How does On1PR 2021 calculate Exif data?
I suppose you think the answer to this question is obvious but it is not. I will tell you the reason for my question.
My equipment: Sony alpha 6500 + Zeiss 16-70 f / 4.
I usually shoot with the hyperfocal distance in mind.
Working with a RAW file on my On1PR2001 I checked for an unwanted blur and to make sure it had not been an error in choosing the focus distance, I went to the Exif data that the program shows in the Info section of the Browse module, I expected 20 m more or less and to my amazement the program indicated "Focus Distance 1.98 m"?
I checked with different lenses, fixed, zoom in their different focal points and with two different bodies and in all cases the data is incoherent and far from reality.
How does the program calculate this data? And what is this “Focus Distance” data for?
Is it a program error or am I misinterpreting the data?
EXIF data is not calculated. It is read from the image file and displayed. Focus distance is what the camera reports for the distance at which it was focused when the photo was taken.
If you want to verify what Photo RAW is reporting you can use another program such as Adobe Bridge (it's free) to compare what it reports vs PR. There is also the very powerful but difficult to use ExifTool (also free) that allows you to modify as well as read the EXIF data.0
Of course Brian, it was just a rhetorical question and I am sorry for the misunderstanding.
If you take a photo focusing on a point at 20-25 m, you can see that the focus distance recorded in the Exif data is very different, why?
That is my question.0
For more confusion, I have looked at the Exif data of the same photo in DarkTable and On1PRaw and as you can see they give different focus distance.
I think I am misinterpreting some data as this is not logical.
Datos en DarkTable.
Exif en On10
That's a question tech support will have to answer, sorry.
I know that for some of the photos I took with my older Canon 10D Photo RAW occasionally shows the shutter speed like "10878679/134217728" which is 1/12.337682209. Bridge shows the far more readable 1/13. That tells me the program isn't even trying to interpret that data, it's simply reporting it.
I'd be interested in hearing what support has to say.0
Thanks Brian, I will ask the technical support question and if they answer me I will tell you.
Thanks for your attention.0
Hi Brian, this is the answer from technical support for the moment:
In response to Stevie's kind request I have sent a photograph in which I took the focus point at a distance of 30-40 m and this is how my report showed it. I enclose Stevie's kind response:
Reviewing your files, it looks like there are some differences in the Exif Data between what is being recorded in the Raw file and what we are reporting.
I've used ExifTool to compare what metadata is present in the file and we are reporting in the app.
ExifTool reports 1.06m for Focus Distance.
ON1 reports .71m for Focus Distance.
I'm not sure why the discrepancies, but the difference is not as extreme to what you are indicating.
I've sent this to our dev team for further review, but this will be considered a very minor bug, and priority for investigation and fixing will be set accordingly.
I don't have any immediate solutions.
But we'll keep you posted with updates as they become available.
I find it amazing that a technician affirms that the 30% difference between data is a minor problem and it is more amazing that the program provides a data 0.71m compared to 30m in reality and the answer does not even mention it.
In summary, I still do not know what the data provided by the program under the section "Focus distance" means and above all I am disappointed by the response I have obtained from On1.
Of course I intend to continue investigating this "mystery" and if in your answer you express your wish, I will be happy to inform you.
Thanks for everything.0
I think that I can explain the two diffent values for 'Focal Distance' in PhotoRAW and Darktable.
Looking at a Canon CR2 image, ExifTool reports two values for 'Focal Distance':
Focus Distance Lower : 4.17 m
Focus Distance Upper : 5.6 m
PhotoRaw always takes the lower distance 4.17 m, which is shown in the exif data. But Darktable calculates the mean value and shows 4.88 m, which is the better one in my opinion.0
Thanks Holger, it is certainly a good contribution. This clearly justifies the difference between the data provided by both programs.
The most important part of the problem is deciphering the relationship between the data provided by the program and the actual focus distance.
I have made some measurements and I can provide the following information:
1º At short distances (less than 10 m) and using a 50mm fixed lens, the Exif data is very close to the real distance.
2º The data collected with other focal variable optics do not seem to have a logical relationship.
To obtain the following data, I have placed the camera on the tripod, I have selected a point and I have taken pictures with each focal point after setting the focus at the chosen point for each shot. I think the data will be puzzling to you.0
This is all great info, thanks all. Antolin, have you passed your findings along to support? Giving them a link to this thread might be helpful and keep you from having to retype the same stuff all over again.
I'm going to play with this some more too and do some testing.0
I think it's a little more complicated...
I have read in the meantime that the 'Focus Distance Upper' and 'Focus Distance Lower' tags are Canon-proprietary notes. However, it appears that these (together) represent the distance at which the lens's focus is set. That is, it's somewhere between the two bounds.
I don't know, which tags Sony cameras write. But your values look like the hyperfocal distance. Antolin, can you say, which aperture you have taken for the values in your diagramm?0
My guess is that Upper and Lower define the depth of field.0
Sony A6500, focal length 50mm, aperture f/5.6, subject distance 5m gives a hyperfocel distance of 22.15 m and depth of field of 2.36 m.0
I did say it was a guess. Also, my comment was specific to the Canon EXIF data mentioned in the post above my comment. Apparently Sony is reporting different EXIF data than Canon so the same suppositions about what the data might mean would be different. I don't have a Sony camera to compare with.
If you really want to get into this I suggest using the Exiftool program Stevie mentioned. It is free but it is a command line program with lots of options for not only reading but writing the EXIF data so it can be somewhat complex. Just dumping the exif data isn't too difficult though.0
I just took another photo with my Canon:
Focus Distance Lower : 3.91 m
Focus Distance Upper : 5.24 m
Canon 5D Mark IV, focal length 70 mm, aperture f/4.0, subject distance 5m gives a hyperfocel distance of 40.9 m and depth of field of 1.23 m. (DoF near limit 4.46 m DoF far limit 5.69 m)
Las 11 fotografías de las que os presenté los datos fueron tomadas a 1/200 seg, f/8 ,ISO 1000
Hyperfocal distance has nothing to do with subject distance. Hyperfocal distance is the closest distance you can focus on and still have focus at infinity. Either the subject is beyond the hyperfocal distance and therefore in focus or it isn't and it is out of focus.
When you focus on the subject hyperfocal distance does not come into play.0
You're right, of course!
But please do not get me wrong. I only want to say that the crazy values in the diagram are similar to the hyperfocal distances for the different focal lengths. So the Sony camera writes a wrong tag or PhotoRaw makes an error.
Hard to say without a Sony camera. Or do you have another explanation?0
Not yet. Care to make one of your Sony photos available for me to look at?
Right now I'm wondering if the camera manufacturers are using the same fields for different, but similar, things and the program is not taking that into account. It could be finding what it believes is the appropriate field while possibly ignoring others, and reports it in a one size fits all manner.0
Ok, I found some ARW RAW-images taken with Sony A6500. (There are a lot of samples in the internet).
PhotoRaw is looking and the exif tag 'Focus Distance 2'. Using exiftool (of course) the first image says 10.09 m and PhotoRAW 6.72 m. As the A6500 is a APS-C camera, dividing 10.09 by 1.5 gives 6,72, which is shown by PhotoRAW.
For the second image exiftool says 0.90 m and PhotoRAW 0.60 m. This looks good.
But unfortunately this doesn't explain the crazy values of Antolin. Antolin, we need one of your photos.0
He instalado ExifTool y ExifToolGui, les envío el valor de "Focus Distance 2" para cada una de las fotografías.
Tenga en cuenta que en la serie 16-70 los números DSC que identifican cada foto no son consecutivos y el salto coincide con cifras anómalas para Focus Distance 2, lo que sugiere que algo está cambiando.
Por supuesto si quieres las fotos, dime cómo puedo enviarlas y con mucho gusto lo haré.0
I set up a test by placing 3 soccer balls at 20, 15, & 10 feet from the camera as measured with a tape measure. This is very rough setup, I wasn't exactly at the focal plane or any particular lens element, just measured from the center of the tripod. I took shots at various ƒ-stops after manually focusing on each ball using the viewfinder zoom feature. The ball's centers were placed at the distances above and I focused on the front surface so there is some small difference (2-3 inches) in the distance I'm reporting vs what the camera recorded.
I haven't looked with any other programs yet but the first thing I found is that Photo RAW 2022 is reporting the distances as 21.0m, 11.0m, & 7.1m. Those numbers are nonsense as reported (68.9ft, 36.1ft, 23.3ft). They don't even make any sense if it is just a units mixup, showing meters instead of feet.
I have to start looking at the actual exif data but every time I start digging into exiftool I keep thinking about how much I need to design a Mac GUI for it. :)
More to come…0
Photo RAW is consistently reporting the Focus Lower Limit for the Focus Distance. I cannot find any entry for the actual point the lens was focused at. There are the 2 Focus Limits and the Hyperfocal Distance. That's all I can see and I cannot figure out how any of that relates to the actual distance at which the lens was focused. Going to take some more research on the EXIF data I guess.0
I have been following this just out of curiosity. Seems EXIF data is some sort of magic.
In IRFanview there is a tag called "Subject Distance" in the EXIF data but the same tag is not in the output of EXIFTool. That said I cannot figure out what the value of 596.47 relates to. Odd that EXIFtool does not output this tag since it outputs about 181 more tags than IRFanview.0
Here is the email I just sent to the engineers through the bug reporting for 2022. It goes straight to them.
There has been some discussion on the Support Forums the past week about the Focus Distance being reported by the program. I, and others, have been digging into the EXIF data recorded by the camera and comparing what we see there with what the program is reporting and with what we know to be our actual focus distance.I set up a test bed with a tape measure and soccer balls placed at 10, 15, and 20 feet from the camera. I manually focused the camera using its viewfinder zoom feature. While the measuring wasn’t exact, and the balls were place with their centers at their respective distances and I focused on the front of each ball introducing some error it’s only a matter of a couple of inches. The distances the program is reporting are far from those. From what we’ve found it appears that the camera is reporting what Canon is calling Focus Distance Lower. The only other focus related fields I found were Focus Distance Upper and Hyperfocal Distance.Here is the EXIF data reported by ExifTool:======== _A5A0361.CR3 =========== focused @20’—reported 21m (68.9ft)Focus Distance Upper : 50 mFocus Distance Lower : 21 mHyperfocal Distance : 8.16 m======== _A5A0365.CR3 =========== focused @15’—reported 11m (36.1ft)Focus Distance Upper : 21 mFocus Distance Lower : 11 mHyperfocal Distance : 10.34 m======== _A5A0368.CR3 =========== focused @10’— reported 7.1m (23.3ft)Focus Distance Upper : 11 mFocus Distance Lower : 7.1 mHyperfocal Distance : 10.34 mNone of the distances reported comes close to where I focused. Canon R5 with Canon EF 28-135mm ƒ4-5.6 zoom lens and the EF to RF adapter.For longer focus distances these values are far lower than seems right. In my case they are far too great, in some cases they would have been on the next street over.Other users are reporting the same thing, the program seems to be reporting the lower focus distance as Focus Distance. This is causing a lot of confusion when we know we were not focused anywhere near that.If the program is reporting something that is so far off base, should it report it at all? I’m not sure what the solution is.=====If anyone has any suggestions on how this might be improved now is the time. Once 2022 has been released my open door to the engineers closes and I go through tech support like everyone else. I'm not saying that even if they agree it will get in before the release but at least it will be on their radar.0
David, the question that your contribution generates is: Does that distance of 596.47 coincide with the actual distance of the subject? Check that the unit of measurement can be both feet and meters.0
1) @Antolin: IrfanView shows this value in feet.
2) Canon CR3: No idea, why the values from Brian are so wrong.
3) Canon CR2: I analyzed some of my CR2 images and read some articles concerning these exif data. The values for FocusDistanceLower and FocusDistanceUpper only represent the range, where the lens was focused. There is no real distance measure for the subject. For example
Focus Distance Upper : 404 m
Focus Distance Lower : 15.57 m
Hyperfocal Distance : 39.36 m
for a subject distance between 25 and 30 m, I remember. PhotoRAW shows the lower value 15.57 m. Second even more interesting example
Focus Distance Upper : inf
Focus Distance Lower : 15.07 m
Hyperfocal Distance : 8.49 m
The 'Hyperfocal Distance' is less than 'Focus Distance Lower', so the upper bound of the range of "acceptable sharpness" is given as infinity. PhotoRAW is clever enough to take the lower value again, als always with CR2 images.0
Friends, the problem is complicated.
In the little table that I published yesterday I could observe an anomaly in the data when skipping the sequence of files (-DSC). This has led me to carry out a small test, the results of which I present in the attached table.
The tripod remains at the same point of my previous photos, the exposure time 1/200, the aperture f / 8, Iso 100
In order to detect the possible influence of the previous approach on the following approach I have proceeded according to the following guidelineL
a-Focus to a close point (1 m)
b-I focus on the object of my photographs yesterday and shoot DSC 4508
c- I focus on a point further than the object
d- I focus on the object of my photographs from yesterday and shoot DSC 4509
I turn off the camera and repeat the sequence a, b, c, d two more times.
Both the data provided by On1PR and by ExifTool (Focus Position 2) are not only not coincident, they are not repetitive and what is more worrying, they grow from the first to the last.
It would seem that there is a cumulative effect and that makes me think that perhaps the figure provided as the focus distance could be assimilated with a counter in the focus motor and that it is increased as a result of the previous focus.
I intend to continue this frequency by detecting when the "counter" is reset.
I hope this contribution is useful.0
As you may have noticed, my contributions are translated using Google Translate, which surely forces you to make an effort to understand them. So I want to thank all of you and Google Translate for making this communication possible.
I have completed the previous data with three more sequences following the same pattern and as you can see what looked like an increasing sequence, now it has been broken.
It does not seem that we are giving the correct approach to the problem, I think we need the knowledge of both an expert in the data generated by our cameras and of course a consistent contribution from the On1PR Technical Service, only they can answer my initial questions: How can I does On1PR process Exif data? What does the "Focus Distance" data provided by the program mean? How can I know the distance to the object?
I feel ridiculous trying to deduce something that I could know if an On1 technician dedicated us a few minutes of his time, ideally this technician would be the programmer responsible for the lines of the program that read and cook the Exif data.
I hope that some of you find a way to continue, I will keep looking.0
@Antolin: I think I have an idea, where these values come from for your Sony ARW image and which value PhotoRAW shows.
In your diagrams you have given only the values for tag 'Focus Position 2'. If you could also publish the values of tags 'Focus Distance 2' and 'Focal Length' for three of these images, I can examine, if I am right. I have already tested my idea for three other ARW images, where it works.
I hope that ExifToolGui on Windows will show theses valuues. I use the command line version of ExifTool, which shows these values.0
Ok, good news:
I just saw that you already have published the important values. You just have to calculate using the following simple formula:
((2^(focalposition/16-5) + 1)*focallength) / 1000
Example for your 50 mm camera lens:
focalposition: tag 'Focus Position 2'=221
folcallength: for your camera either tag 'Focal Length'=50 or tag 'FocalLengthIn35mm Format'=75. For full frame cameras both values are equal of course.
If you apply the formula above, you will get
- 10.086119264243 (with 'FocalLengthIn35mm Format'). This value is shown by exiftool as 'Focus Distance 2'
- 6.72407950949534 (with 'Focal Length'). This value is shown by PhotoRAW.
You can verify that this formula holds for all your data, you have given. I have found this formula in the Perl sourcecode of exiftool. What I dont't is where the value of 'Focus Position 2' comes from.
I hope this explains the different values, which of course are only valid for Sony ARW images. Other RAW files may have other tags, like Canon.0
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