Warren;
Is that all??? <G>
You're right, I should try something like this if I can spring loose the time, I
will.
I'm not quite sure how to do tests which will measure contrast. I usually tape
colored new or magazine print to the wall for lens (sharpness) tests. I can
certainly do that for the 21s. Use this for close focusing. Could take the
existing star tests for infinity, at wide apertures.
If there are any suggestions for better tests, I'm open to input.
george
*************Here's the lens test results I posted couple weeks
ago.*****************
Hello. For those who asked, here's what I did.
I tested several lenses for wide-open sharpness/lack of distortion
using a star field as the test subject. The star field for most tests
contained the very bright object, Jupiter, as well as more modest
magnitude stars.
Results: (Blank is did not test) All lenses MC unless noted.
Wide Open One stop down
21/2 - Some Coma Good
21/3.5-(SC) Slight Coma
28/2 - Slight Coma and
very slight blue fringing Good
35/2 - Some Coma Good
50/1.2 - Coma
50/1.4 - Coma,slight blue fringe Good
50/2 macro - Good
85/2 - (SC) Some blue fringing
90/2 macro - Good.
100/2 - Slight coma
The 50/2 and 90/2 were the only lenses that proved sharp and
distortion-free when used wide open.The 50/2 macro wide open was
slightly better than the 50/1.4 at F/2. The distortive effects were gone
for all practical purposes on all lenses when closed down one stop.
The 21/3.5 was much better than the 21/2 wide open. However, the 21/2
at F/2.8 was better that the 21/3.5 at F/3.5.
The worst coma was exhibited by the 50/1.2 and 50/1.4
The blue fringing, of course, is chromatic aberation. I was less
surprised to see it on the SC 85/2 than on the MC 28/2.
The coma was seen mainly on the very bright objects - Jupiter and a
bright star of magnitude 1 or so. Lesser magnitude objects showed no
visible coma (thru an 8x loupe.)
That's it. Hope this is useful. .
take care
george
WKato@xxxxxxx wrote:
> In a message dated 98-09-27 11:58:53 EDT, you, George, write:
>
> << Havent't had a chance to
> really put it thru its' paces yet, but you make it sound like I won't be
> disappointed. BTW, I have (and am selling) the 21/3.5 and it is also a
> wonderful
> lens. I wouldn't hesitate to own either 21 Zuiko. I just like the faster
> f/stops, so that's why I'm selling the 3.5 (which was almost as good wide
> open as
> the f/2 was one stop down at 2.8) >>
>
> Please shoot a roll of Velvia for us and do some A/B comparisons before you
> sell the 21/3.5. I have the 21/3.5 and it's one of my favorite lens. I
> usually shoot it stopped down to get foreground/background photos so I'm
> interested in close focusing abilities and infinity sharpness. Please also do
> a comparison of edge and corner sharpness. Note on the L. Hawkins review site
> that the edge contrast of the 21/3.5 is unusally high.
>
> 21/3.5 SC (1/75 p. 173):
> 3.5 5.6 8 11 16
> Contrast (%) at 30 lines/mm
> Center: Low 42 Med 58 Med 64 Hi 67 Hi 67
> Corner: Hi 60 Hi 62 Hi 63 Hi 64 Hi 64
>
> Also please tell us of the star test results, if possible, for both lens.
> Seldom in life do we get to own the 21/3.5 and 21/2.0 at the same time.
>
> Thanks.
>
> Warren Kato
>
> < This message was delivered via the Olympus Mailing List >
> < For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
> < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|