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Old Dec 8, 2008, 9:54 AM   #1
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Hello Everyone,

Question 1: What inexpensive lenses have you found that is fast at acquiring and taking pictures in low light?

One of my pet peeves about my Pentax K100D is it's slow focus response in low light with either using the built-in flash for focus assistor no flash at all. (No. I don't have a Pentax Flash with built-in focus assist yet.)

I have three AF lenses [ 1) The kit Pentax 18-55 3.5-5.6?, 2) An old film camera Pentax28-80 3.5-5.6 (The silver one), and 3) A Sigma 18-200 3.5-6.3]

Just as a not-very-scientific-experiment I sat myself down in a room with only a single 60watt light on [At night, so it was low light] and tried out the 3 lenses to see how fast they were able to acquire and take a picture (with and without the built-in flash) and . . . low and behold, there was a big difference between the old Pentax 28-80 3.5-5.6 compared to the other two lenses.

The old Pentax 28-80 3.5-5.6 was able to focus about twice as fast as the other two lenses. (Often just requiring a single focus sweep to acquire focus and take a shot. And the pictures were in fact in focus.) [And I only paid about $30 + taxes & shipping for this lens. +$20 for the UV filter.]

Knowing this, the next time I go out and take some friends and family shots in less than ideal house lighting, I'm trying this lens out to see if in the real-world it is more responsive . . .

Question 2: Has anyone else experienced this with their lenses?

Question 3: (A repeat of Question 1) Ifthere is a difference in AF performance of lenses (even at similar F-Stop values), what other inexpensive lenses have this same magical low light AF performance?

Now that I'm thinking about it, I'm going to try this same experiment without the UV filters on my lenses to see if that improves performance in low light. (Has anyone experimented with that?)

Take care,
Glen



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Old Dec 8, 2008, 10:55 AM   #2
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FA 50mm 1.4

Dawg
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Old Dec 8, 2008, 1:13 PM   #3
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glen,

out of 11 only 2 are AF.
with all, i never miss focus.. (??????????)


dawg, is correct about the 50/1.4 and i think he knows what i'm saying

roy
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Old Dec 8, 2008, 1:23 PM   #4
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oh,
i've found the 28-80 to be a great lens(me? $17) if doing shots that are close..
sold($34), but i did get a few of our pets that i have'nt done better.

roy
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Old Dec 8, 2008, 6:30 PM   #5
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Glen for low light always take the filters off. You can loose as much as a full stop with them on. I had a Takumar A lens that did very nice in low light and it cost about 12.95 with shipping...It was a 28-80. Manual focus seems to work better for me in extreme low light.. I don't know why but it just does.

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Old Dec 8, 2008, 7:55 PM   #6
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bigdawg wrote:
Quote:
Glen for low light always take the filters off. You can loose as much as a full stop with them on. I had a Takumar A lens that did very nice in low light and it cost about 12.95 with shipping...It was a 28-80. Manual focus seems to work better for me in extreme low light.. I don't know why but it just does.

Dawg
A UV filter shouldn't slow down the lens unless if it is dirty or a really cheap one at least from what I've experience.

But as dawg suggested, you should take off your filters in low light or indoors unless if you are using it as a lens protector.

As far as the lens goes, I would agree that the FA 50mm f/1.4 is an great lens and very fast. Another lens that I would suggest is the DA 40mm limited f/2.8. Not as bright as the FA 50mm but I notices that the AF on that lens is faster than the FA 50mm.
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Old Dec 8, 2008, 8:31 PM   #7
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I have found the Sigma 24-60mm f/2.8 to have nice quick AF response. I have not done any low light experiments with it but I would think it also would be good. If you are looking at real low light though, I agree with the 50mm suggestion, the extra two stops should make a difference.

Tim
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Old Dec 9, 2008, 1:18 AM   #8
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I just looked up the pricesfor the FA 50mm 1.4 ($200cdn)& DA 40mm 2.8 ($250US). If that is right, these are pretty reasonable prices for what they do.

I couldn't find the Sigma 24-60 f2.8 anywhere. (Of course I only looked at Vistek.ca, Henrys.ca & BHphotovideo.com). Is this a current lens or older lens?

B.T.W. I saw the Sigma 18-200 < $300 (with free shipping) and the Sigma 28-300 ~$250 at BHphotovideo.com while I was browsing around. (Just a side note. <grin>)

Take care,
Glen



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Old Dec 9, 2008, 2:27 PM   #9
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tacticdesigns wrote:
Quote:
I couldn't find the Sigma 24-60 f2.8 anywhere. (Of course I only looked at Vistek.ca, Henrys.ca & BHphotovideo.com). Is this a current lens or older lens?

Glen
*
It is available in amazon.com at $199US
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Old Jan 4, 2009, 7:19 PM   #10
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Right now there are some good buys on this recently discontinues Sigma EX DG 24-60 f2.8 (not a variable aperture lens), which has been replaced by a 24-70. This is a highly regarded lens and can be gotten in the $200 - 230 range (depending on mount), which is 1/2 or less than the price when it was still current. The best prices now seem to be from Cameta (US) and Henry's (Toronto) - both reliable dealers - if you are concerned about failure rates, get it from Henry's as Sigma's Canadian distributor provides a 10 yr warranty on EX lenses, vs the US 1 yr warranty (you would have to mail it for repairs in either case, but the EX series is the top of the line and has good build quality, so failure is unlikely in ordinary use. I ordered one from Henry's and had in in California in less than a week
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