2 Important K10 Issues that need to be settled for good!! (Please read!)

Started Jan 5, 2007 | Discussions thread
OP SFT007 Veteran Member • Posts: 5,912
Daylight experience and observations about FF

Thanks for the extensive reply Steve - I appreciate it very much.

Well I just threw my FA50 on the K10 and took some shots on this very overcast day (so nice even flat lighting) at f1.4 and f2 and it is absolutely spot on perfect. Couldnt focus any better.

So its obvious the problem is low artificial light only. I found this article concerning the AF accuracy of Pentax SLR's with regards to color temp, etc. interesting by RiceHigh: http://www.geocities.com/ricehigh/DS_AF_Dependency_on_KEV.html

As for the 18-55 - it also managed to focus just fine at the wide-end and I didnt have to zoom in fully lock focus and then zoom back out to 18mm. So there isnt anything wrong with any of the lenses - I am certain of this. Its amazing though just how bad the 18-55 was at the 18mm end last night - a huge difference between last night and today shooting in flat natural outdoor light. I wonder if it gets worse as you shoot WA and better as you do tele in the low-light artifical lighting situations. I guess that may make sense as the wider the angle the more the aritificial light is going to be coming in from all directions and the more it may put the AF off.

So are you imlpying that all other cameras like the D80, Xti, 30D, A100, etc.. will, have the same problems I encountered above. Of course a fast lens (like a f1.4 or f2) must be used to really pinpoint the degree of accuracy. I cant see how a $1000 camera cant focus in anything but natural light? I would love to be able to be compare it to my Fuji F30 but of course even at f2.8 with the F30 - we have HUGE DOF so a direct comparison cant be made unfortunately. If I stop the K10 down to something like F8 or so (which is still less DOF than the f2.8 of the F30 I believe) I also get good focus - but thats hardly desirable.

So I know for a fact now that with all my lenses (FA50, DA18-55 and DA50-200) I am getting good focus outdoors in natural light but bad focus in artificial low-light. What to do? Will Pentax not consider this faulty? I certainly think its faulty and I would expect a $1000 camera to not require so much work to get a good shot indoors. I am going to call them on Monday and see what they say - I will explain to them my exact experience. I wish I had a D80 with a 50mm f1.4 or f1.8 lens to compare to side by side - that would reassure me. If the D80 did better than its just pure fact that the Pentax's cant focus in artificial light and that would be very dissapointing for me, if the D80 acted the same way - than all is good and I would know its a universal problem for all consumer dSLR's.

*isteve wrote:

Sinan Tarlan wrote:

I did similar tests and the DA18-55 is terrible at the wide-end -
terrible! I can however zoom in fully - lock focus and zoom back
out and it does much better. Its however good at the tele-end but I
am sure this is no doubt due to the DOF of f5.6!! All in all - Im
not sure what to think - can I expect this level of FF from all
K10's? Can I expect this level of FF from other brands in similar
lighting and similar large apertures of f2, etc.?? Or is my K10 in
need of being sent in to Pentax? Sorry for the long post.

Well mine is less than perfect in low light too unless I use an "AF
friendly" focus target. I have a mosiac tiled worktop which all my
lenses focus perfectly on all the time, even of they have trouble
with "standard" focus targets.

Same was true of all my film cameras (Nikon, Minolta) but I didnt
have the luxury of testing them exhaustively. Same was also true of
the *istD and DS, and my friends that shoot Nikon and Canon
low-midrange systems report similar issues even in good light (the
Canon 10D was notorious). However these cameras tend to report a
good lock even when not in focus. I have read many threads on the
Canon forums about focus misses too and some have posted here.

AF simply is not foolproof especially if the level of contrast is
low. I also thing AF sensors are more sensitive in the middle of
the spectrum (green) which is not as prevalent in incandescent
light (so contrast is even lower than it looks from the scene). I
have NEVER had a camera that had perfect AF, though you will find
the pro bodies (D2X, 1D etc) are generally much better, but then
they are also much higher spec.

Also, cameras are calibrated post assembly for 2 or 3 standard
lenses. There is a tolerance and margin for error involved
especially if you are using wider focal lengths.

If your camera is focusing well in good light, then I suggest there
is nothing much Pentax can do. If its out in good light, then they
may be able to adjust it.

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Sinan

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