FA 20mm 2.8 performance with K1 at low light??

kooks · 05-12-2017, 09:43 AM

Hello guys.. i kind of want a wide angle lens to match my K1.. mainly i will use this lens at low light situations, so im wondering, have any of you tried the K1 with the FA 20mm or the 20-35mm at low light?? How is the hunting?? im kind of worry that this lenses would struggle at dim light to lock focus. I own the Tokina 19-35 but the IQ some how i feel it not that good.

I dont want the 15-30mm cuz #1 is heavy #2 is much expensive #3. for the kind of shots where i would use the lens the reasos #1 and #2 doesnt justify the price.

**mattt** · 05-12-2017, 09:50 AM

@SandyHancock can fill you in.

**jatrax** · 05-12-2017, 12:31 PM

Originally posted by kooks

im kind of worry that this lenses would struggle at dim light to lock focus.

Why are you worried? Curious what the logic is on that, especially on the FA 20mm f/2.8. The 20-35 is f/4, so slower but still should not be an issue. Surely AF lock is a function of the camera not the lens, provided the lens is bright enough?

I have used the FA 20-35 on the K-1 extensively but without knowing your definition of 'low light' is it difficult to say if it would suit you. This shot is with the DFA 24-70 @ f/5 and focus locked reliably. This is inside a refrigerator and the only illumination is my cell phone. Several other people with other brand cameras trying the same shot at the same time. One I know was using a Nikon with 50mm f/1.4 lens. I was the only one to get good images which I attribute to the low light ability of the K-1.

kooks · 05-12-2017, 03:49 PM

Originally posted by jatrax

Why are you worried? Curious what the logic is on that, especially on the FA 20mm f/2.8.

well some lenses are known to hunt for focus more than others.. my question was.. how is the hunting of the FA 20mm or the FA 20-35 match with the low light performance of the K1??

I shoot weddings so a good example of "low light" could be a wedding reception, for example the dance part.

Adam · 05-12-2017, 03:52 PM

At F2.8 youll get close to optimal AF performance. The K-1 and all of the other -3 EV Pentax models all do a good job. I recently shot a show with the 28-105mm and didn't have any issues even at the long end.

**jatrax** · 05-12-2017, 04:59 PM

Originally posted by kooks

well some lenses are known to hunt for focus more than others

Most lenses "known to hunt" are either slow consumer zooms like the DA 55-300 or macro types that have very long focus throw. Neither of which is the case with your two examples. Anyway, I cannot help with the FA 20mm, I do not have one. But the FA 20-35 is fine, IMHO. I don't use it inside much, mostly landscapes but never remember it hunting at all.

Just tested it in a closet. I had to use ISO 9,000 to get the shutter speed up to 1/10 at F/4 to show you how dark it was. No hunting at all, just chirp, focus lock. Tried it about 30 times at different focal lengths. Not really a scientific test but maybe it will help.

kooks · 05-13-2017, 03:23 AM

Originally posted by jatrax

Just tested it in a closet. I had to use ISO 9,000 to get the shutter speed up to 1/10 at F/4 to show you how dark it was. No hunting at all, just chirp, focus lock. Tried it about 30 times at different focal lengths. Not really a scientific test but maybe it will help.

Good to know

.. Thanks for the test.

05-12-2017, 03:52 PM	#5
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,608	At F2.8 youll get close to optimal AF performance. The K-1 and all of the other -3 EV Pentax models all do a good job. I recently shot a show with the 28-105mm and didn't have any issues even at the long end. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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05-12-2017, 09:43 AM	#1
kooks Veteran Member Join Date: Apr 2011 Location: San José, Costa Rica Photos: Albums Posts: 794	FA 20mm 2.8 performance with K1 at low light?? Hello guys.. i kind of want a wide angle lens to match my K1.. mainly i will use this lens at low light situations, so im wondering, have any of you tried the K1 with the FA 20mm or the 20-35mm at low light?? How is the hunting?? im kind of worry that this lenses would struggle at dim light to lock focus. I own the Tokina 19-35 but the IQ some how i feel it not that good. I dont want the 15-30mm cuz #1 is heavy #2 is much expensive #3. for the kind of shots where i would use the lens the reasos #1 and #2 doesnt justify the price.

05-12-2017, 09:50 AM	#2
mattt Site Supporter Join Date: Feb 2011 Location: Niagara Photos: Gallery \| Albums Posts: 3,907	@SandyHancock can fill you in.

05-12-2017, 03:49 PM	#4
kooks Veteran Member Join Date: Apr 2011 Location: San José, Costa Rica Photos: Albums Posts: 794 Original Poster	Originally posted by jatrax Why are you worried? Curious what the logic is on that, especially on the FA 20mm f/2.8. well some lenses are known to hunt for focus more than others.. my question was.. how is the hunting of the FA 20mm or the FA 20-35 match with the low light performance of the K1?? I shoot weddings so a good example of "low light" could be a wedding reception, for example the dance part.

05-12-2017, 04:59 PM	#6
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	Originally posted by kooks well some lenses are known to hunt for focus more than others Most lenses "known to hunt" are either slow consumer zooms like the DA 55-300 or macro types that have very long focus throw. Neither of which is the case with your two examples. Anyway, I cannot help with the FA 20mm, I do not have one. But the FA 20-35 is fine, IMHO. I don't use it inside much, mostly landscapes but never remember it hunting at all. Just tested it in a closet. I had to use ISO 9,000 to get the shutter speed up to 1/10 at F/4 to show you how dark it was. No hunting at all, just chirp, focus lock. Tried it about 30 times at different focal lengths. Not really a scientific test but maybe it will help.

05-13-2017, 03:23 AM	#7
kooks Veteran Member Join Date: Apr 2011 Location: San José, Costa Rica Photos: Albums Posts: 794 Original Poster	Originally posted by jatrax Just tested it in a closet. I had to use ISO 9,000 to get the shutter speed up to 1/10 at F/4 to show you how dark it was. No hunting at all, just chirp, focus lock. Tried it about 30 times at different focal lengths. Not really a scientific test but maybe it will help. Good to know .. Thanks for the test.