Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-02-2008, 03:50 AM   #211
Forum Member




Join Date: Jun 2008
Location: Philippines
Posts: 99
QuoteOriginally posted by TanGU Quote
What do you mean you used this focus chart BEFORE buying it ???

Do you mean by that that you bring your camera, and a print paper of the chart and did some test directly at the store?

Did you use a tripod?

thanks
Yes I did all of that except to bring a tripod. I wanted to make sure that I got a good lens.

09-02-2008, 05:36 PM   #212
Senior Member
Sleepy's Avatar

Join Date: Jan 2007
Location: Miami
Photos: Gallery
Posts: 133
I received my 2nd one today, but it has back focus issue.
Does anyone know how long it would take if I send it back to Pentax to adjust?
Thank you very much ^_^.
09-02-2008, 07:10 PM   #213
Veteran Member
PentaxPoke's Avatar

Join Date: Jan 2008
Location: Oklahoma
Posts: 1,411
QuoteOriginally posted by Sleepy Quote
I received my 2nd one today, but it has back focus issue.
Does anyone know how long it would take if I send it back to Pentax to adjust?
Thank you very much ^_^.
If you just got it today, I wouldn't send it to Pentax. I would send it back to where you bought it and get a refund, credit, or spin the roulette wheel again.
09-02-2008, 07:49 PM   #214
Senior Member
hinckc's Avatar

Join Date: Apr 2007
Location: New Jersey, USA
Photos: Gallery
Posts: 298
QuoteOriginally posted by PentaxPoke Quote
If you just got it today, I wouldn't send it to Pentax. I would send it back to where you bought it and get a refund, credit, or spin the roulette wheel again.
On the other hand, if I had a backup camera, I'd consider sending my camera back to Pentax for a camera checkup. It's my guess that not all, but many of the DA*16-50 issues have been related to back/front focus, and at the fault of the camera, not the lens. I'm not the only one who thinks that:

QuoteOriginally posted by benjikan Quote
It has more to do with the K10D than the lens. I would have a software revision done on the K10D or test your 16-50 on a K20D. If you have access to a store try it out. I am quite certain that those problems will disappear. My shitty 21 Ltd and 16-50 on the K10D morphed in to two incredibly sharp lenses on my K20D's..

Ben

@sleepy: Can you share how you came to the conclusion that it has back-focus issues?
Have you tested any other f/2.8 or wider aperture lenses for front/back focus, especially wide angle lenses? Many other lenses aren't under the same scrutiny as the DA*16-50, and many wouldn't show slight back-focus issues as severely as a wide angle, f/2.8 lens.

While a return to the retailer delivers more "immediate remedy", it doesn't provide nearly as likely a "final resolve" that an investigation by the manufacturer could give you, though I suspect they'll request you send your lens and your camera to do definitive testing.
Personally, I'd rather wait a short while for a "final resolve" than to "spin the roulette wheel again."


-Chris

09-03-2008, 08:36 PM   #215
Senior Member
Sleepy's Avatar

Join Date: Jan 2007
Location: Miami
Photos: Gallery
Posts: 133
PentaxPoke and hinckc, thank you very much for your reply.
I guess I'd send it back to Pentax for adjustments because I still need to pay for shipping it back to the seller if I would like to get a replacement or return.

Regarding how I know the back-focus issue, I used two different types of focus test chart and I got the same results (back-focus). I have sigma 24mm f1.8 and some other lens, and all of them could focus correctly.

I think I'd pay $25 to Pentax for a rush service. Hopefully I could get my lens back soon.
09-05-2008, 05:54 PM   #216
Site Supporter




Join Date: Jul 2008
Location: Illinois, USA
Photos: Gallery
Posts: 55
Third time NOT the charm

Try #3 from Calumat Photographic - S/N 9027069 - BAD. Right 25% (held horizontally) remained soft / blurred at all focal lengths and at all apertures from f/2.8 thru f/11. RETURNED to store for refund.
09-05-2008, 06:02 PM   #217
Site Supporter




Join Date: Jul 2008
Location: Illinois, USA
Photos: Gallery
Posts: 55
NOT "4 of a Kind"

Try #4 from Amazon.com (again) - S/N 9025329 - GOOD!

I finally got my hands on a GOOD copy of a DA* 16-50mm lens. It was the first one that I had to adjust the AF on my K20D for front focusing. However, once that was done, I finally have one that the right side delivers the same IQ as the left side.

Curiously, all three of my bad copies had S/Ns in the 9027xxx range, while this one has an earlier S/N.
09-05-2008, 06:44 PM   #218
Veteran Member
PentaxPoke's Avatar

Join Date: Jan 2008
Location: Oklahoma
Posts: 1,411
QuoteOriginally posted by Imagination4 Quote
Try #4 from Amazon.com (again) - S/N 9025329 - GOOD!

I finally got my hands on a GOOD copy of a DA* 16-50mm lens. It was the first one that I had to adjust the AF on my K20D for front focusing. However, once that was done, I finally have one that the right side delivers the same IQ as the left side.

Curiously, all three of my bad copies had S/Ns in the 9027xxx range, while this one has an earlier S/N.
Wow, maybe you got a factory repaired one. Congratulations! Alas, I will not be trying again. I am happy with my Tamron, and I am having a blast with the Pentax 10-17 that I bought with the refund!

09-05-2008, 09:08 PM   #219
Site Supporter




Join Date: Jul 2008
Location: Illinois, USA
Photos: Gallery
Posts: 55
QuoteOriginally posted by PentaxPoke Quote
Wow, maybe you got a factory repaired one. I am happy with my Tamron, and I am having a blast with the Pentax 10-17 that I bought with the refund!
Based upon the samples you had posted earlier, the Tamron 17-50 that you had looked excellent - so I can fully understand your position there. Enjoy the Fish-Eye.
09-06-2008, 09:54 PM   #220
Forum Member
TiminyCricket's Avatar

Join Date: Aug 2008
Location: New Jersey
Posts: 76
Just a thought, but it would be nice if more people who receive what they feel to be a bad copy of the lens would also post, or include links to some full-res pictures taken with "said lens" so that the rest of us could see exactly what you were seeing when you declared the lens to be bad.

With the number of bad lenses people seem to be receiving this would seemingly yield a rather "thorough" image collection for comparison purposes. Then we could all better see and understand just how much IQ variation exists between the lenses and be able to decide if each of our own lens' defects are bad-enough to warrant concern.

Like all of you, when I plop down the money for a $700 lens I'd like for everything to be perfect... but in reality hardly anything is ever perfect. It's more about seeing just how close to perfect any given lens might seem to be... for any and all copies of lenses will have one shortcoming, or another.

I personally have what I believe to be a relatively good copy of the lens, but have put off posting the serial and either the "good/bad" designation, as it is still hard to gauge the lens image quality without having more people's photos (from both good and bad copies) available for comparison. I mean even if the subjects and conditions are different at least we would still be able to get some idea... especially if the defects of some lenses is to the extreme.

Those of you who read my post located here may have looked at the pictures posted from my copy of this lens. At this point I still have been unable to find a suitable brick wall/building to take pictures of, so I am still uncertain about the actual edge sharpness. For anyone who looked at my pictures and is interested, the serial number from my lens is 9011159.

~Tim
09-08-2008, 03:49 AM   #221
Site Supporter




Join Date: Jul 2008
Location: Illinois, USA
Photos: Gallery
Posts: 55
QuoteOriginally posted by TiminyCricket Quote
Just a thought, but it would be nice if more people who receive what they feel to be a bad copy of the lens would also post, or include links to some full-res pictures taken with "said lens" so that the rest of us could see exactly what you were seeing when you declared the lens to be bad.

~Tim
I'd done some disc housekeeping over the weekend, so I no longer have most of my test images from my 3 bad copies. All of the outdoor test shots, indoors for bad copies #1 and #3, and my 18-55mm AL II (used for comparison/control) are deleted. However, perhaps the following few 100% crops (no other PP) between my 2nd (BAD) and 4th (ACCEPTABLE) copies will shed some light on my perspective.

Once again, my concern/issues were with the lack of symmetrical border IQ, especially since the unsharp right side on the bad copies extended considerably towards the center. The Center and Left sides of even the first 3 bad copies looked very good, but the right side was poor.

Caveats:
1) I taped multiple sheets of newspaper on the wall, and I was not carefull about taping them precisely horizontal - so a lot of the tilting is simply as they were taped.

2) Also, as I had reconciled to forgo the 16-50 after bad copy #3, I had actually dismantled my newspaper wall - so the pages are not the same between the two lenses (but I think that you will still get the idea). Suffice to say, the outdoor tests at both a moderate distance and infinity followed the same trends as the indoor tests.

3) Although I no longer have the test images from the 18-55mm AL II, the trend was that the BAD copies of the 16-50 were better than the 18-55 at LEFT and CENTER, but the 18-55 was better than the 16-50 at the RIGHT.

4) There is some unevenness in the lighting across the different sections of the different crops. Please disregard this, as that does not really affect the conclusions of the test images.

As wide open (f/2.8) and at the widest angle (16mm) are not the strengths of this lens, I am only posting images taken at f/5.6 and at 28mm and 50mm focal lengths.

At 28mm f/5.6 sequence:
LEFT #2, LEFT #4, RIGHT #2, RIGHT #4
Attached Images
View Picture EXIF
PENTAX K20D  Photo 
View Picture EXIF
PENTAX K20D  Photo 
View Picture EXIF
PENTAX K20D  Photo 
View Picture EXIF
PENTAX K20D  Photo 

Last edited by Imagination4; 09-08-2008 at 03:59 AM.
09-08-2008, 03:56 AM   #222
Site Supporter




Join Date: Jul 2008
Location: Illinois, USA
Photos: Gallery
Posts: 55
QuoteOriginally posted by TiminyCricket Quote
Just a thought, but it would be nice if more people who receive what they feel to be a bad copy of the lens would also post, or include links to some full-res pictures taken with "said lens" so that the rest of us could see exactly what you were seeing when you declared the lens to be bad.

~Tim
And now at 50mm f/5.6 sequence: LEFT #2, LEFT #4, RIGHT #2, RIGHT #4

Once again, the softness on the right side of the bad copies extended towards the center by more than 1024 pixels at 100% - and was noticeable in both test and real world images. As for my 4th (Good/Acceptable) copy, the right side IQ fairly evenly matches the left side, and the center is the sharpest (as expected).
Attached Images
View Picture EXIF
PENTAX K20D  Photo 
View Picture EXIF
PENTAX K20D  Photo 
View Picture EXIF
PENTAX K20D  Photo 
View Picture EXIF
PENTAX K20D  Photo 
09-08-2008, 04:04 AM   #223
Site Supporter




Join Date: Jul 2008
Location: Illinois, USA
Photos: Gallery
Posts: 55
QuoteOriginally posted by TiminyCricket Quote
Just a thought, but it would be nice if more people who receive what they feel to be a bad copy of the lens would also post, or include links to some full-res pictures taken with "said lens" so that the rest of us could see exactly what you were seeing when you declared the lens to be bad.

~Tim
Just for reference, here are the 100% crops from near the middle of the images.
SEQUENCE:
BAD copy #2 - 28mm @ f/5.6
BAD copy #2 - 50mm @ f/5.6
Good copy #4 - 28mm @ f/5.6
Good copy #4 - 50mm @ f/5.6
Attached Images
View Picture EXIF
PENTAX K20D  Photo 
View Picture EXIF
PENTAX K20D  Photo 
View Picture EXIF
PENTAX K20D  Photo 
View Picture EXIF
PENTAX K20D  Photo 
09-10-2008, 04:01 PM   #224
New Member




Join Date: Sep 2008
Location: Lutsk, Ukraine
Posts: 4
trouble

Can anybody help me? after installing my new 16-50 lenses into k20d i can access menu. After pressing MENU button menu shows on a backgreen and dissapearing in 1/2 sec. With Fn button - the same situation.

I can get photos in MF mode only... What i must do to activate AF and get access to the menu and fn functions.

Lenses s/n - 9024422.

Please HELP
09-10-2008, 06:51 PM   #225
Loyal Site Supporter
Canada_Rockies's Avatar

Join Date: Nov 2007
Location: Sparwood, BC, Canada
Photos: Gallery | Albums
Posts: 9,134
QuoteOriginally posted by h0rnd0g Quote
Can anybody help me? after installing my new 16-50 lenses into k20d i can access menu. After pressing MENU button menu shows on a backgreen and dissapearing in 1/2 sec. With Fn button - the same situation.

I can get photos in MF mode only... What i must do to activate AF and get access to the menu and fn functions.

Lenses s/n - 9024422.

Please HELP
I suggest that you may have a contact problem. Remove the lens and carefully clean all the contacts with a micro fiber cloth lightly dampened with alcohol, both on the lens and on the body.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
16-50mm, copy, da*, da* 16-50mm, k-mount, pentax lens, serials, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lens Serial Number Database Ole Pentax SLR Lens Discussion 57 04-17-2016 09:58 AM
K1000 Serial Number Database Ole Pentax Film SLR Discussion 233 02-26-2012 10:30 AM
Serial Number Database royal07 Pentax SLR Lens Discussion 1 10-15-2010 05:04 PM
Pentax 50mm f/1.2 lens serial number id? sandpipe Pentax SLR Lens Discussion 8 08-25-2008 05:55 AM



All times are GMT -7. The time now is 09:06 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top