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

Russell Evans wrote:

falcon_wizard wrote:

A 4/3 sensor also makes you lose one stop of DOF control for subject isolation, as well as another stop of low light performance. As far as I am concerned for what I do, this wod not be acceptable.

At 400, 600mm equivalency, you wouldn't find this an advantage? Let alone the advantage of such a small package as the DA 200mm f2.8 providing 400mm, dof f5.6, equivalency. Even the DA 300mm f4 could be considered small for 600mm, dof f8, equivalency. I believe both lenses have the test data to prove sharpness wide open? Are we really expecting the 560mm wide open to outperform these two DA * lenses wide open? Even when the 4/3 sensor crop would be using more of the center of the lenses and dropping the far edges?

That some would find it unacceptable wouldn't really be an issue as there would be the APS-C products to address their needs. In fact, the only reason for the existence of a 4/3 sensor K-5 would be for long lens use and there would be no need to redefine the lens line up for the crop. I just think there would be a market that would prefer to spend $1000, and carry an extra 750g, over spending $7000 and lugging 3040g. Yes, I know it will cost more for the 200mm and 300mm, but I would assume anyone wistfully interested, (like to, but can't afford to), in the 560mm, will probably have one or the other and possibly both of the DA * lenses already.

I also find it strange that we are willing to accept the crop of APS-C as being an advantage for APS-C over FF, with the same loss of one stop in DOF compared to FF, but the argument is somehow not valid for 4/3 compared to APS-C?

To your point, the argument of APS vs FF is certainly just as valid between 4/3 and APS-C. Is is a similar continuum. The question is where on that continuum fitsdi you want to be.

On one axis of the trade-off: pixel size influences S/N ratio. Typically  1 stop from 4/3 to APS-C and another stop from APS-C to FF.

Then subject isolation. Say for wildlife/birding, you want a sweet spot of 750-900mm effective. For basis of comparison, I normally shoot at 500 @ f/6.3 on APS, which gives me some pretty good subject isolation (0.11 ft @ 20ft distance), but even better when I put the 1.4 TC on (0.07ft @20 ft distance). So this equates to:

For approx 0.12 ft DOF @ 20 ft range:

on 4/3: 400mm @ f/5.6  ==  500mm @ f/6.3 on APS-C == 500mm @ F/4 on FF

AND for approx 0.07 ft DOF  @ 20 ft range:

4/3: 500mm @ f/5.6  ==  600mm @ f/5.6 on APS-C == 600mm @ F/4 on FF

A 300/4 on 4/3 equates to having a 400/5.6 on APS-C, which I find is often short for my taste, can be great for mammals or birds in flight.

So bottom line, yes in theory you can get a very nice & light set-up with a 400/5.6 on 4/3 or even 300/4, for the price of one stop in ISO range, provided you can find find a good sharp lens to put on your 4/3 body. On the plus side, you also have a more hand-holdable set-up that has more wiggle room on shutter speed. The better sensors get, the more real this becomes.

It seems though that such long/fast/high quality lenses are not part of the target audience of 4/3 systems camera makers. That's what Olympus tried to do, they have good glass and a very potent system but they have not kept up with the competition in the last few years. On Panasonic the longest you get is 300/5.6, which is essentially consumer grade. You can grab yourself the Zuiko 300 /2.8 from Olympus, but its cost is...(drum roll).....7000$.

All this to say that in today's market, the APS-C is a pretty good compromise between IQ/size/weight/price for someone looking for high quality images, and I think that's exactly what Pentax thought when they decided to invest in what may arguably be the most complete APS-C system currently available.


Thank you

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Stephane Neron

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