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Forum: Lens Clubs
10-11-2013, 04:26 AM
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OK...
... set up the "USAF 1951 Resolution Resolving Power High Contrast (Tri-Bar) Chart" on the wall. Mounted camera with 85mm on tripod and took shots of all stops from f/ 1.4 - 22 in 1/3 stop steps. Carefully eyeballed the files on the monitor at both 100% and 400% zoom.
I won't bore you with posting the files and all the details but briefly:
1. Maximum useable range without a lot of PP = f 2.2 - f 13.
2. Sweet spot = f 4 - f 8 with a peak at about f 5.
No real surprises but I had kind of hoped the performance would have been a bit better at the fast end but there you are.
Not a DXO level test but I think I have a good practical idea of where to use this lens and it's limits.
A quick and dirty hand held shot full frame of my beloved 22 year old Siamese lighted indirectly by a 7 watt florescent desk lamp about 8 feet away from subject at f/2.2
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Forum: Lens Clubs
10-10-2013, 01:21 AM
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Recently upgraded my Tammy 18-200 superzoom to a Sigma 18-250 only to find there was not that much difference, optically, between the two plus the Sigma was bigger and heaver. So I sent it back for refund and got the Rokinon 85mm. For 250 bucks - why not give it a try?
Not sure what to make out of it yet. For me it's not really a f/1.4 - it's just too soft for me at 1.4. My FA 35/2 at f/2 is sharper than the Rokinon at f/2 for instance. At about 2.8 the Rokinon, FA 35, and the Sigma 105mm macro are about the same for all practical purposes. After taking test shots my guess is that the resolution curve is very steep starting at 1.4 and starts to firm up at about 2.2 or so. After that it holds it own against anything else I have. Both the FA 35 and the macro have a flatter curve so far as I can tell. Also I don't mind the lack of AF but I wish it would focus closer for my purposes.
On the other hand it has a kind of artsy soft pastel color rendition that really lends it's self to nature shots. For this reason alone I'm going to keep it. For me It's a specialized artisan's lens for special purposes and I think in the long run it will grow on me. It's not as if I have 1000 bucks into it. Also tried a few BW conversions and the tonal quality seems to be particularly nice - don't know why but I'll take it.
Anyway here's a few quick snapshots taken around the house...
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