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11-25-2013, 08:50 AM - 1 Like   #901
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QuoteOriginally posted by atiratha Quote
I would still go for Tamron 17-50/2.8.
I think most people would, and I would (probably) too, if I was in the market for a normal zoom.

To extend this to the absurd, though... I'd rather have a 24-70 than a fisheye lens. I still want Pentax to have a fisheye lens though.

11-25-2013, 09:05 AM   #902
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It would seem that there's agreement among several posters here that the the PERFECT lens is whatever one Pentax doesn't make.
11-25-2013, 09:07 AM   #903
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QuoteOriginally posted by Parallax Quote
It would seem that there's agreement among several posters here that the the PERFECT lens is whatever one Pentax doesn't make.
Yes, we're missing (looking at you, Pentax)

DFA* 24-70/2.8
DFA* 70-200/2.8

oh... and the Pentax KR-1 FX camera, of course

+ FA 31/1.8, FA 43/1.9, FA 77/1.8 = PERFECTION!

Last edited by Gray; 11-25-2013 at 09:25 AM.
11-25-2013, 09:11 AM   #904
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Of course a 15-45 f:1.2 WR Ltd would be a nice addition, although it would be too heavy, too light, too long, too short, too big, and too small.

11-25-2013, 09:24 AM   #905
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QuoteOriginally posted by lytrytyr Quote
By that token, transferred to our photographic discussion,
it seems as if Greg should be perceiving the FA 24-90 output as sub-standard,
since whatever its virtues, that lens is not noted for its build quality or superior feel.
I'm not saying all perceived differences are nothing more than perceptions. I'm just saying it is possible, that is all. And until you compare directly, you don't actually know. When I look at the same photo twice in a week, it may be that the first time I am content with the color or sharpness, but the second time, I am not. I don't think that has anything to do with my computer, I think it has something to do with the computer in my head.

By the way, judging lens performance from random photos posted by other people is hardly a reliable method. Differences in post-processing can also lead to visible differences, while the lenses themselves may not render so differently. Even the way the screens used by those respective users were calibrated at the time of PP can have an effect.

QuoteOriginally posted by lytrytyr Quote
It is usually quantified by the 40 lp/mm MTF curve,
so resolution of very fine detail.
Ah, ok. Thanks for clarifying that.

QuoteOriginally posted by lytrytyr Quote
The answer (I guess "no") matters to the relevance of Greg's argument.
Could be.

QuoteOriginally posted by lytrytyr Quote
It's certainly not all physics.

Perception is closely tied to how human systems
(brains, ears, eyes, and the connections between them)
interpret physical signals,
so there is a lot of biology and psychology involved,
much of it not yet understood.

Several people have attempted to measure bokeh quality, for example,
but those attempts do not yet seem to be satisfactory.
I was talking about image quality, not the perception of image quality. My point is, everything that affects the image - and thus image quality - can be measured, in one way or another. It is light going through a number of glass pieces with certain refractive indexes and other properties (I'm no expert beyond the basics I got at high school, but I'm sure there are experts). Not everything that affects the perception of image quality can be measured. Those are different domains.
11-25-2013, 04:16 PM   #906
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QuoteOriginally posted by starbase218 Quote
I was talking about image quality, not the perception of image quality. My point is, everything that affects the image - and thus image quality - can be measured, in one way or another. It is light going through a number of glass pieces with certain refractive indexes and other properties (I'm no expert beyond the basics I got at high school, but I'm sure there are experts). Not everything that affects the perception of image quality can be measured. Those are different domains.
OK, I suppose that you could restrict the concept of "image quality"
to features that are readily measurable by tools such as Imatest,
but I believe that most active photographers
would want to bring in aspects like bokeh
that we cannot nail down so readily.
11-25-2013, 04:32 PM   #907
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An unfortunate drawback of the astonishing scientific progress digital technology has promulgated across all aspects of life is our ability, and thus our new found desire, to measure everything and rank qualities in quantitative terms.
11-25-2013, 07:00 PM   #908
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QuoteOriginally posted by monochrome Quote
An unfortunate drawback of the astonishing scientific progress digital technology has promulgated across all aspects of life is our ability, and thus our new found desire, to measure everything and rank qualities in quantitative terms.
Thank god my quality is ranked high.

11-25-2013, 09:36 PM   #909
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Quickie with the 20-40:



20mm @ f/2.8
11-26-2013, 01:02 AM   #910
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QuoteOriginally posted by lytrytyr Quote
OK, I suppose that you could restrict the concept of "image quality"
to features that are readily measurable by tools such as Imatest,
but I believe that most active photographers
would want to bring in aspects like bokeh
that we cannot nail down so readily.
I am not. The rendition of bokeh is still based on physics. Everything around us is. So there must be a way to determine how bokeh from a certain lens is going to render, based on things like the optical formula from that lens. That will not generate a scale by which the "goodness" of the bokeh can be measured. But then again, that is subjective in nature, and really not what I meant.
11-26-2013, 01:03 AM   #911
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QuoteOriginally posted by Gray Quote
Yes, we're missing (looking at you, Pentax)

DFA* 24-70/2.8
DFA* 70-200/2.8

Pentax has already made them....

DA* 16-50
DA* 50-135

And yes, it is meant for APSC; FF equiv. FL of 24-70 and 70-200...
And just in case, yes, Pentax has said they are committed to APSC, not FF...

Why are you asking for FF focal length when you are shooting APSC? Pentax has made most commonly-used FF equiv. focal length..
You want FF focal length, go shoot a FF....

QuoteOriginally posted by deadwolfbones Quote
Quickie with the 20-40:



20mm @ f/2.8
Darn... Looks nice! The image that is...
11-26-2013, 04:45 AM   #912
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QuoteOriginally posted by SyncGuy Quote
Pentax has already made them....
DA* 16-50
DA* 50-135
And yes, it is meant for APSC; FF equiv. FL of 24-70 and 70-200...
And just in case, yes, Pentax has said they are committed to APSC, not FF...
Why are you asking for FF focal length when you are shooting APSC? Pentax has made most commonly-used FF equiv. focal length..
You want FF focal length, go shoot a FF....
Darn... Looks nice! The image that is...
Perhaps it's better to try to read posts a little more carefully before replying, particularly if your reply could be perceived as unjustifiably agressive and condescending.

I'm not asking for FF focal lengths when shooting APS-C. I know about the 16-55 and 50-135 and why they were designed. I was replying in jest to Parallax, and suggesting perfection would be two FF lenses with a FF camera. I do shoot FF, but was positing that modern FF lenses coupled to a modern Pentax digital FF camera would be perfect. That was the context.

(Unfortunately I am not at all interested in the two lenses you mention because of the unreliability of SDM in them, but that does not hamper my photography in any way whatsoever).
11-26-2013, 05:10 AM   #913
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QuoteOriginally posted by deadwolfbones Quote
Quickie with the 20-40:
like the rendering. Haven't been following the whole post. did you get your hands on one?
11-26-2013, 05:13 AM   #914
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Yeah, we've had one in the office for a week or so. I haven't had much time to actually shoot with it, though.
11-26-2013, 05:19 AM   #915
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what was your impression? distortion, IQ?
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