1 ACCEPTED SOLUTION
I got my EF 28-300L IS USM back in about 2011. It was second-hand but in good condition. The lens is the one of the super zooms that Canon brought out for their L series, if I recall correctly there was there was a 35-300 and one other. It is built like a proverbial tank, all-metal, heavy and with great optics, especially considering the range across which it was designed to perform. I am not a huge fan of push-pull lenses, but that was how that generation of lenses was designed: I had another lens from that era, the EF 100-400L IS USM that was also good for its time, but again push-pull.
I found the resolution to be excellent on my copy, and it focused very quickly, with good IS. It had a beautiful colour tonal quality about the images, one that I found only on a select few of the L-series lenses. It was with regret that I sold it last year to help fund my move across to RF optics, but I was downsizing my menagerie of DSLR bodies and lenses as I just had too many and having had a heart attack, I was suddenly aware of how much challenge a huge amount of legacy gear would put upon my family (who are not into photography) to deal with when I go. So, it sold.
I can only relate my own experience, but it was very, very positive.
The following image may indicated what I mean about the tonal quality. This was taken on an early morning walk, with the 400D (Rebel Xti), hand-held, available light. It is a memorial very close to where I lived on Vancouver Island to celebrate the life of a very brave young man, Terry Fox: Learn about Terry Fox. His life is commemorated in many statues and annual marathons across the county. 
I hope this is of some assistance.
I got my EF 28-300L IS USM back in about 2011. It was second-hand but in good condition. The lens is the one of the super zooms that Canon brought out for their L series, if I recall correctly there was there was a 35-300 and one other. It is built like a proverbial tank, all-metal, heavy and with great optics, especially considering the range across which it was designed to perform. I am not a huge fan of push-pull lenses, but that was how that generation of lenses was designed: I had another lens from that era, the EF 100-400L IS USM that was also good for its time, but again push-pull.
I found the resolution to be excellent on my copy, and it focused very quickly, with good IS. It had a beautiful colour tonal quality about the images, one that I found only on a select few of the L-series lenses. It was with regret that I sold it last year to help fund my move across to RF optics, but I was downsizing my menagerie of DSLR bodies and lenses as I just had too many and having had a heart attack, I was suddenly aware of how much challenge a huge amount of legacy gear would put upon my family (who are not into photography) to deal with when I go. So, it sold.
I can only relate my own experience, but it was very, very positive.
The following image may indicated what I mean about the tonal quality. This was taken on an early morning walk, with the 400D (Rebel Xti), hand-held, available light. It is a memorial very close to where I lived on Vancouver Island to celebrate the life of a very brave young man, Terry Fox: Learn about Terry Fox. His life is commemorated in many statues and annual marathons across the county.
I hope this is of some assistance.
Thank you for your kind words. We all have to go some time, so I'm trying to make the most of each day.
Now, if you are considering an R-series camera, just to confuse your choice :-), I was amazed at the RF 24-240 IS USM lens. I had originally ordered the 24-105 f/4 and then it went on back-order for about 6 months. Keen to get something to work with, I ordered as a stopgap: the 24-240, which is Canon's first journey into the super zoom range since those heavy L lenses.
I was frankly amazed at the level of performance and even after getting my original 24-105, I use this optic far more. Lens design has come a long way since those venerable, excellent but heavy and expensive optics. I had looked at several reviews from people I trust and had borrowed a lens and was really impressed. When I got the RF 24-105L I tried it in a series of comparison shots and found no noticeable difference in the optical quality - obviously the 24-240 does not keep a constant aperture, but neither did the EF 28-300L. I liked that it was very light, because of its modern composite materials, but it still felt solid to me. It balances really well on the R5 and R6 model bodies that I have, which is nice, whereas the EF 28-300L was definitely nose heavy and more so as it seriously extended to zoom. The performance of this lens was instrumental in my decision to relinquish the EF 28-300L.
The 24-240 is one of the first of several Canon RF lenses to use computational photography to improve its wide-angle performance. As I had it explained to me, the lens actually shoots at around 21mm, but uses the 3mm difference with in-camera correction (or for PS or LR auto import lens correction) to correct distortions and vignetting to produce excellent images at the widest angle. This feature is not limited to non-L lenses: my RF 14-35L f/4 lens uses the same technology - I think this had to happen as camera makers finally started to use some of the processes that have long been in use for cell phones.
Here are some examples taken at the rather dimly lit Auckland museum. Sadly, I forgot that on one of my R6 bodies I had auto ISO on, so some of the exposure values for ISO and SS are somewhat different.
Absolutely, it's not an L lens, so it does not come with significant weather sealing, or a lens hood (3rd party ones are very cheap) but the range is great and the IS and focusing work brilliantly with the advanced features of R5 and R6 bodies.
