69xchange Posted April 19, 2023 Share #1  Posted April 19, 2023 (edited) Advertisement (gone after registration) I decided to test the accuracy of my MP. so I shot a roll of fuji superia 400 (USA) on an overcast day and took 3 frames/shots per shutter speed and adjusted the aperture based on shutter speed for correct exposure. The results: 1/1000, 1/125 and below are all consistent; however 1/500 and 1/250 have a green cast to the shadows. I am not sure if this is due to inaccuracy of the 1/500 & 1/250 speed and was wondering if this looks like a stop or more under exposed? I know that the tolerance could be 1/3 +/- of faster speeds but I am not sure if 1/3 stops are differentiable?  First picture is over all picture and second picture is centre crop All pictures on the left is 1/125 @ f8 while pictures on the right is 1/250 @ f5.6 Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Edited April 19, 2023 by 69xchange Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/375725-mp-shutter-speed-accuracy/?do=findComment&comment=4753761'>More sharing options...
Advertisement Posted April 19, 2023 Posted April 19, 2023 Hi 69xchange, Take a look here MP shutter speed accuracy. I'm sure you'll find what you were looking for!
69xchange Posted April 19, 2023 Author Share #2  Posted April 19, 2023 Top right corner crop Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! 1 Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/375725-mp-shutter-speed-accuracy/?do=findComment&comment=4753762'>More sharing options...
250swb Posted April 19, 2023 Share #3 Â Posted April 19, 2023 The colour balance is off in all of the pictures and colour balance is no way to judge shutter accuracy anyway. The problem may be in how you or the lab scan the pictures 2 1 Link to post Share on other sites More sharing options...
Huss Posted April 19, 2023 Share #4 Â Posted April 19, 2023 You cannot test the accuracy of your shutter by shooting a colour negative film that has very wide exposure latitude. 5 1 Link to post Share on other sites More sharing options...
Mikep996 Posted April 21, 2023 Share #5 Â Posted April 21, 2023 (edited) Yep, shoot some slide film using the same procedure. Edited April 21, 2023 by Mikep996 Link to post Share on other sites More sharing options...
69xchange Posted April 22, 2023 Author Share #6  Posted April 22, 2023 (edited) On 4/19/2023 at 10:11 AM, Huss said: You cannot test the accuracy of your shutter by shooting a colour negative film that has very wide exposure latitude. Hmm, but based on the negatives wouldn’t this show that frame 8 is a bit thinner than frame 9? Both shot at correct exposure but frame 8 is 1/250 f/5.8 while frame 9 is 1/125 f/8.  My question is does this look like 1 stop exposure difference or within tolerance? Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Edited April 22, 2023 by 69xchange Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/375725-mp-shutter-speed-accuracy/?do=findComment&comment=4755868'>More sharing options...
spydrxx Posted April 22, 2023 Share #7 Â Posted April 22, 2023 Advertisement (gone after registration) The film has too much latitude to properly assess minute differences. Your best bet is either color positive film or an inexpensive shutter speed tester. 1 Link to post Share on other sites More sharing options...
TomB_tx Posted April 22, 2023 Share #8  Posted April 22, 2023 Film camera shutter speeds have a fairly loose tolerance, so the small variation in exposure you show doesn't look too bad to me. One speed might be to the + tolerance and the other to the - tolerance.  For example, it's common for a Leica cloth shutter to have a 1/1000 shutter speed test more like 1/700 after some use. 1 1 Link to post Share on other sites More sharing options...
Pyrogallol Posted April 22, 2023 Share #9 Â Posted April 22, 2023 They both look ok to me. There are many variables and the running of the shutter is one of them. The light changing a bit would also affect the negatives. 1 Link to post Share on other sites More sharing options...
andrew01 Posted April 22, 2023 Share #10 Â Posted April 22, 2023 (edited) 11 hours ago, 69xchange said: Â Â Â Edited April 22, 2023 by andrew01 Link to post Share on other sites More sharing options...
andrew01 Posted April 22, 2023 Share #11  Posted April 22, 2023 11 hours ago, 69xchange said: Hmm, but based on the negatives wouldn’t this show that frame 8 is a bit thinner than frame 9? Both shot at correct exposure but frame 8 is 1/250 f/5.8 while frame 9 is 1/125 f/8.  My question is does this look like 1 stop exposure difference or within tolerance? Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Thats probably 1/10 a stop difference, which is completely irrelevant. Just adjust the image to taste in processing.  1 Link to post Share on other sites More sharing options...
69xchange Posted April 22, 2023 Author Share #12 Â Posted April 22, 2023 1 hour ago, andrew01 said: Thats probably 1/10 a stop difference, which is completely irrelevant. Just adjust the image to taste in processing. Â Thank you! Link to post Share on other sites More sharing options...
Fotoklaus Posted April 23, 2023 Share #13 Â Posted April 23, 2023 You can't get absolute precision with a mechanical controlled cloth shutter like this one. But so far my pictures werden t affected by that if i have done my part correctly. Don' t think to much about that, go out and use your lovely camera. Everything fine! 1 1 Link to post Share on other sites More sharing options...
Kl@usW. Posted May 1, 2023 Share #14  Posted May 1, 2023 It's long ago that I did experimental physics, but I think that the set-up for testing the accuracy of the shutter is wrong. It depends on your  assumption that the  aperture of your lens has a highly precise step  from 5,6 to 8.   The aperture error  should at least  be 2, better 3 orders ( Größenordnungen) less than the parameter you want to measure. 1 Link to post Share on other sites More sharing options...
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