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02-08-2011, 06:30 AM   #1
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Why are the wide-ange limiteds slower?

I would love to get a DA 21 or 15mm Ltd for street photography etc - however, they are f3.2 and f4 respectively. This is annoying - especially as a K10D owner where going over 400 ISO is not really an option.

Is it mechanically more difficult to make a wide angle lens fast? Or is the assumption that this is not needed for most uses? I guess a lot of people stop down to f8 or 11 for hyperfocal - still this is not always an option, or desirable. On Pentax Imaging they say these lenses are recommended for use indoors - IMHO f4 is often too slow for available light indoors.


Last edited by jeztastic; 02-08-2011 at 06:37 AM.
02-08-2011, 06:38 AM   #2
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Fast wide angles lenses are not small, which defeats the purpose of the "limited" tag
you could always try a da14 f/2.8 if your wanting a fast wide angle, but its not a limited.

Ive havent run into any problems shooting with the da15 in low light, its easy to take crisp hand held pictures at 1/15 of a second
02-08-2011, 06:42 AM   #3
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QuoteOriginally posted by TOUGEFC Quote
its easy to take crisp hand held pictures at 1/15 of a second
Really? What's your secret? You must drink less coffee than me...
02-08-2011, 06:44 AM   #4
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Shake reduction

02-08-2011, 06:53 AM   #5
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wide aperture means narrow depth of field, which is bad for landscape or panoramas. what else is wide angle used for I wonder, which would make narrow sharpness zone acceptable? portraits?

and yes, SR is quite effective for wide angle in my experience, but you should make a few shots because sometimes SR ruins the shot instead of saving it.
02-08-2011, 06:54 AM   #6
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because on higher F is less aberrations, i think
02-08-2011, 07:35 AM   #7
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QuoteOriginally posted by olenl Quote
wide aperture means narrow depth of field, which is bad for landscape or panoramas. what else is wide angle used for I wonder, which would make narrow sharpness zone acceptable? portraits?

and yes, SR is quite effective for wide angle in my experience, but you should make a few shots because sometimes SR ruins the shot instead of saving it.
Large aperture isn't really a problem in respect of limited DOF for wide angle lenses. You can easily convince yourself about that on this online DOF-calculator:

Online Depth of Field Calculator

What can be a problem is poor optical quality at full aperture for certain lenses - but I use my 24mm lens (Model 01B - Tamron Adaptall-2 system) happily at f/2.5 for street photos and similar.

Steen G. B.
02-08-2011, 10:11 AM   #8
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QuoteOriginally posted by jeztastic Quote
This is annoying - especially as a K10D owner where going over 400 ISO is not really an option.
Why is anything greater than 400 not an option?

02-08-2011, 10:17 AM   #9
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this link is a k10d @ 1250 iso
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02-08-2011, 10:18 AM   #10
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QuoteOriginally posted by olenl Quote
wide aperture means narrow depth of field, which is bad for landscape or panoramas. what else is wide angle used for I wonder, which would make narrow sharpness zone acceptable? portraits?

and yes, SR is quite effective for wide angle in my experience, but you should make a few shots because sometimes SR ruins the shot instead of saving it.
Shooting pictures or video inside houses with small rooms and low light.

My problem is that the kiddo is moving so fast these days that I still have to use the flash because even with a k-x and shooting up to 1600 on a k-x I need to use tV mode and use flash or underexpose to avoid motion blur using a da 21 ltd.
02-08-2011, 10:39 AM   #11
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QuoteOriginally posted by jeztastic Quote
This is annoying - especially as a K10D owner where going over 400 ISO is not really an option.
double post....sorry. goodle k10d high iso
02-08-2011, 10:47 AM - 1 Like   #12
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QuoteOriginally posted by jeztastic Quote
I would love to get a DA 21 or 15mm Ltd for street photography etc - however, they are f3.2 and f4 respectively. This is annoying - especially as a K10D owner where going over 400 ISO is not really an option.

Is it mechanically more difficult to make a wide angle lens fast? Or is the assumption that this is not needed for most uses? I guess a lot of people stop down to f8 or 11 for hyperfocal - still this is not always an option, or desirable. On Pentax Imaging they say these lenses are recommended for use indoors - IMHO f4 is often too slow for available light indoors.
It is much more difficult to design a wide angle lens than a tele-photo lens. It needs many more elements to correct the lens aberrations. Also faster the lens is, higher is the chances for aberrations. So all the wide-fast lens designs are very complicated. You will be convinced if you just compare the number of elements in such lenses mentioned in our lens database.
02-08-2011, 12:00 PM   #13
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In the case of the limiteds, it's mainly a matter of size. Look at the 28 mm f2 and you'll see the size required to make such a lens. Or look at the Sigma 20 mm f1.8.

Also consider that at wide angles, you get more aberrations. A way to limit those is to use a smaller aperrture.

If you want faster to get a shallower DOF, you can get a lens with a longer focal length. Otherwise, handholding the DA21 wide open is easily feasible even with SR.
02-08-2011, 03:35 PM   #14
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QuoteOriginally posted by bdery Quote
In the case of the limiteds, it's mainly a matter of size. Look at the 28 mm f2 and you'll see the size required to make such a lens. Or look at the Sigma 20 mm f1.8.

Also consider that at wide angles, you get more aberrations. A way to limit those is to use a smaller aperrture.

If you want faster to get a shallower DOF, you can get a lens with a longer focal length. Otherwise, handholding the DA21 wide open is easily feasible even with SR.
Exactly. It is just to keep size (and filter size too) down. Seems like Pentax tried to keep 49 mm filters for all of the DA limiteds. Also, for many uses of wide angles, you are more likely to shoot stopped down anyway, so an f4 aperture may not be so much of an impediment.
02-08-2011, 04:40 PM   #15
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QuoteOriginally posted by Deiberson Quote
I have a question, I know I am on a K20D but how do you set the iso like that for example, my next step up from iso 800 is 1600 and then 3200(Also cant seem to select 6400)
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