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08-19-2010, 06:57 AM   #16
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Don't forget about the FA* 24/2.

08-19-2010, 07:20 AM   #17
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I felt the same after my last trip to Vegas and bought the FA*24/2. But I've sold it since.

I've found there really is no substitute for tripod and iso 100 for serious landscape/cityscape shots. Also, the 24/2 is much bukier than the 21.

Most of the older F2 lenses are very expensive as well and hard to find, and you may want to try the 24/2 as your milage may vary. Also, Pentax may introduce one in Photokina so it's worth waiting for that.
08-19-2010, 07:35 AM   #18
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Marc Sabatella has ably pointed out on a number of occasions (had to convince me, but he did) that many of the issues with soft corners arise from depth of field. Even at wide focal lengths, an aperture of F1.8 will not have much depth of field. I found this out trying to do group photos with the DA21. F4 is the minimum that really makes sense if you need a fairly large area in focus. Even at F4, it is difficult to get all of a group the size of which might fill a stage in focus. Each year, I seem to make the aperture smaller and the ISO higher.
08-19-2010, 09:59 AM   #19
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It seems you're really putting too many constraints on this to have much chance of getting something to work. If I have this all straight you want:

- 21mm or wider
- f/2 or faster
- small
- inexpensive

I think no lens is likely to give you more than 2 things from this list, 3 *at most* depending on your definition of inexpensive.

Realistically, I agree with those saying you need to just get over your reservations about higher ISO. Figure out what sharpening and NR settings to use in camera or in your favorite PP software to give you a decent starting point for whatever additional custom PP you may do. I've seen excellent results from the K-7 at twice the ISO you are arbitrarily limiting yourself to. And given the sharpness and DOF issues you are going to encounter shooting at twice as large an aperture, you'll probably end up throwing away more shots from a 20/2 than from the 21/3.2.

BTW, also remember you that you can get away with shutter speeds twice as slow with a 21mm lens as a 50mm lens. A lot of people have the idea that this only applies to camera shake but doesn't help with subject motion, but that's actually not true. Subject motion is less of a problem at shorter focal lengths for *exactly* the same reason that camera shake is - the same physical motion translates into less angular motion through the frame. The math may not work out identically, but the concept is the same.

08-19-2010, 11:20 AM   #20
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I agree with you, Marc. Personally, I find the DA21 quite usable in low light.
08-19-2010, 12:56 PM   #21
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QuoteOriginally posted by GeneV Quote
Marc Sabatella has ably pointed out on a number of occasions (had to convince me, but he did) that many of the issues with soft corners arise from depth of field.
And many lenses have a quite curved field of focus, so even square to a wall, a wide aperture image will have soft corners.
08-19-2010, 01:38 PM   #22
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QuoteOriginally posted by amaurosis Quote
I agree with you, Marc. Personally, I find the DA21 quite usable in low light.
Depending on what 'low light' is, it's certainly useable. But there's useable and then there's useable - it's not going to be great for freezing motion in low light, even though it's reasonably wide, f/3.2 just isn't fast.

I'm a big fan of the 21mm though.
08-19-2010, 02:23 PM   #23
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Yes, but what kind of motion are you really going to freeze at f/2 or more in low light? If you need to freeze motion in low light, you really need flash. But if your subject is relatively still - ordinary conversation, posing, etc - the kind of shutter speeds you can get at ISO 2500 and f/3.2 should be fine.

08-19-2010, 02:35 PM   #24
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QuoteOriginally posted by Marc Sabatella Quote
Yes, but what kind of motion are you really going to freeze at f/2 or more in low light?
...But if your subject is relatively still
I'm mostly referring to low-light street photography. I don't use flash. If people don't hold still, you need very high ISO or a faster lens. Even at f/1.4 with a standard lens you can get a few metres DOF to freeze motion.

I like the 21mm a lot, but at even at dusk on the streets, sometimes even ISO 6400 will give you pretty long shutter speeds.
08-20-2010, 10:05 AM   #25
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Yeah, if there's no light at all as is the case outdoors in the absence of street lights, and your subjects are walking, that's pushing it. Still, I'm surprised you say you get several meters of DOF at f/1.4 - maybe at screen size, but I suspect pixel peeping would should you don't really have that much. And when dealing those distances, you're talking about subjects small enough in the frame with a 21mm lens that I'd still suspect you'd do just fine at the 1/20"-ish shutter speeds you might be getting at that ISO. After all, if the subject is that small in the frame, it's not like you were going to be making out much in the way of facial details anyhow.
08-20-2010, 12:21 PM   #26
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Street lights aren't bright, and in my experience don't provide enough light for a f/3.2 lens to achieve sharpness for any decent street photography unless you want serious motion blur.

According to the online DOF calculator, a K-7 with a 30mm f/1.4 like the Sigma lens (which is what I've chosen over the DA limited), wide open, focused at:

3 metres, gives you 0.56 metres DOF
4 metres, gives you 1 metre DOF
5 metres, gives you 1.6 metres DOF
6 metres, gives you 2.3 metres DOF

I would say 'acceptable' sharpness is what matters in street photography.
08-20-2010, 01:29 PM   #27
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I agree, "acceptable" sharpness is what matters, but I think that also applies to the amount of blur you'd see with f/3.2. I guess I'd have to see apples-to-apples comparisons to be convinced, but *my* experience is as I've described - with my wider angle lenses, you *can* get away with slower shutter speeds, and I've done it many times. Admittedly, though, I have no comparison shots taken at night on the street with people walking. Just plenty of other situations (night street scenes without people, indoors with people engaged in conversation and not walking, musicians under stage lights, etc).

Anyhow, even if turns out the special case of people walking away from you at 6 meters away under street lights is one situations in which f/3.2 won't cut it for a 21mm lens, I'm not sure that really applies that much to the OP - he never said anything about doing anything like that. Plus, as I said, it kind of doesn't matter, because the lens he is looking for (remember, he said even 24mm was too long, the Sigma 20/1.8 too big, and other options too expensive) just doesn't exist. So while sure, if a wider, faster cheaper lens came along, it would be great for him, as things stand, I still think simply getting over the reluctance to raise ISO above 1250 is the way to go.
08-20-2010, 01:42 PM   #28
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I agree. That is, in this scheme of things, a very low ISO.
08-20-2010, 01:44 PM   #29
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I have the same need as CWyatt and like Blende8 I've solved it by getting the Sigma20/1.8. It is a good lens, though not as well built as Pentax lenses. It is much bigger than a ltd, but not as big as it cause me a problem. Living as far north as I do and doing street shooting is a problem. Not only is the streets dark because the sun is only up a few hours in winter, much of the places I shoot at like shopping streets are also under roof, to protect against the weather. And in street shooting, not only do the subject move, bot often I do as well. So I cannot use long shutter times. Flash is not an option. When there is enough light I prefere the DA15ltd (and have considered getting the DA21ltd), but when it isn't I switch to the Sigma20/1.8. Even if Pentax makes a fast lens around 20mm it will not be as small as the ltd's though it may be smaller than the Sigma.

You have some "street shots" with the Sigma 20 at my flickr: Sigma 20mm 1:1.8 EX DG - a set on Flickr
08-20-2010, 02:09 PM   #30
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Douglas, absolutely loved the image "roslagsbanan".....WOW!

I am not a huge fan of street candids and such, but that train image is beyond amazing for my eyes....enjoyed it very much.

The new flickr foramt is not showing the proper exif, what was the expsoure settings on that shot.
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