The Canon FD 20mm 2.8 is an affordable wideangle lens (around $200 mid 2015) which performs well on the Alpha 7. I have owned and used my copy for more than a year now and wanted to share my experience with you.
|CANON FD 20 2.8|
|Short focusing distance||25cm|
As far as I know Canon made two mechanically different 2.8/20 lenses which share the optical design but I have no good source about Canon FD lenses to back this up.
- The older FD version has the classic silver breech lock mounting system and weights 345g.
- The newer nFD version is 40g lighter and has the newer nFD mounting system. I own this version
I would prefer the nFD version because it is 40g lighter than the older version and it might have better coatings.
Size, Weight and Handling
I think the 2.8/20 is well balanced on the a7. At 305g it is a little heavier than your typical 1.4/50, it is also a bit longer and has significantly larger diameter at the front.
The focusing ring turns about 130° from the short focusing distance of 25m to 1m and a further 30° to infinity. Focusing is smooth with a pleasant resistance.
The aperture ring of the Canon has a higher resistance than I would prefer and the lens stops down in half steps to f/22.
The barrel of the lens is made from metal and some parts like the aperture ring and the plate around the front of the lens are made from plastics. By todays standards this is a rock solid lens but some older lenses feel a bit more solid.
The front ring rotates as the lens is focused which makes the usage of polarizers a bit of a pain.
Flare resistance is not a strength of this lens. You can get very obnoxious flare like in this sample:
This does not mean that any image with a brighter light source shows ugly flares, here is another example:
The lens does not lose much contrast in backlit situations.
At f/2.8 vignetting is very noticable, by f/8.0 it’s gone for all practical purposes.
For a 20mm lens it’s probably okay but it can be distracting, especially in the corners. Specular highlights have a very defined brighter outer ring.
The lens has lots of coma, you can even see it in the small image below.
There is a significant amount of lateral CA and you want to correct that.
f/2.8: The lens is sharp in the central area covering about 40% of the frame. The cornes are actually not that bad resolved but contrast is very low and there is lot’s of coma and saturation is very low as well. I hardly ever use this aperture.
f/4: Still only the center of the image is usable but the performance is very good there. There is less coma outside of the center but it is still very notable.
f/5.6: very good sharpness across 90% of the frame with a very notable drop in the far corners.
f/8: Very similar to f/5.6 with a small gain in the corners.
At f/11 the Canon is sharp across the frame, only the last few pixels are soft. This is my default setting for this lens.
The lens shows some field curvature but in my experience that works in my favor more often than not. For best corner sharpness I would recommend to focus the edges, not the center.
From time to time I have noticed a hotspot in images with my Canon FD 2.8/20, it was only in a very few images mostly at sunset but it can be a bit annoying.
I have no personal experience with other 20mm lenses but from what I have read online these lenses have a good reputation:
- Olympus Zuiko 3.5/21: s very small and users report good across the frame sharpness at the expense of a little less sharp center.
- Voigtländer 3.5/20: another very small lens with good performance at f/8 and because it is a modern lens it seems to be very flare resistant. I plan to test one in the future but it is a bit more expensive than the FD.
- Voigtländer Ultron 1.8/21: a M-mount lens which is faster and much better in the f/1.8-f/4 range. Modern coatings will also help with reflections. In the F/5.6-f/11 range performance is very comparable to the FD 2.8/20, only vignetting is still noticeable at f/8 and there is a slight color cast.
- Zeiss 2.8/21: a legend of a lens with very good across the frame sharpness from f/2.8. It is large heavy and expensive though.
- Sony FE 4/16-35: the Sony is more flare resistant and performs well from f/4. The larger zoom range and OSS are also handy. But it is bigger, heavier and much more expensive. At f/11 the Zeiss has a little more contrast but less details in the corners.
The Canon FD 20mm 1:2.8 has it’s limitations: You will want to avoid f/2.8 for almost any allpication and you need to stop down at least to f/5.6 for good across the frame sharpness and the corners are best at f/11. The mediocre flare resistance can be a bit limiting and other 20mm lenses are smaller.
In the field it usually delivers a very good performance, at f/8 or f/11 my images are very sharp, contrast and colors are nice. The corners are a little sharper even than the much more expensive Sony 4/16-35 ZA OSS.
SoI think it is a very interesting lens for anyone on a budget.
Sample Images Canon FD 20mm 1:2.8
You can find more full resolution images in this flickr set: Canon FD 20mm 1:2.8
- An introduction to manual lenses on the a7
- User-Guide to Canon FD lenses
- User-Guide to wide-angle lenses for Sony a7 a7ii a7rii
- User guide to Ultra Wideangle lenses for the Sony Alpha 7 series