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11-18-2013, 10:35 AM   #181
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QuoteOriginally posted by monochrome Quote
Link to PF Post for Hands-on opinion of the 20~40 at DFW PhotoExpo HERE
"The lens lineup included the 20-40 Limited; that lens on the K3 is just....solid. And fast. And solid. The combo reminds me of my classic Pentax stuff; the 135 1.8 ED on an LX, for example."
Link not working.

11-18-2013, 11:39 AM - 1 Like   #182
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QuoteOriginally posted by tripodquest Quote
See my follow-up question above and please answer it if you can. I really want to understand all these things better, understand why my thinking is backwards. It doesn't seem backwards to me so I need someone to help me understand how and why it's backwards.
When I get back I will try to explain if someone hasn't already done it. There are a lot of points you can address with your question.

The simple answer is that APS-C lenses need to be sharper at wider apertures and faster in general to match the image quality of FF. To match FF you have to shoot at a wider aperture which means the lens needs to be designed for peak sharpness at a wider aperture. The Sigma 18-35 F/1.8 is the FF equivalent of a 27-53mm F/2.8. So the 18-35 has to be as sharp at F/1.8 as a 24-70 does at F/2.8.

There is a lot more too it, but that is one key reason.
11-18-2013, 12:01 PM   #183
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QuoteOriginally posted by i83N Quote
Link not working.
Fixed now - sorry.
11-18-2013, 12:11 PM - 1 Like   #184
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For those that don't want to click back to find that post, here's the link: https://www.pentaxforums.com/forums/16-pentax-news-rumors/242898-pentax-dfw-photo-expo.html

QuoteOriginally posted by monochrome Quote
Fixed now - sorry.


11-19-2013, 07:31 PM   #185
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QuoteOriginally posted by Vylen Quote
Which is why I'm keen on getting the Sigma 24-70mm... a full frame lens with no-so-great edge performance and vignetting but looks fantastic on APS-C cameras haha
I considered that lens before, with with a front element and filter thread of 82mm and weighs like a couple of bricks in the bag, I decided to go with the Tamron 17-50 instead... (and foot zoom all the way, in case I have no time to switch to my 50-135!)
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