28mm f/2.8 vs. 28mm f/1.8

I searched the archives, but couldn't find any direct comparisons. I just got the Canon 28mm f/2.8 and I am really disappointed by the (lack of) corner sharpness at the largest aperture. The center of the lens is capable of delivering a sharp image, but the corners are almost unusable - very very blurry. I wanted to use this lens on my 5D for low light photography, but the quality won't do. How does the f/1.8 version compare to the f/2.8. I have read so much about the performance issues of the 1.8 on FF cameras, that I shied away from it, but now I feel that I made a mistake (not a big one, as I only paid $50 for this lens). Thanks for any and all help.

I would go with the f1.8 lens. We're talking 1-1/3 stops faster. And speed in a prime is where it's at.

5Dmaniac wrote in post #6560436
I searched the archives, but couldn't find any direct comparisons. I just got the Canon 28mm f/2.8 and I am really disappointed by the (lack of) corner sharpness at the largest aperture. The center of the lens is capable of delivering a sharp image, but the corners are almost unusable - very very blurry. I wanted to use this lens on my 5D for low light photography, but the quality won't do. How does the f/1.8 version compare to the f/2.8. I have read so much about the performance issues of the 1.8 on FF cameras, that I shied away from it, but now I feel that I made a mistake (not a big one, as I only paid $50 for this lens). Thanks for any and all help.

For low light photography, most of the time it is about the centre of the image, so this shouldn't really be a problem in most cases.

However, on a 5D, this lens starts shining at F/5.6, whereas a 28 F/1.8 starts a little sooner. Even with this lens on a 5D you need to stop down to get very sharp corners. However, it is very usable from about F/2.

If you want better performance, you may want to consider the 24L. It is very good at F/1.4, but even here the corners are a little soft at F/1.4 on FF.

With WA lenses there is always some fall-off at the edges and corners, and this will show up more strongly on FF than it will on APS-C, using the same lens of course. Note that the sharpest and best WA lenses often have maximum apertures of F/2.8 or even smaller, and still command quite a premium. It is hard to make a (relatively) fast WA that is qualitatively as good in the corners as it is in the centre, and this is caused entirely by the combination of rectilinear image projection and large AoVs in the first place.

Kind regards, Wim

The 28mm 1.8 is much better than the 2.8 version. I had the 28mm and it was about the same as your copy. Good (but not excellent) centre sharpness when wide open, but the corners were very poor. For a prime, I expected more... some of the zoom lenses I had (e.g. Tamron 28-75, also f2.8) were much better than the 28/2.8.

It's better than the 28/2.8 but the corner sharpness wide-open isn't satisfactory either - and I'm talking on a crop camera. On a FF, I would imagine it wouldn't be too good. For that reason I got myself a 35L and the difference of course is phenomenal. I still kept my 28/1.8 since it is so light and makes for a great street lens. You might want to take a look at the Sigma 30 f/1.4.

Edit: Forget the Sigma. I'm a spazzo since you said you were on FF.

I understand the issue with wide lenses and the light fall-off - but the 2.8 is just horrible in the corners. I usually shoot landscapes and I use my 17-40 and 25-105 mostly for that. But I love the nifty fifty and the 85 f/1.8 and wanted a fast wide angle lens as well. On the other hand, I don;t use it often enough to justify the 35L or the 24L - that's why I was looking at the 28mm lenses. The Sigma 39 f/1.4 is for crop sensors only AFAIK and not an option. Thank you all, I guess I will give the 28 f/1.8 a try!

Ah, the dark side of primes. We all chant the mantra "Fast Primes for Low Light" but the truth is that many (most) primes are not all that sharp wide open. My 50 f/1.4 is soft at 1.4. It's OK in the middle but soft at the corners. If I stop it down to 2.0 the center and about 1/2 way to the corners becomes pretty sharp. By f/2.8, the corners are looking pretty good and I finally have a truly sharp lens. My 85 f/1.8 is similar.

Oh, and I'm shooting APS-C so the corners would be worse on your FF camera.

My primes are still very useful lenses, I just need to know that I can't expect great sharpness until stop down a couple of stops.

I am able to get the EF 28mm f/2.8 for a very cheap price (~$125). What do you guys think? Is it worth it?

i've posted this before but this was taken with the 28 1.8 at f/1.8 on a 5d

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Icediamond wrote in post #6684841
I am able to get the EF 28mm f/2.8 for a very cheap price (~$125). What do you guys think? Is it worth it?

not a bad price but also not a lens i would want. if i were to settle for an inexpensive f2.8 prime i'd be looking at the 24 f2.8.

ed rader

The 28 1.8 is a lot better than the 28 2.8. I had the 1.8 version and it was really good - even wide open. Extremely good at f/2.8. USM, FTM, and close focusing make it all in all a terrific wide angle prime on the 5D.

Thank you guys for all the answers - I will buy the 28 f1.8 and sell the 2.8. As I said before, I cannot justify the 35L, as I would not be using it enough.

My 28/2.8 is a turkey lens- I have it, and enjoy using it for happy snaps at f/2.8, but I'd never use it for serious photos.

Just my 2 cents, ut I have the 28 2.8 and hate it. It's pointless. I have the 24-70 and I think I've put this thing on my cam maybe twice. If you're going prime, get the 35L 50L, 85L or 24L...those are things dreams are made of!

For those that shoot the 28 f/1.8..........

CA is horrible on this lens (according to the statistics)

My question: Do you have to do much PP after shooting to eliminate the CA or is CA really not that much of an issue?

I would love to use the lens, but I do not believe in PP after the fact.

Your comments, please, and thank you.