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12-06-2009, 12:17 PM   #1
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Most of my low light flash pics are blurry...why?

Pentax K100D. Seems my pics are actually better with the kit lens vs. my "fast 50". The fast 50 really shines in low light, since my pics come out properly exposed and not dark like my kit lens, however, seems like it has a hard time focusing.

In good light, it has no problems, but low light I have a hard time with it focusing on automatic focus. I actually have better luck (a little, anyway) with manual focus, which I hate doing.

What settings should my k100d be set at for low light with the fast 50? Thank you.

vmax84

12-06-2009, 12:52 PM   #2
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I think you have encoutered the limits of the K100D AF system.
Unfortunatly.

I can think of no better solution than to use a flash (which uses an assist light for AF purposes), or a split focus, focus screen for MF support (I don't know if you could change the focus screen of a K100D).

My (new) K-7 has a much, much, much better low light AF (plus assist light) than my K10D (which I assume is K100D like), however, that is not a cheap solution. And, of course, it still has its limits.
12-06-2009, 12:59 PM   #3
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vmax84,
An example with EXIF intact would have been helpful, but I am wondering whether you're aware of the shutter speeds you're using in low light.

Blurry photos are due to subject motion and more importantly camera shake due to a shutter speed to long to be able to handhold the camera effectively. From what you're saying it's likely camera shake's to blame and you need to make adjustments accordingly, regardless of lens.

If you're asking for what settings to be on for low light situations then you ought to go back to the books and study the exposure triad. Once you understand the concept, the 'settings' you need will become quite clear. Handholding a fast fifty, you'll want a shutter speed of faster than 1/50 sec or so assuming the subject is not moving. The aperture and sensitivity to achieve this shutter speed should be chosen (or worked out by the camera) with this in mind.
12-06-2009, 01:01 PM   #4
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QuoteOriginally posted by bymy141 Quote
I think you have encoutered the limits of the K100D AF system.
Unfortunatly.

I can think of no better solution than to use a flash (which uses an assist light for AF purposes), or a split focus, focus screen for MF support (I don't know if you could change the focus screen of a K100D).

My (new) K-7 has a much, much, much better low light AF (plus assist light) than my K10D (which I assume is K100D like), however, that is not a cheap solution. And, of course, it still has its limits.
Your theory and post should be deleted.........NOT what I wanted to hear.

I was taking a few shots last night at a retirement party, and, it was pretty dark at the reception hall. Many of my shots were blurry and my best shots were where I "guessed" and went to manual focus. The kit lens I almost feel does better than the fast 50 for this particualar situation for me, but you have to get in pretty close in order so the pic isn't dark. The fast 50 really does let a lot of light in compared to the kit lens.

vmax84

12-06-2009, 01:05 PM   #5
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QuoteOriginally posted by Ash Quote
vmax84,
An example with EXIF intact would have been helpful, but I am wondering whether you're aware of the shutter speeds you're using in low light.

Blurry photos are due to subject motion and more importantly camera shake due to a shutter speed to long to be able to handhold the camera effectively. From what you're saying it's likely camera shake's to blame and you need to make adjustments accordingly, regardless of lens.

If you're asking for what settings to be on for low light situations then you ought to go back to the books and study the exposure triad. Once you understand the concept, the 'settings' you need will become quite clear. Handholding a fast fifty, you'll want a shutter speed of faster than 1/50 sec or so assuming the subject is not moving. The aperture and sensitivity to achieve this shutter speed should be chosen (or worked out by the camera) with this in mind.
Thanks for responding. I do have a pretty good grasp on what causes blurry pics, etc., and I was shooting fast enough (I think 60 was the slowest using the flash) and it's definately a problem with mis-focus. I tried shooting in "auto", then switch to TV and set the shutter (I think) at 60 and higher. It's definately a mis-focus problem.

should I try bumping my ISO up (from 200), setting the camera on TV, and then letting the camera give me a larger depth of field? Guess it's something I should simply try.

Was just wondering what settings you veterans used, especially since I hardly ever use the flash. I do, however, get very good results shooting soccer games, football, etc.

Thanks a lot.

vmax84
12-06-2009, 01:46 PM   #6
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I assumed you were able to find focus. My apologies.
Focusing in low light with the K100D will always prove difficult, manually focusing is tough and you may have to live with that limitation. Finding a higher contrast part of the scene close to the subject to focus on usually helps, though.

But once you get focus, and the shutter speed's fast enough, then you should have no problems handholding. Even ISO 1600 is in some cases quite usable on the K100D, so don't be afraid to go higher with it if it means speeding up your shots.
12-06-2009, 01:50 PM   #7
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What autofocus mode are you using? Auto, multi, or center?
12-06-2009, 02:10 PM   #8
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QuoteOriginally posted by K McCall Quote
What autofocus mode are you using? Auto, multi, or center?
I think that might be my problem........I stuck with auto. Should of tried center?

vmax84

12-06-2009, 02:14 PM   #9
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QuoteOriginally posted by Ash Quote
I assumed you were able to find focus. My apologies.
Focusing in low light with the K100D will always prove difficult, manually focusing is tough and you may have to live with that limitation. Finding a higher contrast part of the scene close to the subject to focus on usually helps, though.

But once you get focus, and the shutter speed's fast enough, then you should have no problems handholding. Even ISO 1600 is in some cases quite usable on the K100D, so don't be afraid to go higher with it if it means speeding up your shots.
No need to apologigize (sp). I was trying to use my flash, in auto, with the ISO set at 200. I hate using higher ISO's since I don't like the grainy look.

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12-06-2009, 02:31 PM   #10
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Your problem sounds like it's fairly dark, your flash doesn't quite have enough power with the kit lens, and with the "fast 50", the camera tries to use a very large aperture like f1.4. The lighting is OK with the 50mm prime because the flash has enough power to work. But at very large apertures like that, the depth of field is really small. It's possible for the camera to focus on someone's ear and have their face be out of focus. The camera is thinking "fine, this is something to focus on, take the shot." You can't see the true depth of field in the viewfinder until about f2.8. The kit lens photos appear to be more in focus because the kit lens would be at f5.6 or a smaller aperture, but they are dark because the flash can't supply enough light for the whole scene.

I think you are on the track of the easy solution. Try these pictures at ISO 800 and your equipment will not be at/beyond its limits. The 50mm can then use apertures with a larger DOF like f2.8 or f3.5, so when focus locks on an ear, the face is OK. Or the flash can put out enough power so the kit lens works better too. There is a marginal gain in quality by staying with ISO 200, but if that setting pushes the other variables into critical zones, it's not worth it.

I'm assuming a few things without knowing which 50mm lens or flash you're using, so those details might make a difference
12-06-2009, 02:40 PM   #11
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QuoteOriginally posted by Just1MoreDave Quote
Your problem sounds like it's fairly dark, your flash doesn't quite have enough power with the kit lens, and with the "fast 50", the camera tries to use a very large aperture like f1.4. The lighting is OK with the 50mm prime because the flash has enough power to work. But at very large apertures like that, the depth of field is really small. It's possible for the camera to focus on someone's ear and have their face be out of focus. The camera is thinking "fine, this is something to focus on, take the shot." You can't see the true depth of field in the viewfinder until about f2.8. The kit lens photos appear to be more in focus because the kit lens would be at f5.6 or a smaller aperture, but they are dark because the flash can't supply enough light for the whole scene.

I think you are on the track of the easy solution. Try these pictures at ISO 800 and your equipment will not be at/beyond its limits. The 50mm can then use apertures with a larger DOF like f2.8 or f3.5, so when focus locks on an ear, the face is OK. Or the flash can put out enough power so the kit lens works better too. There is a marginal gain in quality by staying with ISO 200, but if that setting pushes the other variables into critical zones, it's not worth it.

I'm assuming a few things without knowing which 50mm lens or flash you're using, so those details might make a difference
That is a fantastic explanation and it really helps. I totally follow what you're saying and at the reception, thought about bumping my ISO up to 800 (I don't mind using 800, but anything after that, I can't stand the grain), but simply took enough shots that I did end up getting most of what I wanted (although, blinding folks in the process!!).

I'm using the pentax fast 50 with the camera's built in flash. I do understand the DOF concept and knew i was working with a limited DOF for this application.

Thanks again for the explanation as it was written for folks like me (know just enough about photography to be dangerous!!). Your explanation is spot on with what's happening.

Hope you get lots of cool stuff for Christmas!!

vmax84
12-06-2009, 03:19 PM   #12
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I have to admit that my camera stays on ISO 200 too much. I only learned how effective "raising ISO with flash" can be this summer. My brother handed me his *ist DL, with the kit lens and popup flash, to take some photos in a big dark room. I looked at the first photo on the LCD and it was amazingly bright. He had set ISO 1600. That's probably too high, but you can't tell on the LCD. I turned it down to 800 and got some good shots. (The stupid thing is, we both had external flashes, and I had a bag of better lenses, but none of that stuff was out and ready when we needed it.) I learned not to worry so much about ISO.
12-06-2009, 03:29 PM   #13
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QuoteOriginally posted by Just1MoreDave Quote
I have to admit that my camera stays on ISO 200 too much. I only learned how effective "raising ISO with flash" can be this summer. My brother handed me his *ist DL, with the kit lens and popup flash, to take some photos in a big dark room. I looked at the first photo on the LCD and it was amazingly bright. He had set ISO 1600. That's probably too high, but you can't tell on the LCD. I turned it down to 800 and got some good shots. (The stupid thing is, we both had external flashes, and I had a bag of better lenses, but none of that stuff was out and ready when we needed it.) I learned not to worry so much about ISO.
Thanks again, Dave. Like I said, 800 is ok, and 1600 is ok if I just have to get the shot, but i'm ok with 800 and will try that with flash next time. With the fast 50, should really open up my depth of field.

But now that I've got that figured out, should I set it to TV and set my shutter speed myself, or, set it to automatic and let the camera figure that out? Thanks again.

vmax84
12-06-2009, 09:45 PM   #14
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QuoteOriginally posted by vmax84 Quote
I don't mind using 800, but anything after that, I can't stand the grain
It also helps to learn how to do noise reduction.
12-07-2009, 05:52 AM   #15
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QuoteOriginally posted by Marc Sabatella Quote
It also helps to learn how to do noise reduction.
Marc, are you talking in camera (cause' I think I have it turned on.....I think!) or using gimp or something like that? I have gimp, but don't do very much with it except lighten or darken my pics. Thank you.

vmax84
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