Sigma 50mm f1.4 - SOFT?

Hi everybody. I know these sorts of threads have been beaten to death, but I am sitting on the fence as what to do with my Sigma 50mm f1.4. I bought it second hand and made sure to ask the seller if they thought it was sharp etc and they said yes it is quite sharp (they shoot with many L lenses, so that was good enough for me. They also sent me 3 photos and they looked great, at f1.4. However, I have been comparing my f1.4 shots to those of f2.8 etc and f1.4 looks incredibly soft. I have tried manual focusing and that does not seem to make my images sharper at all, so focus seems spot on to me.

Here are some shots I have taken. The two of the 50mm f2.5 were outside at about 5pm and the pictures of the Solo can were in my room with my computer monitors and bedroom light on (sat camera on desk and used remote trigger so no camera shake would be possible). I have not bothered so far with any non cylindrical objects due to the fact it is very obvious there are some issues at f1.4 even with manual focusing. Also, CENTRE focusing point was used.

Links below for full resolution (fingers crossed you can actually view these)

F1.4: http://imageshack.us/a​/img832/8451/16177664.​jpg
F2.5: http://imageshack.us/a​/img26/1184/95474424.j​pg

F1.4: http://imageshack.us/a​/img515/2724/28773288.​jpg
F2.8: http://imageshack.us/a​/img594/7056/95583470.​jpg

Any help would be appreciated, thanks

I have the Sigmalux and tbh with you wide open shots aren't designed for pixel peeping...

Mine is soft too and therefore I either don't pixel peep or I treat it as a f2.8 lens.

Your sample seem to be indoor, what ISO did you use?

When the lighting is flat, it does gives unflattening results.

The only lens that I dare to pixel peep @ large aperture is my new Sigma 35, it's unbelievably sharp wide open

Yeah I figured pixel peeping wouldn't fair well, but I could just tell from my 1D mk II screen and 30D screen that 1.4 was FAR worse than f2.8, I didn't even have to zoom in. Would you say mine at 1.4 is horrible like I believe it is, or would you need more examples in different lighting conditions and of different subjects etc? Also, the first samples were taken outdoors under shelter with ISO 100 and a shutter speed of 1/1250 was used. The second samples were taking indoors with 100 ISO also but fully stabilised camera and shutter speed of half a second.

I understand with poor lighting I will get poor results, but I would expect that for f2.8 as well and not f1.4, where as f2.8 seems fine to me and f1.4 terrible (I even tried adjusting the focus manually and didn't yield any better results, so the AF mustn't be completely off or anything).

And that's great that Sigma can make a good 35 then as their 50mm f1.4 seem to have lots of problems but there certainly are gems out there that's for sure...

Yea I know what you are saying...the f2.8 shot does look a whole lot better than the f1.4 one.

Have to say mine isn't much better wide open and I do often think mine is just soft as well. Not sure if other Sigmalux owners have similar experience.

The fact that MF being the same means it isn't the AF either.

Another possible cause is your sample looks to be shot close to MFD which means the dof is just that much shallower, and that isn't helping sharpness wise.

I actually just shot two pictures of the can sitting on a chair approx 3m away and at 2.8 it was pretty good but at 1.4 the focus plane was behind the can itself even though I used autofocus and the centre point. So it would seem I am getting focus issues afterall... I really don't know what to do now. Perhaps some more testing tomorrow?

I purchased a brand new Sigma 50mm f/1.4 earlier this Month and did some testing at f/1.4 which pretty much indicated it was Front-Focusing. Initially used a focus chart to ensure the focus plane was parallel to the camera sensor (your tests with round objects are not ideal as I understand it).

It is currently with Sigma / CR Kennedy in Melbourne (with my 5D Camera Body) getting recalibrated under Warranty so will let you know how it measures up once it has been returned.

Another test you can try...get Wife / Husband / Child / Partner to model for you. Get them to turn their head to a 3/4 position so you can see both eyes. Focus on the distant eye and check the results. Mine was showing the closest eye in focus even though I was focusing on the eye furthest from the camera....another confirmation that it was front-focusing.

Thanks, looking forward to hearing your reply I was considering purchasing brand new but if purchasing brand new, I would rather purchase from a physical store here in Melbourne and they generally seem to be about $100 more than used and since there is a pretty much equal chance of getting a poor copy brand new or used, I figured I'd be better off saving the $100 since I am a Uni student after all and I am the kind of person who will buy something for 5% cheaper even if it means waiting a month more to get it haha. However, if the lens is soft in the first place won't a calibration do pretty much nothing (if there were NO focus issues whatsoever)? Because my copy seems that it does indeed have some focusing issues, but softness issues in general as well, so I'm not sure if getting it recalibrated would even be worth it.

What tests did you do exactly to determine that it was definitely front focusing? Thanks.

I purchased through DC Expert (CR Kennedy's "unofficial" Online store) to ensure I got Australian Warranty. CR Kennedy are the Australian Distributers of Sigma lenses. Cost me $425.

Click on this link https://photography-on-the.net/forum/showthre​ad.php?t=750736 which one of the forum members kindly created.

You will see what is required and can print out the Chart that is shown in the link

Your perception of softness may be simply because the lens is not focusing on the correct spot. Increasing the depth of field (smaller aperture) merely "masks" this.

Wow, that is about the best example I have ever seen of a soft lens wide open. Soft and some funky chromatic aberration happening as well. If your going to re-test, do so with live view and zoom in 10x just to make sure you totally nail focus, but I'm not sure it's going to help a whole lot.

I've been to the CRK office in Sydney wanting them to calibrate mine too. But they want my body as well for 2 weeks which I am reluntant to do.

Besides, I think this is the design flaw of the lens, that is front focus in close range, back focus at longer range.

It's well documented and that's the nature of this lens no calibration can fix unfortunately.

Sample looks damn sharp @ f2.5, look treat it as a max f1.8 lens and you'd feel a lot happier

I would send it in for calibration..I have owned 3 copies of this lens and none of them were even close to that bad wide open..They were all pretty sharp at 1.4

In response to "I Like to Watch" Thanks. Yeah I was considering CR Kennedy and then forgot all about them and ended up winning the auction for this Sigma on ebay haha. Thanks for the link. Just did it then. I took photos at f1.4 and 5.6 just for the sake of it. I am pretty tired now so I'm sure I would have done something wrong, so please let me know what that was haha. I will redo this tomorrow if necessary (I only just realised the pieces of paper are far from being straight etc and have no time to set it back up again).

http://imageshack.us/a​/img405/7679/img2341vi​.jpg
http://imageshack.us/a​/img824/4219/img2342s.​jpg

gjl711 wrote in post #15713635
Wow, that is about the best example I have ever seen of a soft lens wide open. Soft and some funky chromatic aberration happening as well. If your going to re-test, do so with live view and zoom in 10x just to make sure you totally nail focus, but I'm not sure it's going to help a whole lot.

Haha yeah I was surprised (and disappointed) at its performance wide open. Unfortunately none of my DSLRs have live view (I was going to begin saving for a 6D but that may have to go on hold until I can get a low light prime figured out).

kin2son wrote in post #15713652
I've been to the CRK office in Sydney wanting them to calibrate mine too. But they want my body as well for 2 weeks which I am reluntant to do.

Besides, I think this is the design flaw of the lens, that is front focus in close range, back focus at longer range.

It's well documented and that's the nature of this lens no calibration can fix unfortunately.

Sample looks damn sharp @ f2.5, look treat it as a max f1.8 lens and you'd feel a lot happier

Haha well I'm glad you see it as being sharp as well. I'm just so surprised it's this bad at f1.4 if it's pretty damn sharp at f2.5

05Xrunner wrote in post #15713656
I would send it in for calibration..I have owned 3 copies of this lens and none of them were even close to that bad wide open..They were all pretty sharp at 1.4

Oh, haha, definitely seems that this lens has issues wide open for sure. Do you think sending it in for calibration would help a lot? Or would I be best off just trying to sell this one and try again or just purchase brand new?

if it still has its warranty I would send it in..you cant lose anything by letting them calibrate it and possibly update the firmware in it if needed. If it doesnt work for you after that then sell it for another

05Xrunner wrote in post #15713741
if it still has its warranty I would send it in..you cant lose anything by letting them calibrate it and possibly update the firmware in it if needed. If it doesnt work for you after that then sell it for another

Unfortunately it is no longer under warranty. I suppose I better try sell it then. I've only had it for about 8 hours Hopefully I won't get bombarded with requests of images wide open because then I probably won't ever sell it haha. I suppose I will list it tomorrow evening unless something else pops up in this thread etc.