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03-14-2013, 08:26 AM   #1
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Multi Segments Metering

Hello

I have found two very interestings pages refering to Multi Segment Metering and how to modify lenses in this way.
The first one is in english : www. robertstech.com/matrix.htm
The second, in french: pentax/multizone.htm
I think my Nikon/Pentax zoom lenses will receive this surgery.

Best regards.

Bernard

03-14-2013, 09:29 AM   #2
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Caution

Quoted from that article: "Note, however, that this does not include any of the new digital SLR's . . . "

H2
03-15-2013, 10:36 PM   #3
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QuoteOriginally posted by pacerr Quote
Quoted from that article: "Note, however, that this does not include any of the new digital SLR's . . . "

H2
What he said.


Steve
03-16-2013, 01:32 AM   #4
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Mlti Segment Metering

Hello Steve

I agree with you but I wonder if, with this modification, apertures informations are transmited, or not, in the wiewfinder.
Before to drill a mount I am going to try with insulating tape.

Bernard

03-16-2013, 03:48 AM   #5
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Aperture information requires the third pin from the lens locking pin, to be shorted. This pin, on camera bodies is recessed, and therefore is not shorted when either drilling or masking off the aperture coding pins. You need to either modify the body(to short this pin) or install a pin on the lens in this position. Note that some people use a small ball of tin foil in this position.

Also, this only tells the camera the max and min aperture not the shooting aperture, and if you set aperture via the camera body in AV mode(for example) there are serious exosure errors due to the difference in motion of non A lenses in the aperture vs aperture arm position, as these lenses were designed such that the aperture arm is more of an on off switch, A lenses had a more complex mechanism that has linear pasture area with arm movement, that makes AV mode possible

Been there, tried that, got the tee-shirt.
03-16-2013, 09:08 AM   #6
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QuoteOriginally posted by Bernard Quote
Hello Steve

I agree with you but I wonder if, with this modification, apertures informations are transmited, or not, in the wiewfinder.
Before to drill a mount I am going to try with insulating tape.

Bernard
As Lowell notes, hacking the "A" contacts is a complicated topic and potential results even vary between camera model. A few things to consider:
  • Matrix metering only works when the body sets the aperture
  • You can fool the body, but not the mechanicals. The aperture lever on most non-A lenses works as an open-shut switch and is not calibrated to provide a certain aperture for a certain amount of travel.
Translation...You may be able to access the more sophisticated metering, but the actual taking aperture will probably not be what was intended.

As for the aperture information in the viewfinder...The viewfinder displays what the body intends to set. There is no way with the current mount for the camera to "know" a manually (using the ring on the lens) set aperture. And, to say it again, the body has no way to accurately set the aperture on a non-A lens.


Steve
03-17-2013, 02:27 PM   #7
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QuoteOriginally posted by Lowell Goudge Quote
Aperture information requires the third pin from the lens locking pin, to be shorted. This pin, on camera bodies is recessed, and therefore is not shorted when either drilling or masking off the aperture coding pins. You need to either modify the body(to short this pin) or install a pin on the lens in this position. Note that some people use a small ball of tin foil in this position.

Also, this only tells the camera the max and min aperture not the shooting aperture, and if you set aperture via the camera body in AV mode(for example) there are serious exosure errors due to the difference in motion of non A lenses in the aperture vs aperture arm position, as these lenses were designed such that the aperture arm is more of an on off switch, A lenses had a more complex mechanism that has linear pasture area with arm movement, that makes AV mode possible

Been there, tried that, got the tee-shirt.
Thank you Lowell and Steve for theses very goods informations, I will continue, with my manuals lenses to count the aperture rings stop down clicks.
Bernard
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