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05-21-2010, 11:56 PM   #1
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New Sigma 50mm f1.4 worst FRONT FOCUS i've ever seen

Just got a brand new Sigma f1.4 50mm and it requires a -150um adjustment on my Kx to be correct! I also bought a Mack international 7 yr warranty with it.

So what should I do? Send it back to Adorama or send it in for a service under warranty?

Shipping to and from the USA was something like $60.....

Also while on the topic, I've never had a lens that was perfect they always require some adjustment and on my Kx always a negative adjustment, so i'm going to assume my body is slightly out? My best lens is a DA 70mm and requires -20um.


Last edited by WerTicus; 05-22-2010 at 12:03 AM.
05-22-2010, 12:29 AM   #2
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Does the other lenses you have focus well with the adjustment you made or it's good only for the sigma?
05-22-2010, 01:40 AM   #3
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The Kx can only have one adjustment .... and my DA 70mm is massively back focused with the 50mm's correction in place. (as you'd expect.)

So i'm asking for advice regarding just sending it back for a replacement or refund or if i should send it to the local MACK service and get it adjusted...

Last edited by WerTicus; 05-22-2010 at 01:53 AM.
05-22-2010, 02:04 AM   #4
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If i liked the lens the first thing i'd do is ask for a replacement, or local service if it was easyer and faster than sending back to the seller.


I was asking about how the correction worked for the other lenses because when i made adjustment using the M50 1.4 i ended in something like -100um, after i got an FA135 f2.8 and redo the correction and this time i set it at -30um and works well with every lens i've, including the fifty.
I think i made the mistake of using only minimum focus distance when i did the first correction, i hope you hadn't done the same with the sigma.

05-22-2010, 04:04 AM   #5
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I do all my focus correction at around 1000mm... which is double the sigma's min of 450mm (the da 70 is 750mm)

I then check it against infinity.
05-22-2010, 04:15 AM   #6
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I guess I'd have it serviced. 60 dollars is 10 percent of the lens cost (roughly) and there is no guarantee that the next one wouldn't front or back focus too. As long as everything else seems fine, seems silly to spend the money on shipping.
05-22-2010, 04:25 AM   #7
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I just got the same lens - Sigma 50mm f/1.4 - while in London, and I have to say that my copy seems to be perfect. Only taken some "snapshot" pics so far, due to flying home and jetlag, but will try to put up some pics over the next few days to show you what I mean. And that focus with the HSM is SO quick and SILENT!

Maybe you just got a bad copy? Or, as you suggest, there may also be a problem in the camrea body - worth contacting C R Kennedy here in Australia re a check/service of the body, and get them to test it with 2 or 3 lenses, including the new Siggie 50.
05-22-2010, 04:52 AM   #8
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This lens is notorious for sample variations and focus problems.
When it's within specs, it's supposed to be one of the best 50mm available - for certain applications.
+1 for getting it serviced.

05-22-2010, 04:54 AM   #9
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Mine was obviously bad before I checked it with a chart, I knew it had a problem.
It was front focusing meters ahead of the only obvious focus point in my initial pictures.

It might well be partially my body so i guess getting a local service is the best answer.

then if i don't like the lens at the end of the day for whatever reason, i know its in sale-able condition.

I also must say i think the bokeh is a little harsh, the hsm not 'that' fast and seems to hunt slightly compared to the DA70mm.

Im currently thinking ditch it and get a DA40mm instead, as my experience with the limited 70 has been so good.
I guess i need to sleep on it, and probably use the lens a bit with the focus correction to see if i do like it 'fixed'.

Last edited by WerTicus; 05-22-2010 at 05:00 AM.
05-22-2010, 08:44 AM   #10
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*Meters* ahead? That's flat out impossible. If it's focusing meters away from where you intended, that's not front focus - that's simply the camera choosing a different target than you intended. Focus problems are measured in millimeters, not meters.
05-22-2010, 11:44 AM   #11
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What initially prompted me to test it was a photo where nothing else could have been in focus and yet what was was in focus was 3 meters away not the 5 of the only possible object the camera could lock on.

perhaps it was just error and not a front focus issue but then the charts are telling me it does have terribad front focus now with proper testing.
05-22-2010, 03:36 PM   #12
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Don't know if it makes any difference, but I virtually always use the single point spot focus on my K20D. I never use the multi-focus points or the "Select the point" type.

But I don't know if that has anything to do with this....

Here is a pic of my Dad on his 96th birthday taken with the Siggy 50mm f/1.4:



No tweaking or sharpening - shot in RAW on the K20D

Can't see too much problem with the focus point, which was his eyes.

And another - again using single-point autofocus:


Last edited by Derridale; 05-22-2010 at 03:47 PM.
05-22-2010, 04:56 PM   #13
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QuoteOriginally posted by WerTicus Quote
What initially prompted me to test it was a photo where nothing else could have been in focus and yet what was was in focus was 3 meters away not the 5 of the only possible object the camera could lock on.
If there was nothing the camera could lock on only 3 meters away, then how do you know it focused there? Sounds to me like there *was* indeed something there to focus on. If your eyes were able to find it, why do you think the camera would not have been able to?

It's really hard to say more without seeing sample images including images from the test charts. It's certainly possible you have an FF issue that the charts are showing. I'm just saying there's absolutely no way this has anything whatsoever to do with the camera focusing at 3 meters instead of 5. That one has got to be a simple case of the camera choosing to focus somewhere other than where you intended. There is, again, absolutely no possible way an FF problem could be causing that.
05-22-2010, 05:49 PM   #14
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One thing I have noticed though - the EXIF data on photos taken with this lens show it as the Sigma 70-200mm f/2.8, using Aperture 3.0.3 on an iMac.

Which it clearly is not....

Anyone else noticed the same?
05-22-2010, 07:18 PM   #15
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Sigma actually uses the same numbers identifying a couple of their lenses. This can be a problem with the K20/K7 where if you own both the 70-200 and the 50 f1.4 and you put in a focus correction to the one, the camera applies it to the other lens as well.
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