Bronica SQ-Ai / PS lens - Unsharp Negatives due to Shutter (Not Mirror) Vibrations.
I am having problems with critical optical performance of my Bronica SQ-Ai/PS lens system and finally narrowed the problem down to the vibrations caused by shutter. [COLOR=Blue]I do NOT mean 'mirror flap' [/COLOR] - What I am reffering to is a critically unsharp image problem even with mirror locked up, and time allowed for those vibrations to subside - due to the heavy mechnism in camera and lenses that trip the actual leafs in the lens. It seems the problem is most pronounced with focal lengths 150mm and longer, and starts at shutter speeds of 1/60th second, but in my limited tests was more likely to be very prononced at 1/30th second.
I did testing with a heavy 1300 series Gitzo w/ center column weighted down and Arca Swiss B1 head, and RRS arca style quick plate.
Anyone who is familiar with the shutter mechanism knows that it causes vibrations itself even though the actual blades are leaf, very subtle, and not a problem in themselves. The mechanism that trigger these leafs, are pretty heavy duty high tension springs, rapidly rotating levers and a rapid stop there of. When you trip shutter carefully via cable release you can feel the camera vibrate even with the mirror locked up.
My question is for any Bronica users who are already aware of this and have addressed it: Other than fastening camera on a steady tripod, using cable release and mirror lock up - [COLOR=blue]what have you done - if anything - to get critically sharp shots at shutter speeds 1/30th and slower?[/COLOR]
Second question: I only tetsted three speeds 1/125, 1/60/ 1/30 so far - problem was most often at 1/30th and w/ longer lenses 150mm, 180mm, 250mm - especially the 250mm at 1/30th.
[COLOR=blue]At what longer shutter speed can one expect the problem of uncrtically sharp iamges due to camera vibrations to be minimized again?[/COLOR]
Thanks in advance for any knowledgeable or general input on shuutere vibrations on this particular system.
I don't have problems getting critically sharp negs and transparencies at any speed with my Bronicas. I use 150mm and 250mm lenses (amongst others) and I think 1/30 would be about the speed I use most frequently. I use a decent tripod- but only Manfrotto 055/190 models. Mostly I don't use a cable release, but the shutter release on a Speedgrip. Fortunately it does seem like yours is the exception not the rule and the steps you are taking have provided sharp images for me on my current and previous cameras. Maybe it needs technical help?
Hello David, we corresponded a few weeks ago on Zeiss vs. Zenzanon via email.
I am getting much better performance from my PS lenses with Mirror lock up, cable release, and tripod but noticed that my frequent speeds of 1-60th and especially 1-30th of a second, images show blur due to shutter vibrations hence this post.
Particular camera does not need servicing. This problem occurs with all my SQ'Ai bodies. Its shutter vibration. If you look with a high quality loupe at 12x there is a distinct effect at 1-30th and sometimes 1'60th. I will test slower speeds later.
In general, mirror/shutter vibration issues are most problematic between 1/30-1/4 sec, but of course it will depend on your system, and it would be easy enough to test for yourself.
Have you tried another tripod system? Even if you have an heavy tripod and head, it may be tuned to a resonant frequency that is produced by the camera, and there is no convenient way to predict it without testing. You might also experiment with putting a beanbag on the camera to dampen vibrations with long lenses.
I'm 8 years too late with this reply but I guess it's still relevant for anyone experiencing this problem, and it's the only reference I've found online so far which suggests the problem exists at all.
Originally Posted by Andre Noble
My experience is actually with the Bronica GS-1 not the SQ, but your issue sounds so similar to what I experience that I'd bet that it's similar mechanics which are causing the problem. Unfortunately I haven't resolved the problem so my contribution here is simply to confirm the problem exists and add a bit of detail.
My test setup was with an old silver version of the Manfrotto 055 tripod, resting on a concrete floor and set to a height somewhat below head height. Of course I used mirror lock and cable release, and exposed at a series of shutter speeds but kept aperture the same and maintained consistent exposure by increasing illumination on the subject as shutter speed increased. I made darkroom prints of the sharpest section of the negative at high enlargement and ensured grain was sharp in the print. I used the standard 100mm PG lens for this test. I also shot a 'control' exposure, where I used the light source as a shutter (open the shutter with the light off, wait a couple of seconds, turn the light on, turn light off, close shutter).
Although all the shots could easily be deemed 'sharp' by many, it is clear that some are significantly sharper than others, with the finest detail being lost at a number of shutter speeds. I tested at 2s, 1/2s, 1/8s, 1/30s and 1/125s (plus the control). My results are as follows:
There's no discernible difference from the control at 2s and 1/2s.
There's a pretty significant drop in sharpness at 1/8s
At 1/30s, sharpness is somewhat worse than at 1/8s
At 1/125s sharpness is the same as at 1/8s
Based on my results, I would suggest that shake becomes significant at 1/4s, peaks at 1/30s, and is almost gone by 1/250s. With longer lenses, I would expect the pattern to be the same, but with greater amplitude to the vibration-induced blur. This would seem to back-up your own findings.
I have been slightly disappointed generally with the level of sharpness I have been getting in real-world shots with this camera. At times I have wondered whether the lenses were a little below par. However, I recently conducted a test which proved otherwise, where I mounted the 100mm PG on an 18 MP APS-C DSLR and compared results to those from a Sigma 70mm macro lens on the same sensor. The Sigma is generally considered to be a very sharp lens even on these small formats, yet I was surprised to find that the PG was just as sharp. This kind of resolving power on a large negative should result in fantastic quality. So I'm now pretty convinced that the slightly underwhelming sharpness of my real-world shots are largely down to shutter vibration.
On the GS-1 at least, most of the vibration comes from the mechanism inside the body which triggers the shutter, rather than the shutter itself. This seems to correlate to what you have found. I was thinking that the solution might be to use a heavier tripod, but it sounds like your tripod is heavier than mine and you still get the problem. The vibration does appear to be mostly horizontal, so I'm thinking that having the tripod legs spread at a greater angle may help. The only other solution I can think of would be to use an ND filter to bring the shutter speed down to 1/2s or slower. However, if you are at 1/125s, this would require a 6-stop ND. It would need to be a high quality filter to avoid blurring, colour shifts or flare, but this is perhaps workable with static subjects.
Sorry I can't help much with a solution to this. If anyone else has found a solution to this for the SQ or GS I'd like to hear from them.
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Can't say I've ever noticed any issues related to this with my SQ-A, SQ-B, or my erstwhile SQ-Ai with any of my lenses, including the 135mm and 180mm PS.
Originally Posted by jgboothe
jg, my old 055 isn't very stiff in torsion. This is a design problem, the bearing surfaces in the joints between leg sections are too short.
In addition, the little set screws that help hold the head tight against the tripod's platform tend to back out during travel. This isn't a design problem. Check the set screws, then see how much the top of the tripod will rotate under gentle pressure when it is set up as you've been using it.
I have shot both the ETRSI 645 camera AND the GS-1 with a good variety of glass. Never seen a problem as Andre describes personally though I have not done any tests per say. Once or twice I have gotten an unsharp neg or two but almost always I can attribute this to something along the lines of heavy wind (the 250mm PE is very susceptible to this..it also balances poorly on the camera so I have to be very very careful when using it) or poor technique on my part. I definitely notice a difference in sharpness if I forget to use the MLU function with just about any Bronica lens unless my shutter speeds are quite high.
I use a manfrotto tripod with a 3047 head. I find even if the tripod handles are a little loose I have no problems getting critically sharp images at 1/15th//1/8th etc even with long glass. I have not noticed any difference in sharpness between these negs/trannies and those of say a 30 second exposure. I use the 110mm macro most frequently as the geometric distortion in the copy of the 100mm PG lens I used to have was intolerable for my needs (though my sample was very sharp, subjectively sharper than the 110mm Macro PG at infinity as would be expected).
Unfortunately, Andre has a very very negative view of the Bronica system as witnessed by his constant derogatory comments on greenspuns site. I would take anything he posts with a grain of salt. My experiences with Bronica have been very good and I have shot many medium format cameras over the years.
If jgboothe wishes me to conduct a test with my GS-1 I would be happy to oblige. Contact me through apug. I have a number of rolls being shipped off early next week for processing so now would be an opportune time for me to conduct a quick test.
The question you have to ask, what does a print at a proper viewing distance look like?
Not in the least related to the topic of this thread.
Originally Posted by hoffy