First experience with MIN-AF lens

[connloyalist]

Today I tried out my first Minolta AF lens: a 100-200mm 4.5. This is on an Olympus E-M1 Mk.II with adapter, so completely manual

This being a screw drive AF lens there are the expected drawbacks: narrow focus ring with no resistance whatsoever and the adapter does the aperture so it isn't very convenient to know what aperture you are at (I turned down the aperture ring on the adapter until the shutter speed read half of what it did wide open; then you should be at +1 F-stop).

That being said.... I really like this lens. Based on today's experience, it is very sharp (passed my "brickwall at ± 750 meters" test with flying colors). While I haven't tested it specifically for CA, I suspect it is well controlled judging from spots where my test pics usually suffer from purple fringing if there is any. And I like the way the pictures are rendered, but I am not sure what exactly it is that I like. The colors? Bokeh? Something else?

Straight out of camera *.jpg, of one of my favorite photographic subjects at this time of year. Should be around f/6.3 somewhere between 150 - 200mm.



Regards, C.

[RokkorDoctor]

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.