f 1.4 Driving me nuts!

Sigma50 1.4 is my 1st fast lens wider than 1.8. I am able to attain good focus satrtint @1.8 but by the time I use larger than that, I get random blurry photos which annoys me in using it that wide. I am not blaming the lens, its me who is at fault here. How should I deal with it? Or is there a possibility that the lens could be faulty at these apertures ( 1.4 to be exact)? I get sharp images from f2 onwards and don't have any issues of front or back focus from there. 1.8 is a bit softer but nails. Its just that when I attempt to go lower than 1.8, the dilemma starts. Again, I consider it human error so any tips or maybe tricks from you guys in using this lens at 1.4 can help me a lot.

Here is my observation, if the lens is focusing, it makes a little adjustment before confirming focus. It is then that I get good photos. But sometimes (lets say often times), the camera beeps without that micro movement and thats the time I get blurry photos. Your advises will be appreciated. Thanks

try bracing your arms and holding your breath. also if its a living object ask them not to move as movement from the subject or you will result in out of focus and soft images

What camera? I usually grab the ring and manual it after the af locks on to get perfect focus. I do have the precision screens on the bodies I have to make manual focusing at f1.4 easy

Are you focus/recomposing?
At f/1.4... it will very frequently miss focus due to razor-thin DoF.

I find at f/1.4 [Canon] it's more a DOF issue than a lens issue.

What's it like on a tripod shooing a static object?

LeeRatters wrote in post #17211739
What's it like on a tripod shooing a static object?

This^^

You first need to establish if it is an issue with the lens or lens/body combo before wondering if its user error. Test using a tripod at f/1.4 to satisfy yourself that a) the lens is sharp wide open and b) it does not need microadjusted on your body.

Once you confirm the lens is ok and is adjusted ok for your body you then know that any blurry photos are user error and you can work on that. Also make sure your shutter speeds are high enough to eliminate motion blur. Also try and avoid focus recompose if you can as the dof at 1.4 is very narrow if you are focussing on a close subject

tacoman1423 wrote in post #17211668
What camera? I usually grab the ring and manual it after the af locks on to get perfect focus. I do have the precision screens on the bodies I have to make manual focusing at f1.4 easy

70D. What are precision screens?

@Leeratters: Tried it on a tripod a while ago and had some blurry photos without the final adjustment (I should say) of the lens.

@1Tanker: Nope, I do not recompose on test shots actually.

I am starting to feel its a lens issue. But does great @ f2 as I mentioned.

If you are getting blurry shots at f/1.4 on a tripod then its definately the lens or the calibration with the body. You should get the sigma dock if you havent already. When I first got the 35 ART it was all over the place. I then ran it through the dock and it was perfect

xpfloyd wrote in post #17212095
If you are getting blurry shots at f/1.4 on a tripod then its definately the lens or the calibration with the body. You should get the sigma dock if you havent already. When I first got the 35 ART it was all over the place. I then ran it through the dock and it was perfect

oops... Im sorry, its the non art version I purchased. Brand new.

ahh sorry, I had just assumed it was the new version. I dont have any knowledge of the original one but someone may be able to tell you if they are known to be soft wide open

You have a 70D, why don't you try AFMA to see if it will help?

The old Sigma 50s can be dodgy - I went through a few to get one that was sharp. As others have suggested stick it on a tripod and try focusing it - use live view if you have that available - and check how sharp the image is.

If the tripoded image is sharp (at various distances and consistently so) then it's your technique that is an issue. If its soft, then it's definitely the lens that is at fault. Hopefully, it's not the latter in your case, but if so return it for another copy.

Lbsimon wrote in post #17212496
You have a 70D, why don't you try AFMA to see if it will help?

Its on a +3... I still get random results even on a tripod. I already contacted my dealer and they are willing to replace the unit. But I will still give it a try for testing this morning. I'm kind of having 2nd thoughts due to its consistency on f2 onwards and Im afraid of getting a replacement that might be worse. The store is 600 miles from me and shipping is not my best friend due to annoying feeling of waiting brings to me... .

Jiggo0109 wrote in post #17211627
SI get random blurry photos which annoys me in using it that wide. I am not blaming the lens, its me who is at fault here. How should I deal with it?

Are you saying it's always "blurry" at f/1.4, or that it's blurry or too blurry sometimes at f/1.4? Too many shooters fall into the trap of feeling like they have to shoot their lenses wide open, f1.4 isn't right for all subjects, in fact it's not right for most subjects imo. If it's that hard to nail the focus where you want at f/1.4 you likely should be stopping down just a tad anyway.

Short of that, it just takes practice. I shoot all my lenses manually (don't have a choice when using the 6D, don't have anymore EF lenses :lol and rarely have an issue even when shooting at f1.4. I also highly recommend a precision matte focusing screen if you're camera is compatible with one, for me the EG-S screen makes a huge difference in being able to see my DOF (and thus, focus) through the viewfinder.

EverydayGetaway wrote in post #17213233
Are you saying it's always "blurry" at f/1.4, or that it's blurry or too blurry sometimes at f/1.4?

Here's what I observed, if it nailed a shot @ 1.4, it will go sharp for at least 7 to 10 shots. When it misses, it's also the same thing. It will go OOF all the way and I have to turn the focusing ring (almost a full turn) to make it work properly again. This is the time I get random focus until it nails again for several shots and will miss continuously until I turn the ring again. And its getting worse now, it lost its consistency at f2 (just noticed it this morning) unlike yesterday. I did the same field tests both outdoors and indoors. My shutter never goes slower than 1/1000th indoors. Maximum ISO Ive used is 1600 so far.

About your question, It's too blurry for 1.4. I can't tell it sometimes because it's unpredictable. It follows a sequence (I guess). Consistent sharpness-Consistent OOf-turn the ring- Will give random results- And then back to its sharpness and so on. My life with it is a loop.

I have also thought it could be my 70D but I just got my unit from Canon and they had successfully resolved my issues with it. I have borrowed my friend's EF 50mm 1.8 just to check if I still have the lemon on my camera but it was sharp at 1.8.

I called my dealer today again and they are willing to replace the lens but I suggested I'll send my camera with it for them to check if it's lens calibration issue. I bought the lens directly from Sigma's authorized dealer and repair center here in our country and the sad thing is it's 600 miles from my town.

Now, I am torn. Questioning my stance and knowledge at 1.4 and thinking the lens issue. I've tested it on a tripod and took a target at about 2.5 meters but gives me the same thing.