On 7/14/2018 9:49 AM, Jan Steinman wrote:
On Jul 14, 2018, at 03:16,Ken Norton <ken@xxxxxxxxxxx <mailto:ken@xxxxxxxxxxx>>
wrote:
It reminds me of my time with the 600/6.5 lens. It is one of those
lenses that when everything is perfect, the lens is perfect. But
man-o-man, everything from aperture actuation vibration to tides will
cause you to get a blurry image.
YES! I was so impressed with the 600 when I shot those eagles. (Which, being on
an E-300 via adapter, would rule out aperture actuation vibration.)
Moose can say what he will about subject motion and thermal refraction, but the
fact remains that all those eagle shots with various lenses were all under the
same conditions, and the 600 came out on top. What, does it possess some
mysterious subject-motion-calming or magical atmospheric-settling qualities? :-)
Welll . . ., not really the same. Did you view my video? Look again, paying attention to how the amount of degradation
varies quite a bit as the air moves.
So - the moment chosen - AND - shutter speed are going to affect how much air
movement affects the photo.
I'm new to this dance. I've long been aware of these effects at long distances, high temps and over some sorts of land.
I use them to create effects I like. <http://zone-10.com/tope2/main.php?g2_itemId=22233>
And
<http://galleries.moosemystic.net/MooseFoto/index.php?gallery=Alt_Dot_Moose&image=_A140105rotfp.jpg>
And yet, through eight miles of clear, cool mountain air, a few thousand feet above the ground, air refraction wasn't
much of a problem.
<http://galleries.moosemystic.net/MooseFoto/index.php?gallery=California/Yosemite/Yosemite_2011/Yosemite_Valley&image=_MG_0382oof80m.jpg>
This test was neither particularly long distance, high temp nor low over baking hot desert. Mild day, temp under 70 F,
camera 8' off the ground, subject maybe 35' up (?) and mostly over front yards with various sorts of foliage. But LOTS
of air movement.
It's only now, with this set of tests and this video, that I've revised my opinion. I often take several shots of small,
distant subjects, thinking that the differences are subtle differences in focus accuracy. Now, I'm thinking it's what I
described above, random chance of air movement and refraction when I shoot.
I took a few shots of this hawk. This was the best.
<https://photos.app.goo.gl/tXS6mekE8q1XS23p8>
But look at the lower left part of the body and wing. OoF in a way that makes no sense relative to other parts. I think
that's a particularly bad bit of refraction. Focal distance over 100 m, so lots of air to see through.
Looking at my new tests slightly differently, I see that that IQ deteriorates
as the FL goes up.
Then, I've just again been looking at test charts of this lens @ 400 mm, and it's pretty darn sharp. I think it's all in
the air.
But I haven’t been able to get a clear shot out of it since.
Which suggests the possibility that is wasn't that great in this test, just better than others suffering from air
movement, subject movement and some rather slow shutter speeds.
There's another factor at work here, too. Take a shot of something with the 300/4.5. Now move to half the distance and
shoot it again. Crop both to the same viewing size. The closer one will have twice the resolution. In the case at hand,
the modest resolution of the E-300 likely had an effect on the results of cropping, too.
My test chart shots are 9274 x 6926 pixels, and have no loss of detail from Bayer interpolation. The E-300 is 3340 x
2504, and loses about 50% of detail resolution in Bayer conversion. Your E-M1 II is even slightly higher resolution in
HR Mode.
Comparing the 300/4.5 to the 600/6.5 is fair for the purpose of shooting something far away, but not a fair comparison
of the quality of the two lenses.
In fact, if air movement didn't have such an effect, and assuming your copy of the Celestron is not a bad one, it should
again win on sheer magnification. Reading the tea leaves of Modern's tests show it to likely have as good resolution, or
better, as the Oly 500/8.
I tried two tripods in various combos, with or without extra weight, both hanging from below or sitting on
top. I tried standing on one foot, with and without sticking my tongue in various cheek positions, with and
without chanting either “OM” or “Our Father, Who Art In Heaven...,” both
forwards and backwards.
As I recall, Gary said he later got good results, better than in his published tests, by resting it on a big sand bag,
on top of something solid.
Well, that’s not exactly true. Using the E-M1.2 silent shutter seemed to make it behave better, but
that was just a random shot of nothing particularly interesting. I’ll have to give it one more
serious go before deciding its “space in the case” is better served with something else.
Also, some old film era lenses just don't get on well with some digital bodies. My Tokina 150-500 was a pretty good lens
on film, even at 500 mm. On my Canon digis, I could not get a good image. Sold it.
Wavering Moose
--
What if the Hokey Pokey *IS* what it's all about?
--
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