Posted: Sat Apr 23, 2022 9:08 pm Post subject: |
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RokkorDoctor wrote:
Careful, some geese don't like their photo being taken
Re. aperture control; I don't own any Minolta AF gear so never understood how the aperture control of the A-mount worked. Having just had a look at he Maxxum A5000 service manual it is clear that the aperture is servo-controlled, but without any feedback from the lens itself; the feedback loop is entirely inside the camera itself where a rotary counter in the gear train counts 8 rotational steps for each stop. Not the way I would have designed it, but never mind... Therefore in theory the aperture control pin on the lens moves by the same amount for every additional stop. It should therefore be possible to calibrate the control ring on the adapter yourself and apply some markings (-1 stop, -2 stops, -3 stops etc.). Not perfect and no idea how accurate the repeatability is (may depend on the play in the adapter mount lock).
EDIT: obviously used with a Minolta AF camera the chip in the lens must be telling the camera what the fully open aperture value of the lens is, otherwise the camera would be totally in the dark as to what the actual aperture is after e.g. stopping down 3 stops. _________________ Mark
SONY A7S, A7RII + dust-sealed modded Novoflex/Fotodiox/Rayqual MD-NEX adapters
Minolta SR-1, SRT-101/303, XD7/XD11, XGM, X700
Bronica SQAi
Ricoh GX100
Minolta majority of all Rokkor SR/AR/MC/MD models made
Sigma 14mm/3.5 for SR mount
Tamron SP 60B 300mm/2.8 (Adaptall)
Samyang T-S 24mm/3.5 (Nikon mount, DIY converted to SR mount)
Schneider-Kreuznach PC-Super-Angulon 28mm/2.8 (SR mount)
Bronica PS 35/40/50/65/80/110/135/150/180/200/250mm |