Minolta A1 IR-sensitivity
|Camera: Minolta A1 @ISO100 @RAW
RAW-software: RAW Shooters Essentials
Filter: Heliopan RG715
without IR Filter
time: around 11:00 o clock MET
date: 03 June
weather: some clouds
~ -13 EV (+-0.7 EV)
Comment: Please note, this
value is not very accurate. Compared to other test scenes, this one shows
very much chlorophyll.
I have taken some shots with my C-4040 and the Dimage A1 for testing
different focal lengths and apertures, but forgot the visible light
picture. I have done this a bit later (~20 minutes), with much more clouds
in the sky. If I take the C-4040 shots for comparison, the A1's light loss
is approximately 13.7 EV.
For the A1 you need a tripod, you
can't take sharp pictures without one.
without filter (WB: cloudy):
with RG715 (WB Auto):
with RG715 (WB manual):
comment: The pictures
were taken in RAW. Of course this isn't the usual way of testing, but the
Dimage A1 really needs it's RAW mode, even in visible light. Colors are
fine with manual white balance.
If you look closer to the three channels of the manual white balanced
picture, you see the hotspot is only a problem of the blue channel. The
green channel has some kind of a weak hotspot too, but it's useable.
If you use the green-channel also as
blue channel, you will nearly hotspot free pictures. After channel shift
you have the typical color infrared appearance.
The Dimage A1 equals more a SLR-type camera with a super zoom, than a
compact one. In visible light it isn't as sharp at open aperture as other
compact cameras like the C-4040, especially at the wide angle position and
at focal lengths over 100 mm. For really sharp pictures you have to close
the aperture a bit.
In infrared the problem gets worse, at f2.8 in the 28 mm wide angle
position the borders are soft. If you take your pictures with f4, it's
getting much better. Noise is visible, but OK (at least with RAW Shooters
Because of the very long exposure times, wind is your biggest enemy.
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