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10-14-2010, 08:11 AM   #1
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Max Aperture f1

When looking at the Exif of my Pentax FA 80-320, the Max Aperture is f1.

Im assuming this is to do with the body, rather than the lens, so chose this forum instead of the Pentax lens forum.

I have ' enable aperture ring ' sorted , and use the 80-320 on the 'A' setting, so is this normal, to see a Max Ap of f1 in the Exif ?

The actual aperture used to take a shot in Av mode, is certainly showing up ok in the Exif

10-14-2010, 09:03 AM   #2
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incorrect aperture can be either body or lens because both can cause the problem if the contacts are open circuit,

the way aperture sensing works is that there are 6 pins to the left of the lens locking pin. (ignore the 7th as it is the data pin for AF)

the third pin is the A switch and shorts the pin to the lens mount.

If you look at this site

http://www.robertstech.com/matrix.htm

you will see the pin arrangement for each aperture varient.

Unfortunately, it should not ever be F1 because there has never been a lens from pentax faster than F1.2

Are you sure of the number, or is it possible that exif data is somehow truncated
10-14-2010, 09:25 AM   #3
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More info then you would ever want to know about the K-mount.

K-Mount Evolution, Features and Operation
10-14-2010, 10:27 AM   #4
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Lowell - i'm pretty sure it wasnt truncated. At least, it doesnt look that way.

I shot a .DNG to show you the Exif.

By the way, thanks for the links Lowell and Boris




10-14-2010, 10:39 AM   #5
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Roberstech wouldnt let me in


Forbidden

You don't have permission to access /matrix.htm on this server.
10-14-2010, 11:04 AM   #6
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Mark has some IP addresses blocked because of malicious attacks. If you send him an email with your IP address and a request to unblock you, he will probably allow access. His email is mark at robertstech dot com.

Ira
10-14-2010, 11:12 AM   #7
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Thanks Ira
10-14-2010, 12:21 PM   #8
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have you looked at other lenses to see what they do

max aperture is blank on many of my lenses,. maybe the 1 is being shown because it is unknown.

10-14-2010, 12:34 PM   #9
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I hadnt really noticed till today, but its worth checking.

I'm just surprised that a Pentax AF lens, for a Pentax DSLR, doesnt display the correct Max Ap in the Exif
10-14-2010, 12:40 PM   #10
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QuoteOriginally posted by Squier Quote
Lowell - i'm pretty sure it wasnt truncated. At least, it doesnt look that way.

I shot a .DNG to show you the Exif.
It seems the screen shot information is from FastStone MaxView. Is that right?

I also use FS and I am getting the same information with all Pentax lenses and cameras. Same with my friend's Canon bodies and lenses. However, both of us are getting correct max aperture with compact digicams.

My conclusion: either bodies with interchangeable lenses (or just DSLRs?) do not store max aperture information in EXIF (at least not Pentax DS, Pentax K10D, Canon 300D and Canon 500D I just verified), or FastStone MaxView does not know hot to read that information.

In either case ignore the reading, it is not relevant anyway.

The actual used aperture is correctly displayed.
10-14-2010, 12:44 PM   #11
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I looked at the same image with Faststone and Photome - Fastone said max aperture F1, but Photome had f3.2 (I was using a DA21) - see tag 206 in Photome. Doesn't seem to be consistent
10-14-2010, 12:58 PM   #12
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QuoteOriginally posted by Bobe416 Quote
I looked at the same image with Faststone and Photome - Fastone said max aperture F1, but Photome had f3.2 (I was using a DA21) - see tag 206 in Photome. Doesn't seem to be consistent
Might be a difference in Exif version. I don't know enough about the protocols to know for sure. . .

Scott
10-14-2010, 01:34 PM   #13
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QuoteOriginally posted by Ivan Glisin Quote
It seems the screen shot information is from FastStone MaxView. Is that right?

I also use FS and I am getting the same information with all Pentax lenses and cameras. Same with my friend's Canon bodies and lenses. However, both of us are getting correct max aperture with compact digicams.

My conclusion: either bodies with interchangeable lenses (or just DSLRs?) do not store max aperture information in EXIF (at least not Pentax DS, Pentax K10D, Canon 300D and Canon 500D I just verified), or FastStone MaxView does not know hot to read that information.

In either case ignore the reading, it is not relevant anyway.

The actual used aperture is correctly displayed.
You are correct there Ivan - i use Fast Stone to drag RAWs straight from the reader, and it sorts them into folders with dates. I like that !

I also have now noticed that when i've put the card reader in my USB slot, and opened FS to download, before you click the download, with other cameras like my Canon, it says ' Canon DCM ' or words to that effect. When I've shot photos on the K200D, ( using the same SDHC card ) Fast Stone only sees ' Removable Drive H DCM ' or something similar. It hasnt recognised that the photos are from a Pentax even at that stage, whereas my little Canon P&S is recognised instantly before D/L the files

Yes, best ignored, as it affects nothing and the correct aperture of any shot is diplayed correctly, so no big deal really
10-14-2010, 01:37 PM   #14
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QuoteOriginally posted by Bobe416 Quote
I looked at the same image with Faststone and Photome - Fastone said max aperture F1, but Photome had f3.2 (I was using a DA21) - see tag 206 in Photome. Doesn't seem to be consistent

I have PhotoMe so i might check that later tonight ( its 9.30pm already )

Also, i might just throw my Kit 18-55 on the K200 to see if a fully auto lens makes a difference
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