Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-14-2017, 12:02 AM   #1
Site Supporter
Site Supporter




Join Date: Dec 2016
Photos: Gallery
Posts: 169
Issue with Sigma 35mm 1.4 Art and Pentax K1

Hi All,

Just upgraded to Pentax K1 from Pentax K30 and I don't have any regrets whatsoever. Its an amazing camera especially good for low light photography. Having said that, am using my existing lens Sigma 35mm 1.4 and noticed focusing issue. It back focuses which is very much visible when used in further distance say 2 meters or over. I also read lot of comments in regards to known issue with this lens when focused at infinity. I have sent the lens to the distributor (crkennedy) to fix the known mount issue with K1 and also to resolve the focus issue. I was told that it will be likely that my camera need to be adjusted to resolve it even though they try to fix the issue. They also stated that they will be testing the lens and calibrating using their camera which may or may not resolve the issue once I start using it on my camera. Their expectation is to send the camera and lens to get it calibrated I believe. They said they will look into it anyway and let me know in a week or so.

Am currently using my K1 with Pentax 100mm 2.8 macro lens but did not face any issue. I do not own a sigma dock and am not sure if its worth to purchase it to calibrate the lens. Any one else had this issue and done any adjustment within the camera?

Regards,
Matt

06-14-2017, 12:10 AM   #2
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 51,584
It's normal for calibrations to vary between different lenses. If they're taking care of the Sigma for you, I wouldn't worry about the dock for now.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:
06-14-2017, 01:30 AM   #3
Veteran Member




Join Date: Jun 2009
Posts: 11,913
CRK's suggestion to send both the lens and camera in to them so that they may calibrate them together is, of course, the best course of action. AF performance and adjustment is lens/body interdependent. CRK's tech team is competent and turnaround times are usually fast, so it's not risky to do.

Having said all that, I'd also buy the Sigma disk dock. It gives you options to tune the AF more precisely that you can using the in-camera AF correction, if need be in future. It may also be handy when/if you get another Sigma lens.
06-14-2017, 01:37 AM   #4
Site Supporter
Site Supporter




Join Date: Dec 2016
Photos: Gallery
Posts: 169
Original Poster
Thanks Adam and rawr. The way CRK stated to me was that even if they try to fix it, it may not work as per my expectation on my camera was bit concerning. I did ask them about the dock but did not get any positive response on it. Based on my experience with this sigma lens, am not sure if I would purchase any of Sigma lens in future. This is supposed to be a professional grade lens.

When dock was released, I thought it may be the indication that these lens will have issues and we need to get it fixed using that. That is just the way I thought.

06-14-2017, 01:56 AM   #5
Pentaxian
Paul the Sunman's Avatar

Join Date: Aug 2011
Location: Melbourne
Photos: Gallery
Posts: 4,838
There are no firmware updates available for that lens in K-mount, so the dock is no use there. However, of course it does give you focus fine tuning. Having said that, when I tested mine, it needed no adjustment.

I also had the mount changed at CRK. It was quick and there were no issues. If the focus fine tuning in the K-1 can correct your problem, be happy with that. That's what it's there for.
06-14-2017, 01:58 AM   #6
Site Supporter
Site Supporter
Digitalis's Avatar

Join Date: Mar 2009
Location: Melbourne, Victoria
Photos: Gallery
Posts: 11,694
QuoteOriginally posted by rawr Quote
I'd also buy the Sigma disk dock
This is my recommendation as well, however I also recommend a suitable focus calibration target such as the Lens align. This is to ensure accurate and repeatable results when calibrating lenses.

QuoteOriginally posted by rawr Quote
CRK's tech team is competent
Interesting choice of words there. Being competent indicates they have the bare minimum of skill and knowledge to perform a task, proficient indicates a degree of skill and knowledge approaching mastery.

In my experience they are particularly incompetent when it comes to detecting optical faults.
06-14-2017, 01:59 AM   #7
Site Supporter
Site Supporter




Join Date: Dec 2016
Photos: Gallery
Posts: 169
Original Poster
Thanks Paul. The fine tuning in K1 applies to all lens which are connected or we can fine tune to a particular lens?. Apologies if this is a lame question since I have not done any fine tuning before.

06-14-2017, 02:01 AM   #8
Veteran Member
RAART's Avatar

Join Date: Apr 2013
Location: Oakville, ON
Photos: Gallery
Posts: 1,095
If the lens is still under warranty and you are original owner (you need to have receipt as well) then yes, they will/should adjust it complimentary however if not expect to pay somewhere around 150-200$... It is also recommended to send or drop the body with lens to be calibrated. I did that once and did not knew that they will charge me even I had original receipt but the warranty (7 years) was not transferable (purchased Sigma lens in store as returned or traded back item). Even the tech submitted the charges to Sigma but they declined and I had to pay.

Just my 2c.
06-14-2017, 02:01 AM   #9
Veteran Member




Join Date: Jun 2009
Posts: 11,913
QuoteOriginally posted by matroxication Quote
Based on my experience with this sigma lens, am not sure if I would purchase any of Sigma lens in future.
To be fair, front/back focus is not un-common in a lens/camera. Even Pentax lenses have been known to suffer from that.

My beef with this lens is it's AF performance on the K-3. The problem I had there was erratic and in-consistent focus results, not something nice and easy to fix like consistent back-focus. I haven't used the lens much on the K-1, but it seems to work more reliably there.
06-14-2017, 02:04 AM   #10
Pentaxian
Paul the Sunman's Avatar

Join Date: Aug 2011
Location: Melbourne
Photos: Gallery
Posts: 4,838
QuoteOriginally posted by matroxication Quote
Thanks Paul. The fine tuning in K1 applies to all lens which are connected or we can fine tune to a particular lens?. Apologies if this is a lame question since I have not done any fine tuning before.
You can adjust for each lens separately. See page 54 of the manual. C4 menu, item 25.

Last edited by Paul the Sunman; 06-14-2017 at 02:22 AM.
06-14-2017, 02:05 AM   #11
Veteran Member




Join Date: Jun 2009
Posts: 11,913
QuoteOriginally posted by matroxication Quote
Thanks Paul. The fine tuning in K1 applies to all lens which are connected or we can fine tune to a particular lens?. Apologies if this is a lame question since I have not done any fine tuning before.
You can fine tune for individual lenses. The camera can store the settings for 20 different lenses of the user.
06-14-2017, 02:30 AM   #12
Site Supporter
Site Supporter




Join Date: Dec 2016
Photos: Gallery
Posts: 169
Original Poster
Thanks Guyz. Am the original owner of the lens and its within warranty and I have the original receipt from CRK as well. Will check on the camera manual for the lens fine tuning. So at this point, I will have to wait and see what they come up with and hope they fix the issue.
06-14-2017, 05:49 AM   #13
Junior Member




Join Date: Mar 2015
Posts: 26
QuoteOriginally posted by rawr Quote
To be fair, front/back focus is not un-common in a lens/camera. Even Pentax lenses have been known to suffer from that.

My beef with this lens is it's AF performance on the K-3. The problem I had there was erratic and in-consistent focus results, not something nice and easy to fix like consistent back-focus. I haven't used the lens much on the K-1, but it seems to work more reliably there.
I've had exactly the same experience with the Sigma 35 Art on my K3; probably 80% keeper rate when focused at infinity, even when I'm careful to use center point focusing on a high contrast target. The other 20% of the time it's wildly, wildly off. This is even after using the Sigma dock for adjustment.

OTOH, I have pretty much the same issue with the Pentax 55mm, even after adjustment. Other Pentax and Sigma lenses work perfectly fine and focus consistently.
06-14-2017, 06:04 AM   #14
Pentaxian
Paul the Sunman's Avatar

Join Date: Aug 2011
Location: Melbourne
Photos: Gallery
Posts: 4,838
My issue with the Sigma 35mm Art on the K3 is exposure, not focus. It consistently overexposes by 1 - 1.7 stops. But on the K1 it's perfect!
06-14-2017, 07:33 AM   #15
Loyal Site Supporter
Loyal Site Supporter




Join Date: May 2016
Location: East Coast
Posts: 2,903
I find this whole focus thing with this lens interesting. I recently picked up a copy from B&H when it was bundled with the dock, and I'm using it on a K3II. I have found almost every lens I have, which are almost all Pentax, need some level of fine focus adjustment. This was true for the Sigma Art 35 as well, but I got better luck dialing it in with the dock than I did using the camera's adjustment. I haven't had any issues with the lens focusing correctly now that I've tuned it. I can't make a really accurate statement on exposure, as I often make some slight adjustments with any lens as I shoot, depending on what the subject is, but generically, I think exposure has been fine. For those not familiar with the Sigma dock, it does have the ability to set a different focus calibration for different distances. I found this interesting. For the moment, I've been OK with the same setting adjustment applied for all distances. Now it's dialed in, I find the lens very sharp and quite nice to use. Bokeh is also very nice. Hopefully your lens will come out fine.
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!
35mm 1.4 art, art and pentax, camera, dslr, full frame, full-frame, issue, issue with sigma, k-1, k1, lens, pentax, pentax k-1, sigma, sigma 35mm
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
New video review: Pentax 31mm f1.8 limited Vs Sigma 35mm f1.4 Art lens on K1 englishphotographer Pentax SLR Lens Discussion 27 07-27-2017 07:53 AM
For Sale - Sold: Like new Sigma 35mm Art FOR Your Sigma 18-35mm Art lens! Fenwoodian Sold Items 7 10-09-2016 05:47 PM
Which Lens are better to K3:Pentax 43 - Pentax 55mm - Sigma 35mm Art - Sigma 30mm Art Genki Pentax K-3 & K-3 II 20 05-13-2016 12:15 PM
sigma 18-35mm f1.8 Art or 35mm F1.8 ART ? Help needed ajaya Pentax SLR Lens Discussion 13 02-25-2014 08:11 PM



All times are GMT -7. The time now is 06:26 AM. | See also: NikonForums.com, CanonForums.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