Image quality of the Canon EF 70-300mm f/4-5.6 USM L IS

I'm thinking on finaly selling my canon 200mm f2.8 II and my trusty 300mm f4 IS, and buy the new Canon EF 70-300mm f/4-5.6 USM L IS

In terms of image quality what are your opinions about the new lens against the older ones?

Best regards,
paulo anjo

It's a good lens but it is far from new.  It's been on the market for more than 7 years.  As such, it was introduced in a Canon world of 16 megapixel cameras.  When this lens is tested by DXO on a 50mp EOS 5DSR it only resolves 17 megapixels which is pretty poor by today's standards.  When tested on a 5D Mk IV it also resolves just 17mp so it is fundamentally limited optically at that level and not at all up to today's standards.  As a point of comparison, the 70-200 f/2.8L Mk I resolves 33 megapixels on a 5DSR...


Compared to your 300 f/4, your old lens slightly outresolves the zoom

This may be considered slightly off topic but I would like to know exactly what these DXO measurements of how many megapixels a given lens will resolve are actually measured.The link on their website to perceptual pixels is broken and over the past five years there seems to have been no explanation offered. I cannot find any answers from DXO, having done a quick Google, to the critique in this article.

https://fstoppers.com/originals/are-you ... lete-85888

Just sold the 70-300 L IS lens after it had been sitting on a self for almost two years.
It was a well balanced lens, very easy to use, easy to pack as it collapses unlike the 300 f 4.0 L IS
Excellent for BIF as it focuses fast.
However, it has a major limitation: reach.
The 100-400 L IS Mark II lens has a longer reach and it has better IQ.
I have one right now and I love it.

The DXO measurement seems to be at the lens sweetspot and that's 100mm and f2.8 for the 70-200 quoted above. Photozone tests seems a bit more informative to me even though tested at "only" 21 MP. It still shows the 75-300 about matching the 300mm f4 in performance and the 70-200 and 100-400 out performing the other two, though the 70-200 is clearly best at shorter focal lengths, In fact the 300mm f4 gets quite close to the 100-400 at 300 (100-400 is clearly better) and resolves similar detail to the 100-400 at 400.

To me the Photozone tests mirror what DXO reports at the sweet spot but adds in extra info on how performance varies through the zoom range.

I have the 300mm f4 and while the 100-400 seems tempting with my camera, budget and ultimate use of my images, the 300mm f4 does just fine for me. Resolution wise I wouldn't upgrade, but the better IS and flexibility of the newer zooms would be the reasons that seem most compelling to me.

ChrisRoss wrote:The DXO measurement seems to be at the lens sweetspot and that's 100mm and f2.8 for the 70-200 quoted above.  Photozone tests seems a bit more informative to me  even though tested at "only" 21 MP.  It still shows the 75-300 about matching the 300mm f4 in performance and the 70-200 and 100-400 out performing the other two, though the 70-200 is clearly best at shorter focal lengths,   In fact the 300mm f4 gets quite close to the 100-400 at 300 (100-400 is clearly better) and resolves similar detail to the 100-400 at 400.  

To me the Photozone tests mirror what DXO reports at the sweet spot but adds in extra info on how performance varies through the zoom range.

I have the 300mm f4 and while the 100-400 seems tempting with my camera, budget and ultimate use of my images, the 300mm f4 does just fine for me.  Resolution wise I wouldn't upgrade, but the better IS and flexibility of the newer zooms would be the reasons that seem most compelling to me.

If you dig into the DXO data and don't just look at the headline, you will see all the tests of everything through the whole focal length range.  There are many tabs and even sub tabs and a ton of info to explore on any test they do, whether it's a lens or a camera.  And then on each graph you can click down further to specific focal lengths, apertures, etc. Here it is for the 70-300L
https://www.dxomark.com/Lenses/Canon/EF70-300mm-f-4-5.6L-IS-USM-mounted-on-Canon-EOS-5DS-R---Measurements__1009

Yeah I tried digging and gave up. I found the coloured maps, but to me having separate charts at each focal length in a bar chart format is easier to interpret, on the lenses in question the DXO charts are all green until you stop down enough to cause diffraction and you are trying to remember shades of green when jumping among charts.