Focal Length Setting

**sibyrnes** · 08-12-2017, 08:46 AM - **2 Likes**

I would like Pentax to introduce a firmware update allowing focal lengths other than the ones on the list to be entered. For example, when using a 25mm lens I must enter 24mm as the length. I realize that 1mm probably does not affect the shake reduction much(if at all) but I would like to see an accurate focal length recorded in the EXIF file. It would help me to remember which lens I used when reviewing images. In the old film days I used to record all photo data in a log book provided by the New York Institute of Photography. I still have a bunch of those old log books but it is way to much trouble and I wonder how many shots I have lost while writing in my book!
.

Last edited by sibyrnes; 08-12-2017 at 08:53 AM.

**Tonytee** · 08-12-2017, 09:23 AM

Interesting situation. I am wondering why your lens information is not appearing at the bottom of your EXIF File. I have been into Digital Photography for approximately six years and the lens info., is there in the EXIF File every time. As an effort to point you in the right direction, you will receive a better response by posting this issue in the Troubleshooting Section. I hope this helps.

Rgds,

Tony

**twilhelm** · 08-12-2017, 09:44 AM

Originally posted by Tonytee

Interesting situation. I am wondering why your lens information is not appearing at the bottom of your EXIF File. I have been into Digital Photography for approximately six years and the lens info., is there in the EXIF File every time. As an effort to point you in the right direction, you will receive a better response by posting this issue in the Troubleshooting Section. I hope this helps.

Rgds,

Tony

You won't get correct EXIF data on old lenses, i.e. Screw mount, M series and etc.

The OP would like Pentax to add all focal lengths to the manual entered shake reduction, as per his example, if he uses a 25mm lens, the only option for him to enter is 24mm and that is what is recorded into EXIF.

Apparently Pentax chose to use only the focal lengths they have created over the years. I would assume it has to do with the programming of the shake reduction system, but I'm no expert there. What would be nice, if when we use an old lens, if we could enter lens info into the camera which would be saved to EXIF. That would seem doable to me.

**sibyrnes** · 08-12-2017, 10:07 AM

Originally posted by twilhelm

You won't get correct EXIF data on old lenses, i.e. Screw mount, M series and etc.

Actually, no correct EXIF data with any non-autofocus lens. Focal length must be manually selected even with A lenses.

Last edited by sibyrnes; 08-12-2017 at 10:13 AM.

**Tonytee** · 08-12-2017, 11:26 AM

Originally posted by twilhelm

You won't get correct EXIF data on old lenses, i.e. Screw mount, M series and etc.

The OP would like Pentax to add all focal lengths to the manual entered shake reduction, as per his example, if he uses a 25mm lens, the only option for him to enter is 24mm and that is what is recorded into EXIF.

Apparently Pentax chose to use only the focal lengths they have created over the years. I would assume it has to do with the programming of the shake reduction system, but I'm no expert there. What would be nice, if when we use an old lens, if we could enter lens info into the camera which would be saved to EXIF. That would seem doable to me.

Yes, I totally understood what he was asking. The OP must have a boatload of 25mm lenses. I have only one Pentax-A 50mm 1.7 lens, so when I take a shot, then check the EXIF Data, the Focal Length tells me that the nifty fifty is what I used. That is what I was basing my response on.

Thnx,

TT

**twilhelm** · 08-12-2017, 11:45 AM

Originally posted by Tonytee

Yes, I totally understood what he was asking. The OP must have a boatload of 25mm lenses. I have only one Pentax-A 50mm 1.7 lens, so when I take a shot, then check the EXIF Data, the Focal Length tells me that the nifty fifty is what I used. That is what I was basing my response on.

Thnx,

TT

I understand. I also have a 90mm which, as far as shake reduction is conserned, I have to enter 85. In with him where I wish we could enter the actual so that it is recorded as such.

**sibyrnes** · 08-13-2017, 08:45 AM - **1 Like**

Originally posted by Tonytee

Yes, I totally understood what he was asking. The OP must have a boatload of 25mm lenses. I have only one Pentax-A 50mm 1.7 lens, so when I take a shot, then check the EXIF Data, the Focal Length tells me that the nifty fifty is what I used. That is what I was basing my response on.

Thnx,

TT

No, I don't have "a boat load of 25mm lens" - only one. But I do have a 24mm lens and I would like to set the focal length to 25mm to distinguish between the two.

35mmfilmfan · 08-13-2017, 10:00 AM

Originally posted by sibyrnes

I don't have "a boat load of 25mm lens" - only one. But I do have a 24mm lens

Can I ask what the visible difference is between these two focal lengths, please ?

**sibyrnes** · 08-13-2017, 07:25 PM

Originally posted by 35mmfilmfan

Can I ask what the visible difference is between these two focal lengths, please ?

Sure you can ask, but I bet you know the answer. The 24mm will offer a slightly wider view than the 25mm in photos shot from the same distance/perspective. Since I don't shoot all photos at the same distance/perspective, I would like to see the focal length specified in the EXIF file. I have the same issue with 20mm and 21mm lens.

**Lowell Goudge** · 08-14-2017, 05:11 PM

Originally posted by 35mmfilmfan

Can I ask what the visible difference is between these two focal lengths, please ?

Originally posted by sibyrnes

Sure you can ask, but I bet you know the answer. The 24mm will offer a slightly wider view than the 25mm in photos shot from the same distance/perspective. Since I don't shoot all photos at the same distance/perspective, I would like to see the focal length specified in the EXIF file. I have the same issue with 20mm and 21mm lens.

As I am ever the sceptic, the two lenses are probably identical just marked differently to allow one maker to have bragging rights .

Look at the samyang lens line up, the 14/2.8 is marked 13mm by only vivitar. But all the lenses, vivitar, bower, samyang Robinson etc are identical optically

**sibyrnes** · 08-14-2017, 08:02 PM

Originally posted by Lowell Goudge

As I am ever the sceptic, the two lenses are probably identical just marked differently to allow one maker to have bragging rights .

Please, give me a break! I don't think my Pentax K24mm is "probably identical" to my Zeiss Distagon 25mm - even if the EXIF file doesn't show the difference!(and that is the real subject of this thread)

I will admit, though, that my K20mm is pretty darn close to my Distagon 21mm!

**Lowell Goudge** · 08-15-2017, 03:28 AM

Originally posted by 35mmfilmfan

Can I ask what the visible difference is between these two focal lengths, please ?

Originally posted by sibyrnes

Please, give me a break! I don't think my Pentax K24mm is "probably identical" to my Zeiss Distagon 25mm - even if the EXIF file doesn't show the difference!(and that is the real subject of this thread)

I will admit, though, that my K20mm is pretty darn close to my Distagon 21mm!

All I was eluding to is that within the lens standards, such as they are, there are tolerances allowed for not only focal length but maximum aperture as well, and that the makers have some freedom to advertise the lenses somewhat as they wish.

In the past, when photo magazines were free (or seemingly independent enough to report this data) it was not common in a lens report to provide the maximum aperture and focal length of the sample tested. Try out the lenses, you may get a surprise.

**Larrymc** · 08-15-2017, 09:12 AM - **1 Like**

Originally posted by sibyrnes

I would like Pentax to introduce a firmware update allowing focal lengths other than the ones on the list to be entered. For example, when using a 25mm lens I must enter 24mm as the length. I realize that 1mm probably does not affect the shake reduction much(if at all) but I would like to see an accurate focal length recorded in the EXIF file. It would help me to remember which lens I used when reviewing images. In the old film days I used to record all photo data in a log book provided by the New York Institute of Photography. I still have a bunch of those old log books but it is way to much trouble and I wonder how many shots I have lost while writing in my book!
.

Have you given any thought to an EXIF file editor like EXIFToolGUI which allows you to edit certain EXIF file data such as Lens model and Focal length. Some of my Sigma lens do not register with my K3 so I have set up a cut and paste routine to correct the lens data immediately after I down load the files. Just a thought.

35mmfilmfan · 08-15-2017, 09:41 AM

Originally posted by sibyrnes

The 24mm will offer a slightly wider view than the 25mm in photos shot from the same distance/perspective.

You are right, I do know that, but I asked about the visible difference between the two - i.e. what can you actually see that indicates the use of one lens or the other ? In other words, is there a major or a minor change to the visible field of view ?

**sibyrnes** · 08-15-2017, 11:49 AM

Originally posted by Larrymc

Have you given any thought to an EXIF file editor like EXIFToolGUI which allows you to edit certain EXIF file data such as Lens model and Focal length. Some of my Sigma lens do not register with my K3 so I have set up a cut and paste routine to correct the lens data immediately after I down load the files. Just a thought.

Thank you. That could help somewhat but it would be nice to edit in camera.

08-12-2017, 08:46 AM - 2 Likes	#1
sibyrnes Site Supporter Join Date: May 2016 Location: Pittsburgh, Pa. Photos: Gallery \| Albums Posts: 447	Focal Length Setting I would like Pentax to introduce a firmware update allowing focal lengths other than the ones on the list to be entered. For example, when using a 25mm lens I must enter 24mm as the length. I realize that 1mm probably does not affect the shake reduction much(if at all) but I would like to see an accurate focal length recorded in the EXIF file. It would help me to remember which lens I used when reviewing images. In the old film days I used to record all photo data in a log book provided by the New York Institute of Photography. I still have a bunch of those old log books but it is way to much trouble and I wonder how many shots I have lost while writing in my book! . Last edited by sibyrnes; 08-12-2017 at 08:53 AM.

08-14-2017, 08:02 PM	#11
sibyrnes Site Supporter Join Date: May 2016 Location: Pittsburgh, Pa. Photos: Gallery \| Albums Posts: 447 Original Poster	Originally posted by Lowell Goudge As I am ever the sceptic, the two lenses are probably identical just marked differently to allow one maker to have bragging rights . Please, give me a break! I don't think my Pentax K24mm is "probably identical" to my Zeiss Distagon 25mm - even if the EXIF file doesn't show the difference!(and that is the real subject of this thread) I will admit, though, that my K20mm is pretty darn close to my Distagon 21mm! Last edited by sibyrnes; 08-14-2017 at 09:13 PM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Image stabilization with focal length that isn't on the list?	pentax360	Pentax DSLR Discussion	4	08-13-2017 12:11 AM
Focal Length Analysis from Recent Event / Lens Choice Optimization	6BQ5	Pentax SLR Lens Discussion	37	11-10-2015 01:29 AM
Focal Length Change.	KLAATU	Pentax SLR Lens Discussion	16	09-15-2015 06:29 AM
Macro Macro lens focal length variation and FOV images to compare?	JayR	Photographic Technique	2	02-04-2015 05:29 PM
Image Stabilization and Focal Length	trevorgrout	Troubleshooting and Beginner Help	7	04-20-2010 07:40 AM

08-12-2017, 09:23 AM	#2
Tonytee Loyal Site Supporter Join Date: Jul 2012 Photos: Gallery \| Albums Posts: 21,430	Interesting situation. I am wondering why your lens information is not appearing at the bottom of your EXIF File. I have been into Digital Photography for approximately six years and the lens info., is there in the EXIF File every time. As an effort to point you in the right direction, you will receive a better response by posting this issue in the Troubleshooting Section. I hope this helps. Rgds, Tony

08-12-2017, 09:44 AM	#3
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	Originally posted by Tonytee Interesting situation. I am wondering why your lens information is not appearing at the bottom of your EXIF File. I have been into Digital Photography for approximately six years and the lens info., is there in the EXIF File every time. As an effort to point you in the right direction, you will receive a better response by posting this issue in the Troubleshooting Section. I hope this helps. Rgds, Tony You won't get correct EXIF data on old lenses, i.e. Screw mount, M series and etc. The OP would like Pentax to add all focal lengths to the manual entered shake reduction, as per his example, if he uses a 25mm lens, the only option for him to enter is 24mm and that is what is recorded into EXIF. Apparently Pentax chose to use only the focal lengths they have created over the years. I would assume it has to do with the programming of the shake reduction system, but I'm no expert there. What would be nice, if when we use an old lens, if we could enter lens info into the camera which would be saved to EXIF. That would seem doable to me.

08-12-2017, 10:07 AM	#4
sibyrnes Site Supporter Join Date: May 2016 Location: Pittsburgh, Pa. Photos: Gallery \| Albums Posts: 447 Original Poster	Originally posted by twilhelm You won't get correct EXIF data on old lenses, i.e. Screw mount, M series and etc. Actually, no correct EXIF data with any non-autofocus lens. Focal length must be manually selected even with A lenses. Last edited by sibyrnes; 08-12-2017 at 10:13 AM.

08-12-2017, 11:26 AM	#5
Tonytee Loyal Site Supporter Join Date: Jul 2012 Photos: Gallery \| Albums Posts: 21,430	Originally posted by twilhelm You won't get correct EXIF data on old lenses, i.e. Screw mount, M series and etc. The OP would like Pentax to add all focal lengths to the manual entered shake reduction, as per his example, if he uses a 25mm lens, the only option for him to enter is 24mm and that is what is recorded into EXIF. Apparently Pentax chose to use only the focal lengths they have created over the years. I would assume it has to do with the programming of the shake reduction system, but I'm no expert there. What would be nice, if when we use an old lens, if we could enter lens info into the camera which would be saved to EXIF. That would seem doable to me. Yes, I totally understood what he was asking. The OP must have a boatload of 25mm lenses. I have only one Pentax-A 50mm 1.7 lens, so when I take a shot, then check the EXIF Data, the Focal Length tells me that the nifty fifty is what I used. That is what I was basing my response on. Thnx, TT

08-12-2017, 11:45 AM	#6
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	Originally posted by Tonytee Yes, I totally understood what he was asking. The OP must have a boatload of 25mm lenses. I have only one Pentax-A 50mm 1.7 lens, so when I take a shot, then check the EXIF Data, the Focal Length tells me that the nifty fifty is what I used. That is what I was basing my response on. Thnx, TT I understand. I also have a 90mm which, as far as shake reduction is conserned, I have to enter 85. In with him where I wish we could enter the actual so that it is recorded as such.

08-13-2017, 08:45 AM - 1 Like	#7
sibyrnes Site Supporter Join Date: May 2016 Location: Pittsburgh, Pa. Photos: Gallery \| Albums Posts: 447 Original Poster	Originally posted by Tonytee Yes, I totally understood what he was asking. The OP must have a boatload of 25mm lenses. I have only one Pentax-A 50mm 1.7 lens, so when I take a shot, then check the EXIF Data, the Focal Length tells me that the nifty fifty is what I used. That is what I was basing my response on. Thnx, TT No, I don't have "a boat load of 25mm lens" - only one. But I do have a 24mm lens and I would like to set the focal length to 25mm to distinguish between the two.

08-13-2017, 10:00 AM	#8
35mmfilmfan Pentaxian Join Date: Oct 2016 Location: Norfolk, UK Posts: 4,312	Originally posted by sibyrnes I don't have "a boat load of 25mm lens" - only one. But I do have a 24mm lens Can I ask what the visible difference is between these two focal lengths, please ?

08-13-2017, 07:25 PM	#9
sibyrnes Site Supporter Join Date: May 2016 Location: Pittsburgh, Pa. Photos: Gallery \| Albums Posts: 447 Original Poster	Originally posted by 35mmfilmfan Can I ask what the visible difference is between these two focal lengths, please ? Sure you can ask, but I bet you know the answer. The 24mm will offer a slightly wider view than the 25mm in photos shot from the same distance/perspective. Since I don't shoot all photos at the same distance/perspective, I would like to see the focal length specified in the EXIF file. I have the same issue with 20mm and 21mm lens.

08-14-2017, 05:11 PM	#10
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,886	Originally posted by 35mmfilmfan Can I ask what the visible difference is between these two focal lengths, please ? Originally posted by sibyrnes Sure you can ask, but I bet you know the answer. The 24mm will offer a slightly wider view than the 25mm in photos shot from the same distance/perspective. Since I don't shoot all photos at the same distance/perspective, I would like to see the focal length specified in the EXIF file. I have the same issue with 20mm and 21mm lens. As I am ever the sceptic, the two lenses are probably identical just marked differently to allow one maker to have bragging rights . Look at the samyang lens line up, the 14/2.8 is marked 13mm by only vivitar. But all the lenses, vivitar, bower, samyang Robinson etc are identical optically

08-15-2017, 03:28 AM	#12
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,886	Originally posted by 35mmfilmfan Can I ask what the visible difference is between these two focal lengths, please ? Originally posted by sibyrnes Please, give me a break! I don't think my Pentax K24mm is "probably identical" to my Zeiss Distagon 25mm - even if the EXIF file doesn't show the difference!(and that is the real subject of this thread) I will admit, though, that my K20mm is pretty darn close to my Distagon 21mm! All I was eluding to is that within the lens standards, such as they are, there are tolerances allowed for not only focal length but maximum aperture as well, and that the makers have some freedom to advertise the lenses somewhat as they wish. In the past, when photo magazines were free (or seemingly independent enough to report this data) it was not common in a lens report to provide the maximum aperture and focal length of the sample tested. Try out the lenses, you may get a surprise.

Thread Tools	Search this Thread
	Search this Thread: Advanced Search

08-15-2017, 09:12 AM - 1 Like	#13
Larrymc Site Supporter Join Date: Jun 2014 Location: Mississippi, USA Posts: 5,251	Originally posted by sibyrnes I would like Pentax to introduce a firmware update allowing focal lengths other than the ones on the list to be entered. For example, when using a 25mm lens I must enter 24mm as the length. I realize that 1mm probably does not affect the shake reduction much(if at all) but I would like to see an accurate focal length recorded in the EXIF file. It would help me to remember which lens I used when reviewing images. In the old film days I used to record all photo data in a log book provided by the New York Institute of Photography. I still have a bunch of those old log books but it is way to much trouble and I wonder how many shots I have lost while writing in my book! . Have you given any thought to an EXIF file editor like EXIFToolGUI which allows you to edit certain EXIF file data such as Lens model and Focal length. Some of my Sigma lens do not register with my K3 so I have set up a cut and paste routine to correct the lens data immediately after I down load the files. Just a thought.

08-15-2017, 09:41 AM	#14
35mmfilmfan Pentaxian Join Date: Oct 2016 Location: Norfolk, UK Posts: 4,312	Originally posted by sibyrnes The 24mm will offer a slightly wider view than the 25mm in photos shot from the same distance/perspective. You are right, I do know that, but I asked about the visible difference between the two - i.e. what can you actually see that indicates the use of one lens or the other ? In other words, is there a major or a minor change to the visible field of view ?

08-15-2017, 11:49 AM	#15
sibyrnes Site Supporter Join Date: May 2016 Location: Pittsburgh, Pa. Photos: Gallery \| Albums Posts: 447 Original Poster	Originally posted by Larrymc Have you given any thought to an EXIF file editor like EXIFToolGUI which allows you to edit certain EXIF file data such as Lens model and Focal length. Some of my Sigma lens do not register with my K3 so I have set up a cut and paste routine to correct the lens data immediately after I down load the files. Just a thought. Thank you. That could help somewhat but it would be nice to edit in camera.