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08-12-2017, 08:46 AM - 1 Like   #1
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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!
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Last edited by sibyrnes; 08-12-2017 at 08:53 AM.
08-12-2017, 09:23 AM   #2
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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
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QuoteOriginally posted by Tonytee Quote
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
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QuoteOriginally posted by twilhelm Quote
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
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QuoteOriginally posted by twilhelm Quote
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
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QuoteOriginally posted by Tonytee Quote
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
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QuoteOriginally posted by Tonytee Quote
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
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QuoteOriginally posted by sibyrnes Quote
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
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QuoteOriginally posted by 35mmfilmfan Quote
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
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QuoteOriginally posted by 35mmfilmfan Quote
Can I ask what the visible difference is between these two focal lengths, please ?
QuoteOriginally posted by sibyrnes Quote
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
08-14-2017, 08:02 PM   #11
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QuoteOriginally posted by Lowell Goudge Quote
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.
08-15-2017, 03:28 AM   #12
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QuoteOriginally posted by 35mmfilmfan Quote
Can I ask what the visible difference is between these two focal lengths, please ?
QuoteOriginally posted by sibyrnes Quote
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.
08-15-2017, 09:12 AM - 1 Like   #13
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QuoteOriginally posted by sibyrnes Quote
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
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QuoteOriginally posted by sibyrnes Quote
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
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QuoteOriginally posted by Larrymc Quote
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.
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