When the lens model doesn't show up in the Exif

Many a Pentax photographer wonders why their exif data fails to show the lens used.... sometimes!
In fact the problem isn't just one for Pentax users, looking at comments regarding images taken on other marques suggests the same problem arises. Yet sometimes the lens model does show up in the exif, what is going on?

So how can the lens model be sometimes included when viewing the exif in some images and not in others? The reason is that Pentax do not include the lens model in the exif data, ever. But it is included in the 'maker notes' that are also written into the images' metadata. It would be helpful if all cameras wrote the lens model detail to both the exif and maker notes so the problem being experienced by many wouldn't arise. Some brands may do this but it isn't an exif requirement.

What's more puzzling is that some images' exif include the lens model and some don't when someone else has used the same lens. The answer lies in the program that has been used to process the image, be it raw or jpeg. The Adobe programs, for instance, do copy the lens model from the maker notes to the exif, but it appears they only do this if the lens pre-dates the software. It's not that it cannot be done though so one has to presume it deliberately fails to make the transfer to persuade users to upgrade.

The easiest solution I've found which automates the process of transferring the lens model into the exif is a handy free tool named 'ExifToolGUI' which is a front end to a utility named 'Exif Tool'. Both programs need to be downloaded and placed in the same directory. The windows version will run directly whereas the Mac version needs an actual install.

ExifToolGUI can be downloaded from: http://u88.n24.queensu.ca/exiftool/forum/index.php?topic=2750.0
and its user guide from here: http://u88.n24.queensu.ca/~bogdan/
It looks complicated but don't be put off, the process to copy the lens model couldn't be simpler.

ExifTool can be downloaded from: http://www.sno.phy.queensu.ca/~phil/exiftool/
It could be used without the GUI but why make it more complex than it needs to be?!
ExifTool downloads with the filenme ExifTool(-k).exe, to use it remove the (-k) part.

So running ExifToolGUI and opening a directory will show the metadata for the images in the folder.
To add the lens model to the exif select the image or images you wish to transfer the lens model for and select the menu item Modify> Exif: LensInfo from Makernotes...
In not much more than a blink of the eye, all the files will have the lens model detail copied into the exif. By default it will back the files up, that option can be turned off it preferred (you may have a backup somewhere else so not need this.)
And that's it. It works for raw and jpegs and other types of raw files from other brands.

Those that use fully manual lenses which do not transmit anything due to having no electrical contacts could use the program to add the lens model to the exif manually by adding the LensModel to the Workspace which allows editing of fields.

Other useful functions of ExifToolGUI include the removal of GPS details from an image where privacy might be a concern and amending the date and time details of a batch of photos where you've forgotten to reset the date and time in camera.

Hope that helps solve what on the face of it seems a mystery.

i have a sigma 28-70 af looking at the exif every photo taken at any lenght show 48mm
contacts have been cleaned any idear why it show,s 48mm

As the lens isn't Pentax, I guess the camera is being fed incorrect data from the lens. What I wrote above mainly relates to sorting out the lens type but ExifToolGUI will show other details which might give a clue. What does the Exif show for the lens model (if anything?) Usually its 'A Sigma Lens' without being specific.
Strange error though, perhaps someone knows the reason.
Does this error occur when checking direct out of camera images before processing, or after processing? Once in a processing program like Photoshop, the exif will have already been read by the program so may have changed the original data so no good checking that way!
ExifToolGUI won't change anything until you make it do so.
Also check the info in the camera to see which focal length is being set. The K-1 can be made to show this on the info screen. If it's showing 48mm but you're not setting 48mm the shake reduction will be set incorrectly too. I don't think that can be detail can be picked up that way on a K-5ii so check an incamera image for its focal length setting. If that's wrong, (48mm) you'll spot where the error is occurring, i.e. in camera. If it's right it could be in the writing of the metadata, or something to do with your photo processing program.

error occur,s when checking direct out of the camera

Can you check an image in camera to see what the image's info shows for the focal length. We need to work out where the number is coming from.
Also is it this lens: http://www.pentaxforums.com/userreviews/sigma-28-70mm-f2-8-ex-dg.html

its the 28-70 uc f 2.8-4

If it's this one: http://www.pentaxforums.com/userreviews/sigma-28-70mm-f2-8-4-uc.html it's like a Pentax A lens so you have to set the focal length when you turn the camera on if shake reduction is enabled.
I suspect there are variants of the lens though in which case if it is a fully auto version I'll repeat the request: Can you check an image in camera to see what the image's info shows for the focal length. Take several at different zoom settings to check this. We need to work out where the 48 number is coming from.

I believe that the lens sends a code to the camera that identifies the lens, rather than a full description. The software has to know which code corresponds to which lens.

So if a new lens is introduced after the software, the software cannot give a correct description until code-to-lens description table has been updated.

There's a table of the lens type codes which are placed in the maker notes here: http://dev.exiv2.org/projects/exiv2/repository/entry/trunk/src/pentaxmn.cpp#L687

ExifTool seems to be kept more up to date than some commercial packages and provides the facility to have the lens model data in the exif with older software, even to the extent of writing in yourself such as for old M lenses.

WHY? Do you need to know what lens was used to take the photograph? It's immaterial!

Why?
1. Someone might ask you which lens you used to take a particular photo.
2. You might be comparing several lenses for a review to see which performs best (and worst.) Safest to be able to get the detail correct.
3. In ten years time you may have forgotten.
4. Because you can.
Some lenses are better for certain uses than others making it useful to be able to check back which it was. Mind, if someone only has one lens I guess they might consider the detail academic! But it isn't immaterial for everyone as it does seem to be a common question on forums, etc. and even the fact that the lens model is missing from the exif. What prompted the original post was an emailed query as to why the photos in my gallery showed the lens model in the exif while theirs using the same gallery software didn't. I thought I'd share my research. Sorry if you find it immaterial, others seem to think differently. Next you'll be asking why people bother doing lens reviews, I guess.

It's no more immaterial than other basic data in EXIF.
YOU may not find it useful, but most photographers want to be able to look at the data & learn (or draw false conclusions)
The data is often available to others when the image is shared on a photography website, though it can be stripped when up-loading if you prefer.

It isn't the lens or the camera that makes a photograph good, it's the person behind the equipment. that determines the image, i.e. composition, lighting, etc..
People ask because they are ignorant of the facts, they think a "good" camera and "lens" make "good" photographs.
One of my early photographs, taken on a K1000 and a 40mm f4 lens, was of my brother taking a golf shot. I was told I had a "good camera" as you could see the golf ball in the picture. Need I say more? BTW, that was in the days of film, no such thing as EXIF in those days. EXIF was created by software programmers who no little or nothing about photography.

I agree entirely with part of your sentient that it's the person behind the equipment that determines the image. Absolutely. 100%. But that isn't what this is about!
Some photographers and dealers in photographic equipment do wish to know which equipment is being used. Imagine someone selling a lens and advertises it with a photograph from their archives thought to be taken with that lens to back up the advert. Then someone happens to check the photograph and finds the photograph wasn't taken with that lens after all. A pure mistake, but one that can happen. The poor photographer/seller could up in court for misrepresentation! If only the photograph had had accurate exif info visible the mistake wouldn't have happened. The photographer wasn't aware the lens model detail was hidden in the 'maker notes' but just not visible in the exif. The simple two second process I described in the OP would have avoided that error.
I cannot really understand why you're posting about what some might find to be a useful process when it doesn't actually bother you one way or the other. Presumably no one's ever asked you why the lens model detail is missing from the exif in your own photographs (I've checked, it is missing.) I take it your response would be it doesn't matter? But it did to the person asking. In the case of film you'd likely just have to say I cannot remember, but with digital why not share the detail if you wish, it's the photographer's choice. If it hadn't bothered me I wouldn't have bothered finding out about it and making that post. But you don't have to read it if you're not interested and certainly not complain about something written to possibly help others with an often asked question. I often see things written that seem irrelevant to me such as which is the best Canikon lens to purchase but I just ignore them as I appreciate it might help someone else.

A further example. I have two Pentax 28-105mm lenses. One's the old FA version and the other's the new DFA version. I go out with both and come back with dozens of photos. Some of the photos seem to show a problem of some kind (imaginery here!) I notice some chromatic aberration in the tree branches. Oh heck, which lens is doing that, the other one's fine. Do I just Ignore it or decide one lens is better than the other and identify which lens has the problem?
Am I correct in thinking you'd go for the former option whereas I'd go for the second? If you agree the second version is right for you too you'd need the means to identify which lens was used for which photograph and might find the process in the OP useful.

It matters to them because they think the camera and lens take good photographs! How do you think we got on in the days of film?