Bronica SQ-Ai / PS lens - Unsharp Negatives due to Shutter (Not Mirror) Vibrations.

Discussion in 'Medium Format Cameras and Accessories' started by Andre Noble, Aug 2, 2006.

  1. Andre Noble

    Andre Noble Subscriber

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    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.
     
  2. David Henderson

    David Henderson Member

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    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?
     
  3. Andre Noble

    Andre Noble Subscriber

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    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.
     
  4. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    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.
     
  5. jgboothe

    jgboothe Member

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    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.
     
  6. skysh4rk

    skysh4rk Member

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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.
     
  7. Dan Fromm

    Dan Fromm Member

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    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.
     
  8. johns photos

    johns photos Member

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    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.
     
  9. hoffy

    hoffy Member

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    The question you have to ask, what does a print at a proper viewing distance look like?
     
  10. johns photos

    johns photos Member

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    Not in the least related to the topic of this thread.
     
  11. 250swb

    250swb Member

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    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
     
  12. hoffy

    hoffy Member

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    Thanks Steve. You summed up exactly what I wanted to say about the issue, but couldn't quite type it out (without sounding rude).

    Cheers
     
  13. DWThomas

    DWThomas Subscriber

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    Maybe it's my aging eyesight, but I use my SQ-A on an off-brand carbon fiber tripod rated for something like 17 pound load and I can't say I've ever noticed a problem. If you use MLU, all the heavy duty mechanical motion is out of the way before the exposure is made, including the cocking of the shutter. The actual exposure shutter operation is barely audible when working outdoors, I find it difficult to believe there is much energy being dissipated during that shutter operation.

    My 1.3 (after tax) cents. :whistling:
     
  14. dynachrome

    dynachrome Member

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    I have a number of cameras in each Bronica category: ETR/SQ/GS-1. The leaf shutter mechanism itself is very quiet. It is sometimes necessary to enlarge a negative quite a bit before it is obvious that a loss of sharpness is being caused by vibration rather than poor focusing technique. The tripod I have used most often with medium format cameras is a Gitzo with a Slik Pro ball head. I have not seen the problem which is the subject of this thread.
     
  15. jgboothe

    jgboothe Member

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    Thanks for everyone's replies on this - I didn't expect so many so soon. It seems that myself and Andre are alone so far in experiencing this problem. Unfortunately this doesn't help a great deal in determining how I can improve things (I believe my tests are conclusive in showing that the problem actually exists with my setup at least).

    Perhaps it's possible that my copy of the camera is producing more vibration than other copies? The vibration from the shutter mechanism (using MLU of course) is fairly pronounced and easy to feel when holding the camera, which seems to be at odds to what some say. My Mamiya C330 shutter is many times quieter and barely detectable by feel. Not so the GS-1. The vibration only occurs when the shutter opens - the closing is barely audible/detectable. As I said before, it is the camera which is causing most of the vibration, not the lens, because I get the same vibration with the lens off.

    I'd certainly be interested to hear if this description of the shutter action seems to differ from your camera.

    What seems more likely to me is that the tripod and head happen to resonate with the shutter more than most. A number of people have mentioned carbon fibre tripods, which of course are meant to dampen vibrations better. Or perhaps I just need a heavier tripod. I think I'm going to do some tests with some other tripods and heads, plus different methods of damping them. I'll try attaching a laser pointer and then move to film exposure when I feel like I'm getting somewhere. This is frustrating because my decision to buy the GS1 was partly based on what I had read about its low vibration characteristics. I fully expected my Manfrotto to provide adequate stability. It was only after using the combo and getting slightly sub-par results that I decided to do the vibration testing.

    Many thanks to Johns Photos for the offer of a vibration test. Of course I would be very interested to hear about the results of this if you have the time and inclination to do it.
     
  16. johns photos

    johns photos Member

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    jgboothe,

    sent you a pm.
     
  17. Neil Souch

    Neil Souch Subscriber

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    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.
     
  18. jgboothe

    jgboothe Member

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    I only have two lenses for the GS-1 at present. Although I only conducted the specific vibration test with the 100mm, when I have used the 150mm in the shutter speed range I mention, I have had what I would consider to be slightly sub-optimal results consistent with a vibration issue (in fact I have never used it outside this range so I can't confirm this is down to vibration for definite). Leaving other lenses out of the equation however, my test showed the 100mm producing very sharp images at 1/2s and less sharp images at 1/30s and other intermediate speeds, with everything else in the setup remaining exactly the same. I can't explain that with anything other than shutter vibration.

    You mention long exposures. I wouldn't expect any shutter-induced vibration at any speeds longer than a quarter of a second based on my tests - the slowest speed which showed vibration was 1/8s. This is what I would expect because the period during which vibration occurs becomes an insignificant percentage of the exposure time as exposure time increases. However, I take the point that you have never noticed any vibration problems with your SQ-Ai, like most others here. A tripod/head issue is certainly one of the possibilities. What kind of tripod/head do you use?

    When I get chance I might post my results as images here, so people can see the results I'm talking about. I've never posted images on this forum before though and I might end up doing it wrong, so bear with me. Any tips welcome.
     
  19. jgboothe

    jgboothe Member

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    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 at somewhat below head height with no column extension. Tripod resting on hard tiles over concrete floor. 100mm PG lens, focus and aperture (f11) not changed throughout. Mirror lock-up and cable release used on all but one shot. The film was Fuji Pro160C. Each shot was enlarged by exactly the same degree (a lot) onto Multigrade paper and the print scanned on an Epson V700. The scans have been cropped and down-sampled a bit (all by the same amount) for posting. There were some slight exposure variations at both the shooting and enlarging stage, which I have equalized in the scans, but I have done no sharpening. I also took a reference shot with a 10MP DSLR (K10D) in raw, mimicking the composition with the Bronica, just to get an idea of the difference in detail possible with the two formats. I'd say this shot is as sharp as is possible to get with that sensor. The crop of this shot has been scaled up to the same size as the others.

    Hopefully the images will be viewable on screen at 1:1 (100%).

    To me, it's clear that vibration is reducing detail significantly at 1/8s, 1/30s and 1/125s, with the peak being at 1/30s. It's a shame I didn't test 1/250s because I'd like to know whether the problem has gone by then. Even 1/2s is slightly worse than at 2s, I think. Ok, I realize it's quite subtle, but it's there, no? I'm sure that many people will consider these effects to be insignificant in real photography, which is perfectly valid given the number of other factors which can limit sharpness, but personally I find that it negates the potential advantage of the 6x7 format over say 645 in terms of detail capture. Plus I would expect the effect to increase when using longer lenses and to become a little more pronounced when using finer-grained film. It's impossible for me to be sure whether there is something about my particular camera which is causing this, but at present I know of no defect which would contribute to it.

    It would be good to hear what people think of these tests. The results seem (to me at least) to go against accepted wisdom on this camera. I'm still open to suggestions as to how best to reduce these vibrations by damping, stabilizing or using a different tripod/head etc. (although the 055 is about as much as I can manage in terms of weight in many cases).

    shutter vibration results.jpg
     
  20. DWThomas

    DWThomas Subscriber

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    An interesting test control would be to mount the camera on some sort of "immovable" object using heavy clamps, or in a bench vise on a monster work bench, just to get the tripod and head out of the system. 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! :whistling:
     
  21. benjiboy

    benjiboy Subscriber

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    Have you had a professional camera tech. Check your camera out ?.
     
  22. itsdoable

    itsdoable Member

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    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.
     
  23. johns photos

    johns photos Member

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    PMed tester regarding Grain Focusing. 1/30th grain looks a little off relatively speaking in my view after looking at the exposures in a viewer.

    To Itsdoable; still investigating the consequences of the "clack". Not conclusive its the "clack" that is causing is this.

    I have both ETRSI and GS-1 systems. The shutter actuation on the ETRSI is significantly greater than the GS-1 though I've never noticed any loss of sharpness during MLU exposures in the zone of susceptible shutter speeds. However, I sure have noticed blur if I forget to Lock the mirror up at just about any shutter speed from 1/125th down. The GS-1 is also sharper handheld. The only time I get consistently sharp results handheld with the ETRSi is either at 1/250th/1/500th or with Flash at any speed. Cannot believe they even marketed the ETR/ETRS back in the 70's without the MLU feature. Maybe internal damping was better with the heavier materials versus the ETRSI body which uses a lot of plastic.

    This is a good "gearhead" thread and thanks to jgboothe for posting this. Unlike the original poster from 2006 who never posts anything in terms of "data" its refreshing to see jgboothe post the data so other owners can ask questions or give feedback.
     
  24. jgboothe

    jgboothe Member

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    Yes sorry for shifting this discussion to the GS-1. You're right of course that the mechanics may differ in significant ways to the SQ series. I think that the point about the cable release could be a significant one. Without any mechanical force from the cable release to gently push the actuating lever until it trips the shutter, a significant force from within the camera must be used to drive it. My guess is that it's a spring, which is tensioned during wind-on, and released when an electronic signal is received from the cable release. I believe the earlier SQs have a mechanical release - would be interested to know whether these produce less vibration than later models (assuming they have an electronic release).
     
  25. jgboothe

    jgboothe Member

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    Thank you very much for this confirmation. Your description of the mechanics and the feel of the vibration matches my experience exactly (although I haven't used any Hasselblads, unfortunately). So either we both have defective cameras or this is normal behaviour for the GS-1.

    Yes I wouldn't expect it to have any noticeable effect when handholding because the general shake from handholding is always likely to be more significant. Your Hasselblad 500 series experience sounds similar to my Mamiya C330 experience - ie. virtually no vibration from the shutter. Interesting that they both use a mechanical shutter release (see my post above).

    All fair points. Apart from the degree of enlargement, much also depends on the type of subject and intensions of the photographer of course. The type of thing I do does depend a lot on the description of detail for its effect, so I find the effects I have found significant. I do occasionally show work in gallery-type settings and would like to feel confident that I could print large. There's something I find very satisfying about the interaction of detail with the film grain when the rendering is sharp. As you said, very anal!

    The head isn't a ball head actually - it's a kind of three-way head without pan/tilt handles and a broad mounting surface. I will be looking into getting something else though. It's going to be hard to avoid the problematic shutter speeds in most cases as I am usually outside in daylight, at f16 or f11. Using an ISO50 speed film will help in some cases, and an ND might also help to get me out of the danger zone, though they can bring their own problems.