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07-19-2013, 05:29 AM   #61
arv
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I was reading this thread, and it became interesting
So just for fun - I took these crops from ephotozine.com site. One lens is USD400+, other - USD2000+. Both are short teles. Here are the MTF data:

Attachment 180898 Attachment 180899

Both shots where taken between f5.6 and f8.0. And here are the 100% crops

Attachment 180900


Attachment 180901

Let's not talk about different cameras, demosaicing, AA filters, Raw converters, different shot distance, default sharpening and etc. - sharp is sharp... or isn't? So who's who? And don't cheat

A.


Last edited by arv; 03-21-2016 at 10:26 AM.
07-19-2013, 05:30 AM   #62
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QuoteOriginally posted by DominicVII Quote
I agree that that lenses have a "character" which hinges on many more factors than merely sharpness, but sharpness is the very substratum of a good lens. The less I have to exert myself by means of auxiliary equipment in order to achieve this sharpness, the better the lens.
My point exactly. And for those of you in Rio Linda, Substratum means " A Foundation or Groundwork".
07-19-2013, 05:43 AM   #63
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QuoteOriginally posted by Docrwm Quote
Sorry, No. It's entire reason for existance is that it has no AA filter and is therefore sharper. If that were not the case we would only have the K-5II. End.
I hesitate to jump into this camera argument that has totally taken over a lens thread, but...I gotta agree with Docrwm. I bought a IIs so that I could have sharper pictures without using a tripod. Using a tripod for every shot is not possible for all types of photography, but that doesn't mean that I don't care about getting the sharpest picture for the given conditions. Yes, I use a tripod when I can, but probably 90% of a wedding ends up being tripod free. Photojournalists...they can't always use a tripod, but they want the sharpest picture possible in that situation.

And when I look at a lens, sharpness doesn't trump everything. It totally depends on the application. Some people need an all in one, so they sacrifice the sharpness of a price for a big range zoom. Sometimes it is about aperture and knowing the sub2.8 will be a requirement. Sometimes it is about the size of the lens so you are less noticeable on the street. It might be that most people are considering sharpness above all, but if it was the only factor I don't think anyone would shoot with a zoom.
07-19-2013, 06:09 AM - 1 Like   #64
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QuoteOriginally posted by Docrwm Quote
It's entire reason for existance is that it has no AA filter and is therefore sharper.
No, its entire reason for existence is to sell units. And its a whole package: convenience, features, are all important factors, more so than just sharpness. The K-01 has a weaker AA filter than the K-5 and missing mirror, so it produces sharper images. Does that mean the K-01 is the better camera? I love the K-01, but even I wouldnt make such a claim. Because there are so many other factors, apart from just sharpness. It goes for the cameras and it goes for the lenses as well.

07-19-2013, 07:16 AM   #65
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Personally, if edge-to-edge, corner-to-corner sharpness is my only basis for lens selection and retention, I would have sold everything except for that DFA 100mm macro. Fortunately, photography is a very subjective art, and that allows everyone to enjoy a very "unsharp" maybe obscure Soviet lens, a temperamentally (wide open) soft FA 43 limited, or a dreamy FA 50.

Sharpness is just one trait of a lens. For some, sharpness may be the be-all and end-all, and everything else is an icing. For some, sharpness is a lens trait that shares EQUAL footing with contrast, OOF rendering, and other "pixie" dust we can think of.

Neither point of view seems right or wrong. Photography, after all, at the risk of sounding cliche, will always be a very subjective art.
07-19-2013, 08:24 AM   #66
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QuoteOriginally posted by drypenn Quote
Personally, if edge-to-edge, corner-to-corner sharpness is my only basis for lens selection and retention, I would have sold everything except for that DFA 100mm macro. Fortunately, photography is a very subjective art, and that allows everyone to enjoy a very "unsharp" maybe obscure Soviet lens, a temperamentally (wide open) soft FA 43 limited, or a dreamy FA 50.

Sharpness is just one trait of a lens. For some, sharpness may be the be-all and end-all, and everything else is an icing. For some, sharpness is a lens trait that shares EQUAL footing with contrast, OOF rendering, and other "pixie" dust we can think of.

Neither point of view seems right or wrong. Photography, after all, at the risk of sounding cliche, will always be a very subjective art.
Yes, my dream lens is 10-100mm, f/1.2 fixed aperture, 1:1 macro, weighing no more than 300 grams. That should keep everyone happy.
07-19-2013, 10:07 AM   #67
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QuoteOriginally posted by DominicVII Quote
Yes, my dream lens is 10-100mm, f/1.2 fixed aperture, 1:1 macro, weighing no more than 300 grams. That should keep everyone happy.
better make it 10-500 if everyone is going to be happy.
07-20-2013, 07:33 PM   #68
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Tripod + f/8 on virtually any modern glass, properly focused, should provide an image with enough resolution that it will be literally impossible to tell on a poster size print. People even get confused shooting formal test charts and pixel peeping 400%.

We argue about all the sharpness NOT on a tripod and shot at f/8. The difference between kit glass and high-end glass has narrowed considerably in the last decade and there's no more headroom for optics to get much more resolution. And the difference between say Leica and Zeiss and Canon or Nikon has also substantially narrowed.

There's a LOT of overpaying for marginal increases in "perceived" IQ in photography. Manufacturers know this and laugh all the way to the bank on our insecurities and egos.

07-20-2013, 08:38 PM   #69
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QuoteOriginally posted by Aristophanes Quote
...The difference between kit glass and high-end glass has narrowed considerably in the last decade and there's no more headroom for optics to get much more resolution. And the difference between say Leica and Zeiss and Canon or Nikon has also substantially narrowed.

There's a LOT of overpaying for marginal increases in "perceived" IQ in photography. Manufacturers know this and laugh all the way to the bank on our insecurities and egos.
I see your point, but I respectfully disagree. Maybe your point has more merit with certain subjects in photography, but there's a lot more to this and the proof is in the photos, even resized for the Web.

For example a landscape photo taken with both the kit lens and the DA 15 Limited at f/8 will show the difference in optics, especially when it comes to flare and colors. You can't tell me there's just a marginal difference when comparing the two. Maybe the two will show marginal to no difference in a brick wall test, but I don't make a practice of shooting brick walls. In real-world use I find a noticeable difference taking portraits with the FA 43 and FA 77 instead of using an 18-55 or 50-200.
07-20-2013, 09:35 PM - 1 Like   #70
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QuoteOriginally posted by builttospill Quote
In real-world use I find a noticeable difference taking portraits with the FA 43 and FA 77 instead of using an 18-55 or 50-200.
You must not be using a tripod with your 18-55 or 50-200 because if you did they would look exactly like the FA 43 or FA 77 LOL
07-21-2013, 12:05 PM - 1 Like   #71
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QuoteOriginally posted by builttospill Quote
I see your point, but I respectfully disagree. Maybe your point has more merit with certain subjects in photography, but there's a lot more to this and the proof is in the photos, even resized for the Web.

For example a landscape photo taken with both the kit lens and the DA 15 Limited at f/8 will show the difference in optics, especially when it comes to flare and colors. You can't tell me there's just a marginal difference when comparing the two. Maybe the two will show marginal to no difference in a brick wall test, but I don't make a practice of shooting brick walls. In real-world use I find a noticeable difference taking portraits with the FA 43 and FA 77 instead of using an 18-55 or 50-200.
The discussion was about sharpness.

MTF from Photozone, both on the K-5 so we keep the same sensor.

DA 70 (closes to the 77 on the same sensor):



Da 18-55 WR:



Go under each column and compare the f/8 data.

Of course these tests were all done on a tripod.

With regards to flare the SMC coating is a factor for all Pentax glass. Distortion and vignetting are, of course, other optical factors (so to be fair look at the MTF for 28mm on the 18-55WR). CA and distortion of course both have controls either in LR or in-camera,so both can be made non-relevant.

Resolution goes way up when stopped down and using a tripod to the point where both lenses are comparable at f/8. You can look a other tests and see pretty much the same thing.

The sensor doesn't care what lens you use for resolution which is why they do these tests. MTF is MTF using iMatest. Photozone calls the centre resolution on the kit lens at f/8 excellent. Even at the border and extreme it's very close where even the brick wall test would give you fits at 200%.

It's off the centre that lesser glass starts to fall apart, especially at the edges and at max aperture. That's what you're paying for with primes an DA*s. The 18-55 edges start to look smeary at f/5.6, but even at 18mm the kit lens gets very respectable MTF at the centre.

I'm not saying anything revelatory here. Many test sites, pro photographers, advice columns, etc. have long said exactly the same thing: you can get terrific results with OEM basic glass with a tripod and stopping down to f/8 or f/11.
07-21-2013, 01:03 PM   #72
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QuoteOriginally posted by Aristophanes Quote
It's off the centre that lesser glass starts to fall apart, especially at the edges and at max aperture
That's what I'm seeing. I guess maybe where the mis-understanding came in is when calsan claimed that the use of a tripod makes any lens sharp . Yes it will help to sharpen even a poor lens up a bit, but its not going to replace it with a limited lens that is 10 times sharper coming out of the gate.

Last edited by Driline; 07-21-2013 at 01:17 PM.
07-21-2013, 02:52 PM   #73
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QuoteOriginally posted by Driline Quote
That's what I'm seeing. I guess maybe where the mis-understanding came in is when calsan claimed that the use of a tripod makes any lens sharp . Yes it will help to sharpen even a poor lens up a bit, but its not going to replace it with a limited lens that is 10 times sharper coming out of the gate.
The tripod eliminates the biggest sources of user error. Camera shake and mirror slap.

At f/8 at optimum FL averaged across the frame the Limited lens is maybe 2% sharper,if that. Not 10x.

Frankly, at no point is there a tenfold advantage. More like 45% and those only at extremes: absolute centre at f/8 for the DA70 and 18mm extremes wide open for the 18-55.

You buy maybe 20% averaged absolute resolution for about 10x the price between a DA70 and a DA18-55.. But...for wide open and centre at f/4-5.6 it is definitely better for Ltd. At f/8 to f/11...you cannot tell from resolution tests. If you crop from centre at f/5.6...also good luck telling them apart. The data measured is too close for the human eye to tell without substantial magnification. Often a discerning eye can tell the difference based on bokeh. It's a qualitative measure, not empirical, but counting aperture blades is common.

Last edited by Aristophanes; 07-21-2013 at 02:59 PM.
07-21-2013, 03:15 PM   #74
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QuoteOriginally posted by Aristophanes Quote
The discussion was about sharpness.
I'm not saying anything revelatory here. Many test sites, pro photographers, advice columns, etc. have long said exactly the same thing: you can get terrific results with OEM basic glass with a tripod and stopping down to f/8 or f/11.
Okay, very good points. The discussion was about sharpness and the kit lens from Pentax is no slouch compared to other competitors' offerings.

QuoteOriginally posted by Aristophanes Quote
The difference between kit glass and high-end glass has narrowed considerably in the last decade and there's no more headroom for optics to get much more resolution.
I think this was the statement I had the most difficulty accepting as I'm not sure if there's room for much improvement or not. On the other hand I can't strongly argue this because I don't know anything about MTF scales and tests. That doesn't mean I ignore those tests when shopping for a lens, but real-world tests are more important in my decision-making process, especially because I don't shoot every picture at f/8. But after reviewing the charts you posted I would like to see how the new HD lenses compare.

QuoteOriginally posted by Aristophanes Quote
Resolution goes way up when stopped down and using a tripod to the point where both lenses are comparable at f/8. You can look a other tests and see pretty much the same thing.
I also took a look at tests with the same sensor (k10D) and tried to find something closer to 77mm vs. the 18-55. Since we were discussing kit lenses, which the 50-200 is considered, the numbers are a little farther apart in the tests. In your comparison the 70 Limited was still better, even if not by much, and the OP asked about sharp lenses. The FA 77 looks to be quite a bit better than the 50-200, both at f/8:



07-21-2013, 03:55 PM   #75
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Photozone numbers are in general statistically meaningless - their tests are usually based on single lens sample measurements and essential data such as confidence limits are never published. Numerology at its best.
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