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. I do NOT mean 'mirror flap' - 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 - what have you done - if anything - to get critically sharp shots at shutter speeds 1/30th and slower?
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.
At what longer shutter speed can one expect the problem of uncrtically sharp iamges due to camera vibrations to be minimized again?
Thanks in advance for any knowledgeable or general input on shuutere vibrations on this particular system.
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.
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.
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.
No, it does relate to the thread in the matter of judgement. What are assumed to be critically sharp images often turn out to be slightly un-sharp if viewed with your nose against the glass. Look at enough Ansel Adams prints and the same images are always slightly un-sharp viewed close up, which rules out printing, and it also rules out the idea that the image is junk just because the camera moved a bit in the wind, or that he used a lens that gave him something more special than being perfectly sharp.
As for the Bronica, sorry, never seen this shake caused by the mechanism. I use it (not so much nowadays) on a medium weight Manfrotto carbon tripod, and carbon does dampen vibrations more than aluminium which may have helped.
Steve
I have used Bronicas since the 80s and still use a SQ-Ai regularly, nearly always with the mirror locked and with a cable release - tripod mounted. Quite often I use the SQ-Ai on very long timed exposures with a 135mm lens and have never noticed and un-sharpness problems caused by the shutter of my lenses. If this problem shows with all your lenses I would have thought it was pointing to a tripod issue. If it is just one lens that is causing the problem there could well be an issue with that lens.
Neil.
Ok, so here are the results from my GS-1 vibration test. GS-1 mounted on old (but solid) silver Manfrotto 055 tripod with 115 head ...
This specific discussion has moved to the GS-1 which could, for all I know, be different structurally from the SQxx series. I'm thinking maybe the "cable release" in some of the last Bronica stuff is electric rather than mechanical -- could there be some pretty nasty solenoid actuating the shutter -- more plastic in the body -- a floating lens element that is a little too buoyant ?? Aye, the mind reels at the possibilities! They all looked better than the 10 MP electrocuted bits!
Although I have never done controled tests, my GS-1 definitely has a pretty loud clack when the shutter is released with the mirror pre-released. The shutter tensioning arm and mechanism at the bottom of the camera travels a short distance to the left when the shutter is release, and there is a lot of mass there. It starts and stops very abruptly, so much so that you can feel it when you hold the camera. It "feels" about the same as the FP shutter on a 200 serise Hasselblad, (ie: amount to mass moving and stopping - but I've never actually measured it quantitatively), and I definitely have observed shutter vibration on those when a long lens was mounted on an inadequate ball head. The 500 serise leaf shutter Hasselblads are not only quite when the shutter releases with the mirror up, you definitely don't feel any vibration (probably because all the actuating motion is rotating instad of translating)
I've never really noticed this on the GS-1, but then I've never had it on an inadequate ball head with a long lens - most of the time I use it hand held. But I've always wondered what effect that "clack" had, thanks for illuminating that.
However, the question is, is the loss of resolution visually significant when you view an enlarged print on the wall. If it is, then I would get a better ball head or not use those shutter speeds. Myself, I would probably be OK with what you have - but I would "try" to avoid those shutter speeds. I think only us photographers get anal over these pixel/grain peeking measurements, to most people, a good photograph is a good photograph.
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