Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Pentax / Samsung dSLR, K Mount Mirrorless

Reply
 
Thread Tools Search this Thread
Old May 1, 2008, 5:08 AM   #21
Senior Member
 
Driver3's Avatar
 
Join Date: Feb 2007
Posts: 481
Default

Harriet,

This is still an ongoing evaluation but I am a happy guy so far. This weekend I'm shooting my sons swim meet and that will be a bit better test with moving subjects. Last night was impromptu and a bit hurried but the results were much better than before. Hopefully this doesn't change my mind. The last meet the results weren't very good.

Dennis
Driver3 is offline   Reply With Quote
Old May 2, 2008, 3:25 PM   #22
Senior Member
 
bilybianca's Avatar
 
Join Date: Nov 2005
Location: Hassleholm, Sweden
Posts: 3,435
Default

Up like a rocket, down like a lame duck!

I haven't come to grips with my K20D yet. Today, as I had a half day off, I did some more serious testing, trying all my prime lenses at short and long distance. There's nothing wrong with my lenses, they have worked perfectly with my DS. Some of you know what lens line up I have.

I made the test shot using a tripod, with AS on and off, individual lens focus calibration on and off after calibrating with the test chart at closest focusing distance. Result?

My K20D is so far off focus it's a scandal it left the factory building! With focus calibration on it misses focus with 50 metres at 80 metres focusing distance, when I put the 28 mm on! No wonder I wasn't satisfied with the shots I took "for real".

Monday morning I'll contact the seller to see if they will give me a replacement body or if I'll have to send it in for calibration.

I won't jump the ship, but I hope Ned Bunnell reads this and sharpen up the act for Pentax QC.

Hope to be back in a week or two with good news.

Kjell

bilybianca is offline   Reply With Quote
Old May 2, 2008, 5:30 PM   #23
Senior Member
 
snostorm's Avatar
 
Join Date: Jan 2004
Location: Chicago Suburb, IL, USA
Posts: 2,770
Default

bilybianca wrote:
Quote:
Up like a rocket, down like a lame duck!

I haven't come to grips with my K20D yet. Today, as I had a half day off, I did some more serious testing, trying all my prime lenses at short and long distance. There's nothing wrong with my lenses, they have worked perfectly with my DS. Some of you know what lens line up I have.

I made the test shot using a tripod, with AS on and off, individual lens focus calibration on and off after calibrating with the test chart at closest focusing distance. Result?

My K20D is so far off focus it's a scandal it left the factory building! With focus calibration on it misses focus with 50 metres at 80 metres focusing distance, when I put the 28 mm on! No wonder I wasn't satisfied with the shots I took "for real".

Monday morning I'll contact the seller to see if they will give me a replacement body or if I'll have to send it in for calibration.

I won't jump the skip, but I hope Ken Rockwell reads this and sharpen up the act for Pentax QC.

Hope to be back in a week or two with good news.
Hi Kjell,

My experience, and the vast majority of opinions I've read from other users has been exactly the opposite, with the K20 having noticeably the most accurate AF of the three generations of bodies that I own. It almost sounds like you got the body that 2many returned when he jumped to Sony. I really hope that you get this resolved quickly and easily. I think your chances of getting a good one if they give you an exchange are very good. This must be frustrating.

My K20, with some adjustments made for a few lenses, focuses more consistently and reliably with just about all my lenses. I have a Tok 20-35 f2.8 which backfocuses to the point of unusability with the DS and K10 (I even sent it back to Tokina for recalibration to find that it's well within spec), but with a +5 correction on the K20, it lives up to its generally good reputation. My DA *50-135 was a real disappointment on the DS and especially the K10, but is brilliant with no corrections on the K20.

Luckily, all the lenses that I use frequently focus well on all my bodies -- but then maybe I've just gotten used to using only the lenses that perform well. . .

I'll keep my fingers crossed for you. . .

Scott
snostorm is offline   Reply With Quote
Old May 3, 2008, 5:20 PM   #24
Senior Member
 
Monza76's Avatar
 
Join Date: Jul 2004
Posts: 4,093
Default

I have a K10D with known focus issues yet I find that some lenses work very well. Here are some examples taken today with the F 100-300mm .

Notice the pulley:



Two shots of a Junco (cropped)





Ira
Monza76 is offline   Reply With Quote
Old May 3, 2008, 6:12 PM   #25
Senior Member
 
mtngal's Avatar
 
Join Date: Nov 2005
Location: Frazier Park, CA
Posts: 16,052
Default

I'm so sorry to hear that your K20 has focus issues - it sounds like the same thing Terry had trouble with. I only have 3 AF lenses (kit, DA12-24 and DA*50-135) so not anywhere close to your collection of fine lenses and I haven't had trouble with any of them. The DA*50-135 didn't need focus adjustment at all - it was perfect, as was the DA 12-24 (though it's harder to be off with such a wide-angle). I have only used the kit lens on the K20 a couple of times, but didn't notice any problems (I should probably test it, just to make sure. I normally use the kit lens on the K100).

I'll keep my fingers crossed that your replacement camera is going to be perfect.
mtngal is offline   Reply With Quote
Old May 3, 2008, 9:39 PM   #26
Senior Member
 
NonEntity1's Avatar
 
Join Date: Jul 2006
Location: Lake Placid Florida USA
Posts: 2,689
Default

Are these focus issues only with AF lenses or do they also affect focus with MF lenses? In other words, is this a flaw where it looks like you have focus through the viewfinder when you actually do not?

Tim
NonEntity1 is offline   Reply With Quote
Old May 3, 2008, 9:52 PM   #27
Senior Member
 
mtngal's Avatar
 
Join Date: Nov 2005
Location: Frazier Park, CA
Posts: 16,052
Default

As far as my K10 went - it was only with AF lenses. Never had any trouble with manual focus lenses - the focus indicator was pretty accurate with them.

Out of curiosity, Kjell - did you ever try to manually focus your faulty K20?
mtngal is offline   Reply With Quote
Old May 4, 2008, 2:05 AM   #28
Senior Member
 
bilybianca's Avatar
 
Join Date: Nov 2005
Location: Hassleholm, Sweden
Posts: 3,435
Default

When doing the systematic test shooting i used the AF lenses in AF mode, and used the focus indicator rather than the eye to confirm focus with the MFs. But actually I suspect the focus to be off even when it looks OK in the viewfinder. And I think that even what actually happens to be in focus is too soft to be OK, but that might be me being overcritical du to the other problems.

These are the lenses i tried, no POS.

FA 28 mm 2.8

FA35 mm 2.0

FA 50 mm 1.4

A* 85 mm 1.4

A* 200 mm 2.8

First I calibrated all the lenses with the Focus Chart at about one meter. For the FA 50 I had to go down to -10! Then I put the camera on the tripod and tried all the lenses focusing at 3 meters and 65 meters. I "unfocused" manually between every shot to see if focus was inconsistent (which it partly was, but not that bad).

I took two shots at every setting using focus calibration "on" and "off", and SR "on" and "off". That sums up to 8 shots with every lens. Largest aperture was used to narrow DOF, in order to decide the focus plane easier.

The results where somewhat better with focus calibration "on" (and that should really be expected!). With the 28 mm lens, calibration "on" (that means perfect focus at 1 meter distance) the focus plane was at 20 meters when the camera focuses at 65! I really hope Pentax doesn't claim that to be "within specs". With the 200 m lens the error was 7,5 meters at 65 meters distance.

I've also noticed the problem when using my 200 mm with the AF Converter 1.7 and with my A* 600 mm 5.6. And it's obvious also when I use smaller apertures than in the test. So there is no way to blame a faulty lens.

Kjell

bilybianca is offline   Reply With Quote
Old May 4, 2008, 6:06 AM   #29
Senior Member
 
danielchtong's Avatar
 
Join Date: Dec 2005
Posts: 2,888
Default

bilybianca wrote:
Quote:
When doing the systematic test shooting i used the AF lenses in AF mode, and used the focus indicator rather than the eye to confirm focus with the MFs. But actually I suspect the focus to be off even when it looks OK in the viewfinder. And I think that even what actually happens to be in focus is too soft to be OK, but that might be me being overcritical du to the other problems.

These are the lenses i tried, no POS.

FA 28 mm 2.8

FA35 mm 2.0

FA 50 mm 1.4

A* 85 mm 1.4

A* 200 mm 2.8

First I calibrated all the lenses with the Focus Chart at about one meter. For the FA 50 I had to go down to -10! Then I put the camera on the tripod and tried all the lenses focusing at 3 meters and 65 meters. I "unfocused" manually between every shot to see if focus was inconsistent (which it partly was, but not that bad).

I took two shots at every setting using focus calibration "on" and "off", and SR "on" and "off". That sums up to 8 shots with every lens. Largest aperture was used to narrow DOF, in order to decide the focus plane easier.

The results where somewhat better with focus calibration "on" (and that should really be expected!). With the 28 mm lens, calibration "on" (that means perfect focus at 1 meter distance) the focus plane was at 20 meters when the camera focuses at 65! I really hope Pentax doesn't claim that to be "within specs". With the 200 m lens the error was 7,5 meters at 65 meters distance.

I've also noticed the problem when using my 200 mm with the AF Converter 1.7 and with my A* 600 mm 5.6. And it's obvious also when I use smaller apertures than in the test. So there is no way to blame a faulty lens.

Kjell
Kjell,

Sorry to hear your early sample result. After doing preview to decide softness or sharpness, I rely on the preview 12x option of the dead centre. Fairly accurate. See if you can verify it.

About focus issue: is that the K20D has way to do/remember focus adjustment for a number of lens? Would that help?

Daniel
danielchtong is offline   Reply With Quote
Old May 4, 2008, 6:17 AM   #30
Senior Member
 
bilybianca's Avatar
 
Join Date: Nov 2005
Location: Hassleholm, Sweden
Posts: 3,435
Default

danielchtong wrote:
Quote:
Kjell,

Sorry to hear your early sample result. After doing preview to decide softness or sharpness, I rely on the preview 12x option of the dead centre. Fairly accurate. See if you can verify it.

About focus issue: is that the K20D has way to do/remember focus adjustment for a number of lens? Would that help?

Daniel
The focus adjustment feature is what I call "focus calibration" in my post. If corrected for close focus distance, the long distance focusstill is far off. I did try that with all the mentioned lenses.

Even with 12X or 36X preview the resolution is a bit low, so I took my test shots in RAW and looked at them in Lightroom. That helped me to make a better judgement, but didn't improve the camera though.:-?

Kjell


bilybianca is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 12:12 PM.