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04-08-2010, 04:09 AM   #1
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K-x shake - camera issue or poor technique?

I hate to add to the K-x mirror-slap scaremongering but I'm beginning to think I actually have an issue with mine. Having said that I'm new to SLR photography (I've had the camera for about three or four months) so I'm cognisant of the fact that the issue may well be with my technique and not with the camera. So I thought I'd let you more experienced lot decide for me.

Hopefully GIMP has saved the exif data but if not:

Pic 1: F11, 1/80, 32mm focus
Pic 2: F8, 1/100, 40mm focus
Pic 3: F10, 1/125, 55mm focus

Now it seems to me that with those sort of focal lengths and shutter speeds I should be able to get pretty sharp details, even as a beginner. All the pictures were taken using centre point focusing, and I've verified that SR was enabled for each one. This hasn't been an issue with all my shots but as far as I can tell I haven't had any issues with pictures shot at 1/160 or faster, irrespective of focal length (I also have the 50-200mm kit lens).

I know this has been gone over before, but what would be the best way of verifying if the fault lies with the camera? Taking dozens of hand-held shots at 1/80, 1/100 and 1/125 using the 2-second timer and comparing them to normally-taken pictures? Live view vs non-live view? Tripod (which I don't have, and may possibly dampen vibrations) vs hand-held? I'm going overseas in a few months so if I do have a problem that would be repairable under warranty I'd like to sort it out now, but I don't want to send the camera away if I don't have to.

Let me know if you'd like me to post further samples, and thanks in advance.

Edwin

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04-08-2010, 04:53 AM   #2
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in looking at the photos, there are a couple of things that need to be explained before we discuss anything else.

When people discuss 1/focal length as a rule of thumb for photos, they are discussing shutter speeds that are acceptable for a relitively sharp or acceptably sharp image when the entire frame is printed at 8 inch by 10 inch from a 35 mm frame. when you consider the format of the 35mm frame (36mm wide x 24 mm high) and compare that to an ASP-C sensor in a DSLR, (24mm wide x 16 mm high) it equates to a 6 inch print.

WHen you crop a small portion of the frame, the rule no longer applies as even minor shake is amplified by the magnification that you get by cropping in and displaying the cropped section at much higher magnification.

You may be expecting too much.

Having said that , it does appear that there is some additional blurring in the picture. So lets discuss technique. How are you focusing, and framing the image, with the viewing screen or the eye peice.

Using the back viewing screen is not practical for good technique, because the camera is held only by your 2 hands and is not stable. To get good stable camera support, you really need to bring the camera to your eye, brace your body (arms in against your side) have your feet apart, and one foot slightly in front of the other. Breathe out when pressing the shutter.

If technique is fine, then next is to look at whether you can get better images on a tripod, or camera resting on a solid surface, just to compare, also with shake reduction on and off.

clearly work through all the possibilities.

post same photos hand held with and without SR, with and withoug camera support etc. Lets look at all the different shots and then move forward
04-08-2010, 04:59 AM   #3
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I'd agree Lowell. After figuring out some good technique. The best thing would be to turn SR off and take some test shots with the camera on a table or tripod and then repeat the shots with SR on at similar settings. That could help to see if the camera has an issue or it's technique (like LV shooting).
04-08-2010, 04:59 AM   #4
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I too would be interested in some additional information as Lowell suggests.
If you are holding the camera up using LV and not braced then I could see this happening but if you are using proper technique then I would not accept any of the above photos as they do display an unacceptable amount of motion blur from shake.
I get much, much better results at 100% crop from my 55-300 and k10d at these shuttle speeds.

04-08-2010, 06:09 AM   #5
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All photos were taken using the viewfinder, I've rarely used liveview so far. Thanks for the tips re: technique Lowell, I'll keep them in mind for next time and see if that improves things. I suppose the frustrating thing is that these problems aren't consistent - some shots are amazingly sharp, and a few have heaps of blur like the ones I attached earlier. For example I took several five of that cruise liner, three were sharp, one was blurry (or rather, really really soft which is what I would've thought you'd see if I was the one holding the camera unsteadily) and I've attached the other one. What I also find curious is that the shake on the picture I attached seems so well defined (if that makes any sense) - as if two separate exposures were taken, one aimed a few pixels higher than the other.

A while back I took a focus test chart and took a few dozen pictures of it at 1/100 and 1/125 at a focal length of 55mm, all in landscape, with shake reduction on and off. From memory I focused once and then switched to manual focusing so that the results weren't dependent on focus accuracy.

From what I can tell the results were as expected - at each shutter speed there were some slightly blurry shots, and turning on SR seemed on average to give sharper photos with less blur. I also took a reference shot at 1/250 to see how sharp the ideal picture would be (first attachment), which to me looks pretty good.

The blurriest photo taken at 1/100 with SR on is the second attachment, and even that doesn't look to me to be THAT bad. The third attachment shows an average sort of shot at 1/100 with SR on.

So my first test seems to indicate the camera is behaving as expected, but these obviously blurred shots keep on cropping up. I'd like to run some more tests (as exciting as they are) but there are so many variables (landscape or portrait, freshly charged or nearly empty batteries, at least 4 different shutter speeds to test, SR on or off, 2-second timer on or off, tripod or hand held etc) I could be shooting hundreds of test shots before I reach a conclusion.

Anyway, thanks for your responses. As I said, next time I'll concentrate more on my technique holding the camera steady and see what happens.

Edwin
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04-08-2010, 06:43 AM   #6
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The SR takes a moment to "settle in". Do you monitor the symbol in the viewfinder and delay shooting until it shows that the SR mechanism is ready? I'm asking becasue of your "double-take" photo, where, as you point out, it looks as if you have two pictures overlaid a few pixels apart.

Regarding mirror slap, I don't have the reference, but some users once studied the phenomenon on film cameras and found that it was pronounced in a certain, narrow, shutter speed range only depending somewhat on camera model, but always as far as I recall down around 1/15s - 1/30 s.

I agree with Peter, you need to rule out the possible areas of fault one by one. Turn SR off, do some hand held and tripod shots, then repeast with SR on. Try a range of shutter speeds, below and above the X-synch speed.

Above the X-synch speed (1/500s for example) the shutter becomes a slit that passes over the sensor and the blur may look different at the top than at the bottom of the image. Perhaps that would be telling.
04-08-2010, 06:52 AM   #7
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QuoteOriginally posted by Ole Quote
The SR takes a moment to "settle in". Do you monitor the symbol in the viewfinder and delay shooting until it shows that the SR mechanism is ready? ...
That's good advice, something I sometimes overlook as well.

These photos reminded me of those taken by my coworker w/ a 5D, an excellent camera. His photos, however, often came out blurry. In his case he could use steadier hands.... If I were you I'd try a couple of things to narrow it down:
1) tripod+timer
2) SR off/on
3) various shutter speed (maybe >1/500?)
4) various apertures

Just experiment with it and I'm sure you'll figure it out, good luck.
04-08-2010, 07:43 AM   #8
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I've verified that SR was enabled by looking at the exif data in the Pentax Digital Utility 4 program - does this mean the shake reduction HAD actually settled in and was active by the time the photo was taken or does it just mean that shake reduction had been selected on the camera?

X-sync speed for the K-x is 1/180 right, the fastest shutter speed possible with flash?

I'll do more testing over the weekend and see what I can find. If I do end up returning it to the distributor at some point I'll let you all know what happens, might be interesting to see what they say is faulty (if anything).

04-08-2010, 09:43 AM   #9
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QuoteOriginally posted by shawnxji Quote
That's good advice, something I sometimes overlook as well.
That's why I switch it off till I think that I need it. And next promptly forget that it's on
04-08-2010, 09:44 AM   #10
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QuoteOriginally posted by Edwin13 Quote
I've verified that SR was enabled by looking at the exif data in the Pentax Digital Utility 4 program - does this mean the shake reduction HAD actually settled in and was active by the time the photo was taken or does it just mean that shake reduction had been selected on the camera?
As far as I know it means it's on, not that it is stable yet.

Just tested it with K100D; I did not see the hand when I took a shot but SilkyPix states that it is on.

Last edited by sterretje; 04-08-2010 at 09:53 AM.
04-09-2010, 02:53 PM   #11
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IMO it is camera problem, spend hours trying to resolve.

Here is my test: http://i824.photobucket.com/albums/zz165/akpch/test/mirror_shake_k-x.jpg

All pictures are sequential, no gaps.

Although, Pentax claims it is poor technique. Spoke with them on the phone today.
04-09-2010, 03:07 PM   #12
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QuoteOriginally posted by akpch Quote
IMO it is camera problem, spend hours trying to resolve.

Here is my test: http://i824.photobucket.com/albums/zz165/akpch/test/mirror_shake_k-x.jpg

All pictures are sequential, no gaps.

Although, Pentax claims it is poor technique. Spoke with them on the phone today.
Now that is just ridiculous!! I don't think that I could be hung over enough to get results THAT poor!!
I would bring it back and as much as I love my Pentax, I would not buy from a company that tried that explanation at 1/200s
04-09-2010, 07:55 PM   #13
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check your battery power level

some folks report that this "blurring" issue is more prevalent with batteries that are close to being depleted.

just my 2 cents
04-11-2010, 05:09 AM   #14
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I've done a whole bunch of testing this weekend but these two sets of photos probably best demonstrate the issue. Photos were taken with eneloops (still full green), at 18mm, camera held vertically, shake reduction off, latest firmware (1.01.00.10 - another silent update). I took two shots at 1/30 and then four shots at 1/100, right after each other. The second shot at 1/30 shows that I can take a reasonably still shot at that speed. What's interesting is that the first shot at 1/30 is blurred, and soft - but the bad shots at 1/100 look (once again) like double-exposures. On the left hand side of each crop you can clearly see each of the small horizontal lines has doubled.

Based on my other testing (I'll post the results when I've finished collating all 120-odd shots) the issue seems much worse with the camera held vertically.
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04-11-2010, 06:10 AM   #15
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I've been shooting exclusively with SR off.... really wondering if I really need SR on the camera because I almost never use it now.
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