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07-10-2011, 09:28 PM   #31
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QuoteOriginally posted by Marc Sabatella Quote
Unless that petal was perfectly flat and perfectly perpendicular to the camera, and was large enough in the frame to cover the entire focus sensor area, then all this shows is that you and the camera disagreed about where exactly to focus. After all, it would have been presenting several mm of depth to the sensor just on the petal itself, and if the petal didn,t complete cover the snesor, then who knows how much ,ore in front of or in back. Also, if not conducted on a tripod, tests like that are suspect because there is no guarantee you aren't moving by an amount that is significant compared to the DOF.
Of course, when I perform an AF test, I am not trying to challenge the AF system by choosing a tiny subject. I try the same thing that I try with other lenses - the result is that I find the DA performing below expectations. Yes, a tripod test would be more formal, but it would also be irrelevant for my shooting style.

I've been using the Tamron over this weekend and it is a great performer, very sharp at 200mm. Here is a full frame shot and a crop from it:





Click on them to access slightly larger versions on flickr. This is manually focused. I don't remember trying the AF on this lens. It may not be any better than the DA, but it has a longer focus throw, so I find it much easier to MF.

07-11-2011, 09:56 AM   #32
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thanks marc, about the iso, i already have it at auto iso up to 1600, noise being much more fixable than blur post processing. for birds i've been setting it to sports program figuring it would favor high shutter speeds, but i was asking about pushing it even farther since once it's wide open the camera will opt to lengthen shutter as light drops further. the only way i can think of to override (without manually resetting each shot) is to go shutter priority and set the speed at 1/250 or 1/500. then as the light drops when it hits that floor it will just underexpose rather than lengthen shutter speed.
07-11-2011, 01:51 PM   #33
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I'm still a newbie, but couldn't you also do exposure compentation. I believe if you 'minus' it increases the shutter speed in Tv mode. or is it plus?

Of couse the image is darker.
07-17-2011, 09:16 AM   #34
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QuoteOriginally posted by Laurentiu Cristofor Quote
+1. TCs are meant for fast lenses, not for consumer zooms. Use a longer consumer zoom or a mirror. If you are going to get a mirror, ignore the Samyang 500/8 version and go for the Samyang 500/6.3 - it is a bit more expensive but it seems to have better IQ.
I have mixed feelings about the faster aperture, though. My biggest challenge with the mirror lens DOF. At F8, DOF at 500mm is already very thin.

By the way, your mirror lens set is great. Did you use a tripod for the pond shots?

07-17-2011, 12:54 PM   #35
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I wonder if the brighter viewfinder would compensate for the shallower DOF. Someday I might spring for the 500/6.3 just to do a comparison.
07-17-2011, 01:45 PM   #36
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QuoteOriginally posted by GeneV Quote
By the way, your mirror lens set is great. Did you use a tripod for the pond shots?
Thanks! I only used a tripod for the moon shots, everything else at 500mm is handheld. The 800mm and 1000mm are with a monopod - besides the longer focal length and slower apertures, those lenses are also significantly heavier than my 500mm.
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