Anybody got a Sigma 50 1.4 able to help me?

cuthbert

cuthbert

Pugh Pugh Barney McGrew Me Dibble and Grubb
Messages
2,042
Name
Mark
Edit My Images
Yes
well, i had this lens about a year ago and returned it because it was a grey import and had focus issues (seemed ok at the start, then became very indecisive), and i spent the money on something else.

anyway, i was asked what i wanted for crimbo and a sigma 50 1.4 still tugged at me, i love the way it frames on a full frame camera, it's a very natural fov that's great for indoors. i intend to use this lens for close ups and intimate portraits.

but i'm not sure if this lens is a duffer too.

i've set it at +15 mfa and it still seems a bit off. even up to +20 it doesn't seem quite right.

this is a 100% crop from under the centre focus point.

6555496113_c2910a4211_b.jpg


the focus itself seems consistent, contrary to many peoples experiences - am i just expecting too much? i've probably been spoilt by the 135 f2 and sigma 85 which are very sharp wide open.

if any of you guys could share your experiences or post an crops with the lens used wide open in a real world photograph it will at least enable me to decide weather my lens is typical or it's faulty.

Here's another test:

6555554429_ffbff34d84_b.jpg


crop

6555564547_bff9182b32_b.jpg


what do you think?
 
Last edited:
cuthbert said:
well, i had this lens about a year ago and returned it because it was a grey import and had focus issues (seemed ok at the start, then became very indecisive), and i spent the money on something else.

anyway, i was asked what i wanted for crimbo and a sigma 50 1.4 still tugged at me, i love the way it frames on a full frame camera, it's a very natural fov that's great for indoors. i intend to use this lens for close ups and intimate portraits.

but i'm not sure if this lens is a duffer too.

i've set it at +15 mfa and it still seems a bit off. even up to +20 it doesn't seem quite right.

this is a 100% crop from under the centre focus point.

the focus itself seems consistent, contrary to many peoples experiences - am i just expecting too much? i've probably been spoilt by the 135 f2 and sigma 85 which are very sharp wide open.

if any of you guys could share your experiences or post an crops with the lens used wide open in a real world photograph it will at least enable me to decide weather my lens is typical or it's faulty.

Here's another test:

crop

what do you think?
Click to expand...

I can have a look in a few days but it wraped under the tree at the min. sorry for not being any help..
 
Last edited:
thanks for that Tristian.

I've done some fairly methodical testing tethered, on a tripod at various distances.

I'm still not sure if this is a characteristic of this lens or whether mine is faulty:

i need to apply varying amounts of MFA depending on subject distance.

At around 20 x focal length it needs +10 to be spot on, at around 50 x focal length it needs about +15

This is perhaps why, in my earlier post it just didn't seem right whatever MFA setting i applied the front focus isn't consistent.

I'm tempted to send it back and not bother anymore and save my pennies for the 35L instead.
 
Last edited:
It should be sharper than that. I bought on and it needed more than the 20 points allowed in camera so I took it back. The replacment had focus inconsistency issues so I just replaced it with a Nikon.
 
I've haven't use this lens properly but my friend have this Sigma 50mm f1.4 HSM on his Canon 7D and i did play around it.

Wide open the lens is still sharp and it shouldn't see any soft focus at all and from f2.0 onwards its dead sharp.

I think you may have a bad copy .......

I not sure tho.
 
I have one of these, I don't think it's razor sharp at f1.4 and on bright subjects you can get some blooming... anyway, just shot this little test for you...

Whole image with focus on "23," hand held.

IMG_8402c.jpg



100% crop...

IMG_8402c1.jpg


These are via photobucket and I haven't done any optimising, just in and out of CS5 with whatever defaults it has.

If you want any real world shots I'll hunt some out and post a few later.
 
Last edited:
Thanks for that Alan, your lens is clearly sharper than mine.

My testing was done tethered, on a tripod.

Using EOS utility (as you can see below), I focused on a target (which i took great pains to ensure was aligned perfectly and flat).

I clicked the '>' button and counted the number of button presses needed until the image was as sharp as possible.

I focused the lens to infinity and did this again. I got the same value. I did it about 5 times and got the same value.

I compared this sharp as possible image in photoshop by pasting them onto layers with the focused image acquired by live view and faded between them - hardly any difference.

I then dialed in the MFA value, which was 10.

I repeated this at least 15 times, refocussing the lens to infinity each time.

The results, at the same subject distance were very, very consistent. The lens probably only misfocused only very slightly once.


6558955477_3290669e9e_b.jpg


6558956393_8eaa5ddbf6_b.jpg


I then took the camera outside and snapped away... i uploaded the images and quite a few are out of focus. I accept these shots were taken handheld and wide open and I'm not saying for a second that i'll get all the shots in focus, but I use an 85 1.4 and a 135 f/2 - my technique is fairly good and i'm used good hit rate, even with children and these shots were taken on static subjects.

So I retry the test as above. Focus is fine.

I then move the camera closer to the subject (about 1.5m away) tethered, on a tripod still target aligned and flat.

There's the problem - at closer subject distances, the MFA which i applied wasn't enough, at that particular distance +15 was needed to get the same level of sharpness as above.

It seems the closer you move to the subject, the more the lens seems to front focus. At near to MFD, the amount of front focus can't be corrected in camera - it's too great, the focus point is clearly 2 or 3mm in front of the focus point (even with +20 mfa applied) at these distances and live view focussing nails it each time, so i at least have a sharpness benchmark at that distance.

i'm a bit disappointed because i *love* the character of the lens, the soft corners add such a dreamy surreal quality.
 
Last edited:
cuthbert said:
The results, at the same subject distance were very, very consistent. The lens probably only misfocused only very slightly once.
Click to expand...

I think that you have to keep in mind that focus isn't just the lens. Canon themselves say on their website that if you take three shots you may (I can't remember if they say "may" "might" or "will") see focus differences between them and that this is normal.

When I think I'm pushing things to the limit I try and take more than one shot so that I can pick the "best." With the best will in the world and the best lens and the best techique your camera is also going to give you different results.

Such is life.
 
The depth of field on a close focus subject at f1.4 is only a few mm.

I found it hard to nail it right with my 5D mk1 when close focusing.

But I don't use a tripod much.

Have a look at the last few sets on my Flickr (link on my sig). I only use a Sigma 50mm f1.4 now, all the exif data is there.

Might give you an idea of my results etc
 
Thanks for that Gaz.

I think, along with shots from woof woof, it's perhaps fair to say I've either been unlucky twice or that particular lens works least well on a 5d2. I'm on an iPad, but even on its small screen those shots look better than from my lens.

I am a bit frustrated by it all, as I really do love the shots it takes, but it did make me realise and reevaluate my camera bag and I've gone for the 35L. I hope them guys at amazon fulfilment get to work soon :-)
 
How did you get on Mark? did you send it back or get it recalibrated?
 
You must log in or register to reply here.
Back
Top