cl: no f-stop exif with coded lens and m adapter

[gteague]

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so what am i missing here? you guys keep telling me that the leica m-adapter used with a coded lens allows f-stop data in the exif. but it's not.

i got a 75/2.4 with the coding (11682) and the body recognizes it and shows the label of the lens. and i understand someone finally told me in the other thread that the auto magnification needed the m body with a cam to detect focus ring movement, so i'm not getting that.

but that leaves the missing exif and why the f-stop doesn't show in the viewfinder. the body evidently read the coding and set the lens type automatically. what am i still missing?

tks /guy

Edited April 29, 2020 by gteague

[Leon Sung]

As i know, there is a separated light sensor in Leica M240.

Then, the camera can guess f-stop based on the difference of light data between light sensor and CMOS chip.

However, CL should not have such sensor. Thus, it can't provide such f-stop info.

[gteague]

so i'm getting the idea that the guy in the other thread was right when he said there's not much point in insisting on a coded lens if it's going to be used with the cl.

where i went off track was (ass)uming that the features of the leica m-adapter all applied to the cl as well as the m cameras. oh well, live and learn, right?

btw, here's one of my first shots with the 75/2.4. it's very sharp when you nail the focus. at least as sharp as the summicron and in some images has better contrast and sharpness. i shot a very similar image with the summicron the other day, but a longer lens kept me from having to crop as much and i caught the horse in a better pose.

/guy

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[Chuck Albertson]

The coded M lens only tells the camera (CL, M, SL, whatever) which lens it is, so the camera can apply a profile for that lens, usually to correct distortion. That's one reason to use a coded lens. Those lenses don't have any means of transmitting the f-stop information to the camera, since they don't have any electronics on board, so it doesn't show up in the exif file. On the M-cameras, as Leon says, the camera makes an estimate of the f-stop by comparing the through-the-lens reading with the reading of a separate sensor at the top of the front plate, and that estimate is what shows up in the exif files from those cameras.

[gteague]

does the profile only apply to raw or do the jpgs get it as well? and if you select your lens from the list, won't it apply the profile for that lens the same as if the /auto/ sensing module picked it up?

in any case, i doubt the 50/2 and the 75/2.4 have enough distortion to matter--the wide angles would benefit more i think. 

good info. thanks! /guy

[motard]

it`s the contrary: they apply only to jpgs, not to RAW ( please excuse my bad knowledge of English ). Please look into the german part of this forum: on september 25 I published a picture of an old Mercedes-car: Thread- title : Verzeichnis 18-56 Vario. Above you see the jpg out of camera ( with automatic correction ), second the same picture as RAW, only developed in Darktabe ( without correction ) Sure the picture is taken with another lens then yours but the principle is the same

Edited April 29, 2020 by motard

[gteague]

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that is very useful information to me as i only very rarely shoot raw. and your english is excellent. thanks very much! /guy

[motard]

Just saw: The name of the thread is "Verzeichnung 18-56 Vario", not Verzeichnis ...

[scott kirkpatrick]

If you use the Leica M to L adapter, which passes the 6 bits of lens ID information to the camera, a profile is invoked that corrects both the DNG file and the jpeg.  There is little distortion in modern M lenses, but there is a need to correct for vignetting and for color shifts near the edges, at least in the lenses with focal lengths of 50 mm or less. And developing the DNG at the "default" settings of a processing package is not a good way to know if the camera has treated the raw file differently from the jpeg, since every package has different default settings.  On an M camera you can see the effects of lens profiles by turning profile corrections off in the menus, then shooting an image with and without the corrections.  But I don't think you can do that with a CL and the M to L adapter.  The SL has this option.  

[jaapv]

But, as the CL is an APS camera, the edge effects that are corrected on full-frame cameras are far less pronounced to non-existent. The only realistic function of the coding is to the record the lens type  in EXIF. And even that does not happen automatically all the time...

If you want to trick the camera into not recognizing the lens and not applying a profile, just don't click it home when mounting.

[motard]

vor 1 Stunde schrieb scott kirkpatrick:

And developing the DNG at the "default" settings of a processing package is not a good way to know if the camera has treated the raw file differently from the jpeg

in my example, Darktable was not set to "default" but to " "original"

[jankap]

I use Lenstagger in Lightroom to set the Exif data.

[gteague]

7 hours ago, scott kirkpatrick said:

[del] On an M camera you can see the effects of lens profiles by turning profile corrections off in the menus, then shooting an image with and without the corrections.  But I don't think you can do that with a CL and the M to L adapter.  The SL has this option.  

i'm pretty sure i saw an /off/ selection in the lens profile settings on my cl. /auto/, /off/, and then /edit/ the list i believe. /guy

[jaapv]

That is correct. It has the options: "Auto" "Off" and "M-Lenses".

[lct]

10 hours ago, motard said:

it`s the contrary: they apply only to jpgs, not to RAW [...]

I beg to differ. Distortion corrections are applied to raw files too. Easy to check with DNG Cleaner.

[motard]

vor einer Stunde schrieb lct:

I beg to differ. Distortion corrections are applied to raw files too. Easy to check with DNG Cleaner.

and how do you explain this: one and the same picture; above jpg (distortion automatically corrected ) beneath DNG ( with heavy distortion ) ?

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[dau]

The formulas for the correction of the distortions are included in the DNG file. If you DNG processor applies the formulas, the image will appear to be corrected. Using software which does not apply the formulas will reveal the distortions, of course.

[motard]

Thank you for explanation! That means that Darktable doesn`t apply?

Edited April 29, 2020 by motard

[lct]

25 minutes ago, motard said:

and how do you explain this: one and the same picture; above jpg (distortion automatically corrected ) beneath DNG ( with heavy distortion ) ?

Sorry i cannot explain your pics and i have no experience with Darktable but distortion correction of raw files is obvious as far as my files are concerned. You may wish to check by yourself through DNG Cleaner. Just one example below (digital CL, 21/3.4 asph, f/3.4) but almost all my coded lenses behave the same. Of course it is more visible with WA and UWA lenses but last time i checked i could easily compare distortion correction or lack thereof on lenses like Summilux 35/1.4 v2, Summicron 35/2 v4 and Summicron 35/2 asph v1. Same when applying Leica 6-bit coding to non-Leica lenses like CV 35/2 or 7art 35/2. I mean on raw files only as i don't use jpegs. 

Uncorrected:

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Corrected:

 

 

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Hallo,

Look here: Leica L-Mount

[motard]

I can`t see any distortion ( neither barrel nor cushion distortion ) in any of them. Hard / impossible to find distortion if there are no straight lines like the marking of the parking place in my picture