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Pano Head, Shutter Shock, Anti-shock, Tripod Size, FocusTune

Discussion in 'Open Discussion' started by tradesmith45, Jun 27, 2015.

  1. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Love shooting Panos. Since converting to digital 2.5 yrs ago have been using a home made head & learning what my OMDs can do. In my film days shot a Widelux & Hasselblad X-Pan. Digital allows me to do things like night sky & much higher res panos I couldn't do w/ film.

    But there's a down side & here's my exploration of it. These high speed shutters & hi pixel density sensors mean shutter induced vibration is a real issue.

    Full disclosure, I'm a geek - degree in physics - testing is a way of life -:) And I worked my way through college as a machinist (Many years ago!) so I assembled a small pano head because the commercial heads are much bigger than needed for mirrorless.

    Here's my head: _4010003 - 2015-04-01 at 16-58-40 by tradesmith45, on Flickr
    _4010001 - 2015-04-01 at 16-57-15 by tradesmith45, on Flickr
    _4010004 - 2015-04-01 at 16-59-59 by tradesmith45, on Flickr

    All pano heads provide leverage for what ever shutter/mirror induced vibration the camera being used generates. All modern cameras with high speed shutters have this problem to some degree. So what follows is an examination of what helps reduce this problem. Never noticed these problems in my film days when the fastest shutter speed was 1/1000" or less and the best film resolved maybe the equivalent of 8 Mp.
     
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  2. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    What is the purpose of a pano head? Why is it needed?

    Brian
     
  3. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Shutter shock & Pano Heads

    Have seen a calculation that shows when one of these small shutters is stopped, it will generate a 40G force for a brief time - sub millisecond. That's enough force to move almost everything & produce blur. The shutter moves vertically so will move things in that direction. As you can see, when the camera is mounted on a pano head, it has lever arms to exert the shutter forces & the tripod is some distance from the camera through the head. So vibration induced blur is a risk - when, how bad & what can be done to reduce it?

    I got a program called FocusTune to do AF calibration on my 43 ZD300mm F2.8 lens. FocusTune is essentially sharpness measurement software & oh is it wonderfully sensitive! Using their standard focus testing target, you can quickly (or at least quicker than anything else) test all sorts of ideas about what causes image degradation. So using FocusTune's "Shot to Shot" analysis, I examined whether shutter induced vibration is a problem & how to reduce it if it is.

    Short version: on the E-M5, shutter induced vibration reduces IQ some for SS slower than 1/250" but a 1/2" anti-shock delay (or electronic 1st curtain on the E-M1, 0-Anti-shock) reduces the problem. Using a larger tripod has almost no impact on this problem because 40G moves everything.

    FocusTune measures image sharpness of their standard target & makes it possible to do that for varying conditions such as different AS settings. But FocusTune is very sensitive & must be used with great care to maintain consistent conditions. I set the camera, head & target up & shot 10 frames for each condition. Then I measured the average sharpness first for different anti-shock delays available in the E-M5. Here's what I found for a shutter speed of 1/25" which I've found to be an especially sensitive speed for shutter induced vibration:
    19217786055_cfbabeea63_o.jpg_6130012 by tradesmith45, on Flickr

    EDIT: these results apply only to the M.Z40-150mm f4-5.6 lens. Other lenses yield different response to vibration.
    19030167440_9907f55b3b_o.jpgSharpness VS AS Delay by tradesmith45, on Flickr

    So an AS delay of 1/2" is as good as it gets. On my E-M1, 0-Antishock & 1/2" AS produced the same results.
     
    Last edited: Jun 29, 2015
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  4. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    How much variation in sharpness was there over the ten samples? Can you show a test image at None and at 1/2 second so we can see how much the delay helped?

    Brian
     
  5. Ross the fiddler

    Ross the fiddler Mu-43 Hall of Famer

    Interesting what you have done. Now that I've posted to it I'll see following posts & can come back to it later when I have time.
     
  6. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Next, I wanted to know if there was a SS where even w/ a 1/2" AS delay, shutter vibration still reduces IQ - unfortunately there is. Here's a test (again 10 frames averaged for each condition) for shutter speeds from 1/250" to 1/2" all w/ 1/2" AS delay.

    EDIT: these results apply only to the M.Z40-150mm f4-5.6 lens. Other lenses yield different response to vibration.

    19211940552_5675f0520a_o.jpgSharpness vs SS 634CF by tradesmith45, on Flickr

    I used my very light weight backpacking tripod (a 2 lb. Slik 634CF w/ a tiny Giottos MH-1002 ball head) for these results. As you can see, IQ drops measurably for 1/4" & 1/2" exposures regardless of the 1/2" AS delay.

    The low IQ for the SS=1/60" frames were a surprise. Until I do additional testing, I can only guess that this is some kind of harmonic in the tripod at this SS.

    I did test my larger tripod & got essentially the same results for SS slower than 1/8" but did not test @ 1/60".
    19030227348_47f9379663_o.jpgSharpness ve SS CT3342 by tradesmith45, on Flickr

    For reference, here's these 2 pods & heads:
    19030174850_6afbef76dd_o.jpg_6270001 by tradesmith45, on Flickr
    _6270003 by tradesmith45, on Flickr
    _6270002 by tradesmith45, on Flickr

    And more importantly heres the modest difference in IQ caused by shutter induced vibration. This is a magnified view of the sharpest & softest images from these tests.
    BFX00002 by tradesmith45, on Flickr

    I've done lots of shutter shock testing w/ my super tele lenses that have shown bigger tripods are of little help simply because a 40G force likely moves the camera on the mount a little.

    YMMV
     
    Last edited: Jun 29, 2015
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  7. TassieFig

    TassieFig Mu-43 Top Veteran

    535
    Oct 28, 2013
    Tasmania, Australia
    I find these geeky scientific tests very interesting and would love to see more like this. Could you upload some pictures to display the difference between the different treatments? I would be interested to see if I could really tell the difference or, rather if it would be significant enough to bother me in real life.

    Also, 1/8 gives better results than 1/4. Not sure if it is significant or not (or if you even test for significance?) but do you have any ideas why that is?

    Edit: I'm slow, I see you posted some useful images before I posted this. Thanks

    Edit 2: It's very hard to see anything on those small images. Full resolution maybe? :)
     
    Last edited: Jun 27, 2015
  8. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    So you tiny tripod owners out there are not now alarmed by these results, here's a reassuring story. Backpacked to the mountains but unfortunately had constant strong winds - frequent gusts I'd guess @ 20-30 mph. Used my pano head & Slik 634CF w/ legs barely extended & weighted down for this 3 image stitch: SS=0.4".

    19031774849_fc972d2b55_o.jpg_6180102 Panorama by tradesmith45, on Flickr
     
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  9. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    The sharpness in your first graph was about 3500 (units?). In the following graphs it is > 5500, judging by the values nearest 1/25 sec. Why is there such a difference?

    Brian
     
  10. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    The FocusTune sharpness values produced in each test are arbitrary & the absolute values can not be compared from 1 test to the next. The pattern can usually be compared however. So softer results w/ SS<1/8" is real.

    For these tests, I had incandescent lights on stands that I moved back & forth to get different SS at a constant aperture (f5.6 @ 40mm). Unfortunately my printing of the FocusTune target even on matte is a bit to glossy. So w/ some light positions, there is reflection off the target which impacts the sharpness measurements. (I don't know much about what the software does under the hood.) Its possible the results for the 634CF @ 1/60" were caused by this variation in lighting (this is really sensitive software!). But when I look at all the results & images, I concluded this is a real interaction between the tripod & 1/2" AS delay - some kind of harmonic. The images at 1/60" are actually softer.

    I hate that conclusion because it means there can be significant surprise results & rules of thumb & trends won't work. But that's reality!
     
    Last edited: Jun 27, 2015
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  11. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    What aspect of the image is the software measuring to calculate the sharpness value?

    I'd like to see a 100% crop of two images, one with no shutter delay and the other with 1/2" second. I can't relate graph numbers to the visual sharpness difference they represent. Without a visual example, there's no way to tell if the numerical differences are significant.

    Brian
     
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  12. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Pano heads ensure the camera/lens is rotated around the nodal point of the lens - the point where all light rays cross. This ensures the stitching software can stitch all the images w/ the least distortion. If you can photograph w/ high SS, say faster than 1/25" depending of the focal length, then a pano head is not necessary if you can hand hold the camera movement around the nodal point.
     
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  13. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    As you can see from my recent post, shutter induced vibration is NOT at big IQ killer but only modest. Whether this is important to you depends entirely on how you display your images. IMHO, its only important if you work hard to get the image &/or want to have a large display - digital or print. For me at my age, I put lots of effort in & want the best results out. There's nothing wrong w/ different choices!
     
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  14. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    For what sort of images is this important? I've only tried a few panos. I just handheld the camera and rotated my body, not at all satisfying the criteria you mentioned. These were landscapes. I didn't notice any stitching artifacts.

    I suggest you use an electronic dimmer on your lamps rather than reposition them. I think moving the lamps invalidates the test unless you do a bunch of measurements to prove that the card albedo doesn't change with incident light angle.

    Brian
     
  15. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    I can't tell from a single image. I need to do an overlay comparison (instantly switched) between two images.

    I often crop my images a great deal so even though I never print and I never display larger than 1600 pixels wide, I think I'm often at the limits where shutter shock comes into play. I've seen it a number of times in images from my E-PL2.

    Brian
     
  16. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    You're absolutely right. Its easy to do hand held panos - so long as there's enough light. I loved shooting the X-pan on the streets of Paris in just this circumstance. But for landscapes, most of my interest is when there isn't enough light to HH or I'm shooting IR B&W panos mid-day w/ really long SS. For these a pano head is required.

    Nice idea but I don't own one so went w/ what I had.
     
  17. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    FWIW, in addition to the numerical analysis, I look through the individual images to see if something unusual is going on other than blur that's causing the results. FocusTune is exquisitely sensitive to changed conditions such as lighting angle. But examination of the images confirms the numerical results I found - for my pano head 1/2" AS delay & SS shorter than 1/4" work best.
     
  18. Brian Beezley

    Brian Beezley Mu-43 All-Pro

    OK, I understand.

    I appreciate the effort you made to do the tests and I'm glad you reported them. But if the image incident on the camera sensor changed from test to test due to lighting shifts, I think they are questionable. How about using a perfectly static image and just recording it at various brightnesses short of saturation? Can the sharpness software cope with that or does it require a fixed image brightness?

    Brian
     
  19. tradesmith45

    tradesmith45 Mu-43 All-Pro

    Dec 13, 2012
    Oregon
    Thanks Brian. Good questions & you are absolutely right to be concerned about small variations. I've learned that the hard way during AF calibration tests w/ FocusTune.

    I was very careful to ensure the target framing did not change during the test & I nailed that one, no movement. Yes, the lighting did vary but inspection of the actual images really shows changes in IQ so the sharpness measurement results reflect easily visible IQ changes regardless of lighting. I was concerned about possible vibration of the floor in my house causing blurring. But its unlikely that happened for all 10 images of the specific images a SS w/ lower IQ.

    Whether the reduced IQ is important to you is a separate question. IMHO, this is only important if you do large display.
     
  20. b_rubenstein

    b_rubenstein Mu-43 All-Pro

    Mar 20, 2012
    Melbourne, FL
    The picture of your setup has so many cantilevers and springy pieces that I'm not surprised there are SS issues. I suggest mounting your setup an a shake table with accelerometers for the X, Y and z axis and run it through a swept sine wave frequency range. The, just mount the camera directly attached to the ball head directly mounted to the table. Or, just redo your tests with just the camera and ball head and see how the sharpness is effected. I suspect that once you're not using a setup that's ringing like a bell, the SS problems will go away.