[BigMackCam]

My test of shutter shock on K-3 III: Pentax SLR Talk Forum: Digital Photography Review

Explanations?

FYI, this thread and another, DPR and Studio Samples, have been merged as they are covering the same ground.

With shutter shock, there can be so many variables... manufacturing tolerances in the individual camera and/or lens, lens model / weight / shape / focal length (if a zoom), hand-held technique, tripod and head supporting the camera, etc. Change any one of those variables and it may introduce, alter or remove the effect of shutter shock, or move it to a slightly different range of speeds.

I can force the shutter shock effect on my K-3 with my copy of the Sigma 18-300 at ~24mm and a shutter speed around 1/100s, hand-held. I don't get the "problem" using the same lens and shutter speed on my K-3II, nor can I replicate it on my K-3 if I use my Sigma 17-50 f/2.8 at the same focal length. My conclusion, in this particular instance, is that there's something about the combined mass and dimensions of the K-3 + Sigma 18-300 when set to that focal length. That may or may not relate to the effect DPR is seeing and the reason why the quoted user can't reproduce it, but it shows how difficult it can be to confirm if, and why, the behaviour occurs.

As an aside, I've previously mentioned how some guitars will have a "dead spot" where a particular string, at a particular fret, will sound muted and won't ring out as expected. Assuming it's not due to a raised fret and the neck has proper relief ("bow"), it can often be improved, resolved completely - or, sometimes, merely moved to a different spot - by adding mass to the instrument. A clip-on metal weight is usually added to the headstock to achieve this.

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Last edited by BigMackCam; 05-31-2021 at 12:35 PM.

[stevebrot]

I'm interested to see what experiences our members report after using the camera for a few weeks or months. If it's shutter shock, we should see a pattern of it happening to numerous members within that same range of speeds...

I agree. Our members seem to be very good at finding issues.


Steve

[stevebrot]

2. It is caused by the sensor movement, which permanently levitates in the magnetic field. That's why this problem doesn't disappear when you turn SR off, or cement the camera to the floor.

Yes, a little daft; however...

The thought has occurred to me that the SR system levitation might be affected by local EM events. For example, I have a relative that lives fairly close to a regional weather radar and when the beam comes round, it is strong enough to deflect a compass needle.


Steve

(...should test it out the next time I am up there...)

[kiwi_jono]

If it is shutter shock then it can vary significantly between bodies and also the lens being used (seems some can help dampen vibrations). Its noticeable with many K-1s with certain lens combinations (including mine - although its not too bad) but not universally reported as a problem.
So its not straight forward to prove or disprove that the issue they appear to be having as being due to shutter shock.

[AstroDave]

lives fairly close to a regional weather radar and when the beam comes round, it is strong enough to deflect a compass needle.

How close? This seems extremely unlikely!! The radar beam radio waves oscillate at frequencies of billions of times per second - the compass needle can not react that fast! If the radar dish metal structure was somehow magnetized, and you were within, say, a hundred feet, you might see an effect as the dish swung around. I've been around a lot of big dishes and don't recall anybody commenting about magnetic effects, though.

(...should test it out the next time I am up there...)

Please do! Take your own compass, too.

[Michael Piziak]

I wander if dpreview ever does a re-test on cameras. Or do they just put, what they have, out there and never revisit the camera/lens - ?

I know in some of the video reviews I've watched, on there, they say they test with what ever lens they have on hand - not always the best route to go when you run such a popular photography website (IMO).

[biz-engineer]

For testing cameras, do they use cameras from amazon warehouse returned by a unhappy customer? e.g. camera with defunct SR mechanism.

[reh321]

How close? This seems extremely unlikely!! The radar beam radio waves oscillate at frequencies of billions of times per second - the compass needle can not react that fast! If the radar dish metal structure was somehow magnetized, and you were within, say, a hundred feet, you might see an effect as the dish swung around. I've been around a lot of big dishes and don't recall anybody commenting about magnetic effects, though.

From 1951 to 1960 we lived within a mile of "WCFL" towers {a 'clear-channel' radio station in Chicago}.
I could get the station on a crystal radio without tuning - I also knew of adults who got it via their tooth fillings - but this is an entirely different issue.

[pschlute]

2. It is caused by the sensor movement, which permanently levitates in the magnetic field. That's why this problem doesn't disappear when you turn SR off, or cement the camera to the floor.
3. The main cause is not the shutter movement, but the mirror movement/shock.

I can only speak for the K1, and indeed only my K1 where shutter shock is evident under certain circumstances. On a tripod with a footed lens and shutter speeds 1/60-1/180 range.

In my experience it is absolutely not the mirror that causes it, because enabling MLU does not change the effect.

Also in my experience placing the camera/lens on a solid surface like a granite worktop the problem disappears.

If using the K1 on a tripod with a footed lens I either avoid 1/60-1/180 shutter speed, or use Electronic shutter to prevent the problem affecting my pictures.

All cameras of all brands can suffer from shutter shock and have done for decades.

[Leoi]

I think I've solved the issue of the magenta "fringing". It seems that the RAW files are particulary sensible regarding the method of interpolation used by the image editing software (in my case, Darktable). Other kinds of artifacts, like 'stepped' diagonal lines, also appear because of this. (img 1)

In Darktable, the "PPG-type" interpolation was on by default, which is a fast, low quality process. I'm pretty sure this was the one used by the DPreview folks. When using the "AMaZE" interpolation option, which is of greater quality, those issues were solved. (img 2)

It seems anyway that there's still some king of "shake" already noticed at low shutter speeds, that affects the sharpness of the image. Probably this is due to the use of a tripod that does not dampens correctly the shutter and mirror movement.

Most importantly, however: it seems that the corrected files may prove that the accelerator unit actually works and it's not just an added NR filter as some may suggest. I've compared the corrected files of the Fuji X-T4 and the Pentax (both downloaded from the DPreview comparison tool): regarding detail, the Pentax blows the X-T4 off the water. (img 3)

(Open the photos in another tab for proper, full resolution examination)

[Rush2112]

I didn't see any shutter shock on ANY of the over 1,500 images I've made with the Pentax K3 Mk III in my weeks of thorough testing so far. Attempts to duplicate their findings brought back nothing. Probably had SR on while on a tripod which is a BIG no no.

Personally, I think DPR screwed up the test somehow. Either way, it's amazing to me, even if true, that of all the things they could be saying about the K3 Mk III out of the gate, they chose to focus on controversial findings in that very limited shutter speed range. Rather than a real flaw, I think DPR are looking to stir up controversy. Typical of that site these days.

[house]

Come on people get a grip. Its just embarassing to read all this crazy talk. The dpreview camera has what looks like shutter shock and no means to work around it. Its an important and serious issue. Hopefully its a sample issue. We know that the conditions for shutter shock are such some never see it and others suffer big issues. It takes a while and some effort to figure out. Its great that this is examined.

[Qwntm]

Come on people get a grip. Its just embarassing to read all this crazy talk. The dpreview camera has what looks like shutter shock and no means to work around it. Its an important and serious issue. Hopefully its a sample issue. We know that the conditions for shutter shock are such some never see it and others suffer big issues. It takes a while and some effort to figure out. Its great that this is examined.

So far not one other person has reported the problem after testing for it, including myself.

It's far more likely the DPReview camera has what is in actuality pilot error, or a fault, and the only people that should be embarrassed about a total lack of professionalism either way, work at DPReview.

Until the problem can be replicated anywhere else by anyone else, it's not really a problem, is it?

[andymuns]

I downloaded the jpeg files, DPR k3 III are smaller resolution files then the fuji camera's by about half, which when blown up cause the k3 III image to look blurry, it could be a mistake. Remember these cameras are around the same megapixels.

[house]

Until the problem can be replicated anywhere else by anyone else, it's not really a problem, is it?

Agree! It's the conspiratorial nonsense I'm critical of. The findings are probably real but could be a faulty camera or unique combination of factors. So far almost all dpreview related shots have been poor.



---------- Post added 05-31-21 at 11:09 PM ----------

I downloaded the jpeg files, DPR k3 III are smaller resolution files then the fuji camera by about half which when blown up cause the k3 III image to look blurry, it could be a mistake.

I just downloaded the files and they have the same pixel dimensions (besides the 30 or so pixels of the differing crops) .