GG, as most LF photographers do, when a dodgy filmholder then shifts your focus by nearly 2 metres in 10?

  2. #12
    tim atherton's Avatar
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    Grafmatic light leaks

    You mean compared to those plastic double sided film holders most of us use instead...?

    tim
    You'd be amazed how small the demand is for pictures of trees... - Fred Astaire to Audrey Hepburn

    www.photo-muse.blogspot.com blog

  3. #13

    Grafmatic light leaks

    Yes, I do mean compared to a normal double dark-slide. A DDS doesn't have springs riveted into the plastic, putting a constant pressure on it for 25 or more years. It's likely that a warped DDS of that age would be more readily discarded than a Grafmatic back too.

    The register of filmholders has been standardised at a 5mm depth for a long time (giving 4.8 mmm to the emulsion face of the film), whereas Wray or Graflex seem to have ignored, or been ignorant of, that standard.I'm still trying to get a straight answer to the question of whether US made Grafmatics ever conformed to the current standard film register, and whether the plastic is as prone to warping as the UK made ones.Anyone with a depth-gauge or caliper and a Grafmatic out there? In fact, just a straightedge across the mating face will show if it's flat or not.

  4. #14

    Join Date
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    Grafmatic light leaks

    Pete,

    Concerning your question at the end of your message, there is and interesting article by Joe Englander in the April 1995 edition of Camera and Darkroom, pages 52-7. Joe compares Riteway holders with Grafmatics, Kodak Readyload, Polaroid 4x5 and Fuji Quickload holders. His conclusions are that the Grafmatic holder comes closest to the industry standard of film distance. You can find this article on the Large Format Photography homepage.

    Permit me to add that the real issue in this question link is the source of possible light leaks with Grafmatics. I am eager to hear the results of Bill's testing efforts from last weekend.

  5. #15

    Grafmatic light leaks

    It seems I have started somewhat of a debate. I loaded the holders up again this weekend and did some more testing. I put my Crown Graphic on a tripod set up on my back porch overcast day in the shade. I exposed one holder all six shots on the same focus plane. The next day I shot the other holder outside hand held still overcast and processed all film at the same time. The holder shot on the porch had no leaks at all and futhermore the images look sharp all across the film plane. The holder exposed outside had small leaks at all corners as well as an eight of an inch at the film edge on the coded end. Upon further inspection I have found a crack in the holder that I used outside. It is cracked where the darkslide goes in right by lock. I think I might be able to glue it if anyone knows what type of glue to use. My conclusions are that I will not be able to use these holders for my intended purpose (handheld with the Crown). I also checked the holders with a straight edge and machinists' ruler and they seem to be flat across the film plane. This is not as precise as a micrometer but the images are sharp and thats what counts. In normal shooting conditions with my 8x10 on a tripod I always shield the holder with my darkcloth to avoid any leaks. Of all the used 4x5 sheet film holders I have purchased only the Riteways are any good the rest all leaked when exposed to normal room lights.

  6. #16

    Join Date
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    Grafmatic light leaks

    Bill: For the crack, try a little Permatex, available in a tube at any auto supply store. It will fill the crack, wipe off what's on the surface and you'll never see the fix. It comes in two "types" one hardens more than the other, both will work. If you get it on your skin you'll have to cut the skin off so smear it on with a glove on.

  7. #17

    Join Date
    Sep 1998
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    63

    Grafmatic light leaks

    Bill,

    It was very interesting to hear the results of your tests. However, I tend to disagree with your conclusion not to use Grafmatics for hand held shootings outdoors. I do this routinely and do not experience any light leaks as long as I keep the Grafmatic in shadow whilst withdrawing the darkslide or the inner magazine. In fact it is easier to use the Grafmatic for handheld shooting since this allows you always to turn around with the camera so that the exposed end of the Grafmatic is in shadow.

    Good luck with your continued handheld Crown/Grafmatic shooting and welcome to the club of new oldtimers that still appreciate this almost lost art.

  8. #18

    Grafmatic light leaks

    Thanks Emil.From that article, it appears that there's a vast difference between the US made Grafmatics and the UK made ones, because even allowing for some distortion of the plastic, there seems to be no way that the Wray holders could ever have given the correct film registration.Apologies to Bill for hijacking his thread, but it was an important point to clear up.

  9. #19

    Grafmatic light leaks

    I have recieved a lot of very useful info on grafmatic holders from this thread. Thanks to you all for your responses. I loaded the holders again last night and will try again to shoot with them hand held, shading the back as best I can while changing sheets. I do think these holders are a very inventive idea and probably worked very well for many years. I have not recieved the partial refund from the seller yet. When I do I may look for another holder in better conditon.

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