K-5 Focus Calibration - Sigma lenses

johnbachel · 05-03-2013, 02:15 PM

I'm looking for some advice, and I hope I'm in the right forum. I recently purchased a K-5, and two Sigma lenses - an 18-135 and a 24-70 2.8. I set the lens focus calibration using FocusTune, which works fine with the K-5 (I was glad to find it, having used Reikan FoCal with the Nikon D7000 that I used to own).

Using live view, both lenses are very sharp at maximum aperture. In fact the Sigma 24-70 is significantly sharper than two Tamron 28-75 f:2.8 lenses that I compared it against. The problem is that one lens has significant front focus issues, while the other back focuses. In fact, the 18-125 could only achieve correct focus calibration using the Debug mode method of expanding the AF calibration range by offsetting the zero point on the AF calibration scale to +40. Unfortunately, when the camera is set up that way, the 24-70's ideal calibration setting is more than -10.

So, I have some options -

1. Send the lenses to Sigma, where I will have to pay to have the 18-125 calibrated. The 24-70 is new, and would presumably be calibrated for free.

2. Leave the camera in debug mode, and shift the base calibration range when I change lenses. I don't know if there is a reason why I shouldn't do this.

3. Sell the 18-125 and buy another lens.

Any thoughts?

By the way, I love the k-5 - it's very solid and the image quality is great.

Thanks.

Adam · 05-03-2013, 03:29 PM

I'd just get rid of the Sigma lens unless you really need an all in one lens. The Pentax 18-135 would be a good alternative to it.

rawr · 05-03-2013, 03:43 PM

You seem to have missed this item from the FocusTune instructions:

Quote:

Do not shoot in Live View mode

Camera Settings Best Practices - Apr 26 - MTD Product Info Center

johnbachel · 05-03-2013, 04:46 PM

Originally posted by rawr

You seem to have missed this item from the FocusTune instructions:

Camera Settings Best Practices - Apr 26 - MTD Product Info Center

I didn't set the lenses up using FocusTune in live view mode - I'm not sure where you got the idea that I did.

The 18-135 Pentax would be an option to replace the Sigma 18-125, although reviews suggest that the 18-135 is a pretty mediocre lens, while the 18-135 Sigma that I have is sharp at maximum aperture.

I want an f:2.8 lens for indoor work, and 24-70 or 28-75 is the right range for the kind of shooting that I do, so I'm sure I'll keep either the Tamron or the Sigma. By the way, an alternative would be to keep the Tamron, although it's not as sharp as the Sigma, since the Tamron I'm looking at doesn't have significant back or front focus issues.

stormtech · 05-03-2013, 05:14 PM

Originally posted by johnbachel

The 18-135 Pentax would be an option to replace the Sigma 18-125, although reviews suggest that the 18-135 is a pretty mediocre lens

Mediocre?

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/179869-da-18-1...at-can-do.html

johnbachel · 05-03-2013, 05:16 PM

Thanks - Nice pictures. The only thing I had seen about the 18-135 was the photozone review, which wasn't positive.

stormtech · 05-03-2013, 05:20 PM

Originally posted by johnbachel

Thanks - Nice pictures. The only thing I had seen about the 18-135 was the photozone review, which wasn't positive.

That is why I wanted you to see that thread. There has also been long discussions on that specific review also. They might have just had a bad copy which can happen with any lens.

I know this is kind of off topic for you, but wanted to be sure you get the right information in helping with your decision.

One3rdEV · 05-03-2013, 09:40 PM

If you are very satisfied with the optical qualities from each of your lenses then I would recommend- send them off to Sigma for calibration to a Master Lens. Having them consistent with each other should solve your problem.

Then if the AF Fine Adjust of your K5 is not capable to accommodate the Sigma adjusted lenses, you should have Pentax Service calibrate your K5 to nominal using their Master Lens.

Actually if you want to try to spare the cost for the non-warranty Sigma... send both the single lens (under warranty) and the K5 (if under warranty) off for their separate nominal calibrations. Then see where the non-warranty lens ends up before considering to send it in.

rawr · 05-03-2013, 11:44 PM

Originally posted by johnbachel

I didn't set the lenses up using FocusTune in live view mode - I'm not sure where you got the idea that I did.

Originally posted by johnbachel

Using live view, both lenses are very sharp at maximum aperture.

That's where I got the impression you ran your tests using live view.

Originally posted by One3rdEV

send both

Indeed. No lens and body combination in the world will share the same tolerances. To get everything 'right', you need lens and body adjusted together, inconvenient as it may be.

Class A · 05-09-2013, 09:41 PM

Originally posted by stormtech

They might have just had a bad copy which can happen with any lens.

FWIW, PZ contacted Pentax and received confirmation that the copy wasn't bad.

The 18-135 just isn't that strong at long settings.

Thanks for the pointer to the samples thread.
The lens certainly got very nice bokeh.

05-03-2013, 02:15 PM	#1
johnbachel Junior Member Join Date: Apr 2013 Posts: 28	K-5 Focus Calibration - Sigma lenses I'm looking for some advice, and I hope I'm in the right forum. I recently purchased a K-5, and two Sigma lenses - an 18-135 and a 24-70 2.8. I set the lens focus calibration using FocusTune, which works fine with the K-5 (I was glad to find it, having used Reikan FoCal with the Nikon D7000 that I used to own). Using live view, both lenses are very sharp at maximum aperture. In fact the Sigma 24-70 is significantly sharper than two Tamron 28-75 f:2.8 lenses that I compared it against. The problem is that one lens has significant front focus issues, while the other back focuses. In fact, the 18-125 could only achieve correct focus calibration using the Debug mode method of expanding the AF calibration range by offsetting the zero point on the AF calibration scale to +40. Unfortunately, when the camera is set up that way, the 24-70's ideal calibration setting is more than -10. So, I have some options - 1. Send the lenses to Sigma, where I will have to pay to have the 18-125 calibrated. The 24-70 is new, and would presumably be calibrated for free. 2. Leave the camera in debug mode, and shift the base calibration range when I change lenses. I don't know if there is a reason why I shouldn't do this. 3. Sell the 18-125 and buy another lens. Any thoughts? By the way, I love the k-5 - it's very solid and the image quality is great. Thanks.

05-03-2013, 03:29 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,594	I'd just get rid of the Sigma lens unless you really need an all in one lens. The Pentax 18-135 would be a good alternative to it. 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:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
pentax k-r focus calibration	Enkhbayar	Troubleshooting and Beginner Help	13	04-24-2021 07:33 AM
K-5 Viewfinder and manual lenses focus problem	PiotrKrochmal	Pentax K-5 & K-5 II	10	03-08-2012 03:54 PM
KatzEye and K-5: does it need calibration?	Edvinas	Pentax K-5 & K-5 II	11	08-16-2011 07:33 AM
How Well Does the K-5 Focus With Old Manual Focus Lenses?	TomBrooklyn	Pentax K-5 & K-5 II	14	07-21-2011 05:16 AM
Sigma 85mm front focus on K-5 update	outsider	Pentax K-5 & K-5 II	6	07-17-2011 12:32 AM

05-03-2013, 03:43 PM	#3
rawr Veteran Member Join Date: Jun 2009 Posts: 11,913	You seem to have missed this item from the FocusTune instructions: Quote: Do not shoot in Live View mode Camera Settings Best Practices - Apr 26 - MTD Product Info Center

05-03-2013, 04:46 PM	#4
johnbachel Junior Member Join Date: Apr 2013 Posts: 28 Original Poster	Originally posted by rawr You seem to have missed this item from the FocusTune instructions: Camera Settings Best Practices - Apr 26 - MTD Product Info Center I didn't set the lenses up using FocusTune in live view mode - I'm not sure where you got the idea that I did. The 18-135 Pentax would be an option to replace the Sigma 18-125, although reviews suggest that the 18-135 is a pretty mediocre lens, while the 18-135 Sigma that I have is sharp at maximum aperture. I want an f:2.8 lens for indoor work, and 24-70 or 28-75 is the right range for the kind of shooting that I do, so I'm sure I'll keep either the Tamron or the Sigma. By the way, an alternative would be to keep the Tamron, although it's not as sharp as the Sigma, since the Tamron I'm looking at doesn't have significant back or front focus issues.

05-03-2013, 05:14 PM	#5
stormtech Veteran Member Join Date: Jan 2011 Location: In the boonies (NW Penna) Photos: Gallery \| Albums Posts: 5,744	Originally posted by johnbachel The 18-135 Pentax would be an option to replace the Sigma 18-125, although reviews suggest that the 18-135 is a pretty mediocre lens Mediocre? https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/179869-da-18-1...at-can-do.html

05-03-2013, 05:16 PM	#6
johnbachel Junior Member Join Date: Apr 2013 Posts: 28 Original Poster	Thanks - Nice pictures. The only thing I had seen about the 18-135 was the photozone review, which wasn't positive.

05-03-2013, 05:20 PM	#7
stormtech Veteran Member Join Date: Jan 2011 Location: In the boonies (NW Penna) Photos: Gallery \| Albums Posts: 5,744	Originally posted by johnbachel Thanks - Nice pictures. The only thing I had seen about the 18-135 was the photozone review, which wasn't positive. That is why I wanted you to see that thread. There has also been long discussions on that specific review also. They might have just had a bad copy which can happen with any lens. I know this is kind of off topic for you, but wanted to be sure you get the right information in helping with your decision.

05-03-2013, 09:40 PM	#8
One3rdEV Senior Member Join Date: Mar 2013 Location: So-central, MI Posts: 285	If you are very satisfied with the optical qualities from each of your lenses then I would recommend- send them off to Sigma for calibration to a Master Lens. Having them consistent with each other should solve your problem. Then if the AF Fine Adjust of your K5 is not capable to accommodate the Sigma adjusted lenses, you should have Pentax Service calibrate your K5 to nominal using their Master Lens. Actually if you want to try to spare the cost for the non-warranty Sigma... send both the single lens (under warranty) and the K5 (if under warranty) off for their separate nominal calibrations. Then see where the non-warranty lens ends up before considering to send it in.

05-03-2013, 11:44 PM	#9
rawr Veteran Member Join Date: Jun 2009 Posts: 11,913	Originally posted by johnbachel I didn't set the lenses up using FocusTune in live view mode - I'm not sure where you got the idea that I did. Originally posted by johnbachel Using live view, both lenses are very sharp at maximum aperture. That's where I got the impression you ran your tests using live view. Originally posted by One3rdEV send both Indeed. No lens and body combination in the world will share the same tolerances. To get everything 'right', you need lens and body adjusted together, inconvenient as it may be.

05-09-2013, 09:41 PM	#10
Class A Pentaxian Join Date: Aug 2008 Location: Wellington, New Zealand Posts: 11,251	Originally posted by stormtech They might have just had a bad copy which can happen with any lens. FWIW, PZ contacted Pentax and received confirmation that the copy wasn't bad. The 18-135 just isn't that strong at long settings. Thanks for the pointer to the samples thread. The lens certainly got very nice bokeh.

Thread Tools	Search this Thread
	Search this Thread: Advanced Search