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11-19-2013, 09:09 PM   #16
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QuoteOriginally posted by elliott Quote
It seems to correspond with the introduction of video. I know next to nothing about video on Pentax cameras though, so I have no idea what the reason for it would be.

The older bodies still determined what the lens was based on this. They put the data in the EXIF, "K, M lens" for shorted contacts or "M42 or no lens" for non-shorted contacts, but they didn't change the behavior based on it.
But it is one thing to put in exif a suspected lens type, it is another to impact control functions

11-20-2013, 05:58 AM   #17
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QuoteOriginally posted by Lowell Goudge Quote
But it is one thing to put in exif a suspected lens type, it is another to impact control functions
I think it might change some metering functions, I don't have my K100D handy right now, but there is a setting in the custom menu about Av mode with screwmount lenses. I don't remember exactly what changes since I had that enabled from the time I got it.

There must be a reason for it if it has been like this in everything since the K-7.
11-20-2013, 03:26 PM   #18
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QuoteOriginally posted by elliott Quote
Based on your lens list I'm assuming you're already using it properly, but it isn't acting like your other M lenses as it should. My guess is there is paint on the mount and it is not shorting the body contacts, so the camera assumes it is an M42 or other adapted lens that does not have an aperture lever. Sand this paint off where it touches the contacts of the camera and it should work just like your other M lenses.
G'day, Elliot. Is there another way to remove the paint (i.e., other than sanding)? Will alcohol or paint thinner do the same? I really would like to have an evenly clean and unpainted lens mount, if that is possible. Thanks.
11-20-2013, 03:29 PM   #19
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QuoteOriginally posted by el baroda Quote
G'day, Elliot. Is there another way to remove the paint (i.e., other than sanding)? Will alcohol or paint thinner do the same? I really would like to have an evenly clean and unpainted lens mount, if that is possible. Thanks.
Instead of taking away, you can always add a bit of foil tape.

11-20-2013, 03:45 PM   #20
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QuoteOriginally posted by vonBaloney Quote
Instead of taking away, you can always add a bit of foil tape.
I will give foil a try but I really would prefer a permanent fix. I tried sanding off the paint but it looks like it going to be a long process. I ready somewhere yesterday (can't find it now) that acetone and methylated spirit will remove paint. Would you know if this is true? Thanks.
11-20-2013, 03:53 PM   #21
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QuoteOriginally posted by el baroda Quote
I will give foil a try but I really would prefer a permanent fix. I tried sanding off the paint but it looks like it going to be a long process. I ready somewhere yesterday (can't find it now) that acetone and methylated spirit will remove paint. Would you know if this is true? Thanks.
If you want to strip it chemically you should remove the mount from the lens. I'm not sure what will remove that particular paint though, I've used alcohol and brake cleaner on metal lens parts before and it never hurt the paint, it seems like tough stuff.
11-21-2013, 02:34 AM   #22
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QuoteOriginally posted by elliott Quote
If you want to strip it chemically you should remove the mount from the lens. I'm not sure what will remove that particular paint though, I've used alcohol and brake cleaner on metal lens parts before and it never hurt the paint, it seems like tough stuff.
You will normally have more to remove than just some 'paint' and thus, chemistry alone won't do the job.

The anodized layer is basically solid aluminium oxide firmly bound to the metallic aluminium. The black dye is just a cosmetic add on. You can find a diagram of the structure here: https://www.pentaxforums.com/forums/120-general-technical-troubleshooting/206...ml#post2586831

Do note, that anodized aluminium does not have to be black. I have a set of Soligor P/K extension tubes that look deceptively 'metallic' because they have not been dyed, but they have been oxidized anyway and needed the same type of treatment.


My vintage Soligor K-Mount Extension Tubes. The K-mounts may look metallic and electrically conductive - but they ain't.

Last edited by Stone G.; 11-21-2013 at 03:26 AM. Reason: picture added
11-21-2013, 09:23 AM   #23
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QuoteOriginally posted by Stone G. Quote
You will normally have more to remove than just some 'paint' and thus, chemistry alone won't do the job.

The anodized layer is basically solid aluminium oxide firmly bound to the metallic aluminium. The black dye is just a cosmetic add on. You can find a diagram of the structure here: https://www.pentaxforums.com/forums/120-general-technical-troubleshooting/206...ml#post2586831

Do note, that anodized aluminium does not have to be black. I have a set of Soligor P/K extension tubes that look deceptively 'metallic' because they have not been dyed, but they have been oxidized anyway and needed the same type of treatment.


My vintage Soligor K-Mount Extension Tubes. The K-mounts may look metallic and electrically conductive - but they ain't.
Amazing. Too bad we can't have a firmware override for this "feature"


Steve

11-21-2013, 03:59 PM   #24
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QuoteOriginally posted by Stone G. Quote
You will normally have more to remove than just some 'paint' and thus, chemistry alone won't do the job.

The anodized layer is basically solid aluminium oxide firmly bound to the metallic aluminium. The black dye is just a cosmetic add on. You can find a diagram of the structure here: https://www.pentaxforums.com/forums/120-general-technical-troubleshooting/206...ml#post2586831

Do note, that anodized aluminium does not have to be black. I have a set of Soligor P/K extension tubes that look deceptively 'metallic' because they have not been dyed, but they have been oxidized anyway and needed the same type of treatment.


My vintage Soligor K-Mount Extension Tubes. The K-mounts may look metallic and electrically conductive - but they ain't.
Hi Steve. I have sanded off some black paint on the Petri lens mount. Now, the metering works. The shutter speed changes with every change in the aperture (using the green button). This shows that the mount is conductive, right? However, the photos still look the same (over exposed) regardless of what the meter indicates as the right exposure. The depth of field preview remains unresponsive. To check that there is nothing wrong with the lens, I mounted it on my old fully-mechanical SLR and checked the lens opening through the opened back cover. The lens opening changes with each aperture click, so the aperture lever does engage with the camera body. I will try to sand off more paint and see how it goes.
11-21-2013, 04:00 PM   #25
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QuoteOriginally posted by el baroda Quote
Hi Steve. I have sanded off some black paint on the Petri lens mount. Now, the metering works. The shutter speed changes with every change in the aperture (using the green button). This shows that the mount is conductive, right? However, the photos still look the same (over exposed) regardless of what the meter indicates as the right exposure. The depth of field preview remains unresponsive. To check that there is nothing wrong with the lens, I mounted it on my old fully-mechanical SLR and checked the lens opening through the opened back cover. The lens opening changes with each aperture click, so the aperture lever does engage with the camera body. I will try to sand off more paint and see how it goes.
Sorry, I meant my reply for Stone G.
11-21-2013, 04:13 PM   #26
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What does the EXIF say for lens type? If it says "K, M lens" then it is conductive, if it says "M42 or no lens" it is not conductive and you've got more work to do.
11-21-2013, 04:35 PM   #27
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QuoteOriginally posted by elliott Quote
What does the EXIF say for lens type? If it says "K, M lens" then it is conductive, if it says "M42 or no lens" it is not conductive and you've got more work to do.
Hi Elliot. Please tell me how to check the EXIF. I am not familiar with that feature. Thanks a lot.
11-21-2013, 04:50 PM   #28
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It is embedded into the image, it tells everything about the settings of the camera when the shot was taken. Most decent photo editing/viewing software will show you the information. If yours doesn't show the lens type tag, I believe PhotoMe is often recommended for Windows users, not sure about OS X.

You could also use this, it is an online viewer where you can upload an image and it will show all of the data.
http://regex.info/exif.cgi
11-21-2013, 05:22 PM   #29
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QuoteOriginally posted by elliott Quote
What does the EXIF say for lens type? If it says "K, M lens" then it is conductive, if it says "M42 or no lens" it is not conductive and you've got more work to do.
Hi Elliot. Just checked the link that you provided and it says "M42 or no lens" on a photo that I uploaded. If my lens is not conductive, "what more work to do" can I pursue? Does this mean M42 lenses can not be used successfully on my K7 and K5 ever? Your advice will be greatly appreciated.
11-21-2013, 05:36 PM   #30
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You need to keep trying get all of the paint/anodizing off or go for the foil tape method. What does it look like so far?

The M42 lenses are just fine, since they don't have that aperture lever. What it is doing is seeing that K mount lens as an M42 lens, so it is ignoring that lever. You need it to see the lens as a K or M lens for it to let go of the aperture lever and allow the lens to stop down.
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