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Forum: Pentax K-r
05-07-2011, 03:12 PM
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If you set the focus point, via the Menu button and the LCD screen, you will know which of the 11 possible positions it is in - but it does not remind you in the viewfinder window!
I use the central position only: focus with a half-press of the shutter release, and that locks the focus so the scene can be recomposed while the release is half pressed (if the AutoFocus mode is in AF.S setting). Or use the AF lock button to do the same.
The "Green Button" can be assigned the duty of forcing the AF point to the central position from where-ever else it may have been set to.
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Forum: Pentax SLR Lens Discussion
03-08-2011, 03:16 PM
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Have any of you run a comparison between the current Tamron AF 90mm f/2.8 SP Di macro and the old Tamron SP 90mm f/2.5, which was so well thought of in the 1990s?
I have one of the old ones (I used to use it on our two Spotmatics, with an M42 Adaptall mount)., and when my wife bought me a K-x for Christmas (my first dSLR) I was looking forward to fitting the old 90 f/2.5. I bought a PK Adaptall-2 mount off eBay.
OK, it's effectively all-manual, but for the static closeups we need it for (mostly museum-type specimens) that isn't much trouble. On the K-x this old lens is still very sharp. What has disappointed me, however, is the noticeable bluish flare in the centre of the field when the centre is something black or very dark. I find that this does not happen at the wider apertures, but can spoil a macro shot when one needs to stop down to f/11 or less for depth of field.
If anyone wants to see a crude test, showing this, I have put a couple of examples up on Flare in Tamron SP90 f/2.5 macro one of my web pages.
Presumably, the current f/2.8 SP Di macro does not show this fault?
Martin
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