On multiple bodies do lenses need consistent focus adjustments?

**othar** · 10-11-2019, 07:34 AM

Originally posted by dlh

Despite the way we talk about it, you're not actually calibrating the lens, you're matching the software in the camera to the lens, calibrating the camera as it were. The variation comes from the differences among the camera bodies, not the lenses.

As BigMackCam pointed out you actually calibrate the software of the AF-system in the camera for every camera/lens combination (as long as the lens has the required connections, old lenses only can be calibrated via a general calibration tool that will be applied to all fully manual lenses)

**Mikesul** · 10-11-2019, 11:48 AM

I think this is still on topic. This is prompted by BigmackCam's comment on making a spreadsheet. I seem to remember that there was a way to get a list of the adjustments made for each lens as well as a count of the number of lens adjusted in camera or from the editing software. Am I imagining this?

swanlefitte · 10-11-2019, 02:37 PM

Well with the lack of data piling up I started thinking about how ibis could move the sensor like a focus screen. This could be used for focus stacking.

Most lenses have a moustache focal plane. How about if as the shutter moved across the sensor the ibis moved the sensor forward and back?
Refer to Lens Rentals | Blog

**BigMackCam** · 10-12-2019, 01:15 PM

Originally posted by Mikesul

I think this is still on topic. This is prompted by BigmackCam's comment on making a spreadsheet. I seem to remember that there was a way to get a list of the adjustments made for each lens as well as a count of the number of lens adjusted in camera or from the editing software. Am I imagining this?

I haven't heard of that, Mike, but it makes sense that it could be done. The individual AF fine adjustment settings for each lens are obviously stored, so it seems likely there's a way of getting at them. I'd imagine it's done through DEBUG mode, probably by downloading the memory contents to a file... but I'm only guessing.

**Mikesul** · 10-12-2019, 04:18 PM

Maybe it was one of the earlier cameras. I never did anything with debug mode. I am sure it was Pentax...unless I imagined it.

totsmuyco · 10-12-2019, 11:06 PM

So now a new thread has been opened got me confused. How do I know if I need to calibrate my lenses? How do I go about this? I'm currently using a k-5II and a k-3II. I have a sigma 10-20, and original lenses 18-135, HD 55-300 and the WR 100 mm macro.

**othar** · 10-13-2019, 02:15 AM

Originally posted by totsmuyco

So now a new thread has been opened got me confused. How do I know if I need to calibrate my lenses? How do I go about this? I'm currently using a k-5II and a k-3II. I have a sigma 10-20, and original lenses 18-135, HD 55-300 and the WR 100 mm macro.

You could check focus accuracy the same way you would adjust it (with the help of a focus calibration tool -> a standing plate with some markings to AF upon and some kind of scale on an ascent next to it (You will need multible focusing tests from minimum focus distance to the target as well as from infinity to the target to establish a reliable starting point).
But the more fun way would be going out photographing for a day or two (using the optical view finder & therefore PDAF and not LV with it's CDAF) and checking on your computer afterwards if you can see any pattern in the images where AF didn't hit the mark.

totsmuyco · 10-13-2019, 02:24 AM

@other, is this focus calibration tool (standing plate with markings) being sold somewhere? I'm really interested not his test.

**othar** · 10-13-2019, 02:33 AM

Originally posted by totsmuyco

@other, is this focus calibration tool (standing plate with markings) being sold somewhere? I'm really interested not his test.

You can search "lens calibration tool" on amazon for example. There are multible vendors for that kind of tool.
On the other hand it is such a simple setup you can build one yourself too

**Kerrowdown** · 10-13-2019, 02:54 AM

Originally posted by swanlefitte

On multiple bodies do lenses need consistent focus adjustments?

I'm lucky... I adjust on the fly by turning my wrist.

Unregistered User · 10-13-2019, 05:50 AM

Originally posted by totsmuyco

So now a new thread has been opened got me confused. How do I know if I need to calibrate my lenses? How do I go about this? I'm currently using a k-5II and a k-3II. I have a sigma 10-20, and original lenses 18-135, HD 55-300 and the WR 100 mm macro.

Individual variations, no matter how slight, in manufactured products rolling off an assembly line, will occur. So you're trying to match one such product to another, and in this case, a lens to multiple bodies. The lens is what it is, there's no easy adjustment there. So you have to go through the process of matching each camera body to each lens, and the cameras do allow an easy way to do that. The simple fact that each piece is slightly different is how you know. If you want to get the most out of each lens, you must "calibrate". The probability that each lens you've got matching up with each body with no adjustment needed is, perhaps, non-zero but so small as to be statistically insignificant.

**othar** · 10-13-2019, 11:50 AM

Originally posted by totsmuyco

is this focus calibration tool (standing plate with markings) being sold somewhere?

While browsing the forum I came across this guide, if you are interested on further information concerning AF adjustment:

Fixing Front and Back Focus - Introduction - In-Depth Articles

totsmuyco · 10-13-2019, 07:42 PM - **1 Like**

@othar and @dlh, thank you.

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10-11-2019, 07:34 AM	#16
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	Originally posted by dlh Despite the way we talk about it, you're not actually calibrating the lens, you're matching the software in the camera to the lens, calibrating the camera as it were. The variation comes from the differences among the camera bodies, not the lenses. As BigMackCam pointed out you actually calibrate the software of the AF-system in the camera for every camera/lens combination (as long as the lens has the required connections, old lenses only can be calibrated via a general calibration tool that will be applied to all fully manual lenses)

10-11-2019, 11:48 AM	#17
Mikesul Loyal Site Supporter Join Date: Sep 2009 Location: Phoenix, AZ Posts: 7,594	I think this is still on topic. This is prompted by BigmackCam's comment on making a spreadsheet. I seem to remember that there was a way to get a list of the adjustments made for each lens as well as a count of the number of lens adjusted in camera or from the editing software. Am I imagining this?

10-11-2019, 02:37 PM	#18
swanlefitte Pentaxian Join Date: May 2015 Location: Minneapolis Photos: Gallery Posts: 4,068 Original Poster	Well with the lack of data piling up I started thinking about how ibis could move the sensor like a focus screen. This could be used for focus stacking. Most lenses have a moustache focal plane. How about if as the shutter moved across the sensor the ibis moved the sensor forward and back? Refer to Lens Rentals \| Blog

10-12-2019, 01:15 PM	#19
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,669	Originally posted by Mikesul I think this is still on topic. This is prompted by BigmackCam's comment on making a spreadsheet. I seem to remember that there was a way to get a list of the adjustments made for each lens as well as a count of the number of lens adjusted in camera or from the editing software. Am I imagining this? I haven't heard of that, Mike, but it makes sense that it could be done. The individual AF fine adjustment settings for each lens are obviously stored, so it seems likely there's a way of getting at them. I'd imagine it's done through DEBUG mode, probably by downloading the memory contents to a file... but I'm only guessing.

10-12-2019, 04:18 PM	#20
Mikesul Loyal Site Supporter Join Date: Sep 2009 Location: Phoenix, AZ Posts: 7,594	Maybe it was one of the earlier cameras. I never did anything with debug mode. I am sure it was Pentax...unless I imagined it.

10-12-2019, 11:06 PM	#21
totsmuyco Pentaxian Join Date: Aug 2013 Location: Iloilo City Photos: Gallery Posts: 2,276	So now a new thread has been opened got me confused. How do I know if I need to calibrate my lenses? How do I go about this? I'm currently using a k-5II and a k-3II. I have a sigma 10-20, and original lenses 18-135, HD 55-300 and the WR 100 mm macro.

10-13-2019, 02:15 AM	#22
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	Originally posted by totsmuyco So now a new thread has been opened got me confused. How do I know if I need to calibrate my lenses? How do I go about this? I'm currently using a k-5II and a k-3II. I have a sigma 10-20, and original lenses 18-135, HD 55-300 and the WR 100 mm macro. You could check focus accuracy the same way you would adjust it (with the help of a focus calibration tool -> a standing plate with some markings to AF upon and some kind of scale on an ascent next to it (You will need multible focusing tests from minimum focus distance to the target as well as from infinity to the target to establish a reliable starting point). But the more fun way would be going out photographing for a day or two (using the optical view finder & therefore PDAF and not LV with it's CDAF) and checking on your computer afterwards if you can see any pattern in the images where AF didn't hit the mark.

10-13-2019, 02:24 AM	#23
totsmuyco Pentaxian Join Date: Aug 2013 Location: Iloilo City Photos: Gallery Posts: 2,276	@other, is this focus calibration tool (standing plate with markings) being sold somewhere? I'm really interested not his test.

10-13-2019, 02:33 AM	#24
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	Originally posted by totsmuyco @other, is this focus calibration tool (standing plate with markings) being sold somewhere? I'm really interested not his test. You can search "lens calibration tool" on amazon for example. There are multible vendors for that kind of tool. On the other hand it is such a simple setup you can build one yourself too

10-13-2019, 02:54 AM	#25
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,816	Originally posted by swanlefitte On multiple bodies do lenses need consistent focus adjustments? I'm lucky... I adjust on the fly by turning my wrist.

10-13-2019, 05:50 AM	#26
Unregistered User Guest	Originally posted by totsmuyco So now a new thread has been opened got me confused. How do I know if I need to calibrate my lenses? How do I go about this? I'm currently using a k-5II and a k-3II. I have a sigma 10-20, and original lenses 18-135, HD 55-300 and the WR 100 mm macro. Individual variations, no matter how slight, in manufactured products rolling off an assembly line, will occur. So you're trying to match one such product to another, and in this case, a lens to multiple bodies. The lens is what it is, there's no easy adjustment there. So you have to go through the process of matching each camera body to each lens, and the cameras do allow an easy way to do that. The simple fact that each piece is slightly different is how you know. If you want to get the most out of each lens, you must "calibrate". The probability that each lens you've got matching up with each body with no adjustment needed is, perhaps, non-zero but so small as to be statistically insignificant.

10-13-2019, 11:50 AM	#27
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	Originally posted by totsmuyco is this focus calibration tool (standing plate with markings) being sold somewhere? While browsing the forum I came across this guide, if you are interested on further information concerning AF adjustment: Fixing Front and Back Focus - Introduction - In-Depth Articles

10-13-2019, 07:42 PM - 1 Like	#28
totsmuyco Pentaxian Join Date: Aug 2013 Location: Iloilo City Photos: Gallery Posts: 2,276	@othar and @dlh, thank you.