On Sat, 02 Jun 2018 10:01:22 +0200, Paul Carmichael
wrote in :

On 01/06/18 19:09, android wrote:
On Fri, 01 Jun 2018 18:33:36 +0200, Paul Carmichael
wrote in :

On 01/06/18 17:39, android wrote:
On Fri, 01 Jun 2018 11:30:25 -0400, nospam
wrote in lid:

In article , android
wrote:

Why does my macro lens (Tamron SP90) open up to 2.5?

Does it ? as it seems to state f2.8 on the web.

It could be that the firmware of the camera has access to the lense
T value in its database. PC uses a fairly modern EOS 6D mark II,
IIRC. There is according to DxO Mark two different Tammies 90SP one
T/3.0 and the other, newer T/3.3. The latter would be more like 2.5
rather than 2.8 if the former is used for reference... HTH!

or it could actually be f/2.5
http://www.adaptall-2.com/lenses/52B.html

Sure. But that would not be reported from lense to camera.


I chipped the adaptall. So yes, it is.

Then you would need to program the chip to report that that you want it
to report...


Well obviously. And knowing that the lens is 2.5-22, that's what I
programmed it as.

You were kind enough to post a link to a picture with the full exif, and
it does not seem to be programmed at all:

Make - Canon
X-Resolution - 240 dpi
Y-Resolution - 240 dpi
Software - Adobe Photoshop Lightroom 6.14 (Windows)
Date and Time (Modified) - 2018:06:02 11:57:16
Artist - PAUL CARMICHAEL
Copyright - Paul Carmichael
ISO Speed - 400
Sensitivity Type - Recommended Exposure Index
Recommended Exposure Index - 400
Exif Version - 0230
Date and Time (Original) - 2018:06:01 14:07:22
Date and Time (Digitized) - 2018:06:01 14:07:22
Exposure Bias - 0 EV
Max Aperture Value - 2.5
Metering Mode - Spot
Sub Sec Time Original - 45
Sub Sec Time Digitized - 45
Color Space - sRGB
Focal Plane X-Resolution - 1736.671661
Focal Plane Y-Resolution - 1736.671661
Focal Plane Resolution Unit - cm
Custom Rendered - Normal
Exposure Mode - Manual
White Balance - Auto
Scene Capture Type - Standard
Lens Info - 1-65535mm f/?
Lens Model - 1-65535mm
Lens Serial Number - 0000000000
Compression - JPEG (old-style)
Thumbnail Offset - 924
Thumbnail Length - 9204
Displayed Units X - inches
Displayed Units Y - inches
Photoshop Thumbnail - (Binary data 9204 bytes, use -b option to extract)
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Coded Character Set - UTF8
Application Record Version - 4
Date Created - 2018:06:01
Time Created - 14:07:22
Digital Creation Date - 2018:06:01
Digital Creation Time - 14:07:22
By-line - PAUL CARMICHAEL
Copyright Notice - Paul Carmichael
Viewing Cond Illuminant - 19.6445 20.3718 16.8089
Viewing Cond Surround - 3.92889 4.07439 3.36179
Viewing Conditions Illuminant Type - D50
Measurement Observer - CIE 1931
Measurement Backing - 0 0 0
Measurement Geometry - Unknown (0)
Measurement Flare - 0.999%
Measurement Illuminant - D65
XMPToolkit - Adobe XMP Core 5.6-c128 79.159124, 2016/03/18-14:01:55
Creator Tool - Adobe Photoshop Lightroom 6.14 (Windows)
Metadata Date - 2018:06:02 11:57:16+02:00
Format - image/jpeg
Creator - PAUL CARMICHAEL
Rights - Paul Carmichael
Lens ID - 27
Image Number - 0
Flash Compensation - 0
Firmware - 1.0.3
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History Action - derived
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saved to new location
History Instance ID - xmp.iid:05a22f79-0fc0-2346-9f19-9bc9f898e189
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History Software Agent - Adobe Photoshop Lightroom 6.14 (Windows)
History Changed - /
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DCTEncode Version - 100
APP14 Flags0 - [14], Encoded with Blend=1 downsampling
APP14 Flags1 - (none)
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Camera ID - 72157662779818774
Camera Type - Digital SLR

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