Canon 75-300mm and Canon 70-200mm test
This is just a quick an un-scientific comparison of two Canon lenses.
Both pictures is taken with the same camera, a Canon 20D, but with two different lenses. The large images is 12% of the original size, note the difference in contrast an color!
The small crops i 100% views to show the difference in resolution and contrast.
Canon 75-300mm f/4-5.6 III USM
| Focal length: | 300mm |
| Shutter: | 1/400s |
| F-stop: | f6.3 |
| ISO: | 100 |
Canon 70-200mm f/2.8L IS USM
| Focal length: | 280mm |
| Shutter: | 1/500s |
| F-stop: | f5.6 |
| ISO: | 100 |
This picture is taken with the 1.4 extender.
Conclusion
You get what you pay. The 75-300mm is probably OK for use with film, but is not up to the task on a DSLR.