Review: Is the Canon EOS RF 70-200mm f2.8 or f4.0 a better choice for R5 studio photographers?

Earlier this summer, when I switched over almost all of my lenses from the EF mount to the RF mount, after buying the Canon EOS R5, I made an assumption that the 70-200mm f4 would be just as sharp as the 2.8 version in the studio at f5.6 to f8. Of course I was being cheap and this lens is normally my second or third choice for portrait photography as I prefer to use my RF 85mm 1.2 most of the time. Well today I’m going to put that miserly assumption to the test and I’m going to discover weather or not I made a mistake back then and if I need to buy myself, well, a new Christmas gift!

Canon RF 70-200mm f/4L IS USM Lens
https://amzn.to/3IfASj7
https://adorama.rfvk.net/9Wz5MQ

Canon RF 70-200mm f/2.8 L IS USM Lens
https://amzn.to/3lAvIED
https://adorama.rfvk.net/MXRLnN

A Digital Picture Test Results:
https://www.the-digital-picture.com/R...

ROUGH TRANSCRIPT:
Most everyone reviews lenses on Youtube by comparing the choices wide open but in the studio that is seldom the way I shoot, so I wanted to discover the results and to provide them to everyone else who shoots stopped down. Last year I made a video comparing 85mm choices and that one ended up costing me $2200 so to say the least, I’m a little nervous that todays results will end up costing me more money!

When I tested out those 85mm lenses, I discovered that they were their sharpest at between 5.6 or f8 so my assumption is that 2.8 lens would be sharp at about 5.6 and the F4 lens would be sharp at around F8. The reason for this is that stopping the lenses down to the middle of their aperture range usually result in the sharpest image, so if we stop down both lenses two stops, I would assume we’d be in The Sweet Spot or close to it. Of course we're going to put that to the test today!

We’ll check the Bokeh and Chromatic Aberration first, then we’ll check the sharpness at every stop on a close up and then we’ll see how they compare in two real world portraits.

So for our first test let’s evaluate the Chromatic aberration and bokeh. My lovely model Sia has agreed to sit here patiently while I l look at every major stop and a few in between from 2.8 to f16. At both 70mm and 135mm.

Starting off at 70mm with the 2.8 lens at 2.8 you can see the bokeh on the edge is a little oval and you can see that the image is Chromatic aberration free, even zoomed in here at 100%.
Stopping down now at 3.2 and 3.5 the results are unchanged. As a total disclaimer, this is not a scientific test, just a practical one. The Digital picture.com tested out the lenses and found CA so just take this as another data point. I will link to their results in the description below.

Now comparing the two lenses for the first time at f4 with the f4 lens on the left, the results are very similar. And as we stop down the edge bokeh is getting rounder and really that’s about all I have to report. All in all I am very impressed by the Chromatic aberration results.

Next let's check the two lenses at 135mm. Well it looks like more of the same, oh wait now here at f4 and the F4 lens has a little bit different bokeh. And by 5.6 it’s smoother. And then more of the same. Boy that was exciting!

Overall I am very impressed! Both of these lenses have 9 aperture blades so the blobs feel very round and pleasing unlike the hexagonal blobs you get from lenses with only 6 blades.

Let's move on now to conducting human trials!

We’ll start off with our lenses at 70mm again pointed at our model Daniel. I noticed when I did my 85mm test that the sharpness fell off significantly with one of the lenses around the subjects hairline and I am going to make sure were seeing that area in these 100% close ups.

So looking at our first comparison here at f4 you can see that the 2.8 lens on the right is sharper.

At 5.6 the two lenses are getting closer, but the facial hair is still sharper on the right.

Things are looking pretty equal here at f8 and I threw in a second close up of his facial hair for comparison sake. The 2.8 is still a little sharper and those hairs are just blacker overall.

Same can be said for f11 and 16.

Now let’s look at just the images from the f4 lens at 70mm. From left to right we have f4, 5.6, f8, f11 and f16. It feels like the lens is sharpest between 5.6 and f11. 5.6 or f8 might be the best frame.

Here are the 6 images from the 2.8 lens at 70mm, starting at 2.8 on the top left and going to f16 on the bottom right The F-stops can be found below each frame. The 2.8 and 16 are falling behind but the others look good. Lets just look at the images now from f4 to f16 Once again 5.6-11 looks pretty good with f8 maybe taking the title.

Music: Evolution by Bensound http://bensound.com/