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wlachan
Guest
Just how tracking and low EV AF abilities are related to AF calibration is totally beyond me.
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Alan Chan
http://www.pbase.com/wlachan
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AF frustrations with SDM lenses
- Thread starter Jerome the Parisian
- Start date
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Alan Chan
http://www.pbase.com/wlachan
howieb101
Leading Member
The K7 (I have it) and presumably Km and Kx are definitely better than K20D in AF with all my lenses barring the 50-135 DA*. This lense is just slow albeit with superb image quality.
I can compare the K7 against K10D and K20D and there is no doubt the K7 is faster and this is even in low light.
Also, I have tried my friends Canon 30D with a usm lense in indoor light it was not rocket fast.
I can compare the K7 against K10D and K20D and there is no doubt the K7 is faster and this is even in low light.
Also, I have tried my friends Canon 30D with a usm lense in indoor light it was not rocket fast.
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wlachan
Guest
There was a time when people questioned certain Pentax quality would be labeled, bashed and abused by some diehards real bad here (there are still a few around). It was a very rough time to those who really wanted to discuss objectively. Then after maybe 2 years or so, people could take shxt no more and started fighting back instead of being abused by those crusaders. Pentax have some nice quality, but they have some on-going issues as well. Without acknowledging the shortcomings, Pentax will remain behind the competitions forever.
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Alan Chan
http://www.pbase.com/wlachan
*isteve
Veteran Member
Looks pretty much in focus to me. For AF to work well in dark rooms, you need to focus on an edge with high contrast and then recompose slightly while holding the shutter half down to take the actual shot.
In the first case, the line between the guitar and shirt should have been enough to get a good lock. In the second case, the wine glass is actually quite small, so there is a risk of focusing on the background. The camera will pick the highest contrast edge it can find within the focus area.
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Steve
Any fool can take a picture OF something. Its much harder to take a picture ABOUT something.
In the first case, the line between the guitar and shirt should have been enough to get a good lock. In the second case, the wine glass is actually quite small, so there is a risk of focusing on the background. The camera will pick the highest contrast edge it can find within the focus area.
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Steve
Any fool can take a picture OF something. Its much harder to take a picture ABOUT something.
Jerome the Parisian
Forum Enthusiast
the 50-135 SDM AF is not slow when light and contrast are present. I shot with this lens for about 2 years now and found AF fast and accurate as long as contrast and some light are in the focused area.
Jerome
Jerome
Jerome the Parisian
Forum Enthusiast
The guitar player: I previously wrote that AF locked only after a few seconds, which is always a frustration under such a decent light environment.
The glass one (as I wrote too) was actually a very fast AF since I focused on the glass and contrast there was enough to lock focus extremely fast.
I love the SDM lenses, but AF from Pentax bodies.... Could be better.
Jerome
The glass one (as I wrote too) was actually a very fast AF since I focused on the glass and contrast there was enough to lock focus extremely fast.
I love the SDM lenses, but AF from Pentax bodies.... Could be better.
Jerome
Real Engineer
Forum Enthusiast
I've had focus issues with the K7.
In bright sunlight on one particular type of plant the thing just has a hell of a time confirming focus.
This is with a manual lens 200mm lens when set to F2.8
I noticed that if I changed the aperture it would work better. It was a working as manual only aperture lens and no lever on it for the camera to be able to set anything.
In my case it turned out to be the CA of the out of focus foreground/background confusing the focus confirmation. Very frustrating at the time till I figured it out.
Of course I've now I've converted it to an A type lens it is always at F2.8 and this pops up every once in a while during normal shooting depending on the subject.
Again very frustrating when it happens.
Obviously not the same problem as the OP however.
In bright sunlight on one particular type of plant the thing just has a hell of a time confirming focus.
This is with a manual lens 200mm lens when set to F2.8
I noticed that if I changed the aperture it would work better. It was a working as manual only aperture lens and no lever on it for the camera to be able to set anything.
In my case it turned out to be the CA of the out of focus foreground/background confusing the focus confirmation. Very frustrating at the time till I figured it out.
Of course I've now I've converted it to an A type lens it is always at F2.8 and this pops up every once in a while during normal shooting depending on the subject.
Again very frustrating when it happens.
Obviously not the same problem as the OP however.
emem
Veteran Member
........ indoors in weak daylight, pointing it at the darkest corner in my loungeroom. At 800ISO, F4.5, 1/10 & 1/15 sec exposures, the lens focused and locked on with no trouble at all. Probably as quick as outdoors in good light. I use centre point, AF-S, centre weighted, Av mode.
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Mike M. (emem)
http://www.veritasmea.com
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Mike M. (emem)
http://www.veritasmea.com
Fast Prime
New member
After reading the other posts in the thread, I would like to offer that I own the 50-135 and have used it on a K200D and a K-7. I also own the f1.9-43 mm Blk Limited and several other good lenses. Generally I have had some difficulty at times shooting sunsets or sunrises with the 50-135. I had the most problems with AF when I was trying to focus on a tree-lined horizon in cold weather. It worked better when I switched from Program to Aperture Priority and made sure I was shooting at a different Aperture than earlier. I was using a tripod and CS-205 Cable Switch on those shots. A time or two, I got what I knew to be a good sharp shot and immediately switched to MF. (I know that doesn't cure the AF, but it gets good images!)
Sometimes my lens has had problems focusing accurately when either strong vertical or strong horizontal lines were at the point of focus. Curiously, it is quick, accurate, and tack sharp when shooting architectural shots and focusing on a brick wall in nearly any light. All of the above was done on a tripod.
For K-7 owners using the Limited lenses, a new firmware update is available today at the Pentax Imaging website.
Sometimes my lens has had problems focusing accurately when either strong vertical or strong horizontal lines were at the point of focus. Curiously, it is quick, accurate, and tack sharp when shooting architectural shots and focusing on a brick wall in nearly any light. All of the above was done on a tripod.
For K-7 owners using the Limited lenses, a new firmware update is available today at the Pentax Imaging website.
Alex Sarbu
Forum Pro
But this isn't a SDM issue ; it's a SAFOX issue. The SDM motor is working just fine; but the camera can't lock focus.
Well, the lens electronics could be involved - but it works fine in better light; also the optics, the contrast wide-open matters a lot. But could it be, he's just hitting the limit of the equipment, in not so good light and with bad contrast/ a non-static subject?
Alex S.
Agreed that SAFOX is the major issue in AF speed below EV5 as compared to SDM. Although I still maintain that the k-7 SD could spin the focus ring faster than the SDM. I have no proof of this other than anecdotal evidence. I think Roger may have been talking about reliability which is a different issue than the SAFOX one.
--Smart alec response alert: The following response is highly sarcastic. Those with weak constitutions should look away, or continue on to the next response.--
This assumes that it is possible for SDM to "work just fine."
I'm tired of sending my gear to service and wait month or longer for fixing it and hoping the fix will help. I already sent to service everything what I had from Pentax in past. I bought new K20D about half-year ago and hoped it will be without issues, but may be I'm wrong. I will see when FA31/1.8 arrives if problems was in lenses or camera.
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S.
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You can help your AF when you put down any filters from lens what you're using. For me also works shutting down SuperImpose AF area in menu and using only centre AF point selected with the ring switch. It will speed the AF process. Also setting on camera everything you can set to static will speed up the AF. So the WB, f number or aperture, ISO and so on. What also works is put camera to AF-C and canceling AF via AF button. In this mode camera let you take shot also if it thinks your photo is not focused, but in real it's. This are my hints. You can try, may be it will help you.
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S.
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Bonjour Jérome,
Generally speaking, the 50-135 isn't the fastest lens in the bunch but it shouldn't take more than a second to lock on such pictures (eg the guitar player you showed).
I don't now if you use auto AF point selection or not (could not find this info in your messages) but generally, to get bet results I would:
1/ select one of the 9 cross sensors;
2/ place it on the eye of your subject or anywhere you have contrast and try to keep it on target (that's the most difficult part if your subject is moving, see below);
3/ if the subject if moving, even slightly, get the camera in AF-C and continuous shooting and use burst of 2-3 images letting the AF regain focus by itself; I have taken the habit of using the back AF button to let the AF do its work continuously and just press the trigger when I think the moment is right.
Ususally, I would get at one good pic out of one burst on my K10 and a bit more with my K20.
I hope this helps, bonne chance.
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http://lol-photoblog.blogspot.com/
... how does that help the OP?
Except for casting the shadow of a doubt on his integrity as a poster, how does the knowledge of your perpetual happiness help him succeed in his quest for better performances out of his gear?
With you, it's either:
1/ Everything is fine in Pentaxland! Move along people!
or:
2/ You are an incredibly unlucky guy: you got te one in a trillion camera/lens/flash/.../ that isn't properly calibrated: send it back to Pentax for them to callibrate to their eternal perfection standards. Hence, GOTO 1/
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http://lol-photoblog.blogspot.com/
Whilst ignoring all the pro and anti pentax jibes that are ruining you legitimate problem, (pretty rude really).As you can see, it's not that dark, so AF should work better on such circumstances.
I have no idea what was the EV at that time, but anyway...
I initially try to focus on his face and it never locked. Then I focused on the guitar and it did work after 2-3 seconds of hunting with the help of some contrast maybe?).
Jerome
I think the cameras issue with this is the lack of contrast in the subject, its all around the 18% grey with no highlights to lock onto.
You need to be in a locked mode of AF to have any chance , I'd sugest.
AF-s
Centre AF selected on the dial wheel
AV ot TV mode.
I find giving the camera as little choice as possible speeds up low light AF considerably.
And if that doesn't work I find screaming in my head 'Fxxxxing Camera get a grip' doesn't help but makes me feel better.
As an aside I also have been know to scream the same when having an eos1ds and the 200 F1.8 in my hands.
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*isteve
Veteran Member
My question is where were you aiming the focus point?
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Steve
Any fool can take a picture OF something. Its much harder to take a picture ABOUT something.
That sounds like a lens or camera defect to me, the K20D shouldnt be that slow. I tried it just now and in a scene metered at ISO800 F4.5 1/90 by the camera (slightly darker than your scene), the camera is still very snappy when locking focus. Shooting a dark part of the room, measured by the camera at ISO800 F4.5 1/15 (a full 3 stops darker than your scene), the camera still locks faster than a second when starting out prefocused at infinity or closest focus.
Its not a SDM lens but a screwdrive Tamron 17-50/2.8 at 50mm. SDM or not, it shouldnt be that difficult to lock focus in the situation you described, especially when you said you tried focusing on the head, which has plenty of contrast in a area easily covered by the surprisingly large center focus point.
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Its not a SDM lens but a screwdrive Tamron 17-50/2.8 at 50mm. SDM or not, it shouldnt be that difficult to lock focus in the situation you described, especially when you said you tried focusing on the head, which has plenty of contrast in a area easily covered by the surprisingly large center focus point.
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S
SBS
Guest
topgun2007
Leading Member
Alex, we are talking about several customer service reps that I have talked to in the U.S. when I have called in. Basically, their opinion is based upon the fact that the SAFOX system hasn't change much going from the K20D to the K7. Therefore AF issues that one had with the K20D are also prevalent in the K7. I can't speak for the K-x, but if it is indeed improved, I hope they will incorporate the improvements in the next K8 or K30D or whatever model number. Maybe that is what is coming and why it has been suggested that I wait for the next model.
Regards, Jim
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