Sigma 30/1.4 Focus test on distant objects

[Andy_T]

Hi all,

after some discussions with forum members who can't get properly focused photos with their Sigma 30/1.4 lenses over greater distances (> 5 meters), I was a bit anxious myself, as it was doubted that the lens is capable at all of getting properly focused distance photos.

So I performed a test with some of my lenses, the 30/1.4, the 50/1.4, the Tamron 28-75/2.8 XR DI and the EF-S 18-55.
So far, the results look very good.

I hope that this test is helpful for others considering the lens.

Target is some kind of antenna on top of the building across the street ... I guess something like 30 meters away.
All images are 100% crops that were shot in RAW and converted without sharpening ... so they look a bit soft (but sharpen up nicely).

First the Canon 50/1.4 and the Sigma 30/1.4 wide open and stopped down a bit:

http://gallery.photo.net/photo/4364294-lg.jpg


Stopped down to f/2.8 and f/4.0:

http://gallery.photo.net/photo/4364338-lg.jpg

At this aperture, the Tamron 28-75/2.8 and the EF-S 18-55 also contribute examples:

http://gallery.photo.net/photo/4364348-lg.jpg

And finally, stopped down to f/5.6 and f/8.0:

http://gallery.photo.net/photo/4364342-lg.jpg
http://gallery.photo.net/photo/4364352-lg.jpg

Best regards,
Andy

*EDIT* Sorry if you can not see the images. This is due to the fact that gallery.photo.net was just recently qualified as 'nudity' by www.securecomputing.net :(

[farrukh]

Yes offcourse, any lens will do soft wide open on distant subjects. so it is never been a focus issue.

[Andy_T]

Farrukh,

absolutely!

The results of the test are what I expected ... but with the Sigma 30/1.4 EX lens there have been discussions whether it is at all capable of getting sharp images of distant objects.

There were examples of incredibly blurry images - ok, this was taken @ f/2.0, so it was nearly wide open.

This is an example linked from the other thread My Sigma 30/1.4 conundrum (http://www.photography-on-the.net/forum/showthread.php?t=148693):
http://img.photobucket.com/albums/v130/GaryWGraley/EOS%2020D/30mm/Trouble/choir30_crop.jpg

Best regards,
Andy

[Gary W. Graley]

Andy that is a center crop so the blur is compounded by that, but it does
show that nothing is really sharp in that area.
G2

[One Eyed Jack]

G2. At first, after reading your continued posts on the problems you had with your Sigma 30mm f1.4, I like others started to think it was all in your head and you may have been the problem. No offence. I think this was mainly due to the fact that I really wanted this lens and talked myself into believing that there was nothing wrong with it. I do appologise as I was also basing my personal judgement on others opinions who were raving about it. Well I went and bought one.
There is no doubt that this lens is supurb close up. I couldn't have been more happy with the sharpness and colour that this lens produced close up. Enter the equation of distance! Whilst playing around with it at my sons chapel service I took a shot of some wording on a sign about 20 metres away from me. I zoomed in with the LCD to see how sharp my new toy was going to be. To my amazement I found not just the wording on the sign to be out of focus but nothing in the immediate area of my chosen focal point was either. I put this down to me having it set wide open at f1.4 as I was indoors and wanted to see the low light capabilities of this lens. I was using Av mode and so proceeded to test every f/stop down to f16 whilst also adjusting the ISO. Still with no luck.
This coupled with further tests both in and outdoors and at different distances led to only one conclusion. My copy of this lens was a dud! I wasn't prepared to go to the lengths that you did to have this lens repaired or recalibrated to my camera and so returned it for a full refund. :cry:
I really had high expectations of this lens but my first venture into Sigma teritory has left a bad taste in my mouth and a ? on future Sigma purchases.

[Gary W. Graley]

Thanks Peter, very sorry to hear of that for you, and as you, I also had high hopes for
this lens, still do I guess, as I can't afford the 35L....yet ;)
I can't wait to see how it works on its' return!
G2

[nadtz]

Indeed. I 90% of the time use my sigma indoors, Im thinking I might have this same issue. I noticed it first with a few outdoor shots while walking around one day, then again with strange focus issues while taking some pics in the subway. I might run around over the weekend and see how my sigma compares to the ops.

Just to ask, do you know about how far away you were focusing?

[benca1]

Thanks much Andy

[Andy_T]

Just to ask, do you know about how far away you were focusing?

Oops, forgot to give that one piece of rather important information.

The target is some kind of antenna mast on top of a house on the other side of a small street, guess it's something like 30-50 meters away.

This is the full image (view from my office), but with a different framing. The target is visible at the right top.

http://gallery.photo.net/photo/4372438-lg.jpg

I also did some shots with focus on the distant building (500-1000 meters away), but I haven't made the 100% crops yet. I just looked over the images, and the results are rather similar to the series I posted.

Best regards,
Andy

[wei328]

I had the Sigma 30mm for a week, did extensive tests against my 50mm f1.4 and 35mm f2. I shot with 3 lenses inside St patrick cathedral under low light condition. Using f1.4 or f2, over half the shots from the Sigma were misfocus, while the other 2 canon lenses had a much better success rate(80%).

The Sigma performs much better outdoor, short or long distance shots.
I really wanted to keep the Sigma, but it just didn't perform as well as the Canon.

[nadtz]

hrmm. I was asking because of some funkyness I found while taking

http://www.badtz.org/images/IMG_2690a.jpg

http://www.badtz.org/images/IMG_2691a.jpg

Focus on both was the no parking sign, and thats nowhere near 30-50 meters (as is obvious from the parts of the image in focus, something pretty strange was going on). I guess I will have to grab a tripod one of these days and compare the 35/2 and the 30 and see whats what. For the most part I love this lens, but Im not quite sure what it will do with distant focus subjects at this point. Thanks for the info and the images.

[Andy_T]

nadtz,

be aware that the focus area is actually bigger than the red dot in your viewfinder. It is well possible that the camera picked something else that yielded more contrast than the sign (e.g. the tree in front of the sign or the background).

I have found that it is generally more difficult to get a properly focused image than a blurry one, because there are just a lot more possibilities to foul up an image than to get it right :wink:

Best regards,
Andy