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12-14-2011, 09:22 AM   #16
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QuoteOriginally posted by cats_five Quote
Come come, surely you know it's the size of your wallet that really counts.

I'm in trouble then mine is dusty inside
and most lenses i use are smaller primes

12-14-2011, 09:31 AM   #17
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BTW the math says if it existed a zoom with f2.0 @ 200mm would have an enormous 100mm front element and likely a 112mm filter then (guess if you could afford the lens the filter would be a mere trifle)

there is a 200mm f2.0 prime from both Nikon and Canon. they use a 52 mm rear filter to overcome this. The Nikon has a 122mm UV built in on the front and the damn thing weighs 6.5 lbs
and costs a mere $5000
12-14-2011, 09:51 AM   #18
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Hey now, let's not forget the really really bigma. The Sigma 200-500 f2.8 monster. It's only 72mm DIA for its filter size. How about that one? Ok, so it's not made in a K-mount and it costs $32,000. But boy, if I had that one, all the women would flock to me and some guys too no doubt.

200-500mm F2.8 APO EX DG - Telephoto Zoom Lenses - SigmaPhoto.com
12-14-2011, 10:04 AM   #19
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that is the rear drop in filter size lol

the diameter at the front is 236.5mm which i guess means no filter mount there

12-14-2011, 10:09 AM   #20
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Does size matter

So I guess it boils down to 'size does matter - sometimes!' for a faster lens you need a bigger front element, but otherwise mine is as good as yours!

Thanks Guys

Tuggie76
12-14-2011, 10:25 AM   #21
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Just remember it's not the size that counts...it's what you do with it.
12-14-2011, 11:13 AM   #22
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QuoteOriginally posted by wildweasel Quote
QuoteOriginally posted by RioRico:
l... sometimes carry a machete.
You must shoot in some dodgy areas of town
In much of the California North Coast area, it's a standard fashion accessory. But I digress.

I am surprised at just how small can be the objective of a fast lens. I have four 28s in front of me now. The Vivitar-Kiron f/2.5 is around 48mm diameter. The Soligor-Tokina f/2.8 is about 44mm. The Vivitar-Komine f/2 CF is about 33mm. And the Tamron BBAR f/2.5 is only about 22mm. So the Tamron f/2.5 is less than 1/2 the diameter (and thus less than 1/4 the area) of the Kiron f/2.5. And both faster and slower 28s are in-between, with the f/2 being much smaller than the f/2.8. Curious, eh?

I suspect that a larger objective gives more leeway for optical corrections. I haven't tested the Tamron for subject-field flatness.

Last edited by RioRico; 12-14-2011 at 01:39 PM.
12-14-2011, 11:16 AM   #23
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QuoteOriginally posted by tuggie76 Quote
it has a tiny 49mm thread size, my friends with canikons have similar lenses with 70mm threads, how does this affect the image?
It doesn't affect the image at all. It just means you pay less for filters.

12-14-2011, 01:03 PM   #24
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I think, though, the OP is mistaken - either about the filter size of his friend's lens, or about its comparability to his. The Canon equivalent of the DA50-200 has only a 58mm filter, even in the IS version. Nikon's is only 52mm. So if they have lenses with anything like 70mm filters, those are definitely not anything like the DA50-200, but are presumably more like the 70-200/2.8's mentioned here, or to the DA55-300.
12-14-2011, 01:33 PM   #25
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QuoteOriginally posted by Marc Sabatella Quote
I think, though, the OP is mistaken - either about the filter size of his friend's lens, or about its comparability to his. The Canon equivalent of the DA50-200 has only a 58mm filter, even in the IS version. Nikon's is only 52mm. So if they have lenses with anything like 70mm filters, those are definitely not anything like the DA50-200, but are presumably more like the 70-200/2.8's mentioned here, or to the DA55-300.
if they are 77s (the 70-200 lenses) then he is comparing apples to oranges.
If they are 58 they would still look large compared to the 49mm of the pentax
12-14-2011, 02:00 PM   #26
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Does size matter

I must admit to generalising about the size, like so many other things, you really can't actually measure the difference.
12-14-2011, 04:25 PM   #27
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QuoteOriginally posted by tuggie76 Quote
I must admit to generalising about the size, like so many other things, you really can't actually measure the difference.
Oh, we can measure all sorts of stuff! Whether it's important stuff that actually does make a difference, that's a trickier question. Do the measured differences in size translate to significant differences in image quality? Does that Vivitar-Kiron 28/2.5 with the 48mm-diameter objective out-perform the Tamron 28/2.5 with a 22mm objective? Not that I can tell, but I haven't tried pixel-peeping them. Some measurements just aren't worth the effort. OK, I'm too lazy. So sue me.
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