Sigma 20mm 24mm 28mm 1.8

Are any of these lenses good? I remember someone saying that the 20mm 1.8 was not that great.

I'm looking for a fast and wide prime on a budget.

I will be using it for low light portraits and Archatecture.

Will these work with a 5D?

I used 28mm F1.8, it is heavy and big, but image quality is quite good. The focus is ok. But I think my lens is a tiny bit front focus.

You may also want to look into the Canon 35mm F2, or the 28mm F1.8 for a little more.

ok thanks, Im assuming that the canons 28mm 1.8 has better low light AF abilities?

DG is for FF and DC is for crop in the sigma world, am I correct?

I have been looking into purchasing the sigma 24mm f/1.8. I have heard and seen the 20mm f/1.8 is not a very good lens, but the 24mm looks great! I have seen some amazing samples from it, and it will probably be my next purchase.

I've had the 28mm f1.8 on a cropped body and currently have the 20mm f1.8 on a 5D.

IQ wise, they are good, but not excellent. Where they excel in in giving good bokeh with a very close MFD, fast aperture speed, and nine round aperture blades. This may be a good thing for portraits but not that big of a deal for architecture, where you probably want a bigger dof. Unless you are a pixel peeper, what matters will be is it sharp enough for decent sized prints. It should be with good technique and proper processing/sharpening. IIRC, the 24/28 version is slightly sharper than the 20mm version. Having said that, comparing my 20mm against the 17-40mm f4L at 17mm, both stopped down didn't show any glaring difference between the two.

Their biggest downfall is the AF. The 28 and the 24 AF pretty bad. In low light you have to mainly use the center AF point only and focus on something very contrasty, or it'll have difficulties. The 20mm is much better and unlike the 24/28 version, it's front element does not extend with AF'ing.

If you are aware of the downsides of the lens and know how to get around it, it can be a fine lens. If you expect to put it on and perform like a 24mm f1.4L lens but at about $1000 less, then you're in for a big disappointment.

Here is a pop photo's review of them
http://archive.popphot​o.com …uperspeed-sigma-trio.html

I think digital picture.com has a review of the 20mm lens.

Any other issue about these lenses?

2.8orfaster wrote in post #9000261
DG is for FF and DC is for crop in the sigma world, am I correct?

Correct