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06-15-2008, 08:12 AM   #1
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Front Focusing - K200D + Tamron 28-75 - Who do I contact?

After many attempted bug shots in the field and then finally testing with the focus test chart, I know my lens is now front-focusing by between 2-10mm. Not a big deal for normal pictures -- horrible for macro bugs.


Question -- who would I contact about this issue? I can't adjust the focusing on my K200D (why the hell that's left for the "pro" K20D I wish I knew ), but would I contact Pentax or Tamron about the issue?

I'm guessing it would be Pentax, but I don't have another lens to test out the issue with (drat!), so I dunno..

Thanks in advance!

06-15-2008, 10:05 AM   #2
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Most likely the issue is due to the lens. If the lens is a new you should send it to where you bought it for a replacement. But before you do that do some more focus tests with one or more lenses to make sure it's not the body.
06-15-2008, 02:23 PM   #3
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Yeah, I think I"m just going to try a replacement from amazon (thank goodness for great return policies!)

The lens was also "shifting" the image when acquiring focus at 75mm, weird.

Shame that this one's having to be returned -- I love the image quality. I wish I could test the camera with another lens, but already sold the kit lens. But, I *did* do focus testing with both lenses and never ran into such a bad FF problem as with this lens...no wonder my live-bug pictures were blurry :P

Oh well, here's hoping it's not the camera and that the replacement I get corrects the problem.
06-15-2008, 02:41 PM   #4
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QuoteOriginally posted by cputeq Quote
Yeah, I think I"m just going to try a replacement from amazon (thank goodness for great return policies!)

The lens was also "shifting" the image when acquiring focus at 75mm, weird.

Shame that this one's having to be returned -- I love the image quality. I wish I could test the camera with another lens, but already sold the kit lens. But, I *did* do focus testing with both lenses and never ran into such a bad FF problem as with this lens...no wonder my live-bug pictures were blurry :P

Oh well, here's hoping it's not the camera and that the replacement I get corrects the problem.
I had to return mine.

From F 4 to F2.8 it was usless.

F5.6 up, it was wonderfull

Dave

06-15-2008, 04:57 PM   #5
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QuoteOriginally posted by pentkon52 Quote
I had to return mine.

From F 4 to F2.8 it was usless.

F5.6 up, it was wonderfull

Dave

What a shame! My copy, on normal pictures, is incredible, from F/2.8 onward. I'm seriously hoping my replacement isn't crap.

As a side note, I can't help but sing praises of Amazon - The replacement lens has already entered the shipping system under 1-day shipping, it'll be here tuesday...I drop off my prepaid UPS label and lens tomorrow to give back to them.

Judging by the ease of this return, I may limited myself to buying only photo gear from them in the future (and not just a vendor listed at their site).
06-16-2008, 03:08 AM   #6
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K200D + DA18-55mm AL II Kit lens Front Focusing Problem

QuoteOriginally posted by cputeq Quote
After many attempted bug shots in the field and then finally testing with the focus test chart, I know my lens is now front-focusing by between 2-10mm. Not a big deal for normal pictures -- horrible for macro bugs.


Question -- who would I contact about this issue? I can't adjust the focusing on my K200D (why the hell that's left for the "pro" K20D I wish I knew ), but would I contact Pentax or Tamron about the issue?

I'm guessing it would be Pentax, but I don't have another lens to test out the issue with (drat!), so I dunno..

Thanks in advance!
Hi Guy,

I am unlucky that after purchasing K200D + the "kit lens" for 1 month, discovering the same/similar problem:

At F/3.5 to F/5.0 and from 18mm to 50mm:
Photo taken at 2m away from the object>> Result: Front focusing 20 cm (10%)
Photo taken at 0.6m away from object>> Result: Front focusing 5cm (8%)
My problem is even worst than your "Tamron".

At F/5.6, F/8 and higher etc and from 50-55mm:
Photo taken at 8m away from object: seemed no problem.
Photo taken for "distant object": seemed no problem ("sharp")

I concluded that the "soften" photos taken were caused by my K200D "short-sight"!!!

I believed that on you issue.. It is not fully a matter of the lens "Tamron".
The problem happened when the K200D matched to my Kit lens (or your Tamron).
It is a typical problem of K10D and is a problem of Pentax (They set the camera to match the old lenses and the new lenses...Resulted that the focal distance of the optical path has to be set this way that when fitting a particular lens on the camera, the focal sharpness is not the optimal!!
K20d can adjust the focal parameters for different lenses vis the user manual. But K200D is NOT!! What is annoying is that I could not press the "Engineer Debugging mode" for the remedial action (As people did on the K100D super as heard on the web-forums).

Let's urge Pentax to put the Lens parameter's adjustment on the user manual of K200D (on the next firmware update)!!! Otherwise, we cannot shot happily>

Last edited by ckanthon; 06-19-2008 at 04:29 AM.
06-16-2008, 06:33 PM   #7
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my 28-75 shows up tomorrow and I hope I don't have that issue. but it's good to know Amazon is easy to deal with as they are the vendor I bought mine from. good luck to you on your next copy!
06-18-2008, 09:53 AM   #8
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QuoteOriginally posted by vagrant10 Quote
my 28-75 shows up tomorrow and I hope I don't have that issue. but it's good to know Amazon is easy to deal with as they are the vendor I bought mine from. good luck to you on your next copy!
You are lucky that you could have your problem resolved by a replacement of the lens only (resolved by chances). But I still think that this is a problem caused by tolerance errors of "Body + lens". I bought my K200D+18-55 Kit lens (II) for older than 1 month, therefore cannot have refund (only possibility is return for a repair or fine-tuning the Body + Kit lens) But they are not sure if problem could happen again if I try fitting another longer lens on it. Also the repair could taken several weeks. (If they could not fix my current problem....another copy or another lens >> No Way!)

Other, I tried to download the Russian's "GX10-K10d Debug control" software and run it. On the PC, the K200D + photos inside K200D were seen but the "Engineer debug mode control" could not activate my K200D's Engineer mode (if it exists). Seemed it did not work for K200D.... No Focus correction. Sounded like I should bear my "short-sightness" without a pair of glasses. I am not going to buy the 77 F1.8 nor A18 as well. (until the focus issue can be re-solved)

Attached Images
 

Last edited by ckanthon; 06-18-2008 at 06:04 PM.
06-18-2008, 07:59 PM   #9
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well got my lens and it has probs https://www.pentaxforums.com/forums/271740-post5.html... usually around 6mm, which to me, seems like a lot. I wonder if Amazon has a bunch of bad copies? I have the sigma on order now, so I'll decide which I will keep.
06-18-2008, 08:57 PM   #10
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Hei, 6mm seemed comparably acceptable.
The last testing results of my copy were:
(my test shot at DA 18-55 lens kit as it was the only lens I have).
0,56m away from object. at 55m lens' barrel length and at F/5.6. The Focus point centered at 20mm in front of the targetted line (of the test chart). 3.5% error. (I must admit that it is just a rough test)
Tried also shooting near fields, 8m away, 20m away and "infinite". On average, the focus was laying 8-10% in front of the object targetted (Front focusing/short-sighted). Never got crytal clear image UNLESS fine-tune the focus ring manually clockwisely by 4 degree (after half pressing the shot button).

I bought it while my wife went to her trip. If she found poor picture quality (comparing to the Kodak DC) I will be in great trouble. Finally I decided to send it back for a checking + fine-tune on the weekend!!! (sigh)

Nevertheless, wish other P fans would not encounter the same problem as I have on my K200d. If it was really caused by tolerance or ill-fine-tuned before packed and shipped out of the factories (Kit Lens made in Vietnam, Body made in Philippine), then accordingly to previous data on web forum: the errors on the focal plane were laying in micrometer scale level. Then the error could hardly be resolved by random matching (I believe). If it is an engineering problem, it'd better be resolved by calibration/fine-tune. Or revising the user's interface on the camera's user manual so that users can make their own adjustment whenever necessary (to certain degree and in safe levels).
(sigh again)

Good luck to all of us.

Last edited by ckanthon; 06-20-2008 at 01:32 AM.
06-19-2008, 06:57 AM   #11
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after reading all the posts, I have a simple question or two

Are you doing all your shots hand held or tripod?

Are you usinf AF or MF for your macro shots

I'll explain when I see a response.
06-19-2008, 05:42 PM   #12
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QuoteOriginally posted by Lowell Goudge Quote
after reading all the posts, I have a simple question or two

Are you doing all your shots hand held or tripod?

Are you usinf AF or MF for your macro shots

I'll explain when I see a response.
Thanks in advance for your advices!!
To my case:
I tried both hand shot and shot on a tripod.
I used SR when hand held and turned off the SR when shot on tripod.
06-19-2008, 07:12 PM   #13
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QuoteOriginally posted by Lowell Goudge Quote
after reading all the posts, I have a simple question or two

Are you doing all your shots hand held or tripod?

Are you usinf AF or MF for your macro shots

I'll explain when I see a response.

For me: Some of my shots hand-held, some on hard surface. I generally use AF for most macro shots, but this lens is forcing me to manually focus bracket.

I posted a followup on the shot results from the 2nd copy in this thread

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/30203-test-sho...-f2-8-a-2.html

Basically I'm awaiting what Pentax says about FF issue, has my camera had it before with other lenses (kit and Tamron 70-300), but this time it's bad on two copies of this lens.
06-19-2008, 09:48 PM   #14
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Hi,

Thanks for the information and pictures shared in the first place.
The pictures token were still better than my K200d 1000 trial shots.
If I have time, I will try to post several pictures of mine. (My wife is flying back earlier next week. I have to remove the cartons and clean up etc. Busy. Busy)
I have passed my camera to my elder bother (he is a Can-fans for 10 years) to have a look and take some more trials before sending it back for checking/repair. Then I will see the results of examination. Perhaps I will write a letter to Pentax Jpn about the F-F issue as well. (Actually, it is somewhat a bad experience to me that I felt reluctant to send my K200d back to the repair shop. Because I owned my camera only for a couple of weeks. My inexpensive Kodak DC never get such problem).
- Could it be a problem of lens only (even kit lens)?
- Could it be more serious for third party lens?
- Could it be a problem of Body only?
- Could it be a problem of Body + lens?
(I suspected that this point is the most likely one.... as since basically, optical alignments is a part which could easily go wrong. It happened on my final year project which involved laser's waveguide alignment years ago )
- Could it be a problem due to factory tuning/calibration procedure?
- Could it be a problem of the "old" focusing system
(taking into account that the CCD pixels number now increased, the lens resolution increased....the expectation from customer increasing)
As a P fans, I will urge them to formally devolve the "focus correction" option to all of K series user's function menu (Like K20d...IF it is a correct solution to deal with the ROOT cause). (Pentax! do you want to be competitive? (As a newbie, if I decide to give up using your DSLR system you care not)

Last edited by ckanthon; 06-20-2008 at 06:25 PM.
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