Yes, loses .8 stops. Oly has significantly more contrast than any
other mirror, but is not as sharp as the longer Questar or Celestron.
>From
( http://brashear.phys.appstate.edu/lhawkins/photo/mp-cat-tests.txt )
500/8.0 Zuiko (8/84 pp. 70-71, 130):
Actual: 498/8.27, Distortion: 1.040incush, Falloff: 0.8 stops at
f/8
8
Resolution (lines/mm) at ???x
Center: Gd 45
Corner: Ex 40
Contrast (%) at 30 lines/mm:
Center: Hi 58
Corner: Hi 55
700/8.0 Questar (1/77 p. 139):
Actual: 710/8.5, Distortion: <0.5%, Falloff: 0.85 stops at f/8
8
Resolution (lines/mm) at 1:40x
Center: Ex 64
Corner: Ex 60
Contrast (%) at 30 lines/mm:
Center: Med 40
Corner: Med 37
750/6.0 Honeywell (6/75 pp. 103-104):
Actual: 755/6.04, Distortion: 1.50incush, Falloff: 0.3 stops at f/6
6
Resolution (lines/mm) at 1:40x
Center: Ex 64
Corner: Ex 44
Contrast (%) at 30 lines/mm:
Center: Med 48
Corner: Med 38
1250/10.0 Celestron (2/77 pp. 106):
Actual: 1260/10.0, Distortion: 1.5%, Falloff: 1.4 stops at f/10
10
Resolution (lines/mm) at 1:41x
Center: Ex 64
Corner: Ex 56
Contrast (%) at 30 lines/mm:
Center: Med 44
Corner: Hi 40
Tom
On Tuesday, June 11, 2002 at 16:20, ll.clark@xxxxxxxxxxx
<olympus@xxxxxxxxxxxxxxx>
wrote re "Re: [OM] long telephoto advice" saying:
> In <3D0612F3.15432.3F3583C@localhost>, on 06/11/02 at 03:10 PM,
> Tom@xxxxxxxxxxxxx said:
>
> >I think that would be better. Mirror lenses lose almost a stop of
> >light
> > from the central 2nd mirror, so that f/8 becomes an f/11, slower
> > than
> >a 300/9.
>
> Are you sure that this is true of the Zuiko?
>
> ---------------------------------------------
> les clark / edgewater, nj / usa
> ---------------------------------------------
>
>
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> < For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
> < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
>
>
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