« on: February 12, 2014, 08:50:01 AM »
That's a lot of very useful info Jon ... thanks for sharing.Thanks Alan,
@ f8 and smaller, Tammy shows better IQ in 600mm. This is good news for those want long zoom & shooting at slower shutter speed.
I'm no expert in BIF photography. Last time I tried, my shutter speed was in 1/2000ish.
F8 + 1/2000ish = IQ
I hear you brother!
The f/8 or narrower makes it a deal breaker for me. I typically shoot birds in a well wooded area. The foliage makes it difficult for me to keep ISOs under control with the f/5.6 aperture. It's all very well shooting in bright daylight but for the shooting I do, I'm yearning for f/4 or faster lenses ... f/8 just won't cut it even with the high ISO performance of the 5D3/6D
Owning a 600mm f/4 lens myself, I can tell you that you are often limited by too-thin DOF than you might expect. At 600mm, an f/4 aperture results in VERY THIN DOF. Quite often too thin. Unless you are photographing particularly large birds (which seems unlikely in a wooded area), even if you owned a 600mm f/4 lens you will find yourself somewhere between f/5.6 to f/8 often enough anyway. It does help having f/4 as an option, and when you really get down to the wire (near sunset in a wooded area) then you open up and deal with the DOF issues regardless.
But having an f/4 lens does not necessarily mean you are always shooting at f/4.
Ha ... I didn't think about that ... Thanks Jon!
I do my birding with the 100-400 right now and being limited to 400mm and f/5.6, I've not run into any serious DOF concerns - that will sure change with a supertele as you quite rightly point out above. The 100-400 isn't the sharpest of lenses and combined with super high ISOs, my pictures turn out too soft and lacking detail - I usually blame high ISOs for the lack of detail and noise and hence my cringing for a faster lens.
Aye, I always used the 100-400 at f/7.1 once I realized it was softish at f/5.6 and f/6.3. With a 7D, that really exacerbated issues with noise. Having the option of f/4 is certainly helpful for that. Keep in mind, you can get the 500/4 L II at a pretty significant discount to the 600mm f/4, and still have the option of using it at 700/5.6 and 1000/8 if you need to. It's a great middle-ground option when you can't afford the extra $2000+ for the 600mm.I've used the 600 only a few times but that was for shooting shore birds in reasonable light so I could stop down happily without any concern over the ISO.
I'd say the 600mm is the best lens on earth for shorebirds. At low perspectives (i.e. laying on the sand of a beach, lens on a ground-level pod of some kind) gets you the most exquisite background blur you'll ever see. The 500mm will do much the same, if you need the cost savings, but the 600mm can't be beat for shorebird work.Jon, a large section of the buyers of the Tammy will end up using them on the APS-C cameras where diffraction sets in real early - sometimes as soon as f/6.3. If you were to stop down to f/11, how much do you think the images will suffer in sharpness?
This is the diffraction myth. Diffraction is diffraction, it is the same regardless of the sensor. The difference in pixel size simply means your imaging the lesser effects of diffraction sooner, but that does not make the effect worse. Diffraction is purely optical, so whether you are using a FF sensor, an APS-C sensor, or a small 4/3rds sensor with even tinier pixels, you should really NEVER worry about diffraction.
So, technically speaking, stopping down to f/11 is stopping down to f/11...the ultimate result on IQ in reach-limmited scenarios (same lens, different cameras, same subject distance) is roughly the same regardless of FF vs. APS-C (technically, APS-C would actually have the edge, barring blurring from other factors...i.e. the 7D has a stronger low pass filter than the 5D III, which mitigates some of the benefit of having smaller pixels, but not entirely.) Smaller pixels will always give you a cropping advantage, and the more you stop down, the returns offered by those smaller pixels simply diminish until they offer no benefit over larger pixels (but at no point would smaller pixel EVER be "worse" than larger pixels from the standpoint of diffraction...noise is another matter.)