Coded lenses = EXIF also tracking aperture?

[castelletta]

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Could someone clarify if, with a coded lens, the M8 can write aperture parameter in addition to focal length in the EXIF data? Because I read only focal lenght and NOT aperture value in my EXIF data.

 

Thank you

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[scott kirkpatrick]

Only the maximum aperture gets in the EXIF for a coded lens. The actual aperture setting can only be estimated, and Leica chooses not to share that estimate in the EXIF (as far as we know). It would not be too accurate at best, and could be wildly inaccurate under some lighting conditions.

 

scott

[ho_co]

Roberto--

Just seconding what Scott said, and letting Leica put it in their words:

 

In the thread "Official Response from Leica on Laundry List,"

in post #2 (http://www.leica-camera-user.com/digital-forum/20079-official-response-leica-laundry-list.html#post212897),

see response #22.

[RSL]

Could someone clarify if, with a coded lens, the M8 can write aperture parameter in addition to focal length in the EXIF data? Because I read only focal lenght and NOT aperture value in my EXIF data.

 

Thank you

 

How, exactly, could even a coded lens provide EXIF data on aperture? Maybe the camera could make a guess, but not a real reading. It takes a lens with its own internal electronics, an actual microprocessor is best, to report its aperture. Six bit "coding" isn't internal electronics. For what you're asking you need a DSLR with a huge lens with its own internal processor.

[ho_co]

Remember, Russ, that the external sensor has to compute approximate aperture in a number of situations, e.g. flash.

 

Leica said when they introduced the M8 that the camera would be able to calculate actual aperture to +/- one f-stop.

 

Roberto's question is completely reasonable.

 

You are correct that an electronic or mechanical linkage could convey the information immediately, but it's one of the wonders of Leica's design that the M8 calculates actual aperture. It's one thing to relay the information from the lens, but something altogether different when the camera figures it out.

[MSA]

my 35mm f2 is recorded in exif as a 1.4. is this normal? max.

[ccc yyy]

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was about to make a similar observation in a new thread.

glad i came across this thread first.

(and yes this is my 1st post here - greetings.)

 

the surrest way to pass the set aperture would indeed

be via a mechanical linkage or lens-embedded electronics.

so based on current guestimate approach to calculating

the set aperture, is it reasonable to think that Leica would

in some later revision of f/w write this data point in the EXIF???

[scott kirkpatrick]

my 35mm f2 is recorded in exif as a 1.4. is this normal? max.

Nope. It's a bug. In 1.06, the 28/2.8 asph had its aperture recorded as a blank, but in 1.09 or 1.092 they got it right. Don't know why it is so hard, though, since this is basically a table of values in the firmware.

 

scott

[ho_co]

so based on current guestimate approach to calculating the set aperture, is it reasonable to think that Leica would in some later revision of f/w write this data point in the EXIF???

Welcome aboard! You'll find a lot of good information around these parts.

 

Your question is a good one, Roman, but your guess is as good as ours.

 

Originally, as mentioned above, Leica said they could calculate the aperture within +/- one stop. But I'm not sure they said they would write the stop into the EXIF data. (I imagine the 'aperture' field is required in the EXIF standard.)

 

Now they say that writing the data would just be more fodder for us forumites to argue that the camera got it wrong. My personal feeling is that some might do that, while others would say instead, "Look how close the M8 comes to getting the aperture right, with a lens design that goes back 50 years or more! Amazing!"

 

My guess is that Leica isn't yet happy with the aperture calculation and may or may not be working on fixing it--though that wouldn't be the highest of priorities at the moment.

 

I think Guy Mancuso (LUF contact person with Leica) implied that the feature may come later.

 

Summary: The possibility to deliver a ballpark figure is definitely built into the camera, but Leica may or may not choose not to implement it.

 

--HC

[Guest guy_mancuso]

Actually it is a feature item we are asking for is the Lens name in the EXIF data with it's maximum aperture.

 

I don't think Leica wants to estimate actually shooting aperture , it's a guess anyway.

[ccc yyy]

thanks for your perspective on the matter, HC.

will be keeping an eye on the progress of this

feature, as it unfolds.

 

[and thanks for the welcome.]

[ccc yyy]

so what you're saying, Guy, is that it's unlikely that

we'll see the shooting aperture in the EXIF data, (at

least not with the current camera/lens arrangement)?

 

Actually it is a feature item we are asking for is the Lens name in the EXIF data with it's maximum aperture.

 

I don't think Leica wants to estimate actually shooting aperture , it's a guess anyway.

[scott kirkpatrick]

Actually it is a feature item we are asking for is the Lens name in the EXIF data with it's maximum aperture.

 

Guy, you've got the largest Leica lens collection at the moment. How precisely is each of your lenses recorded in the EXIF? The 24/2.8 shows up fine for me with 1.092, but that's the only coded lens that I am currently shooting with. I think this is actually done already, but that there are typos lingering, which they don't seem to bother to test for before release, since other problems have more severe consequences.

 

Personally, it does little for me to have them add "Summicron" or "Elmarit" and there may not be a natural EXIF field in which to put the tradename, but i do want to tell a 1.0 from a 1.4 from a 2.0 from a 2.8 or 4.0...

 

scott

[cbretteville]

The full lens name with product number or generation qualifier would be a good thing to see as part of the lens name. There is an exif tag for a string labled 'Lens' (C630h). It isn't in the Exif 2.2 doc, but I've found several other sources for it. As its a string Leica could place any text they'd like. Another posibility is to add a maker note and place the text there. Lastly a numerical value representing the lens' product ID.

 

I've been rooting around in the exif info for the guestimated aperture, but so far I haven't been successful in finding anything that matches.

 

-C

[castelletta]

I think it would be somewhat satisfying that Leica put the estimated (+/- 1 f/ stop) aperture in the EXIF data. If the calculation process of the shutter speed is dependent of that argued aperture value why not to write down all? I think a near correct value is better than nothing at all. IMHO

[Guest guy_mancuso]

Guy, you've got the largest Leica lens collection at the moment. How precisely is each of your lenses recorded in the EXIF? The 24/2.8 shows up fine for me with 1.092, but that's the only coded lens that I am currently shooting with. I think this is actually done already, but that there are typos lingering, which they don't seem to bother to test for before release, since other problems have more severe consequences.

 

Personally, it does little for me to have them add "Summicron" or "Elmarit" and there may not be a natural EXIF field in which to put the tradename, but i do want to tell a 1.0 from a 1.4 from a 2.0 from a 2.8 or 4.0...

 

scott

 

 

I think what we all talked about was the maximum aperture of the lens like F2 or 2.8 and such but some folks wanted the name also. I said to Leica that whatever the code reads if that could be in the EXIF but I am still not sure how the code reads a 50mm summricron F2. The issue is some folks have 2 different 50mm lenses and such.Personnally I like the focal length for sure and the max. aperture..

 

On Leica extimating the shooting aperture if you shot at 5.6 and it came up f8 than it's off and not sure that is truly a help to someone or just bad info. I can get a good idea from the shutter speed. I admit sometimes i like to know if I shot at F4 or F2 just becuase of the look of the image i may want to repeat it. Ifeverybody wants to push this we can at least ask. But i have a bad feeling the would not because it is estimated

[scott kirkpatrick]

I think EXIF has some lasting value in helping you to figure out how you took a picture some time ago. The firmware (1.092) has a table of lens codes in which the focal length, the maximum aperture and the product code are all present. Let's pass that through to EXIF and get it right. I think it has value. And I think that Leica must have had this in mind when they encoded all that information in their firmware.

 

As for the shooting aperture, like the focal distance on DSLRs, it may not be accurate, and would be only sorta interesting. Menu entries for specifying the lens whose corrections we want to trigger comes way higher in priority. let's not take our eyes off that ball.

 

scott

[Guest guy_mancuso]

I agree Scott whatever is in the code than put that in the EXIF data for the end user. The info is there already in the firmware just transfer it completey to the EXIF data. Yes 6 months down the road be nice to know what the heck you shot the images with

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[cbretteville]

I said to Leica that whatever the code reads if that could be in the EXIF but I am still not sure how the code reads a 50mm summricron F2. The issue is some folks have 2 different 50mm lenses and such.Personnally I like the focal length for sure and the max. aperture..

 

The lens table in the M8's firmware has the bare minimum of info already. The entries for the codable 50 'crons have these texts "2.0/50; 11817" for the 3rd gen and "2.0/50; 11819/11825//11826/11816" for the current. All they have to do is to write the string in the files as they're saved.

 

Not necessarily pretty, but already there and easily done, at least from a programmer's point of view.

 

I'm more worried about their attitude towards the users' wishes. I find their reasoning for declining the user selectable lens table insulting. I'm allowed to shoot with the lens cap on, without a memory card and blow the exposure one way or the other (or the meter does it for me), but it's too risky to allow me to select a lens' parameters that doesn't match what I'm using as it might ruin a shot. What's up with that? Feels like a good old NIH ("not invented here" - we didn't think of it so its a bad idea) to me.

 

- C

[ho_co]

Guy--

It seems superfluous to add "Summicron" or "Elmarit" to the EXIF data, since the name is already defined by the maximum aperture. Since Carl says the M8 firmware includes product number, Leica already includes more specific information than would be the case if they added the name. Recommendation would be verify the current information and then pull the data from the table to write to the EXIF.

 

In regard to taking aperture:

 

1) If Leica is finding that getting the aperture within +/- 1 stop most of the time is more difficult than they had thought (which is how it sounds to me), maybe it is best not to record the information. With time, that difficulty might get straightened out.

 

2) If they are getting the aperture pretty accurate most of the time, it would be a bigger feather in their cap to save the information. A few carpers would remark that it wasn't accurate, but most people would remark on what an accomplishment it was to be able to do that for so many lenses that weren't designed to relay that information. (Just look at the steps Nikon had to go through on their SLRs, first linearizing the apertures to be able to get good exposure automation, then developing stage by stage to get the latest bodies to continue working with the older lenses while utilizing completely new technology.)

 

3) Scott is right, there are more important features/adjustments to be made. Recording the taking aperture could be put off to the firmware update released 3 weeks before the M9.

 

--HC