Focusing performance of SMC DA 1:2.4 35mm AL lens

**Robert N** · 12-19-2019, 05:39 AM

I have just bought a SMC DA 1.2.4 35mm AL lens from a 2nd hand camera dealer - advertised as 'nearly new'. Physically it does look nearly new but it has focussing problems.
Initially on the K-3 camera, images were blurred. Using an angled calibration chart, at f 2.4, the correct performance setting is -4 on autofocus calibration. However at this setting,
distance focussing it erratic and it will not auto focus on infinity. However, when setting the autofocus by 'eye' on subjects, the correct camera setting is +6 and it will focus on infinity.
Has anyone had similar experiences with this lens. Due to this odd behaviour I suspect it is a poor copy and I an inclined to reject the purchase.

7.62lew · 12-19-2019, 06:18 AM

That doesn't sound right. I had one, that I purchased new, and it had no focusing issues. It was very quick to focus and very sharp.

May want to return if possible.

**BigMackCam** · 12-19-2019, 06:52 AM

Moved to lens forum

Suzhouren · 12-19-2019, 07:05 AM

My copy is not that consistent. It took a while to calibrate because of this. After extensive testing I settled on a +6 adjustment on my K-5. This has improved matters, but I still get random misses with more frequency than I would like. My other plastic fantastic (DA 50 1.8) is much better in this regard.

**rogerstg** · 12-19-2019, 07:09 AM

Originally posted by Robert N

Initially on the K-3 camera, images were blurred. Using an angled calibration chart, at f 2.4, the correct performance setting is -4 on autofocus calibration. However at this setting,
distance focussing it erratic and it will not auto focus on infinity. However, when setting the autofocus by 'eye' on subjects, the correct camera setting is +6 and it will focus on infinity.

It sounds like you did not take enough images using the calibration chart before making the adjustment or your technique/setup was flawed. Cameras have a range at which they find focus acceptable using the OVF. FWIW, though I didn't notice any problem with focus, I calibrated mine using the Dot Tune method (since it's so easy). The range was -3 to +9, so I set it at the midpoint of +3.

Does it focus OK using live view?

**mikesbike** · 12-19-2019, 12:52 PM

Originally posted by Suzhouren

My copy is not that consistent. It took a while to calibrate because of this. After extensive testing I settled on a +6 adjustment on my K-5. This has improved matters, but I still get random misses with more frequency than I would like. My other plastic fantastic (DA 50 1.8) is much better in this regard.

I don't have a DA 35mm f/2.4, but I've had some AF problems with just a few other lenses on my K-5 that I do not have on the K-5 IIs with the same lenses. Nor do I have such problems with the K-S2 or the KP.

I would say that if after numerous attempts at adjustment that do not result in very good AF performance, it should be returned. The prices out there for this lens brand new are quite reasonable. The lens's construction, though ok is not of premium quality, so anything could be amiss.

**BigMackCam** · 12-19-2019, 01:07 PM

I have the DA35 f/2.4 and use it on my K-3 where it needs -3 AF fine adjustment. It's pretty consistently accurate both at close and longer ranges, though frankly I can't recall when I last tried to focus at infinity... Certainly, I have no problems focusing out to 100 feet or so, and I don't recall any change in accuracy between close range and longer distances.

Are you using the centre AF point during AF fine adjustment work? Which angled calibration chart are you using? Does it have a target that is perpendicular to the camera? Is your camera absolutely parallel to the AF target's plane horizontally and vertically? Is the camera tripod mounted to avoid back and forth movement when taking test shots? Are you performing the tests under good, natural lighting?

**ramseybuckeye** · 12-19-2019, 02:55 PM

Sounds like you got a bad one, send it back.

fsge · 12-19-2019, 03:05 PM

You simply should reject the purchase. I had this issue with a sigma lens long time ago, all copies can not be of equal quality...

**Robert N** · 12-20-2019, 08:05 AM

Originally posted by Robert N

I have just bought a SMC DA 1.2.4 35mm AL lens from a 2nd hand camera dealer - advertised as 'nearly new'. Physically it does look nearly new but it has focussing problems.
Initially on the K-3 camera, images were blurred. Using an angled calibration chart, at f 2.4, the correct performance setting is -4 on autofocus calibration. However at this setting,
distance focussing it erratic and it will not auto focus on infinity. However, when setting the autofocus by 'eye' on subjects, the correct camera setting is +6 and it will focus on infinity.
Has anyone had similar experiences with this lens. Due to this odd behaviour I suspect it is a poor copy and I an inclined to reject the purchase.

Many thanks to all who responded to my SMC DA 1:2.4 35mm AL focussing anomalies. As I don't trust the auto focus performance I have returned the lens for a refund.

12-19-2019, 05:39 AM	#1
Robert N Site Supporter Join Date: Oct 2017 Location: Sale, Cheshire Posts: 247	Focusing performance of SMC DA 1:2.4 35mm AL lens I have just bought a SMC DA 1.2.4 35mm AL lens from a 2nd hand camera dealer - advertised as 'nearly new'. Physically it does look nearly new but it has focussing problems. Initially on the K-3 camera, images were blurred. Using an angled calibration chart, at f 2.4, the correct performance setting is -4 on autofocus calibration. However at this setting, distance focussing it erratic and it will not auto focus on infinity. However, when setting the autofocus by 'eye' on subjects, the correct camera setting is +6 and it will focus on infinity. Has anyone had similar experiences with this lens. Due to this odd behaviour I suspect it is a poor copy and I an inclined to reject the purchase.

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12-19-2019, 06:18 AM	#2
7.62lew Pentaxian Join Date: Mar 2008 Location: North Carolina Photos: Gallery Posts: 1,192	That doesn't sound right. I had one, that I purchased new, and it had no focusing issues. It was very quick to focus and very sharp. May want to return if possible.

12-19-2019, 06:52 AM	#3
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,670	Moved to lens forum

12-19-2019, 07:05 AM	#4
Suzhouren Forum Member Join Date: Jul 2012 Posts: 53	My copy is not that consistent. It took a while to calibrate because of this. After extensive testing I settled on a +6 adjustment on my K-5. This has improved matters, but I still get random misses with more frequency than I would like. My other plastic fantastic (DA 50 1.8) is much better in this regard.

12-19-2019, 07:09 AM	#5
rogerstg Loyal Site Supporter Join Date: Oct 2007 Location: Rhode Island Photos: Albums Posts: 1,168	Originally posted by Robert N Initially on the K-3 camera, images were blurred. Using an angled calibration chart, at f 2.4, the correct performance setting is -4 on autofocus calibration. However at this setting, distance focussing it erratic and it will not auto focus on infinity. However, when setting the autofocus by 'eye' on subjects, the correct camera setting is +6 and it will focus on infinity. It sounds like you did not take enough images using the calibration chart before making the adjustment or your technique/setup was flawed. Cameras have a range at which they find focus acceptable using the OVF. FWIW, though I didn't notice any problem with focus, I calibrated mine using the Dot Tune method (since it's so easy). The range was -3 to +9, so I set it at the midpoint of +3. Does it focus OK using live view?

12-19-2019, 12:52 PM	#6
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,549	Originally posted by Suzhouren My copy is not that consistent. It took a while to calibrate because of this. After extensive testing I settled on a +6 adjustment on my K-5. This has improved matters, but I still get random misses with more frequency than I would like. My other plastic fantastic (DA 50 1.8) is much better in this regard. I don't have a DA 35mm f/2.4, but I've had some AF problems with just a few other lenses on my K-5 that I do not have on the K-5 IIs with the same lenses. Nor do I have such problems with the K-S2 or the KP. I would say that if after numerous attempts at adjustment that do not result in very good AF performance, it should be returned. The prices out there for this lens brand new are quite reasonable. The lens's construction, though ok is not of premium quality, so anything could be amiss.

12-19-2019, 01:07 PM	#7
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,670	I have the DA35 f/2.4 and use it on my K-3 where it needs -3 AF fine adjustment. It's pretty consistently accurate both at close and longer ranges, though frankly I can't recall when I last tried to focus at infinity... Certainly, I have no problems focusing out to 100 feet or so, and I don't recall any change in accuracy between close range and longer distances. Are you using the centre AF point during AF fine adjustment work? Which angled calibration chart are you using? Does it have a target that is perpendicular to the camera? Is your camera absolutely parallel to the AF target's plane horizontally and vertically? Is the camera tripod mounted to avoid back and forth movement when taking test shots? Are you performing the tests under good, natural lighting?

12-19-2019, 02:55 PM	#8
ramseybuckeye Site Supporter Join Date: Apr 2009 Location: Hampstead, NC Photos: Gallery Posts: 17,291	Sounds like you got a bad one, send it back.

12-19-2019, 03:05 PM	#9
fsge Veteran Member Join Date: Jun 2010 Location: Genf Posts: 1,138	You simply should reject the purchase. I had this issue with a sigma lens long time ago, all copies can not be of equal quality...

12-20-2019, 08:05 AM	#10
Robert N Site Supporter Join Date: Oct 2017 Location: Sale, Cheshire Posts: 247 Original Poster	Originally posted by Robert N I have just bought a SMC DA 1.2.4 35mm AL lens from a 2nd hand camera dealer - advertised as 'nearly new'. Physically it does look nearly new but it has focussing problems. Initially on the K-3 camera, images were blurred. Using an angled calibration chart, at f 2.4, the correct performance setting is -4 on autofocus calibration. However at this setting, distance focussing it erratic and it will not auto focus on infinity. However, when setting the autofocus by 'eye' on subjects, the correct camera setting is +6 and it will focus on infinity. Has anyone had similar experiences with this lens. Due to this odd behaviour I suspect it is a poor copy and I an inclined to reject the purchase. Many thanks to all who responded to my SMC DA 1:2.4 35mm AL focussing anomalies. As I don't trust the auto focus performance I have returned the lens for a refund.