FA 35mm hunting

audiobomber · 07-11-2009, 09:41 AM

I was trying to take some candid portraits in dim light with my newish FA 35mm, and I found it would not autofocus. The subject distance was uncomfortably close anyway, so I switched to the FA 50mm. I was very surprised to find that the FA 50 autofocussed with no real difficulty.

The same thing happened while shooting a sunset a couple of days ago. The 16-45 snapped into focus reliably. Several times with the FA 35 I had to work for autofocus. Do you think my FA 35 is defective?

Pentaxor · 07-11-2009, 10:47 AM

how closely were you shooting the subject? I tested the FA 35 last night and it focused really fast even under lowlight. you might want to check you 35 for focusing issues. anyway, could you provide some pictures as well? thanks !

audiobomber · 07-11-2009, 11:28 AM

Originally Posted by Pentaxor

how closely were you shooting the subject? I tested the FA 35 last night and it focused really fast even under lowlight. you might want to check you 35 for focusing issues. anyway, could you provide some pictures as well? thanks !

I didn't succeed in taking a baby photo on AF with the FA 35, and the few MF photos I took were not good enough to keep. I loaded a shot taken with the 50mm just for the record. The 35mm focusses more closely than the 50mm, so I don't see that I could have been too close.

The sunsets are representative. I can't say for sure this very photo caused the FA to have the trouble, but the photos were all pretty similar, slightly different compositions, slightly different apertures, various metering methods, and the FA didn't just hunt once, it happened several times, even though I tried to give it something to focus on.

The photos are here. Picasa Web Albums - Dan - FA 35 AF
My apologies for the Picasa link. It's a big hassle to load somewhere else.

mcjm78 · 07-11-2009, 06:53 PM

Just wondering, do you have a uv filter on your 35mm?

Depending on the quality of the filter, sometimes I find my lens have difficulty in focusing a subject if the filter is creating lots of internal reflection.
I've now ditched all my single coater filters because of that.
Mike

Pentaxor · 07-11-2009, 07:43 PM

Originally Posted by mcjm78

Just wondering, do you have a uv filter on your 35mm?

Depending on the quality of the filter, sometimes I find my lens have difficulty in focusing a subject if the filter is creating lots of internal reflection.
I've now ditched all my single coater filters because of that.
Mike

good observation. this could also be a factor. I had some similar focusing problems with my FA 50 1.7 with a UV filter on it. it does seem to hunt a tiny bit longer compared to the focusing speed of the FA 35, but anyway, it was still able to focus.

to the OP, if you said that you got some subpar photos even using manual focus, maybe there is an issue in the glass itself. you said you got a brand new FA 35, so it may have some ff or bf problems. I'll try to upload some sample pics to see how closely could I focus.

audiobomber · 07-11-2009, 08:10 PM

No filter on the lens. Good question about BF FF. I'll check that out.

24X36NOW · 07-11-2009, 09:14 PM

"Use MANUAL CONTROLS Luke"

Sorry couldn't resist LOL

K-9 · 07-11-2009, 10:26 PM

Originally Posted by 24X36NOW

"Use MANUAL CONTROLS Luke"

Sorry couldn't resist LOL

Yes, but you'd be stupid if you still had a window to return/exchange it. Why keep something that only half functions.

stevebrot · 07-12-2009, 01:29 AM

Originally Posted by Pentaxor

how closely were you shooting the subject? I tested the FA 35 last night and it focused really fast even under lowlight. you might want to check you 35 for focusing issues. anyway, could you provide some pictures as well? thanks !

My experience with the FA 35/2 echos Pentaxor's. I have found that the AF is generally very snappy and extremely accurate even in low light. The only time I have had it fail to lock was in low light with a very low contrast subject. It is easily the most capable of my AF lenses.

Steve

*Andi Lo* · 07-12-2009, 02:58 AM

Mine is relatively snappy even in low light. Definitely at least as fast as FA 50.

**Peter Zack** · 07-12-2009, 03:31 AM

I'd agree with those above, My FA35 was as fast or faster than my FA50 and I find that lens is very good even in low light.

I don't have a possible solution unfortunately to offer other than if you know someone with another body to try it on, you could see if it acts the same way. If so send it to Pentax under warranty if you can't return it to the store. One other thought though. Clean the contacts on both the lens and camera with contact cleaner or de-natured alcohol (never a pencil eraser!!) and see if that helps. It might not be communicating with the body well.

audiobomber · 07-12-2009, 09:10 AM

Originally Posted by Peter Zack

I don't have a possible solution unfortunately to offer other than if you know someone with another body to try it on, you could see if it acts the same way. If so send it to Pentax under warranty if you can't return it to the store. One other thought though. Clean the contacts on both the lens and camera with contact cleaner or de-natured alcohol (never a pencil eraser!!) and see if that helps. It might not be communicating with the body well.

Thanks, more good suggestions. I have a K100DS to try it on.

ll_coffee_lP · 07-12-2009, 10:31 AM

My FA35 is wicked fast too at AF too, and is excellent at nailing focus...

c[_]

GeneV · 07-12-2009, 08:31 PM

Originally Posted by 24X36NOW

"Use MANUAL CONTROLS Luke"

Sorry couldn't resist LOL

I find myself hearing that voice very frequently with the DFA 50 macro. It's a hunter, especially up close in lowish light.

Pentaxor · 07-12-2009, 11:42 PM

no, this is not a macro lens nor cropped. this is the FA 35 as close as I can get using auto-focus. I haven't used the lens on manual focus yet but looking forward for a better result. shot was taken at F2 wide open. jpeg and no pp done for IQ except file compression which really sucked.

sorry, got a little hungry and that's what's left of the sample.

anyway, I'm just wondering if the OP has a problem focusing at this close distance as well.