Canon DO vs L series lenses

[Sean]

Hello all, my first post here

I'm curious, I happened to stumble across a Canon 400mm f4 DO lens when I was intending to read up on the Canon 400mm F2.8 L lens. I was wondering, other than the weight difference and f stop difference, is there anything different between these lenses? I hadn't heard the term DO (Diffractive optics for those that might not know, as I didn't until now) previously.

If anyone could shed some light that would be great. I'm not intending to buy the DO lens (or the L series one, for that matter... yet), but I'm curious about the differences, if any.

Thanks,

Sean

[McQ]

Hi Sean...welcome!

An L series lens works much like an ordinary non-L series lens, except it contains lens elements which are differently shaped (aspherical) or made of different materials (flourite, ultra-low dispersion glass, etc). These elements help control image quality reducing artifacts, such as softness, lack of contrast and chromatic abberations. An L series lens therefore generally has noticably better picture quality, and this improvement is often more noticable for situations that non-L series lenses have the most trouble: wide open or large apertures, extreme wide angles, etc. Other L-series improvements often also include better autofocus motors, build quality and lens coatings.

By contrast, a diffractive optics (DO) lens has a lens element that works by using an entirely different mechanism than ordinary (and L series) lenses. This special element has tiny concentric ridges on it that help direct the light using a property called "diffraction" -- hence the name diffractive optics (DO). I won't go into technical detail, but in a nutshell, these tiny ridges achieve a similar result as the more familiar convex-shaped lenses, but can be made much smaller and use much less glass. My understanding is that DO lenses (at least as Canon envisions them) are also considered their high-end models, so they can include most of the other fancy features that one might get with an L-series lens.

So what does this all mean to a photographer? Which is better? I think that when DO lenses were first announced, everyone got really excited and envisioned DO as the wave of the future for photography. However, as more and more results came in, I think that people started to see that DO, like any other photographic tool, has its unique assets but also its faults. The huge advantage of DO is that the lens can be substantially smaller and lighter than a traditional lens, which is an incredible asset for extreme telephoto photos in the field. However, many have observed DO lenses to be a lot more susceptible to flare, to have micro-contrast that isn't up to par with L-series lenses, and to render bokeh highlights with unusual concentric circles. In practice none of these are huge problems, and are often outweighed by the fact that DO often enables one to get a shot not otherwise possible with a much larger and heavier lens. Going hiking and doing wildlife photography is one such scenario where DO lenses excel. The biggest problem with Canon's DO lens right now is actually price.

I'm sure others will have more to share...

[Colin Southern]

I'm sure others will have more to share...

What could we possibly add to that

[Sean]

What could we possibly add to that

I would have to agree with Colin here, that was a great write up. Thanks for clearing it up!

[William W]

If anyone could shed some light that would be great. I'm not intending to buy the DO lens (or the L series one, for that matter... yet), but I'm curious about the differences, if any. Thanks, Sean

THIS POST HAS BEEN EDITED AS THERE WERE ERRORS OF FACT IN THE ORIGINAL.

In my first response to this question (yesterday) I added to Sean’s information about the optics outlining what I believed to be important differences between these two lenses which would render the F/4 not as suitable for sports and similar uses (apart from the aperture differences)

My first post was based upon information based upon working with Professional Sports Shooters and general conversation amongst that group, and my personal use of the EF400F/2.8L IS USM.

However, being somewhat a pedant to check original sources and not rely on “talk” I have since found much of what I wrote yesterday was incorrect, and I apologize for that.

From Canon’s Data, I can now write the following, (which interestingly contradicts the general perception within the circle of sports Pros I know – which has a large and credible profile – and a couple last night were “shocked” to know this information)

I shall make the corrections obvious by including my original post – If an Administrator , wishes to “clean it up” later to make it as one statement of fact for the record – that’s fine or if you want me to do so in a couple of days, just let me know.

The important thing, (for me) is to correct my error:

This is my original post and the corrections:

*** ***

Hi and welcome too

As well as the main difference in optics, making the F/4 DO IS shorter and lighter (which as explained might render the F/4 DO IS a selection for hiking / bush / birds etc) . . .

There are a few other key differences which are the reasons (apart from the F/2.8) why the F/2.8 is seen in the sports arena, and very few F/4 DO IS find there way into sports coverage.

THIS WAS BASED ON ASSUMPTION AND IT NOW APPEARS TO ME THERE IS SOME MISINFORMATION WITHIN THE RANKS OF SPORTING PRO SHOOTERS

Practical Differences rendering the 400F/2.8 more suitable for sports coverage, the 400DO IS does not have and the 400 F/2.8L IS has:

> Focus Preset 0.5secs (sample use: set focus at finish line – use AF for race– use preset for line shot)

THIS APPEARS TO BE INCORRECT: THE 400F/4 IS DO HAS A WHAT LOOKS TO BE PRESET TRIGGER ON THE FOCUS RING. BUT I CANNOT YET FIND WRITTEN DATA TO CONFIRM

> AF Stop Function (sample use: keeps field focused whilst onlooker walks in front of camera

)THIS IS INCORRECT: CANON DATA STATES THE 400F/4 ID DO HAS “AF STOP FUNCTION”

> L series Dust Proof and weather sealing (not sure what Canon say about any “weatherproofing” of the DO IS – but it is not have L Series seals).

THIS IS INCORRECT – CANON DATA STATES “a thorough going dust proof and moisture proof construction and can be used in the harshest weather conditions (when used with dust proof and drip proof camera bodies and tele-extenders)

> USM type LI - very fast (The 400F/4 DO IS has USM type MI – which is quick, but not as quick as LI version)

This is correct and corroborated by Canon data

IS differences:

The IS the 400F/2.8L IS incorporates Type 1 and Type 2 IS (OK for Panning) and Tripod IS.

The 400F/2.8L IS has an IS rating of 2 stops and the 400F/4 DO IS has an IS rating of 3 stops

These two statements are correct and are corroborated by Canon Data


I am not sure about the complete functionalities of the IS on the 400F/4DO IS, as I have not used the lens, but it is likely it has Type 1 and Type 2 but it might not have Tripod IS – if so the IS needs to be turned of when using a solid tripod – but on this last point, I stress I am not sure.

I suspect now the 400F/4 IS DO does have tripod IS - although I cannot find hard data to corroborate.


*** ***

Again, my apologies for the incorrect statements in my previous post; I suspect (and I mentioned) that there is an element of “snobbery” (for want of a better word) in many Pro circles (I am allowed to say that I think) – and my guess is within the fraternity of Pro Sports Shooters the 400 F/4 IS DO would “not cut the mustard” as a sports lens, and so assumptions are made and they develop into “facts”.

Personally I am quite glad for the knowledge this thread has given me, as I have been under incorrect impressions for a few years.

WW

[Colin Southern]

Hi Bill,

All looks good to me - no need to "beat yourself up" about it

I'm sure we all appreciate your honesty, effort, and above all else, integrity. You'd have made a great reporter!