Exif -- lens reporting incorrect data

robertsmx wrote: Does the A77 recognize the 18-250 as 18-250, and 70-200 as 18-250? I have only the former and my A55 will recognize it as 18-250.

In what way does the A55 recognise your 18-250? I didn't think it would recognise it at all as such. It will see the correct lens data (focal length, aperture etc) but nothing more.

After more investigation, it looks like my original assumption about improved recognition of third party lenses by the A77 for the purpose of micro-adjustment settings is wrong.
Check out this link for a comprehensive list of lens IDs. It isn't complete but it's about the best I've seen. The author invites additions from owners with lenses not on the list. The decimal suffixes are not part of the actual lens ID (as I originally thought!); they're just added to aid the list.
You will see that there is widespread plaguarisation of Sony/Minolta IDs by both Sigma and Tamron. The latter is surprising considering Tamron's link with Sony.

Where there are duplicate lens IDs you will get clashes when attempting to micro-adjust AF settings on A77, A850 and A900. All other functions such as Steady-Shot and auto-exposure seem to work ok which means alpha mount cameras without micro-adjustment will be unaffected. The Sigma 100-300mm F4 that I used to own worked perfectly on my A700 despite (apparently) sharing lens IDs with several other Sigma and Minolta lenses.

Edited by eccles - 24 February 2012 at 10:17

@eccles:
Some of the lens IDs in the comprehensive list you have provided a link to are at odds with the lens IDs in the M Hohner website http://www.mhohner.de/sony-minolta/lenses.php?lang=e that so many Alpha mount users refer to.
I have not gone through all of them, only the ones I own or have owned, and for example:
SAL100M2.8 Macro which is 28 in Hohner, and 25811 in 'importphotos/lenses' http://www.equational.org/importphotos/lenses.txt
Also my Sigma 10-20mm f4-5.6 is identified as 30 and 30.1 respectively.
I guess in summary, there is little consistency in lens ID when it comes to third parties, and as you and others rightly point out, this is a potential problem with micro adjust on a900, a850 and a77 cameras should two different lenses be identified as the same.
Joe

harveyzone wrote: robertsmx wrote: Does the A77 recognize the 18-250 as 18-250, and 70-200 as 18-250? I have only the former and my A55 will recognize it as 18-250. In what way does the A55 recognise your 18-250? I didn't think it would recognise it at all as such. It will see the correct lens data (focal length, aperture etc) but nothing more.

Here's an EXIF from an image taken using A55 with Sigma 18-250/3.5-6.3 HSM.

Camera Maker: SONY
Camera Model: SLT-A55V
Lens: 18-250mm F3.5-6.3
Image Date: 2011-10-17 21:57:37 (no TZ)
Focal Length: 180mm (35mm equivalent: 270mm)
Aperture: f/6.3
Exposure Time: 0.0031 s (1/320)
ISO equiv: 100
Exposure Bias: none
Metering Mode: Matrix
Exposure: aperture priority (semi-auto)
White Balance: Auto
Flash Fired: No (enforced)
Orientation: Normal
Color Space: sRGB
GPS Coordinate: 26° 48′ 47.77″ N, 80° 53′ 22.85″ E
GPS Altitude: 83.4m
Caption: SONY DSC
Software: SLT-A55V v2.00

harveyzone wrote: robertsmx wrote: Here's an EXIF from an image taken using A55 with Sigma 18-250/3.5-6.3 HSM. Camera Maker: SONY Camera Model: SLT-A55V Lens: 18-250mm F3.5-6.3 How strange. Has this image been processed (perhaps from RAW) through Lightroom, Photoshop, or some other software that could have put that data in?

Nope. Thats how it shows up out of camera. The only lens I've issue with is Tamron 90mm macro, which shows up as a 100mm lens (but focal length is correct).

harveyzone wrote: robertsmx wrote: Here's an EXIF from an image taken using A55 with Sigma 18-250/3.5-6.3 HSM. Camera Maker: SONY Camera Model: SLT-A55V Lens: 18-250mm F3.5-6.3 How strange. Has this image been processed (perhaps from RAW) through Lightroom, Photoshop, or some other software that could have put that data in?

All three tags you listed are in makernotes rather than exif. Exiftools reads both of these plus other categories of metadata.

The numerical data for both is there in the first place from the camera in raw files. (I don't know about in camera jpegs.) Exiftool interprets the number into a name as well as it can. In exiftoolgui to see the number that actually came from the camera, change option menu to "show tag values as numbers."   

Raw converters may or may not write all metadata fields to jpegs or tiffs, even if the "copy metadata" or similar option is on. DXO Optics Pro does write makernotes and exif to output image files. Bibile5/ASP writes only exif. As I recall Adobe products (ACR, Lightroom, etc.) write only exif, but I haven't checked lately.

Image editors like photoshop may not retain metadata unless you have that option selected.

robertsmx wrote: The above EXIF information is using FXIF tool (an add-on on FireFox). It doesn't involve RAW/Photoshop processing. The image itself was JPEG out of camera. The key point being that the camera (SLT-A55/v 2.0) recognizes the Sigma 18-250 as such.

Does your camera take 800x532 pixel jpegs?