Home  Donate  New  Search  Gallery  Reviews  How-To  Books  Links  Workshops  About  Contact

Canon 28mm f/1.8
© 2007-2012 KenRockwell.com

Please help KenRockwell..com

Canon 28mm f/1.8

Canon EF 28mm f/1.8.

I got this one here. Here and here are also great places I would use personally. It helps me keep adding to this site when you get yours from these links, too.

More Canon Reviews

Back to where you were in the main Canon 28mm f/1.8 Review

Back to the top of the Canon 28mm f/1.8 Review

 

July 2007

 

SHARPNESS and COMA   

back to Performance or back to Introduction.

It's very sharp, as expected. Also, as expected for a wide lens with a fast aperture, it's a little soft wide open.

Even at f/1.8 it's great for hand-held low-light shooting, but if you're shooting test charts or astronomy, stop down to f/2.8 or spend $1,000 on an L lens like the 24mm /1.4L, 35mm f/1.4L or the Nikon 28mm f/1.4 on a Nikon if you need perfect sharpness wide open.

For regular photography, don't worry: it looks great at every aperture, and if you want perfect test sharpness, shoot at f/2.8 or smaller.

The low contrast wide open comes from spherical aberration, which means that there is always a sharp image, but a veiling haze appears over it wide open.

Stopped down to f/2.8 it's fine for astronomy, too. Here are stars in the moonlit sky.

Four Seasons

Resort by Moonlight. Canon 28mm f/1.8 at f/2.8, Canon 5D at ISO 800, 8 seconds.

Here's a complete guide image from my full-frame Canon 5D, from which I will show you crops.

Full image, Canon 28mm f/1.8, full-frame Canon 5D.

 

Center

Here are crops from the center of the above image at 100%. Remember, the complete image printed at this same magnification would be 44" (1.1m) wide:

Canon 28mm f/1.8 at f/1.8, crop from center of 100% image.

See the slight veiling? That's what happens if you're dumb enough to shoot at f/1.8 in broad daylight. In dark situations where you'd really use f/1.8 hand-held, it looks fine. This is normal and the sort of thing you'd probably never notice until you owned the lens 5 years, then if you saw it for the first time you might worry. Not to worry; this is what this lens does.

 

Canon 28mm f/1.8 at f/2, crop from center of 100% image.

Even stopping down 1/3 stop to f/2 improves the image.

 

Canon 28mm f/1.8 at f/2.8, crop from center of 100% image.

By f/2.8 the center of the image is perfectly sharp, so long as your subject is within the small depth of field at f/2.8.

 

Canon 28mm f/1.8 at f/4, crop from center of 100% image.

This shot's for free: the image is as sharp as it's going to get by f/2.8 in the center, so f/4 looks the same. Diffraction will start to soften the image at f/11 and smaller, as it does on all lenses.

 

Top Right Corner, Full-Frame

Here are crops from the top right corner of a full-frame image at 100%. Like all wide lenses, performance gets worse as one gets further away from the center, so the corner of a full-frame image is the toughest test. It will be better on a 1.3x (1D Mk III) and much better on a 1.6x (Rebel and 30D) image.

Canon 28mm f/1.8 at f/1.8, crop from top right of 100% image.

This is softer due to the veiling of the spherical aberration, but notice that there is a sharp core as well. The details are here, hiding behind lower contrast. It's also a bit darker in the corner due to the slight falloff.

 

Canon 28mm f/1.8 at f/2, crop from top right of 100% image.

Stopping down a third of a stop to f/2 is an improvement, both in improving falloff and sharpness.

 

Canon 28mm f/1.8 at f/2.8, crop from top right of 100% image.

f/2.8 is much better than f/2, but since we're in a far corner, still not as sharp as in the center at f/2.8.

 

Canon 28mm f/1.8 at f/4, crop from top right of 100% image.

By f/4 even the corners are great. f/2.8 is all you need for perfect sharpness, but if you're looking at it with a microscope like this, then stop down to f/4.

 

Coma

Coma is what makes points of light in the corners look like blobs or comas instead of points. If a lens has coma, it's visible at only the widest apertures. Coma is caused by spherical aberration.

The Canon 28mm f/1.8 has pronounced coma at f/1.8 and f/2, and it goes away at f/2.8.

Full-frame image, Canon 28mm f/1.8 at f/1.8 for 6 seconds, 5D at ISO 200.

See what looks like Saturn in the upper left along the top edge? It's actually Jupiter, and should look like a point, not a blob. The huge bright thing is a 12 day old moon (3/4 full). The blobs at the bottom left and right also are not as we'd like them. These blobs are coma.

 

Full-frame image, Canon 28mm f/1.8 at f/2 for 8 seconds, 5D at ISO 200.

Stopping down a third of a stop to f/2 is a small improvement.

 

Full-frame image, Canon 28mm f/1.8 at f/2.8 for 16 seconds, 5D at ISO 200.

By f/2.8 the coma is gone, hooray!

 

Full-frame image, Canon 28mm f/1.8 at f/4 for 32 seconds, 5D at ISO 200.

f/4 is even a little better, and as you can see under Sunstars, the little points of light are starting to grow points. Jupiter now looks a little bit elongated, but that's due to Earth movement making it appear to move towards the lower right, This longer 32 second exposure brings that out.

Back to where you were in the main Canon 28mm f/1.8 Review.

Back to the top of the Canon 28mm f/1.8 Review.

 

Help me help you         top

I support my growing family through this website, as crazy as it might seem.

The biggest help is when you use any of these links when you get anything, regardless of the country in which you live. It costs you nothing, and is this site's, and thus my family's, biggest source of support. These places have the best prices and service, which is why I've used them since before this website existed. I recommend them all personally.

If you find this page as helpful as a book you might have had to buy or a workshop you may have had to take, feel free to help me continue helping everyone.

If you've gotten your gear through one of my links or helped otherwise, you're family. It's great people like you who allow me to keep adding to this site full-time. Thanks!

If you haven't helped yet, please do, and consider helping me with a gift of $5.00.

As this page is copyrighted and formally registered, it is unlawful to make copies, especially in the form of printouts for personal use. If you wish to make a printout for personal use, you are granted one-time permission only if you PayPal me $5.00 per printout or part thereof. Thank you!

 

Thanks for reading!

 

 

Mr. & Mrs. Ken Rockwell, Ryan and Katie.

 

Home  Donate  New  Search  Gallery  Reviews  How-To  Books  Links  Workshops  About  Contact