Pentax 560mm lens now listed on Adorama...any takers!

Started Nov 5, 2012 | Discussions thread
falcon_wizard Regular Member • Posts: 316
Re: Overpriced product - just buy Sigma 500/4.5

Bonjour Leopold

I would expect the IQ jump from the 67 400/4 to be very significant, and gaining AF also. I am very satisfied with the performance of my Sig500, but as always, I'm always on the lookout for ways to improve, whether it's my technique, skill or gear. If you'd like to give the 500/4.5 a try sometimes, let me know and we could meet somewhere. I'm in Mtl, so not too far off...

I've had pretty good results using the Sig 1.4TC (what I would consider almost tack sharp), but it requires lots of light to have sufficient shutter speed to allow to keep sharpness. 1050 mm effective at f/9 requires lots of light if you want to keep your iso below 1600 and a shutter speed of say 1/640 or better.  So the "Operational sweet spot" of using a 1.4 TC when you're already at 750mm effective is actually quite small in the field, if IQ is matters (Which is usually the case when you buy and carry such optics in the first place...) For the 2xTC, it's even slimmer, and you need to accept a less than tack sharp result even in ideal conditions.

What people don't always realize is that not only do you lose an extra stop of light, but you also need to increase your shutter speed to maintain sharpness due to the increase in focal length AND stop down the lens to its sharpest aperture, so it's a double to triple penalty. It you have to crank the iso past 1600 to achieve this, then you've just wasted the potential gain in sensor noise. And we're not talking about wind nor heat haze getting into the mix...

BTW: congrats on your publications in the Canadian Geographic Wildlife issue... well done!

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Stephane Neron

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