Vignetting?

[Nick]

I've decided I'm done with full frame. Sending back the 5dII kit and 20mm f/1.8 tomorrow and going back to my trusty 60d.

But I'm really curious, what is causing the severe vignetting in the photos below? These were taken with my 5d MkII and Sigma 20mm f/1.8 lens with no filters. I've made no adjustments, they are straight out of the camera.

ISO 800, f/2, 30s


ISO 1600, f/1.8, 30s


Any of you photogs know why the edges are so much darker than the center?

 

[Yvonne]

is this only happening with your Sigma lens?

 

[Nick]

is this only happening with your Sigma lens?

Yep. I checked the night shots I did with the 24-105 and it's not nearly as bad.

 

[Yvonne]

Yep. I checked the night shots I did with the 24-105 and it's not nearly as bad.

I've never used a Sigma lens, but is it a specific lens only made for a full frame camera? Maybe that could be the culprit and the lens simply won't fit the larger sensor on a full frame camera?
I'm not totally sure, but I mean the Sigma has strong vignetting on a full frame camera with larger apertures.

 

[pixie1339]

Is it just the vignetting issue that made you decide against full frame or were there other things you didn't like?

 

[barl0w]

Is it just the vignetting issue that made you decide against full frame or were there other things you didn't like?

Yeah - that's a great question. Take a look at this review - says exactly what you are seeing, and that those with a crop sensor see considerably less vignetting:

http://www.the-digital-picture.com/Reviews/Sigma-20mm-f-1.8-EX-DG-Lens-Review.aspx

Moving on - Vignetting. The first line in the first paragraph of Sigma's 20mm lens web page claims "This super-wide-angle lens is ensured minimal light-fall-off with superior peripheral brightness." I don't know what they are looking at, but the Sigma 20mm f/1.8 EX DG Lens turned in some of the strongest vignetting I've seen - 5 stops in the full frame corners at f/1.8. The not-so-funny thing is, the Canon 20mm Lens turned in similar results at f/2.8 and remains over a full f-stop behind the Sigma in vignetting performance as it is stopped down. Full frame users will want to stop this lens down to at least f/4 or f/5.6 to get more even results. Users of 1.6x FOVCF bodies will likely not notice much vignetting.​

I would keep the body and look for another lens. The 60D though is a great camera - so do what you feel is right, although I'm sure you're loving the quality out of the 5DM2 at higher ISO's.

 

[Deadeye008]

I would say that's a lens issue and not the camera. I've never had vignette issues with my 5D classic. Sell the mkII and rock the classic like I do! Then you'd have some dough left over for a nice lens.

Sent from my HTC Sensation 4G using Tapatalk

 

[Bill]

Pretty sure that's common with the sigma 20mm when shooting between F1.8 and F2. Close it down beyond that and you don't see anything.

I took this last weekend with the 5d at F2

Highway 12 by Summit42, on Flickr

Dan Ransom 's Delicate shot with the same lens and a 5d (shot at F2)

Delicate Universe by megascapes, on Flickr

 

[markj]

Any time you shoot with really wide lenses on a full frame you will get vignetting. Some people even go to lengths to photoshop it onto their frames shot with a cropped sensor.