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05-05-2011, 07:26 AM   #46
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QuoteOriginally posted by Rupert Quote
I find this whole conversation perplexing? Maybe I am not looking for absolute perfection in AF, but if I was no camera would live up to that expectation.
I shoot Squirrels. Despite the seemingly easy chore of getting good crisp shots, Squirrel shooting is under all sorts of lighting conditions, and at all sorts of distances. My K5 nails a good 90% of my Squirrel shots and does it fast, using the Bigma that has always hunted like a old Coon Hound on my previous bodies. I can post consecutive shots showing in numerical order the superb abilities of my K5 to repeatedly capture in-focus AF images, should anyone doubt my findings.
So.....not questioning the results of a few here with no such results, it must be a variance in cameras.....a questions of specific lenses....a combination.....I have no real idea, but whatever it is does not affect my K5 in the least?
Best Regards!
Indeed this may be perplexing for those who do not have AF issues with the K5, which I suppose is the majority of users.

However, in a few "isolated" K5 cases, the AF does not acquire proper focus and, to make matters more maddening, it does it inconsistently.
I am quite confident that it does not relate to faulty user's technique, personally speaking here.

I have some absolutely GREAT bird and wildlife shots taken with the K5: tack sharp, great colours even at high ISO settings. The AF is bang on, even at fair distances.
Then, for whatever reason, during the same outing, with the same lighting conditions and aiming at similar subjects (birds and other such creatures), the AF indicates that it is focused on the subject (green hexagon and beep confirmation along with the SR indicator on) but it is not in focus at all.

I am not complaining, just relating the facts.
In the meantime, until the K5 is "repaired" or replaced, I am fortunate enough to have the K7 which, albeit not as good as the K5 for high ISO shots, nonetheless performs almost perfectly nearly 100% of the time.

Frustrating would be the word.

Cheers.

JP

05-05-2011, 08:12 AM   #47
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QuoteOriginally posted by Rupert Quote
I find this whole conversation perplexing? Maybe I am not looking for absolute perfection in AF, but if I was no camera would live up to that expectation.
I shoot Squirrels. Despite the seemingly easy chore of getting good crisp shots, Squirrel shooting is under all sorts of lighting conditions, and at all sorts of distances. My K5 nails a good 90% of my Squirrel shots and does it fast, using the Bigma that has always hunted like a old Coon Hound on my previous bodies. I can post consecutive shots showing in numerical order the superb abilities of my K5 to repeatedly capture in-focus AF images, should anyone doubt my findings.
So.....not questioning the results of a few here with no such results, it must be a variance in cameras.....a questions of specific lenses....a combination.....I have no real idea, but whatever it is does not affect my K5 in the least?
Best Regards!
You know, Rupert, my Bigma locks on tight and fast every time, too; And my Sigma 18-50, and my DA* 50-135, and my DA-L 55-300; but I've got three or four other lenses that misbehave badly. I'm wondering if this might not have a lot to do with individual lenses. My FA 35 f2 misses a lot, and my 50mm f1.4 misses frequently, as well. My 100 macro works great up close, but misses at long distances (non-macro distances). The Tamron 70-300 I have misses badly. In addition, the missed focus is inconsistent, so I can't adjust it away. Note that all of these lenses are dead on the money with my K20D. I didn't think I had any focus problems because the lenses that work well - VERY well - are the lenses I use the most.

Right now I'm manually focusing when I use those lenses, but I'm going to have to send it back sooner or later, I think. I just hate for it to be gone for so long...

And yeah, I know shooting squirrels is tough.
05-05-2011, 08:16 AM   #48
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QuoteOriginally posted by jpzk Quote
Indeed this may be perplexing for those who do not have AF issues with the K5, which I suppose is the majority of users.

However, in a few "isolated" K5 cases, the AF does not acquire proper focus and, to make matters more maddening, it does it inconsistently.
I am quite confident that it does not relate to faulty user's technique, personally speaking here.

JP
I've discovered that some lenses work fast and reliably - and others don't. I thought I didn't have focus issues because the ones that work right are the ones I use the most. But I have seen what you're talking about, very rarely; A "focus lock" when it's CLEARLY not in focus. Fortunately, not too often. I see it less often when I use AF-C, also.
05-05-2011, 08:44 AM   #49
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QuoteOriginally posted by jpzk Quote
Indeed this may be perplexing for those who do not have AF issues with the K5, which I suppose is the majority of users.

However, in a few "isolated" K5 cases, the AF does not acquire proper focus and, to make matters more maddening, it does it inconsistently.
I am quite confident that it does not relate to faulty user's technique, personally speaking here.

I have some absolutely GREAT bird and wildlife shots taken with the K5: tack sharp, great colours even at high ISO settings. The AF is bang on, even at fair distances.
Then, for whatever reason, during the same outing, with the same lighting conditions and aiming at similar subjects (birds and other such creatures), the AF indicates that it is focused on the subject (green hexagon and beep confirmation along with the SR indicator on) but it is not in focus at all.

I am not complaining, just relating the facts.
In the meantime, until the K5 is "repaired" or replaced, I am fortunate enough to have the K7 which, albeit not as good as the K5 for high ISO shots, nonetheless performs almost perfectly nearly 100% of the time.

Frustrating would be the word.

Cheers.

JP
Not questioning the shooters with problems at all......I think most here are honest and loyal Pentax shooters, just looking for answers. I wish I had some, but I don't. It is not an "ability" problem for sure, how much ability does it take to see the focus confirmation and hear the beep?
There are so many factors in a camera that make it hard to nail any specific defect. I have two identical computers, both running XP, but they are not similar in operational results. I have had experts take a good look.....never have found an answer that has explained the differences. There are trillions of lines of code, I am told.....it's in there somewhere, but where?
Best Regards!

05-05-2011, 10:04 AM   #50
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Just to tell a little. I use a gimble mount on the 300mm. Locked down before shooting. That’s how critical focus is on birds. Shots that in good light would just rock. The bad thing is it hits fast and fires. But rarely hits accurately. In good light it is pretty good but I am talking about detail here. I've got to where I stop down to f4-5.6 if possible to help.

In bird photography it has to be perfect and on target. For a bird of say six to eight inches and 2 inches deep it is a must. I am beginning to think that it is not noticed in normal shooting with people and other subjects? Just a guess. I know nothing about other subjects. At close quarter shooting with a 2.8 it is absolutely critical. DOF is so small. But that is why you have lenses of this caliber. Low light and huge lenses.

The 300mm f2.8 is a FANTASTIC lens. I just rave about it. When it hits AF in my opinion it is outstanding.

On the second page of my flickr account: Flickr: gary1844's Photostream
I have some bird portraits with it. In the few times it actually hit? It produces some of the best shots I have ever seen. That stands up to Canon and Nikon in my opinion. But my gosh. It is a struggle at best. If Pentax ever fixes the AF it will be a keeper. But it is killing me right now. It is a huge problem for me.
I talk to another birder from Canon allot. A friend. And he started the same way with Pentax then Olympus before moving to Canon and he summed it up pretty well I think.
Quote:" Just sell everything, chalk it up as a learning experience and move on.. When I moved to Canon I now can concentrate on my photography. And grow." Very painful for me.

And expensive.

Last edited by garyk; 05-05-2011 at 10:15 AM.
05-05-2011, 11:09 AM   #51
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I'm not trying to defend Pentax here. But just to sound a cautionary note that moving brands is not always a panacea. Lots of Canon and Nikon people regularly complain about BF/FF etc too (judging from various forums). And Nikon and Canon lenses aren't immune from all manner of manufacturing, QC and design flaws as well (cf some of the lensrentals.com guy's blog posts and his annual reliability reports).

Figuring out how to work around your problems may be less expense and risk than getting a whole new system, only to find new problems occurring there.

But then again Canon stuff is usually excellent, and the extra amount of crop you get out of their APS-C sensors compared to Pentax or Nikon (1.6 vs 1.5) can be handy too. Just don't look for K-5 equivalent ISO and DR performance out of any of their non-FF bodies .
05-05-2011, 12:18 PM   #52
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QuoteOriginally posted by jstevewhite Quote
I've discovered that some lenses work fast and reliably - and others don't. I thought I didn't have focus issues because the ones that work right are the ones I use the most. But I have seen what you're talking about, very rarely; A "focus lock" when it's CLEARLY not in focus. Fortunately, not too often. I see it less often when I use AF-C, also.
Right!

Focus lock indication which does not actually indicate proper focus ... that is the question at hand.

This is not something that happens all the time, but still very frustrating when it is much needed.

It also does not make a difference whether I use AF-C or AF-S.

JP
05-05-2011, 12:26 PM   #53
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QuoteOriginally posted by garyk Quote
Just to tell a little. I use a gimble mount on the 300mm. Locked down before shooting. That’s how critical focus is on birds. Shots that in good light would just rock. The bad thing is it hits fast and fires. But rarely hits accurately. In good light it is pretty good but I am talking about detail here. I've got to where I stop down to f4-5.6 if possible to help.

In bird photography it has to be perfect and on target. For a bird of say six to eight inches and 2 inches deep it is a must. I am beginning to think that it is not noticed in normal shooting with people and other subjects? Just a guess. I know nothing about other subjects. At close quarter shooting with a 2.8 it is absolutely critical. DOF is so small. But that is why you have lenses of this caliber. Low light and huge lenses.

The 300mm f2.8 is a FANTASTIC lens. I just rave about it. When it hits AF in my opinion it is outstanding.

On the second page of my flickr account: Flickr: gary1844's Photostream
I have some bird portraits with it. In the few times it actually hit? It produces some of the best shots I have ever seen. That stands up to Canon and Nikon in my opinion. But my gosh. It is a struggle at best. If Pentax ever fixes the AF it will be a keeper. But it is killing me right now. It is a huge problem for me.
I talk to another birder from Canon allot. A friend. And he started the same way with Pentax then Olympus before moving to Canon and he summed it up pretty well I think.
Quote:" Just sell everything, chalk it up as a learning experience and move on.. When I moved to Canon I now can concentrate on my photography. And grow." Very painful for me.

And expensive.
I wonder why this is such a pain to get accurate focus even when the camera indicates that "all is good ... go ahead and press the shutter button" while it is not actually so?

I mean, the green hexagon lights up, the beep confirms it and the SR "hand"is on ... good shutter speed, good light, stable camera handling ... this should allow me to have MOST shots in focus, right?

Anyway, I have been trying to get hold of someone at Pentax Canada (Mississauga, Ontario) and I get a message telling me leave a message so they will call back.
Are they kidding me? I have been trying since 9 am today!

By the way, I have no present intention to switch brand ... yet.

JP

05-05-2011, 12:29 PM   #54
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QuoteOriginally posted by Rupert Quote
Not questioning the shooters with problems at all......I think most here are honest and loyal Pentax shooters, just looking for answers. I wish I had some, but I don't. It is not an "ability" problem for sure, how much ability does it take to see the focus confirmation and hear the beep?
There are so many factors in a camera that make it hard to nail any specific defect. I have two identical computers, both running XP, but they are not similar in operational results. I have had experts take a good look.....never have found an answer that has explained the differences. There are trillions of lines of code, I am told.....it's in there somewhere, but where?
Best Regards!
I am hopeful that Pentax customer service will:
1. return my call(s)
2. provide acceptable repair or replacement.

I was starting to question my abilities to handle a (D)/SLR camera, something I have been used to do since 1976!!

Cheers.

JP
05-05-2011, 04:13 PM   #55
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Also have the grossly off focus locking issue at infinity in low light, unlike previous cameras, but got a more generic response to my concern from Pentax support:

In very low light shooting conditions it is possible there isn't enough light for the autofocus system to accurately determine the focus point you want, especially if the subject is very distant. You can check for a back or front focusing issue with a particular lens and use the AF fine adjustment feature in the custom settings menu to store the adjustment in the K-5.

We have posted some general guidelines on DPReview.com regarding testing for back or front focus. It is a good idea (if you haven’t already) to download a focus test chart and shoot a few tests before sending your lens in to be checked out. Also, if you do decide to send your lens in to our shop for evaluation, it is very important that you include your camera body as well (since any lens-specific focus adjustment information is stored in the camera body). The text of the posting is listed below:

The following focus adjustment instructions are based on input from the PENTAX engineering department, and our own experiences in house.

1. Use a focus test chart such as Tim Jackson’s “focus test” chart. Do not use batteries or film canisters set up at an angle. The curved surfaces don't allow for accuracy.

2. Make sure the chart is flat and that you are shooting the chart at a 45-degree angle (or close to it).

3. Use back-lit daylight or tungsten light for the best results.

4. Use a tripod. This will prevent any error due to camera movement.

5. Position the camera approximately 1.5 meters (5 feet) from the test chart. (This may vary of course depending on the lens focal length and minimum focus distance.

6. Set the camera to aperture priority or manual exposure mode and set the lens to its maximum aperture.

7.Shoot the first test shot using manual focus. This is important to establish a baseline for judging back or front focus in regards to the normal depth-of-field of the tested lens at a particular focus distance and f/stop.

****IMPORTANT: Lenses will typically have more depth of field behind the focus point than in front. This is true for any lens from any manufacturer, and is the basis of "hyper focal" charts used in landscape and macro photography. The first shot manually focused will establish a baseline for the particular lens in use****

8. For zoom lenses, set the lens at a middle zoom position or at the zoom position
where front or back focus is suspected. Note: it is not possible to save multiple custom focus adjustments for different focal lengths of a zoom lens. Only 1 adjustment per lens can be saved.


They post in DPreview and not here?
05-05-2011, 05:35 PM   #56
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Actually i like the images out of Pentax. I am going to give Pentax a call and ask some questions. But the OP has the same problems i have exactly.
I will monitor this thread.
Great info here...
05-05-2011, 07:27 PM   #57
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garyk, another thought is regards third-party lenses like your Sigmas. Even if they don't support HSM on Pentax bodies, do they still have a chip in them or something with their own firmware that is responsible for talking to the camera body about aperture, focal length etc? Like some older Sigma flashes, which some users have reported in the past needed to go back to the manufacturer or distributor to be re-chipped in order to be compatible with recent Pentax bodies, perhaps the lens firmware on that 300/2.8 needs an update. Certainly I know for example the firmware on the current 50-500 Sigma OS currently has issues, and Sigma have prepared an update. Who knows. Even seemingly 'dumb' screw drive lenses nowadays are actually chock full of electronics.
05-06-2011, 09:10 AM   #58
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QuoteOriginally posted by Ash Quote
Also have the grossly off focus locking issue at infinity in low light, unlike previous cameras, but got a more generic response to my concern from Pentax support:

In very low light shooting conditions it is possible there isn't enough light for the autofocus system to accurately determine the focus point you want, especially if the subject is very distant.
Of course, this is a well known aspect of focusing, and for any brand I would imagine.
My K5 will not focus properly, intermittently, under such conditions AND even with adequate light/contrast.

You can check for a back or front focusing issue with a particular lens and use the AF fine adjustment feature in the custom settings menu to store the adjustment in the K-5.
Well, this is also not new, is it, but of course something which needs being tested before sending the lens out to Pentax.
We have posted some general guidelines on DPReview.com regarding testing for back or front focus. It is a good idea (if you haven’t already) to download a focus test chart and shoot a few tests before sending your lens in to be checked out. Also, if you do decide to send your lens in to our shop for evaluation, it is very important that you include your camera body as well (since any lens-specific focus adjustment information is stored in the camera body). The text of the posting is listed below:

The following focus adjustment instructions are based on input from the PENTAX engineering department, and our own experiences in house.

1. Use a focus test chart such as Tim Jackson’s “focus test” chart. Do not use batteries or film canisters set up at an angle. The curved surfaces don't allow for accuracy.

2. Make sure the chart is flat and that you are shooting the chart at a 45-degree angle (or close to it).

3. Use back-lit daylight or tungsten light for the best results.

4. Use a tripod. This will prevent any error due to camera movement.

5. Position the camera approximately 1.5 meters (5 feet) from the test chart. (This may vary of course depending on the lens focal length and minimum focus distance.

6. Set the camera to aperture priority or manual exposure mode and set the lens to its maximum aperture.

7.Shoot the first test shot using manual focus. This is important to establish a baseline for judging back or front focus in regards to the normal depth-of-field of the tested lens at a particular focus distance and f/stop.

****IMPORTANT: Lenses will typically have more depth of field behind the focus point than in front. This is true for any lens from any manufacturer, and is the basis of "hyper focal" charts used in landscape and macro photography. The first shot manually focused will establish a baseline for the particular lens in use****

8. For zoom lenses, set the lens at a middle zoom position or at the zoom position
where front or back focus is suspected. Note: it is not possible to save multiple custom focus adjustments for different focal lengths of a zoom lens. Only 1 adjustment per lens can be saved.


They post in DPreview and not here?
Thanks for the info, Ash. I am also surprised that this wasn't posted here before!

Cheers.

JP
05-07-2011, 03:49 PM   #59
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No worries jp.
I've also found an instance when my K-5 failed to lock focus on a well contrasted subject in bright conditions, but it was only during a close-range gun shooting exercise and only with the outermost focus point. Admittedly, the violent sound transmitted by the guns may have disturbed the wavelength sensor for that particular focus point, but that's all speculation. After switching the camera on and off again I found the focus point working as normal again.

Some of these little niggles are a little odd, but some more troublesome than others.
05-09-2011, 05:30 AM   #60
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QuoteOriginally posted by Ash Quote
violent sound transmitted by the guns may have disturbed the wavelength sensor
?? What does sound waves have to do with light wavelength? Nothing.
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