Are "Faster" L series lenses necessarily better?

[Bob Stovall]

I've always heard that faster lenses are better, and to always buy the fastest lens I could afford, but I'm seeing some chatter that this may not always be better. Some discussions I have been listening to says not to bother purchasing "L" series lenses because I won't see much of a difference for video. Most have said if I were shooting that wide open, I would have such limited DOF that focus would be challenging for video. Are APS-C lenses better options for the 7D? I noticed Canon manufactures zero "L" series APS-C lenses. I would love to hear some discussion about choice of lens and if more expensive is always better.

[Thomas Horton]

There are really nice/fast Canon APS-C lenses available... Not quite as rugged and weather (dust) proof as the robust L series full frame lenses, but would be just fine (example - EF-S 17-55 f/2.8 IS USM)..

Tama!

[Ray Bell]

well you can always dumb down a crisp "L" type footage...

but you can't dumb up a soft "non L" type footage...

Build quality, dust/moisture sealing on some lenses, better aperture blades for better
out of focus backgrounds on some lenses... most come with a lens bag/shade
better coatings

and they hold their value better if you ever have to sell them.

of course there are other " non L " lenses to consider... like the Zeiss ones

[Bill Pryor]

In the past, faster lenses were not considered as sharp as equivalent slower ones. I always bought the slower Nikkor lenses (back in the pre-AI days) because they were better. But that was years ago. Possibly today the faster ones are as good, but I wouldn't know without a side-by-side test. You do read lots of reviews where people say the zooms get sharper when stopped down more but that wide open they're still OK.

The night footage we've seen from the 7D shows that you can use faster ISOs than you might think, so if you're in very low light conditions, you can probably live with the slower lenses, up to a point.

[Thomas Horton]

I second Ray on the aperture blades.. The L lenses tend to have more blades (typically 8-blade aperture as opposed to 6 or less) than the less expensive lenses. More blades = smoother circular (rounded) edges on out of focus objects.. The EF-S 17-55 f/2.8 IS USM could almost be considered an L series lens (circular 7-blade aperture), except that it's APS-C and not as rugged of casing and dust tight...

Tama (take 2)!

[Michael Maier]

The thing is that new Canon glass is VERY expensive compared to great older FD lenses, which were really as good as the new stuff. But you can't use FD lenses on EF cameras. So I think the best bang for the buck is going with Nikon lenses. You can get older manual Nikons that are as good as Canon L series for much, MUCH cheaper. All you need is a simple and affordable adapter.

[Terje Rian]

It's hard to give an ultimate answer to your question. It depends what you're shooting and what "picture characteristics" you're after. If you manage to shoot an elephant's flirtation with a giraffe nobody cares about what type of glass you're using. But if you where to shoot ie interior design I would recommend you to get the best possible glass for the job at hand.

Don't forget that you've also got a brilliant photo camera. Make your investment more valuable! In photography you really see the difference between lenses. I would rather buy one quality lens then three or more not so good one's. I started with the usual collection of APS-C lenses, but I've upgraded every single one of them (due to the fact that I've been a happy owner of a Canon 5D for several years. Now I use the Mark II). With the introduction of the Canon 7D I wouldn't mind buying one or two APS-C lenses. Some of them are really great lenses.

Now I've got a good set of quality lenses after year's of doing photography, so for me the switch to DSLR film making hasn't been too troublesome. During a recent lens test shoot I found that every one of my lenses where useful. They have of course their own set of characteristics which I need to learn to utilize. Know your tools, is the most important investment you can make, I believe. The best answers you get by testing for yourself. Only you know what's good (enough) for you.

A tip: In the latest FXPHD term (fxphd - visual effects and production training) they deal with DSLR film making (both Canon and Nikon, but more focused on Canon) and all the aspects involved (lens choices, shooting style, codecs, audio, post-production and more). I can recommend this course for anyone interested in DSLR film making. As always the equipment only get's you half way there...

Good luck with your DSLR film making.

Best wishes,
Terje Rian

[Don Miller]

'L' means "Luxury" and designates advanced technology used in making the lens. Canon isn't claiming that all 'L' are better than non-L.

The 85 1.8 is non-L but certainly produces an extremely good image. For the price of the 85L MKII one can purchase the 85 1.8, the 135L, and the 50 1.4. Which is better?

The question of "better" doesn't mean much without specific needs and focal lengths. But in general, the reason to buy an 'L' prime is to shoot within a stop or two of wide open. By F4 or so most Ls would have little advantage over much less expensive alternatives.
As far as zooms, Canon hasn't put an 'L' on an APS-C lens because they haven't designated that sensor size as fully professional. This has more to do with Nikon than with the quality of the equipment.

The best APS-C lenses are very close to 'L' quality. The 17-55 on the 7D is the practical equivalent of the 24-70 L on the 5D. The 24-70 may have an extra one or two fancy lens coating, but in real shooting there would be little difference.

Since the standard zoom is usually used the most, I feel that money should be first spent on that item.

[Daniel Browning]

Originally Posted by Bob Stovall

I've always heard that faster lenses are better, and to always buy the fastest lens I could afford, but I'm seeing some chatter that this may not always be better.

The chatter is correct. The faster lens is often worse in some ways. For example, the 50mm f/1.8 has higher contrast, resolution, and less chromatic aberration than the 50mm f/1.2, when both are stopped down to f/2.8. This despite the fact that the 50mm f/1.2 costs 16 times as much as the f/1.8! Of course, the f/1.2 has many other advantages that are useful even at f/2.8 (focus ring, bokeh, build, etc.).

Originally Posted by Bob Stovall

Some discussions I have been listening to says not to bother purchasing "L" series lenses because I won't see much of a difference for video.

As others mentioned, there is the difference in bokeh, distortion, flare, and a few other things that can be visible even in a small web-sized video.

But as far as contrast and resolution, there's some truth to the discussions. As long as the cheap lens can hit 80%+ MTF at Nyquist, you wont see a difference in contrast or resolution. But even on the 5D2 that can be a hard target to hit, because the row skipping moves the Nyquist from 1080p (18 lp/mm) to 54 lp/mm (using 2.5 samples per line pair, you can pick 2.0 or 3.0 if you prefer). On the 7D it becomes even more difficult, because instead of having 24mm Picture Height, there's only 15mm. That means 1080p on the 7D, if there were no row skipping, would be 29 lp/mm. Already that's much higher than 18 lp/mm on the 5D2, but once you add row skipping to the mix, you're up to 86 lp/mm. Very few inexpensive lenses can hit even 50% MTF at 86 lp/mm. But most of the time it doesn't really matter if an L lens has more contrast, because they cost so much more.

Originally Posted by Bob Stovall

Most have said if I were shooting that wide open, I would have such limited DOF that focus would be challenging for video.

That's true, but limited DOF is almost the entire point to DSLR video (almost). Without it, there is no low light advantage, and the image will be awash in aliasing and compression artifacts.

Originally Posted by Bob Stovall

Are APS-C lenses better options for the 7D?

Many times, yes. For example, the Tamron 17-50 f/2.8 is less than half the price of the 16-35 f/2.8 L, yet it has higher image quality.

Originally Posted by Ray Bell

The question of "better" doesn't mean much without specific needs and focal lengths. But in general, the reason to buy an 'L' prime is to shoot within a stop or two of wide open.

It's a travesty to have all that aperture go to waste. The 50mm f/1.2, for example, has intentionally undercorrected spherical aberration that gives it milky smooth bokeh at f/1.2. But if you stop down to f/2.8, all that goes away and the bokeh becomes clinical and boring like other lenses.