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08-16-2008, 07:03 AM   #1
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So, what are the chances......?

............a fast wide lens will be introduced by someone for the Pentax line in the next week or two? I think I can give them a couple weeks to design, plan, announce and begin manufacturing this new lens. Hey, maybe Pentax just forgot to put that new 20/2 on their lens road map and we will be surprised when they announce it. Let's not forget that Cosina can make it with or without Zeiss.



OK, back on this planet I do have a real hankering for that 20/2, fast wideish prime to lock onto the front of my K10D. My desire won't stay under control for long though. An A 20/2.8 or DA 21 may find it's way to me in a rush. I like my Tammy 17-50, but the zoom isn't doing it for me. I want something smaller, sharper, and still with speed. I know the DA is tiny, how much bigger is the A20? I expect the cropped sensor seeing only the center of the A20's image circle will help the handling of any distortion from the lens. How do these two lenses compare? I have read separately the praises of both, but are they comparable in performance to each other when compared directly? Used A20s still command a respectable price so the cost difference may not be great if I can find a nice 20. Am I missing any gems in my considerations? A 24/2 I don't know about? ( I would prefer something slightly wider than the 24/2.8 which is why I have not considered it.)

Oh, and thinking, I have not even thought of the FA lenses. Are they the same optics as the A series?

08-16-2008, 07:38 AM   #2
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You just know they can't deliver a newly designed lens on your doorstep in the next month.
Although it's a size I'd love to own

If you want one that fast you might want to look at the Sigma 15mm F2.8 EX DG, or their 20mm F1.8 EX DG

I believe that they're even both Full Frame lenses, although I won't put $ on it.

If you can try the lens before you buy, I understand that one of them has some focus issues. But I don't remember which one.
It's probably the 15mm I'm thinking of. I also shoot Sigma cameras, and they have a problem focusing with really wide angle lenses. So it might just be an In Camera issue.
08-16-2008, 07:39 AM   #3
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QuoteOriginally posted by rover Quote
............a fast wide lens will be introduced by someone for the Pentax line in the next week or two? I think I can give them a couple weeks to design, plan, announce and begin manufacturing this new lens. Hey, maybe Pentax just forgot to put that new 20/2 on their lens road map and we will be surprised when they announce it. Let's not forget that Cosina can make it with or without Zeiss.



OK, back on this planet I do have a real hankering for that 20/2, fast wideish prime to lock onto the front of my K10D. My desire won't stay under control for long though. An A 20/2.8 or DA 21 may find it's way to me in a rush. I like my Tammy 17-50, but the zoom isn't doing it for me. I want something smaller, sharper, and still with speed. I know the DA is tiny, how much bigger is the A20? I expect the cropped sensor seeing only the center of the A20's image circle will help the handling of any distortion from the lens. How do these two lenses compare? I have read separately the praises of both, but are they comparable in performance to each other when compared directly? Used A20s still command a respectable price so the cost difference may not be great if I can find a nice 20. Am I missing any gems in my considerations? A 24/2 I don't know about? ( I would prefer something slightly wider than the 24/2.8 which is why I have not considered it.)

Oh, and thinking, I have not even thought of the FA lenses. Are they the same optics as the A series?

Well, the DA21 is a great lens, but it's not particularly fast f/3.2 and it has SERIOUS vignetting on 35mm film (and full frame sensors). Unlike the DA40 and DA70 that work fine with full frame sensors, the DA21 might be a bad choice if Pentax indeed releases a full-frame DSLR in the next 12 months and you want to upgrade.

The A20 (and FA20) are a quite a bit larger than the DA21 but they are both full frame compatible and can open up to f/2.8 when needed. Both are sharp and contrasty.

Sigma has the 20mm f/1.8 which is nice and fast, but there are some issues with that lens:

1) Barrel distortion (correctable in Photoshop)
2) Low contrast (correctable in Photoshop)
3) Soft wide open (fine stopped down to f/2.8)
4) Physically large and heavy lens (a little bigger than the FA20 and MUCH bigger than the DA21)

On the other hand, the Sigma is cheaper than the FA20 (if you can find the FA20) and you can open it up to f/1.8 if you're in low light and are willing to sacrifice a little sharpness.

Personally, I like the Sigma 20 better than the DA21 ... but I like the FA20 better than the Sigma.
08-16-2008, 07:55 AM   #4
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QuoteOriginally posted by little laker Quote
also shoot Sigma cameras, and they have a problem focusing with really wide angle lenses. So it might just be an In Camera issue.
That's a common problem with ALL camera brands when it comes to extreme wide angle (particularly fisheye) ... to a certain extent.

It has to do with extreme DOF with wide angle lenses and the fact that the AF sensor can be thrown off and think something is perfectly in focus when it's actually slightly out of focus but within the DOF so it still looks "somewhat" in focus.

For example, if you go searching online for fisheye photos taken with lenses between 8mm and 15mm at about f/4 you will notice (if you can find a full-res image to study closely) that many photos of relatively close subjects appear slightly out of focus.

Unless you're using manual focus, a split prism viewfinder, and a 2x or greater viewfinder magnifier you're probably going to have a hard time making sure your extreme wide angle photos are perfectly focused ... unless the subject is very close (macro) or very far away (infinity).

If you're just shooting landscapes it's not not a problem because your focus range is set to infinity, but if you try to use AF on subjects that aren't extremely close to the lens and aren't extremely far away then you may be slightly mis-focused with an extreme wide angle lens.

This is why I rarely shoot with fisheye lenses wide open when shooting fisheye portraits. I usually stop down to f/5.6 or f/8 with fisheye lenses so that I can make sure DOF is working in my favor ... and not just confusing my camera's AF sensor.

08-16-2008, 04:32 PM   #5
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Thanks for the thoughts guys.
08-16-2008, 05:02 PM   #6
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My Tamron rep told me they would be releasing a 10-24 zoom, which may be 2.8 (I can't remember, so don't quote me on it). I also believe it's going to be one of their "SP" lenses, which is their premium line. I don't think we'll see it until next year, though.
09-17-2008, 06:52 AM   #7
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http://www.zeiss.com/C12571FF00438F7A/0/8102670D2E1EEA90C12574C60030F157/$fi...d-28-21-en.pdf

Whodathunk it?

Zeiss has come through.

2.8 though, not f2.......and only a half stop or so faster than the DA 21 which will be @1/4 the price.

Last edited by rover; 09-17-2008 at 07:18 AM.
09-17-2008, 07:16 AM   #8
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the 21 distagon is legendary. there's a reason canon owners pay $3Gs to buy it and convert it to their cameras

09-17-2008, 07:20 AM   #9
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I have to admit, I will find the price to be an issue, but the temptation is there.
09-17-2008, 08:53 AM   #10
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Tokina just released an 11-16mm 2.8mm rectilinear. Pentax wont be far behind with their * version of the lens for pentax bodies.

remember the sigma 15mm 2.8 is a fisheye if i remember my stuff...
09-17-2008, 10:30 AM   #11
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Canon just announced a 24mm f/1.4 for full frame. It's weather-sealed, USM focusing, and at under 5" tall, it's not that large.

Pentax, are you watching?
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