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10-19-2009, 05:58 PM   #16
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I can't find any mention of AF-adjust in any K-x material I've seen. In-built lens distortion/CA correction, yes. AF-adjust, no. This is an entry-level camera...

FWIW even the Nikon D90 lacks AF-adjust.

It may be possible however to enter debug mode in the K-x firmware in a similar way to how you can in the K200D, and do AF-adjust that way. The info for this is in a few threads on this forum.

Given the fact that these AF issues are a lens/body issue, it may also be possible that any lens you currently have that may be 'off' with your current body could work differently (perhaps better - ie AF-adjust may not be required) with any K-x body you might get. Who knows.

10-19-2009, 07:33 PM   #17
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QuoteOriginally posted by schmik Quote
Me too... the quality (or lack of) in the accuracy of the fast glass is pointless with no AF adjustment. What's the point of paying for 2.4 / 2.8 if you ALWAYS haqve to shoot at 5.6 to get a sharp image. Knowing that some of my glass is 'off' makes AF adjustment a must.

Does the KX have it?
Not according to any published reports I've seen. But I think you vastly overstate things. If you can't get an in-focus picture at f/2.4, either your lens or camera is defective, plain and simple. You don't need an AF adjustment setting; you need a new lens or camera, and your warranty should provide for it.

That is to say, if your camera and lens are functioning correctly, this feature is a luxury, not a necessity. Might help you fine tune exactly where with the focus zone the target lies, but with or without the adjustment, you have every right to expect the chosen target will be in focus at f/2.4. If it isn't, simply exchange the camera for one that isn't defective.
10-19-2009, 09:29 PM   #18
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Original Poster
QuoteOriginally posted by Marc Sabatella Quote
Not according to any published reports I've
seen. But I think you vastly overstate things. If you can't get an in-focus picture
at f/2.4, either your lens or camera is defective, plain and simple. You don't need
an AF adjustment setting; you need a new lens or camera, and your warranty
should provide for it.

That is to say, if your camera and lens are functioning correctly, this feature is a
luxury, not a necessity. Might help you fine tune exactly where with the focus
zone the target lies, but with or without the adjustment, you have every right to
expect the chosen target will be in focus at f/2.4. If it isn't, simply exchange the
camera for one that isn't defective.
.

Marc, I have to disagree. A lens can be shown to FF/BF a tiny amount, and still
be considered 'in-spec'. In those cases, sending it in for calibration could result in
it coming back worse than before, or better in that particular FF/BF area but screwed
up at infinity, etc... If you send in your body + lens for calibration, that combo
may be spot-on afterward, but other lenses could then show problems that
didn't before.

If you have a camera body that is consistently back or front-focusing, that might
be an easy fix, but most situations are not like that.

If you haven't already, you should read "This Lens Is Soft and Other Myths," by
Roger Cicala (lensrentals.com)

Excerpt below:

QuoteQuote:
...The good news is newer cameras have taken all this into account and the fix is
right at your fingertips. The following cameras all have a “lens microcalibration”
feature: Canon 1DIII, 1DsIII, 5DII, 50D; Nikon D3, D3x, D300, D700; the Pentax
K20D, the Olympus E-30 and E-620, and the Sony A900. I’m surprised at how
many people don’t take advantage of this feature
– its a bit time consuming to
do, but once done each of your lenses is locked in the camera’s memory and it
will automatically compensate so that each lens is at a nearly perfect focusing
plane whenever you mount it on the camera. I find the feature makes such a
huge difference for most of my better lenses that I consider this feature alone
makes the upgrade to one of the above bodies worthwhile.

.

I agree 100% with that assessment. Almost all of my AF lenses have a minor
amount of AF adjust programmed for them. It's the first thing I do after getting
a new lens, and I think I get pretty sharp results these days.


.
10-19-2009, 10:11 PM   #19
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Hey jsherman999, speaking of focus and DOF, that D90/Tammy 17-50mm photo you provided has amazing DOF when you look at it.

I was initially sceptical that it wasn't shooped or HDR image of some sort. I mean, everything is tack sharp from the bench top up front all the way back to the rear wall down the corridor past the guy walking.

The I did look up some DOF calculators and yes indeed, if shot at for example f8 at 20mm on a crop body like the D90 you would have a DOF (with a subject at 2 metres - eg the proximity of the bench edge) that would go from 1.12m to 9.62m.

Depth of Field Table

More power to SR and good high ISO sensors, to enable such photos to be taken handheld under available light!

10-19-2009, 10:24 PM   #20
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QuoteOriginally posted by jsherman999 Quote
.

Marc, I have to disagree. A lens can be shown to FF/BF a tiny amount, and still
be considered 'in-spec'. In those cases, sending it in for calibration could result in
it coming back worse than before, or better in that particular FF/BF area but screwed
up at infinity, etc... If you send in your body + lens for calibration, that combo
may be spot-on afterward, but other lenses could then show problems that
didn't before.

If you have a camera body that is consistently back or front-focusing, that might
be an easy fix, but most situations are not like that.

If you haven't already, you should read "This Lens Is Soft and Other Myths," by
Roger Cicala (lensrentals.com)

Excerpt below:


.

I agree 100% with that assessment. Almost all of my AF lenses have a minor
amount of AF adjust programmed for them. It's the first thing I do after getting
a new lens, and I think I get pretty sharp results these days.


.
More reason I should wait for a camera above the K-x! gah!

and I am the type to do these kinds of tests, too.
10-20-2009, 06:26 AM   #21
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French high ISO shots, RAWs included

Found this info on dpreview:

Test Pentax K-x : gestion du bruit électronique

RAW download links at the bottom of the page, they sure look good to me!
10-20-2009, 10:43 AM   #22
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QuoteOriginally posted by Ash Quote
A great boost for Pentax.
Keep pushing those boundaries, giving the big guns a run for their money.
Thanks for posting this Jay.
OK, what if the Kx is as good as this thread says? Won't that give Samsung a run for their money regarding future sales of the 14.7 mp sensor. Pentax wouldn't need to do much more than slight modifications to the K7 electronics to accept the D90 sensor to bring out the K8 (i think)

On the other hand, perhaps Samsung can improve the existing K7 sensor to reach the D90 sensor performance. let me see now, if i'm Hoya, would i trust Samsung's commitment to improve the 14.7 sensor, or do i go with the existing proven sensor in the Kx? I know i'm jumping ahead of the Kx testing, but I'd bet that Pentax has already reached a decision on this.
10-20-2009, 12:25 PM   #23
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QuoteOriginally posted by jsherman999 Quote
Marc, I have to disagree. A lens can be shown to FF/BF a tiny amount, and still
be considered 'in-spec'.
Tiny amount, yes. Enough to yield OOF images at the target point at f/2.8? I rather doubt that any manufacturer would consider than "in-spec". A lens that far out is simply defective. The "tiny amount" by which a lens might be out and still be within spec would only be enough to shift *where* in the focus zone the target ends up - whether it's smack dab in the middle, further toward the back, or further toward the front (as it should be).

So in practice, there is no reason for most people to worry about this. AF and these tiny amount" errors have been around for decades and we haven't had in-camera per-lens adjustments until the last couple of years, and somehow lots of great photographers still took lots of great images. Not saying there isn't value in being able to tweak the AF system to levels of precision heretofore unheard of in the history of photography, but it's important to realize that this is exactly what these adjustments are offering. Even without those adjustments, it's still just as reasonable to expect a camera to basically focus correctly today as it was 5, 15, or 25 years ago. Any properly functioning camera and lens will offer that much, and if you happen to get one of the rare defective units, then it is every bit your right to expect a replacement. Buying a camera without AF adjustment does *not* mean accepting you can't autofocus at f/2.8.

10-20-2009, 01:47 PM   #24
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QuoteOriginally posted by Marc Sabatella Quote
Tiny amount, yes. Enough to yield OOF images at the target point at f/2.8?....
.

By f/2.8, the increasing DOF is going to help hide any tiny problems that might
exist. By f/4, and shooting at a distance, they could be hidden altogether.

The problem comes up when you want to shoot at f/1.4, 1.7 or f2, and you notice
that your 'critical sharpness' is missing - you have the option of sending the lens
back, even though it's giving you good results at f/2.8+, or adjusting a small
amount with in-body AF adjust.

Personally, I'd rather keep an 'in spec' lens and make it spot-on than send it
back, try another, test, repeat... until I got the perfect copy. Not when I can
make it 'perfect' myself.

If I have a lens that's giving me noticeable FF/BF at f/4, it's going back. If I have
2mm of FF at f/1.7, I'd like the option to tweak AF. It's an important feature for
me, especially after having shot with my D90 for a while now - I have a couple
very sharp, contrasty lenses in Nikon mount that would be perfect with AF adjust...
10-20-2009, 01:55 PM   #25
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QuoteOriginally posted by Marc Sabatella Quote
. Buying a camera without AF adjustment does *not* mean accepting you can't autofocus at f/2.8.
I didn't say you can't autofocus but the rate of keepers in a lot lower.

eg, my 40mm LTD. On the K7 it FF a lot (i have it set to max adjustment and it is great.)
On my k100d body it BF. On my brothers k100d it also BF but not as back as on mine.

I found that using it wide open uncalibrated i did get some infocus shots. But now, calibrated, i get most shots in focus.

So what is one to do with two bodies, one BF and one FF? My answer..... bitch about their quality control.

BTW, my DA70 LTD exhibits the same behaviour. These, and a fisheye, are my only AF lenses. What AF lenses are you using Marc?

mike
10-20-2009, 01:59 PM   #26
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QuoteOriginally posted by jsherman999 Quote
.
.

Personally, I'd rather keep an 'in spec' lens and make it spot-on than send it
back, try another, test, repeat... until I got the perfect copy. Not when I can
make it 'perfect' myself.
Gee whiz... and add a 2nd body to the equation. Imagine the odds of getting two bodies and a lens that were all spot on. Like winning lotto.

If you were to send them in for calibration i think you would be returned a very large compromise. Not perfect on either body but close.

mike
10-20-2009, 04:32 PM   #27
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Mythical Cells

QuoteOriginally posted by Gooshin Quote
1200 shots off AA's?

what are these mythical beings?
"O brave new world that has such (batteries) in't!"

I think I heard that somewhere else.

I put a set of Energizer lithiums through my K-M and got somewhat more than 1,300 exposures, using flash rather little. Perfectly pleased, particularly considering that a spare set of four is light and takes not much space. As I use AA in my flashes as well, I keep four or eight lithium spares somewhere handy in case I overlook my charging duties.

My usual AAs are Eneloops used in conjunction with a devilishly capable La Crosse Technologies charger/analyzer/fixer. I think that charger is substantially smarter than my second girlfriend. Who was quite a bit more attractive and really very nice, to be fair.

I ended up swapping bags and forgetting my spares a few weeks ago and ended up buying four lithiums for my flash in a village in the Cotswolds. Ouch. Each AA ended up more costly than a pint at the pub (my usual standard of economic comparison). Lesson learnt.
10-20-2009, 04:39 PM   #28
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QuoteOriginally posted by schmik Quote
I didn't say you can't autofocus but the rate of keepers in a lot lower.
If it's a *lot* lower, that's a defective camera or lens.

QuoteQuote:
On the K7 it FF a lot (i have it set to max adjustment and it is great.)
On my k100d body it BF. On my brothers k100d it also BF but not as back as on mine.
If it behaves differently on different bodies, that's pretty much proof positive the lens is fine, but the cameras have the problems. Assuming your testing methodology is solid, of course.

QuoteQuote:
What AF lenses are you using Marc?
DA40 & 70, plus the kit zooms (which obviously won't show any such problem. If there was a problem with the DA70 at f/2.4, that would constitute a problem, but there is no problem. When I conduct a test with a good focus chart in balanced light, I get my target well within the focus zone. If I didn't, no way would I accept some sort of firmware hack workfaround rather than getting my defective camera replaced.
10-20-2009, 04:42 PM   #29
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QuoteOriginally posted by schmik Quote
Gee whiz... and add a 2nd body to the equation. Imagine the odds of getting two bodies and a lens that were all spot on. Like winning lotto.
If this assessment were true, then I could imagine the cause for concern. but it just simply isn't. I've tested 8 different bodies and not found a single actual problem with any of them. Sure, lots of times when a carelessly run initial test would mislead me into *thinking* there was a problem, but more careful testing showed me the error was my own.
10-20-2009, 08:47 PM   #30
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I guess that we tent to disagree on this subject, this is perfectly OK by me.
My testing (i believe) is solid. Camera on tripod, perfectly horizontal (according to bubble level) and test chart at 45 degrees. All done in natural light. Always use a remote release. Always take at lewast 10 shots, resetting focus ring between each shot. Using a focus chart where there is no doubt on what the camera is focussing on. hahaha this constitutes for many many hours of my life i will never get back.

Wide open the DA 40 did not focus with DOF on any of the 3 bodies i have access to. It was close(ish) but no cigar. DA 70 was damn close.

Another saying... the proof is in teh pudding, since AF adjustment i get many many more in focus shots wide open.

BTW, it is my 2nd DA40, the first could not be forrect with AF adjust in camera.

I agree that there is a problem with the bodies. They are made to a tolerance. If the lens + AF adjustment + body focuses within DOF (wide open) then it's OK. BUT, what if the body doesn't have AF adjustment? As i've said many times (in other posts) adding AF adjustment in camera is an admission that things are not perfect out of the box.

BTW, i do not have enough faith in the Aussie dealer to correct matters like this nor do i believe that they would replace the body...... or maybe i just don't want to be with out my gear for weeks.


mike
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