Canon EF 18-200 f/3.5-5.6 IS Lens APS-C vs. Tamron aspherical 28-300 f3.5-6.3 IS

[cuervo]

Got off my film shoot and spent sat. AM looking at the Tamron and Canon superzooms. In summary: 1-the Tamron superzoom outperforms the Canon superzoom by at least 2 points on the standard rez chart, at all f-stops and zoom ratios. I could only comparison test the Tamron at 35mm and 200mm, since the Canon max zoom is 200mm. Minimum focus with the Tamron is 1.5 ft, so, I had to carry 35mm instead of 24 to fit the frame at 1.5 ft. 2-I tested the canon with a Metabones speedbooster and with the standard Metabones Canon->Sony E-mount adapter. It's no surprise that the Speedbooster adds some loss of resolution, on the order of a point on the rez chart, reducing resolution, for example, from 10 to 9. This explains, at least to me, why the Canon resolution is on a par with the Sony 18-200 kit lens. There is no metabones glass on the Sony kit lens. 3-On a "seat of the pants" observation, the Tamron lens looks really really nice. I like it, plus it has that extra 100mm focal length over botht he Sony kit lens and the Canon superzoom. 4-On the down side, the Tamron exhibited some strange behavior with both Metabones adapters. When running in the advanced mode, there is a noticeable exposure step change while zooming the lens. I think the Metabones is trying to hold the aperture, but, the aperture is changing due to the zooming of the lens. So, the aperture changes as I zoom, then the Metabones catches up with the exposure change and there is a sudden step change in aperture. I never noticed this with the Canon glass. It makes shooting and simultaneous zooming rather unuseable. It works better in the green mode, but, there is still a small exposure step near the end of the zoom.... Mounted on my Canon EOS 7D, the Tamron looks really good. I'm surprised, however, how soft the Canon looks. This is NOT a good lens; and, I wouldn't recommend it, at all. Because the Canon is an APS-C lens, it won't work on my Canon 5D, while the Tamron will.