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11-09-2013, 06:44 PM   #46
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QuoteOriginally posted by lytrytyr Quote
This lens has a Super-Low Dispersion (SLD) element:

PENTAX - HD PENTAX-DA 20-40mm F2.8-4 ED Limited DC WR
I didn't see a lens element diagram there, but, just because they don't mention it doesn't mean there isn't an aspherical element. Still, you'd think they would mention it in the specification.

11-09-2013, 06:54 PM   #47
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QuoteOriginally posted by sTi Quote
Doesn't anyone find it strange that the 20-40 contains no aspherical elements?
I admit I do find it a bit of a concern, but it does explain the size of the lens - aspherics help keep the size of lenses down, because the geometry of the elements themselves help keep spherical aberration, field curvature and coma in check, without them it is much harder to correct for things like that. Apsherics are much more common in shorter focal lengths than in longer ones - they are an unheard of rarity in 200mm lenses - yet they are quite common in lenses 50mm and under. Exotic lens elements made of Fluorite, HRLD, ED and SLD glass can be used as a substitute for aspheric* lenses however typically you need two or more of those types of glass to correct for the aberrations that could be eliminated by just one aspheric.

QuoteOriginally posted by RobA_Oz Quote
just because they don't mention it doesn't mean there isn't an aspherical element. Still, you'd think they would mention it in the specification.
Pentax usually designate lenses with aspehics with "AL" E.G : DA15mm f/4. ED AL Limited - though I prefer ASPH, as used by Leica.

QuoteOriginally posted by NitroDC Quote
I don't understand how anyone can speculate on the quality of this lens when no one owns one yet and no sample images have been posted at all.
If Pentax had presented any images i'm sure there would still be a fair amount of speculation, we will have to wait for the lens to get in the hands of capable users to really see what its strengths are.


*but it is a less than Ideal solution with its own set of drawbacks and tradeoffs.

Last edited by Digitalis; 11-09-2013 at 07:07 PM.
11-10-2013, 04:28 AM   #48
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such a weird focal length and way too slow... especially for the size of it geezus. It is fairly pretty tho.
11-10-2013, 05:23 AM   #49
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considering the 20-35/4 is made of 10 elements in 8 groups, and the 20-40 in 9 elements in 8 groups, we can speculate that the formula might be close (considering range and aperture) ?

11-10-2013, 05:27 PM   #50
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QuoteOriginally posted by aurele Quote
considering the 20-35/4 is made of 10 elements in 8 groups, and the 20-40 in 9 elements in 8 groups, we can speculate that the formula might be close (considering range and aperture)
Not a chance, the older 20-35mm f/4 was nearly a stop slower at the wide end and it also had an aspherical element in its design*. So I would hold on to your 20-35mm f/4 lenses and wait for comprehensive reviews before selling them to replace them with this.


*which is curiously absent in the new lens.
11-12-2013, 07:59 PM   #51
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QuoteOriginally posted by richard balonglong Quote
Let's give this thread a photo...


And that's beautiful!
Now, I think I'm going to get this 20-40mm instead of the 16-50mm...
This set-up is like a Leica in the world of DSLR...
My god that is damn sexy!

I can't wait to get my hands on one in the new year. Normally I'd just preorder it for myself, but Christmas is coming and other people want stuff too.

Right when the next lens in line was gonna be a Bigma....Pentax comes out and does that.... geez.
11-12-2013, 11:40 PM   #52
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Pentax K-3 with Grip + the Pentax 20-40mm…
Image courtesy of Pentax Australia, and they're currently testing it and said a review is on its way…
11-13-2013, 02:40 AM   #53
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Hey! That one's set on about 34mm. No unsightly protuberance there. Looks the part, but I'd still like to see some photos taken with it.

11-13-2013, 05:04 AM   #54
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QuoteOriginally posted by richard balonglong Quote
Pentax K-3 with Grip + the Pentax 20-40mm…
this should be censured : this is porn obviously.
11-13-2013, 11:12 AM   #55
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QuoteOriginally posted by richard balonglong Quote
Pentax K-3 with Grip + the Pentax 20-40mm…
Image courtesy of Pentax Australia, and they're currently testing it and said a review is on its way…
Love the look of the lens, But the Grip makes this combo look clunky.

Obviously one of the benefits of the lens is size, So why bulk up the whole combo with a grip?
11-13-2013, 11:19 AM   #56
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QuoteOriginally posted by Corto-PA Quote
Love the look of the lens, But the Grip makes this combo look clunky.

Obviously one of the benefits of the lens is size, So why bulk up the whole combo with a grip?
Grip makes it more bottom heavy, rather than front heavy. I actually think DA 40 with K10D + grip is the most comfortable digital I've ever used. It's a personal preference though.
11-13-2013, 11:26 AM   #57
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QuoteOriginally posted by Andi Lo Quote
Grip makes it more bottom heavy.
Exactly.

But youre right of course, To each their own.
11-13-2013, 11:37 AM   #58
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QuoteOriginally posted by zany225 Quote
Last night I tested aperture on my 18-135mm. (I don't have the 18-55 WR.)
Actually, I want to test the kit 18-55mm WR instead because size should be more similar compare to this limited zoom.

Result:
At 21mm the aperture is at f/4 (I tried to make it stop at 20mm but failed.)
At 31mm the aperture is at f/4.5 (Again, I tried to make it stop at 30mm but failed.)
At 41mm the aperture is at f/4.5 (Not quite sure if it was 41mm or 42mm. I have a bad memory. But I tried to make it stop at 40mm but failed.)

So that means the limited zoom is faster than 18-135mm about 1 stop at wide end, however, it's faster only 1/3 stop at long end.
Result at long end might be different than the kit 18-55mm.
It might not be as usable wide open as the limited, which (I feel safe to assume) will be pretty good even wide open.
11-13-2013, 11:41 AM   #59
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QuoteOriginally posted by Andi Lo Quote
I actually think DA 40 with K10D + grip is the most comfortable digital I've ever used. It's a personal preference though.
Heh. That's my standard walking around kit. Grip attached becasue I have large, wide hands. I actually get stopped fairly often becasue the DA40 pancake is such a distinctive looking lens. People are more surprised the camera is six years old and the lens is almost ten than they are by Pentax.
11-13-2013, 02:27 PM   #60
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QuoteOriginally posted by Corto-PA Quote
Exactly.

But youre right of course, To each their own.
Mmm nobody stops anyone to put the grip on but populate only the grip with a battery and not the camera.
That's really not much heavier, still get the better grip and the added controls.
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