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08-02-2010, 12:40 PM   #1
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Blurred images using flash (difficult problem)

Hi folks,
I am dealing with a difficult problem to solve that seems a a bit inconsistent.
I use my flash as fill flash quite often. Ever since I upgraded from my K10D to the K-7, I am having many blurred images when using flash at pixel peeping level.

I try to keep the shutter time around 1/125 to 1/160 second (iso 200) aperture priority, where the images are visible without flash, and just a little brighter with flash.

Holding the camera vertically seems to be worse than horizontally.

Tried shake reduction on/off

Tried hotshoe flash as well as pop-up flash

Tried ttl-p and ttl-p hss

Tried flash and slow sync flash settings

Searched for other threads about this problem

(Still need to try tripod tests)

(Still need to post images for you to see)

The only consistency I am getting is that images are sharp without flash (and shake reduction) and often blurred with flash.

I have already exchanged one K-7, and my new one seemed OK at first, but is now showing this problem again.

I am pretty good at testing and isolating issues, and haven't found a solution or cause. Has anyone else had this issue? Any ideas what I could do?
Any help is greatly appreciated.

Thanks

08-02-2010, 12:49 PM   #2
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As there are many possible causes for something like this, I'd recommend you upload some sample shots to an album here. Our album system automatically reads EXIF information, so it should help us find the problem.

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08-02-2010, 01:02 PM   #3
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I have noticed a few similar issues with my K-7, but I never took the time to investigate it when it happened. I remember several fill-flash shots that I made in March of this year that had a weird blur to them...maybe I can dig those up and see if looks the same as yours.

It could possibly be related to the shutter-induced blur issue that falconeye has researched

https://www.pentaxforums.com/forums/pentax-news-rumors/108199-lumolabs-shutte...-7-camera.html

Maybe the flash exposure happens at a point when the sensor is not where it is for the majority of the regular exposure. So the flash causes and exposure, then the sensor shifts due to the shutter mechanism, then the rest of the exposure time (accounting for the majority of the ambient exposure) does not match the flash exposure.

If that is the case, that's bad. I'll see what I can find with my photos from earlier this year.
08-02-2010, 02:05 PM   #4
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I had a similar problem but realized later that I had not changed falsh back to P-TTL from slow setting.

08-02-2010, 04:17 PM   #5
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There was an issue of having a slight double image when using flash.
I believe the issue was addressed in firmware upgrade 1.3.
A simple upgrade to the latest firmware would clear this up.
08-02-2010, 05:13 PM   #6
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QuoteOriginally posted by creampuff Quote
There was an issue of having a slight double image when using flash.
I believe the issue was addressed in firmware upgrade 1.3.
A simple upgrade to the latest firmware would clear this up.
Good to know. I tried to replicate what I saw a while back today, and couldn't seem to make it misbehave. I was using an older firmware at the time, so hopefully it did get addressed as you indicate.
08-02-2010, 08:00 PM   #7
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Thanks folks,
I have 1.10 firmware that does not fix my problem.
I tried replicating the problem in my dining room, but seem to get sharp images now. I do have a series outside with enough ambient light that showed the problem well.

arpaagent your theory is interesting, however, with HSS flash, that problem should reduce, and unfortunately that is not the case. The problem seems to worsen when the ambient lighting is brighter.

I'll need to work on adding the sample images and annotate them properly in the next days.

The best way to produce the problem is to go out in sunny weather and use f/8 and iso 200 and shoot an object with flash where the exposure time is around 1/125 to 1/180 second. I am curious if any one has this problem too.

Thanks
08-02-2010, 08:22 PM   #8
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Eric Seavey, instead of just describing the supposed issue, it would be best if you could post actual photos to support what you claim because it doesn't seem to be a problem for a lot of K-7 users.
At this juncture, there is no way to ascertain if the supposed issue lies with the camera or with user error.
Also we have no idea what brand or model of flash that you are using...

08-03-2010, 06:08 AM   #9
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Here are the images that show a series of tests I did a few days ago I focused on the blue sign.
I used a Sigma AF 17-70mm f/2.8-4.5 DC lens and the Metz 48 AF-1 flash.

Here are a few test shots:
flash on - slow speed sync:


Flash off:


Flash on normal flash setting:
08-03-2010, 04:40 PM   #10
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OK, I am a little embarrassed to admit that the problem I have been dealing with was actually user error.... I finally got to doing some tripod tests and all were perfectly sharp, even with SR on. This was now pointing to a mechanical issue as supposed to an electronic issue.
As it turns out, the K-7 does have mirror-up shake, so when I hold my camera vertically I have it resting on one hand and hold my right hand on top. With my glasses, I barely toutch the camera with my forehead. When I press the camera against my forehead, I get sharp images, and can feel the camera vibrate though my head. Not sure why this is more of a problem with flash versus without. Still need to look into that.
08-04-2010, 12:29 AM   #11
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QuoteOriginally posted by Eric Seavey Quote
OK, I am a little embarrassed to admit that the problem I have been dealing with was actually user error.... I finally got to doing some tripod tests and all were perfectly sharp, even with SR on. This was now pointing to a mechanical issue as supposed to an electronic issue.
As it turns out, the K-7 does have mirror-up shake, so when I hold my camera vertically I have it resting on one hand and hold my right hand on top. With my glasses, I barely toutch the camera with my forehead. When I press the camera against my forehead, I get sharp images, and can feel the camera vibrate though my head. Not sure why this is more of a problem with flash versus without. Still need to look into that.
Well, I don't know for sure.
Falk Lumo did extensive testing on the effects of shutter and mirror slab on the K-7.
See: https://www.pentaxforums.com/forums/pentax-news-rumors/108199-lumolabs-shutte...-7-camera.html
His analysis shows that the mirror slab is not an issue for that camera.
Could you please post the EXIF info for the pictures you posted before?
Perhaps that can help us some more.

Thanks, Bert
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