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04-30-2007, 04:23 AM   #16
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QuoteOriginally posted by nosnoop Quote
This is not normal. Make sure your camera is set to AF-S. The AF assist does not work in AF-C. And you can try setting the Flash to "SP" mode; where it would only do AF Assist without firing the flash. The AF assist always comes on when you are at total darkness.
Sorry to "steal" the post here, but I want to thank nosnoop. I had always wondered why the focus assist didn't illuminate on my AF540. Tried it now in AF.S, and sure enough, it works. Probably a case of me not RTFM (reading the fine manual)

04-30-2007, 04:35 AM   #17
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"I found that the focus hunted a lot, then flashed the red square for locked, but after viewing the shot it was major out of focus."

Matrix,
The only thing I will add to this discussion is, the red square does not indicate a focus lock. It just indicates which AF sensor is being used. The green hexagon indicator at the bottom of the viewfinder is your focus lock indicator. If you did not see this, and as you also stated, you did not hear the beep, then you did not have a lock, and indeed your shot could very well be out of focus.
04-30-2007, 01:33 PM   #18
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QuoteOriginally posted by roscot Quote
"I found that the focus hunted a lot, then flashed the red square for locked, but after viewing the shot it was major out of focus."

Matrix,
The only thing I will add to this discussion is, the red square does not indicate a focus lock. It just indicates which AF sensor is being used. The green hexagon indicator at the bottom of the viewfinder is your focus lock indicator. If you did not see this, and as you also stated, you did not hear the beep, then you did not have a lock, and indeed your shot could very well be out of focus.
Aagh, brain fade on that one... thanks.. I knew that too, just forgot to remember it at the time.

matix
04-30-2007, 01:42 PM   #19
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Now I really feel like an idiot!!

QuoteOriginally posted by nosnoop Quote
This is not normal. Make sure your camera is set to AF-S. The AF assist does not work in AF-C. And you can try setting the Flash to "SP" mode; where it would only do AF Assist without firing the flash. The AF assist always comes on when you are at total darkness.
nosnoop, thanks... checked this switch, as I never use AF-C I never thought of it.

So, checked.. the switch was apparently on the AF-S, but on closer inspection and a slight push, it went further and into the detent. Dammit, have to remember that one next time, hard lesson.

Thanks everyone for the tolerance.. add this one to your books, do not assume that the setting is what it appears to be, recheck.

Phil

04-30-2007, 01:53 PM   #20
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QuoteOriginally posted by aabram Quote
20 out of 300 is 6,6% failures. That's not too bad at all for difficult light shooting, I'd say. If you had that many failures with focus locking on at least something in good light, I'd be worried but with that percentage under difficult conditions... Hmm. Perhaps relaxing your criteria would be a good idea?

Not to question your judgment but still I think it's worth asking - where those 20 shots out of focus or were they blurry instead, because SR didn't compensate enough?

Also - you're using center focus for subjects that move and change places around quickly. Have you tried auto? Perhaps it's quicker to lock on areas that can be locked? I don't know about you but I've found that camera sometimes finds focus there where I didn't think it could obtain the lock. Using center focus is certainly good sometimes but you have to be pretty sure that it will agree with you on chosen point.
Good points aabram, have to clarify the percentages... I do not use SR purposely when the flash is on, so do not consider that. The percentages of useless pics because of out of focus were reasonable, of course there were another 20-30% that were unusable for other reasons, eyes closed etc.

Now that I have the reason for the focus assist not working at all sorted (Note to self: Always make sure the AF-S is pushed ALL the way to the detent locator) and my slap on the wrist re considering the red focus location as meaning the focus was ok... doh!

Thanks again.
04-30-2007, 01:58 PM   #21
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QuoteOriginally posted by matix Quote
Hi, hate to open a thread with a gripe, I am 90% totally happy with my K10D these days, is doing a superlative job for my needs, and for the most part is making me look good.. except for this problem that I can not resolve. Mind you, this problem is not limited to Pentax or the other two big names either, but I have used a Sony F-7x7 and F-828 which had a holographic laser focus assist that DID work reliably.

The problem is, when shooting candid and random impromptu shots in dim or low contrast light, the AF lock is very sporadic.

Case in point last night. I was invited to shoot a photo essay for a 21st birthday party, outdoors on a cloudy night with little ambient or other illumination. I found that the focus hunted a lot, then flashed the red square for locked, but after viewing the shot it was major out of focus.

My gear. K10D, Sigma 17-70 DC 2.8, AF360FGZ flash. Shot in P mode, with the focus zone set to centre.

I did notice, the AF illuminator in the flash did not come on at all (Sometimes it works, mostly not???), so I tried my best to zero in on a bright spot of the subject and hold the lock to frame, worked sometimes but not others.

From experience, is the 540 FGZ better than the 360 FGZ in this ??

Is this a common experience? as this is a dynamic environment I tend to shoot in, posing or lighting is not an option... when you lose a shot like this you have no second chance to reshoot it.

Thanks, if anyone has any ideas that would be great.
Using K10d for very low light situations I use a tiny flash light in my left fingers with a tight beam and using one center focus point. Also, use only the AF button, turning off focus from the shutter release button. This in effect locks the focus once so no hunting when I take the shot. Works great!
04-30-2007, 02:14 PM   #22
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QuoteOriginally posted by Photomy Quote
Using K10d for very low light situations I use a tiny flash light in my left fingers with a tight beam and using one center focus point. Also, use only the AF button, turning off focus from the shutter release button. This in effect locks the focus once so no hunting when I take the shot. Works great!
Good suggestion, I have done things like that before too... not as sophisticated as you, but had a family of Kookaburras in a tree beside our house, used to settle in after dark in the tree, same branch every night, but they were 10meters up.. could not focus at all with my 70-300 Sigma.. so, improvise.. used my push bike high intensity light to illuminate them for the focus, worked great.

Thanks.

Here is one of the shots.

Attached Images
 
04-30-2007, 02:22 PM   #23
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QuoteOriginally posted by jfdavis58 Quote
So, you had a grab-it or it's gone situation.

Perhaps similar to the one of the boy and the hat, but the subject was a girl.

A camera that was preset, but got at least one switch bumped out of detent/position.

The flash focus assist light didn't.

You read the wrong indicator in the viewfinder and you blew a few shots out of a couple hundred. The un-blown shots all being within your range of acceptable.

So you post to the forum asking if others have had similar situations, but the situational information you provided is misunderstood because ther is a submarine hiding somewhere.

A couple of folks respond strongly that your original stated situation is on the fringe of normal operation. And that you should be happy you got any results at all.

The up-shot of all this is that preset cameras might not be.

And that for the foreseeable future Beth and I are not allowed our own opinions because we stridently wear the same pair knickers, have changed our sir-name and something is queer.

Oh yeah, as the OP you may need to be shrunk.

All this time I thought it was the British who had trouble with English!
Accurate summary John, thanks for your input... appreciate the help.

I will read my posts more carefully in the future in the interests of clarity, hopefully this will alleviate misunderstandings of their meaning.

Phil
05-01-2007, 12:35 PM   #24
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I am disappointed to hear that the K10D does not improve much on auto focus speed.

I have missed countless candid shots in low light situations (ironic, since I'm not using a flash and using primes, 50mm f/1.4 and 35mm f/2) with my *ist DS.

I'm sure the K10D will make a great studio camera or any situation where you can take your time composing. But since I wear glasses, don't trust what I see through the viewfinder 100%, and want to shoot pics of my 1st born baby girl growing up, I will probably have to abandon Pentax. It's a shame since I've used Pentax since the original K1000.

I hope I'm proven wrong with the new DA* lenses, but I don't think I will since Pentax decided not to include a focus assist lamp in the K10D.

-Ed
05-01-2007, 03:07 PM   #25
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QuoteOriginally posted by Edwood Quote
I am disappointed to hear that the K10D does not improve much on auto focus speed.

I have missed countless candid shots in low light situations (ironic, since I'm not using a flash and using primes, 50mm f/1.4 and 35mm f/2) with my *ist DS.

-Ed


I still think it due to a manufacturing inconsistency. Some people are swearing their's are no worse than anything else and others, like Ed who have problems that are not subtle and I would not assume are operator error any more than I would that they aren't. Just too many reports from people who know what they're doing.
05-01-2007, 05:10 PM   #26
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QuoteOriginally posted by jfdavis58 Quote
How many cameras of the same model have you actually used to make this comparison and deduce this statement?

And you know this, how?

And then how many is many? You really think the web makes-up a significant percentage of the total user base?

...like the title says...

Come on, John. Lets not start that stuff here. This is a discussion forum, not the Library of Congress. The man obviously posted an opinion, which is exactly what casual discussion forums are for. Asking a person who is clearly posting an opinion for documentation, simply because you disagree, is downright absurd. Do you routinely ask those you're talking with (wife, friends, co-workers, emplorers) for "sources and summaries" to support all they say? Since doing so would make you a very unpopular person, I seriously doubt it. So why do so here? Regardless, a requirement for documentation & evidence to back everything said here would clearly have a a chilling effect on this forum. In the end, if you want sources, summaries, and other such nonsense, those are best found at the library, through your own research if you have such a great need for that. At that point, if you so vehemently disagree with what another has said, you can post your own "sources and summaries" to dispute that person's simple opinion.

stewart
05-01-2007, 06:06 PM   #27
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QuoteOriginally posted by stewart_photo Quote
Come on, John. Lets not start that stuff here. This is a discussion forum, not the Library of Congress. The man obviously posted an opinion, which is exactly what casual discussion forums are for. Asking a person who is clearly posting an opinion for documentation, simply because you disagree, is downright absurd. Do you routinely ask those you're talking with (wife, friends, co-workers, emplorers) for "sources and summaries" to support all they say? Since doing so would make you a very unpopular person, I seriously doubt it. So why do so here? Regardless, a requirement for documentation & evidence to back everything said here would clearly have a a chilling effect on this forum. In the end, if you want sources, summaries, and other such nonsense, those are best found at the library, through your own research if you have such a great need for that. At that point, if you so vehemently disagree with what another has said, you can post your own "sources and summaries" to dispute that person's simple opinion.

stewart
Well said Stewart. Let's lighten up everyone, and read Stewart's post before being over critical or pedantic on our replies to any post.

As my mom used to tell me over and over... "If you have nothing nice to say to someone, then say nothing"

I can only imagine how a reply like that earlier one would have hurt a person that was intellectually, literally, grammatically or linguistically challenged, and was doing their best.

This forum is a great site, I enjoy it immensely and find it for the most part a friendly, helpful and supportive environment.

Please let's keep it that way.

Phil
05-01-2007, 06:59 PM   #28
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QuoteOriginally posted by Photomy Quote
Using K10d for very low light situations I use a tiny flash light in my left fingers with a tight beam and using one center focus point. Also, use only the AF button, turning off focus from the shutter release button. This in effect locks the focus once so no hunting when I take the shot. Works great!
I believe I have read that the auto-focus system will work with IR light. Some small flashlights, such as the Photon lights, are available with an IR LED bulb. This could be an effective solution for low-light focus assist, without shining a (visible) light in your subjects face to achieve focus.

Chris
05-02-2007, 10:04 AM   #29
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As Edwood stated, it is disappointing that this issue still exists in the newer models. I have an istDS also and, as I have stated here *many* times, the lowlight autofocus performance is horrendous in terms of speed and accuracy. I understand that AF is a convenience and that ultimately it is up to me to get the shot focused but that is beside the point. This is a matter of poor technology in an area that other manufacturers have achieved excellent results. My wife's Oly P&S (c5050z) uses an infrared assist and it focuses very quickly and accurately in low light conditions. For situations like indoor birthday parties I don't even bother using my istDS anymore because it's so frustrating. Her camera can run circles around it in the ability to get quick, accurate candid shots. I have seen the same high performance AF in my daughter in-law's Canon Rebel. I believe that the Pentax is a far superior camera to those in every other sense but I'm not going to lose dozens of shoots out of loyalty to my Pentax. This is something Pentax can and should address
05-02-2007, 10:25 PM   #30
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QuoteOriginally posted by awjweb Quote
As Edwood stated, it is disappointing that this issue still exists in the newer models. I have an istDS also and, as I have stated here *many* times, the lowlight autofocus performance is horrendous in terms of speed and accuracy.
Have you tried the K10D? It is miles better than the *ist DS. Edwood was wrong, K10D was a big improvement, including low light AF. Other brand may give an impression of faster AF in low light, because they did not do any final checking. Pentax would move past and back the focus point to ensure accuracy. If you don't need this extra accuracy, just switch to AF-C (no AF assist though), and press the shutter when the lens reach its first stop; that would be the same as what Canon and Nikon do.

QuoteQuote:
My wife's Oly P&S (c5050z) uses an infrared assist and it focuses very quickly and accurately in low light conditions.
Comparing with P&S is misleading. Because of the huge DOF due to the tiny sensor, P&S's AF is very approximate, and it does not require high accuracy to get sharp pictures. On the other hand, DSLR has to deal with insane narrow DOF in some lenses with errors allowed limited to millimeters.

Actually, P&S's contrast detection is inherently slower than DSLR's phase detection AF. In contrast detection, the camera has no idea which direction the focus should go. The newer P&S does the apparent fast AF in low light by speeding through the entire range of focus, memorizing the highest contrast point, and "snap" back to the memorized point. This is not very accurate, but good enough as it is covered by the huge DOF.

QuoteQuote:
This is something Pentax can and should address
They already did.
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