RF 400, or EF 400 with adapter?

John Crowe wrote:

Well, you know more about RF than I do, and I have been shooting Canon for 35 years.

First I am shocked they are the same price. Canon usually prefers to gouge it's customers.

It is a large purchase to consider...not just the size of the lens. I have used mirrorless in the past so my main concern is how well you can adapt to how they work for sports. I will make that assumption based on it being the 400/2.8, and I am referring to the EVF. I would master the R5 first to evaluate how it is likely to perform with a big lens. This will also tell you how much you rely on the control ring. If you end up preferring an OVF then go with the EF and control ring adapter, and buy a used DSLR for those times when you prefer the OVF.

If you evaluate the R5 and determine that you are never going back to DSLR then I would chose the RF lens, with one caveat. It certainly looks like the RF 400/2.8 is not truly an RF lens. It seems to be an "affordable" stop gap until Canon themselves get used to the RF system and what they can do with it. I suspect that with continued success of the RF system that Canon will replace this lens before too long. Perhaps with even a 400/2.4.

If you chose the EF 400/2.8 I suggest purchasing a used IS II for half the price, see how it goes, and then resell it at almost no loss, when you see what Canon does with an updated RF 400.

I have used two old 400/2.8 lenses so I know they are all incredible! Any advantage that the current RF lens has over the EF will be virtually unnoticeable. It is the replacement for this RF 400/2.8 that could be the deal break

My experience with the R5 and the RF100-500 lens would cause me to be cautious in overlooking the improvements that may be possible in the RF400f2.8. I own an 16year old EF400f2.8L IS mk 1 which works very well even using the 20fps electronic shutter with R5. It is razor sharp and it is very sharp with enormously nice bokeh using F2.8 on a tripod It is a very heavy 12lb lens providing excellent results. So the prospect of me upgrade to the RF 400f2.8l IS is slight without me knowing a lot more information about the advantages it would bring. That is a lot of money it costs but it is more than 5 lbs lighter and maybe is handy on a monopod while my 12 lb EF 400f2.8L IS beast is not really a monopod friendly lens. I have relevant prior experience in the benefits of expensivie upgrading of my EF100-400 II to RF100-500 which was less upgrade expense than the RF400f2.8 upgrade but still a lot of money.

I have the R5 with the EF 100-400 II and I originally thought that RF 100-500 that I was not sure I would ever buy. I own the 1.4X III and 2.0X III TCs so as to upgrade to the RF lens I would need to by the RF lens and two TCs costing a lot of money.

Both the EF and RF are quite similar except for focal lengths covering 400-500mm, 1lb in weight. and reduces FL ranges during TC usage (RF100-500 becomes 300-500mm when using TC while EF100-400 remains 100-400). The extended reach of 400-500 and 1lb lens weight were both very attractive to me once I tried the RF lens which IQ of both lenses used at in the same conditions seemed very similar in sharpness and rendering. The RF was not better in IQ in any major way but likewise it was not worse than the EF 100-400 II. Weight and lens reach were the two initial benefits.

However, the R5 EVF has has a menu item (red camera, menu tab 7 #3 High Speed Display) that is an EVF enhancing function that is specific only to Mechanical and First Curtain Shutter modes only, requiring both Autofocus ON and the drive mode H (not H+). This High Speed display mode works only with RF lenses like the RF 100-500 and not EF lenses.

When comparing the EF 100-400II with the RF100-500 I tried to evaluate any benefits that the High Speed Display mode of the R5 had when using that is available using the RF100-500. I read did not note a big difference with the HSD menu item turned on or off. It was hard to tell there was a difference. However, when shooting BIF I felt that the RF 100-500 produced for me a higher keeper rate yielding sharper and better tracked images with HSD on or off. I do not if it was AF or my tracking skills assisted by lower weight that was responsible. It remains a mystery but convinced me to spend the money to keep the RF 100-500 and pay the big money for lens and the RF 1.4 and 2X TCs.

So what I thought I learned from this prior upgrade you may really need to get hold of the RF and EF lenses to them shoot with the same camera close to side by side as you can to accurately determine how you feel about each alternative. You can rent both lenses for a week maybe and do your tests. I was surprised by how my opinion of the RF lenses became even more favorable once I tried them and saw the images I could produce. I doubt I will be doing this any time soon for my case since my use for the 400mmf2.8 has been reduced because I am still exploring the benefits of using the wonderful RF 100-500 light weight action shooting on the R5.

The beneficial RF400f2.8 6lbs lens extra nice bokeh and f2.8 lowlight level sensitivity are reduced my interest in my use of this lens by my surprising RF100-500 shooting experiences. The grounding breaking low light sensitivity of the R5 used along with the software power of the DXO PL4 Deep Prime software act to reduce motivation and my needs for the benefit of the RF f2.8 lens over my existing proven performance paid for EF 400f2.8LIS..