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02-04-2009, 01:52 AM   #16
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QuoteOriginally posted by ll_coffee_lP Quote
The TAK definitely out resolves the Sigma (although I love my Sigma 70 macro).
No.

The Tak picture , not necessarily the lens, out resolves the Sigma picture in this case. I can't account for the difference - perhaps I just was not careful enough.

Owning both I can tell you that in general the Sigma is the sharper glass - not by a huge amount but noticeable.


Last edited by wildman; 02-04-2009 at 02:42 AM.
02-04-2009, 07:45 PM   #17
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Nice read on coating for colors,
Historical perspective on Minolta lens design philosophy - dyxum.com
Best, Georg (the other)
02-04-2009, 10:19 PM   #18
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My compliments to the OP and the various contributors, a fascinating thread.

I'd like to throw another wild card into the rendition poker hand.

I've seen any number of new Pentax owners who report that lenses which they had formerly used were no longer adequate for their new K20 cameras.

According to a diffraction article in the most recent Photo Techniques magazine, by Lloyd Chambers, the sensitivity of a DSLR to diffraction is only dependent upon the aperture size being used, and the size of the photosite on a specific sensor. As megapixel sizes are increasing on Pentax DSLRs, from 6 on the k100, to 10 on the K10 to 14.6 on the K20, diffraction is increasingly causing problems with rendering qualities of lenses, showing up first as a loss of contrast and then as a loss of resolution.

According to this magazine article, a 21 MP CAnon 1DMarkIII is only equivalent in its resolution to a 12MP Nikon D3 at an aperture of f22. So i'm wondering whether current concerns about rendering qualities are starting to reflect some symptoms of diffraction with our increasingly smaller DSLR photosites. How can you tell diffraction loss of contrast from normal rendering qualities. Well diffraction is pretty limited to smaller apertures than f8 in the APS sensors.

The only solution to diffraction effects is to buy increasingly more expensive lenses to improve contrast as MP increase. Some of our prized limited Pentax lenses may no longer be adequate as the MP race heats up.
02-05-2009, 02:30 PM   #19
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Thanks everyone for the great replies. The links were very interesting. (I may need a separate thread for this). As it was mentioned, use of coatings on lens' surfaces, ED glass and a lens' contrast play a role in color rendition. I was wondering if someone could explain perhaps with pictures the idea of 'microcontrast'


Again thanks guys/gals

02-05-2009, 04:24 PM   #20
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.


It's probably been said best Here, so I won't try to re-create the wheel


I probably have better examples, but my Sigma 70 set was up - look at the tonal
gradiation in the middle of the flower at center - with good micocontrast, texture
characteristics like translucency is more apparent, and the color accuracy is pretty
great IMO.







.
02-05-2009, 10:48 PM   #21
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From my little experience I can definitely conclude that lenses from different manufactures do exhibit differences in the rendering of color.

Comparing when I had Minolta 50mm to my Nikon 50mm - the Nikon had a lot more contrast to my Minolta and so had a lot more "pop" to the image.

When I had a Zeiss Planar 50mm it was in a different league compared to the above two-wonderful color and contrast - I wouldn't say sharper - but photo's or slides were just lovely.

My friend has Canon lenses (digital) and the Pentax glass has a stronger color rendition & contrast than his lenses.

One of the reasons I chose Pentax was it's ability to almost give me the Velvia look (which I like)

D
02-06-2009, 02:10 AM   #22
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Actually this Color Rendition issue is not limited to photography.

Any serious astronomer or birder will tell you there is a obvious difference in the color tint of the various scopes and binos.

For instance my wife's Leica bins are obviously "warmer" than my Zeiss bins which are more neutral or even a bit "cold". The same thing can be seen in scopes as well.
02-06-2009, 04:49 AM   #23
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QuoteQuote:
Mark/MSM said:
I was wondering if someone could explain perhaps with pictures the idea of 'microcontrast'
Mark, amongst other things microcontrast is being connected to a 3D-ish look respectively a 'perception of roundness'. With certain people on certain forums :-), this goes in hand with the 'Leica 3D look' or even 'the glow', and then others are saying the same thing of Zeiss but only with certain lenses and then the opposite with others and so on.

Basically, there is some consensus that older lenses (til the end of 70s start of 80s) have more of that look and that 'modern' lenses lack it in trade of macro contrast (translate to: 'sheer resolving power').

Easier with unsharp portions: 3D-look in the sheep's fur (?) Please click-enlarge
[IMGwideleft]http://farm4.static.flickr.com/3328/3257215793_11402b1070_o.jpg[/IMGwideleft]
Here's another thread about it,
https://www.pentaxforums.com/forums/everything-else/24444-can-you-please-post...ish-photo.html

Best, Georg (the other)

02-06-2009, 09:45 PM   #24
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QuoteOriginally posted by jsherman999 Quote
It's probably been said best Here, so I won't try to re-create the wheel
Great image and thanks for the link. Very informative. I have become a big fan of Mike Johnston. I just like his style and practicality.

QuoteOriginally posted by georgweb Quote
Mark, amongst other things microcontrast is being connected to a 3D-ish look respectively a 'perception of roundness'. With certain people on certain forums :-), this goes in hand with the 'Leica 3D look' or even 'the glow', and then others are saying the same thing of Zeiss but only with certain lenses and then the opposite with others and so on.

Basically, there is some consensus that older lenses (til the end of 70s start of 80s) have more of that look and that 'modern' lenses lack it in trade of macro contrast (translate to: 'sheer resolving power').

Best, Georg (the other)
Thanks Georg. I think Jsherman's link touches on some of these points. Also, nice link above to regarding the Minolta lenses.

Wow, this thread has turned out to be quite informative!
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