Quote Originally Posted by Fast Glass View Post
On the subject of big white image quality, I am surprised on two counts. The 800mm f/5.6 holds its own compared to the 600mm f/4 II and the 600mm f/4 III. And the mark III's IQ is not really an upgrade, depending on how much CA annoys you. God it must have been years since I've looked at these super telephoto charts.

I have found the III overall somewhat less sharp in many areas depending on which extender you use, but with less red and magenta CA. But it has this weird blueish/low contrast hue with extenders. Especially compared to the II and the 800mm. It probably would not be as noticeable in the real world because pics are not usually black and white lines. But you are not really gaining IQ with the III lens as a whole and defiantly loosing some with extenders.
Agreed. If I were to get a 600 right now it would almost certainly be the Mk II and not the Mk III. A lot of that would be for cost savings, but even trying to balance the performance with extenders advantage of the Mk II vs the weight advantage of the Mk III and ignore the price point difference, I might still go with the Mk II. Granted, I personally hand hold almost all my shots (even with the 500 f/4) but at 600/840/1200, I suspect that would be more of tripod mounted lens, thus the weight savings is more about lugging the bag around and at that point, I'll take the extra IQ.

I actually wonder why Canon released the Mk III versions of the 400/600. Part of me thinks it may have just been "me too" products showing the world that they can produce a low weight design similar (better ) to Sony. That or they were manufacturing trial balloons as Canon learned to move elements back toward the camera. And if you think Canon doesn't do that, just look at the entire EF-m system. But somehow they made it through before Canon shut the door on new EF lenses.

Quote Originally Posted by Fast Glass View Post
I would love to know why they discontinued it. It truly is a crying shame and I can't image it is because of lack of demand, relative to the almost certainly low production numbers to begin with. That lens was amazing on every level.
RF

That is the short answer. The longer answer, Canon does a very good job of producing what will sell and running their business. It could be as revered as the 200 f/2 is by many of us, it wasn't a very profitable lens. But, more, I suspect this tells us than an RF version is coming in the next 12 months and Canon might try to use it to encourage the RF lens conversion. But you have to think production of the EF 200 f/2 ceased awhile (years?) ago if they are running out of stock now. So, there is a plan.