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02-24-2010, 01:54 PM   #16
jas
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Again thank you. So my lens wouldn't be ideal for darkest situations? Having said i already have the DA 16-50, can i get a recommendation on some other lenses i might be interested in looking at for the future? With your experience and ability its highly valued. Interested in all types of subjects too but night photography seems the most interesting to me now....so anything to experiment with is of interest. Cost isnt a huge factor but will be considered of course.

02-24-2010, 02:03 PM   #17
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I hate bulk, i mean I loathe it. Otherwise i'd own the 16-40 as an evening walk around lens

Just set your camera to multi-shot, always fire three images .. better chance one will be sharp.
02-24-2010, 09:12 PM   #18
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QuoteOriginally posted by jas Quote
...
Sterretje, this is a dumb question im sure but the FA31 is referring to?
PENTAX FA Wide-angle Limited Lens for Digital SLRs and Compacts: smc PENTAX FA 31mm F1.8 Limited
02-24-2010, 09:35 PM   #19
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to be honest, you need them both. one can never get enough lenses lol

the Pentax 31/1.8 Limited seems to be a very nice lens, although it is also very expensive

02-25-2010, 12:39 AM   #20
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QuoteOriginally posted by jas Quote
Tootall, those are some excellent photos on your flickr. some of the best ive seen.
Thanks

Just going over the thread, I think you may be asking the wrong question. Try looking up on night photography techniques rather than what lens to buy. Your DA lens will be fine to get you started. Buy yourself a tripod and trigger cable/remote as a starting point.

Some examples from a search on flickr Pentax DA 16-50 Night - Flickr: Search and check out the settings they have used.

Once you get a better understanding of how and type of style, you'll have a better idea of what lens you will want to add to your collection.
02-25-2010, 12:51 PM   #21
jas
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Thanks guys for the suggestions and help. I have a much better understanding of the topic and a direction to go.
02-25-2010, 10:25 PM   #22
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the speed, the depth, and the night

Here's some basic optics:

DOF is the range of distances that are "in focus". DOF (sorta) centers around the point on which you focus -- a little in front, a little more behind. DOF is affected by two variables: the lens' focal length, and the aperture used.

A 'fast' lens has a wide maximum aperture, with a small number: f/1.2, f/2.0, etc. A 'slow' lens has a narrow maximum aperture, with a larger number: f/4, f/5.6, etc. For lenses of comparable build quality, fast lenses usually cost more than slow ones. Sometimes MUCH more.

A 'wide' lens has a shorter focal length than 'normal' (defined as the diagonal of the frame; on your APS-C dSLR, that's around 30mm). 24mm is slightly wide; 21mm and 18mm are wider; 12mm and 10mm are ultrawide. A 'long' (or tele) lens has a longer focal length. 35mm is slightly long; 50mm is a close portrait tele; 100mm is longer; 200mm and beyond are quite long.

[Zoom (variable) lenses are usually a bit slower than 'prime' (fixed focal length) lenses. Fast zoom lenses ARE NOT CHEAP. Lens makers find 50mm to be a "sweet spot", so many fast 50mm prime lenses are available at decent prices.]

For any specific aperture, a wider lens has thicker DOF (more is in focus), and a longer lens has thinner DOF (less is in focus). For any specific focal length, a wider, faster aperture has thinner DOF, and a narrower, slower aperture has thicker, deeper DOF.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Now let's put this all together. I can mount a slow, wide, manual 21/3.5 lens (that's 21mm, f/3.5 maximum) on any SLR, set the aperture to f/5.6, pre-focus to 10 feet, and my DOF is 4.5 feet to infinity -- anything within that range is in focus. Nice for street-shooting. Or I can mount a fast autofocus portrait 50/1.4 lens, aperture wide open, focus at 4 feet -- and my DOF is maybe an inch thick. This is great if I'm doing a portrait, concentrating on their eyes, and want everything else to be soft or irrelevant. A fast 100mm lens has thin DOF; stopped down to f/22 and hyper-focused at 30 feet, its DOF is about 16 feet to infinity.

[Older, manual-focus and prime lenses usually have DOF scales inscribed on their barrels, so it's easy to figure what aperture and hyperfocus distance will give you any desired DOF range. These are lacking on modern lenses. Darn. It's harder to judge DOF when looking through a dSLR's viewfinder. But I digress.]

Shooting in low light, you're always tempted to open the aperture, so you can shoot at higher shutter speeds. But dark subjects are harder to focus on, with either manual or autofocus. And DOF becomes razor-thin at wide apertures (f/1.2-2.0) so you're more likely to get EVERYTHING fuzzy. You can boost the ISO (sensitivity) but then image noise increases. Maybe you can use a flash, or maybe not. You can try to guess where subjects will appear, pre-focus there, and be ready to shoot at the right time. You can yell "STOP!" and shoot anyone who does. There are many tricks; but a fast lens alone is not a solution.

Last edited by RioRico; 02-26-2010 at 01:09 PM.
03-09-2010, 11:30 AM   #23
jas
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RioRico, excellent explanation. thanks!

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