09-15-2017 07:52 PM - edited 09-15-2017 08:02 PM
I just bought a new Canon XT7i and a brand new tamron 16mm-300mm f/3.5-6.3 (B016E). However, when I use the range of 16mm-22mm or so, it distorts the color of the image. Everything has a red/green outline. But if I zoom in past 22/25mm, it works perfectly fine. It is really annoying not to be able to use the full range, part of the reason I bought it in the first place. Same f/stop, ISO, and shutter speed, just different focal range.
Is it the lense, camera, or user error? It does the same on video. (Example photos attached below in reply, two distorted, and two zoomed in and not distorted)?
09-15-2017 08:31 PM - edited 09-15-2017 08:34 PM
It appears to be the lens, and it is called chromatic aberration. It might be correctable in post, but Canon's software does not correct third party lenses. The lens covers a focal range that far exceeds 10:1, which [means] compromises were made in the design..
You do not get that range of zoom without paying a price. The best zoom lenses cover a focal range a with a maximum ration of 4:1. Some of the absolute best are less than 3:1.
[EDIT]. You have found issues at the short end. Do not be surprised if you find similar issues at the long end.
09-15-2017 08:37 PM
If you are not 100% satisfied with the lens, send it back for a refund. One lens cannot do it all. Invest in a Canon EF 70-200mm f/4L USM, for a similar price.
09-16-2017 10:08 AM
It is a poor lens at best. I would return it today. I love lenses and have way more that I should but I would never even try this lens. Let alone buy one. Zooms that zoom more than 1 to 3 or 4 times are usually not the best. They are for convenience not IQ.
You have a very nice camera, why put such a crappy lens on it?
09-16-2017 01:25 PM - edited 09-16-2017 02:42 PM
I do have better lenses, I was trying to get one lense for when I am back packing around other countries, I don't have to worry about packing four different lenses.
If you have the Rebel T7i, then the Canon camera kits that I have seen come with a EF-S 18-55mm f/3.5-5.6 IS STM lens, which is very good lens for walking around like a tourist. That lens alone, should be adequate.
But, you may want something with a wider aperture for indoor shots, or a lens with a wider field of view to grab entire scenes in close quarters. I would suggest the "Canon Portrait Kit", which includes the EF 50mm f/1.8 STM lens, and the EF-S 10-18mm f/4.5-5.6 IS STM lens.
Another item to consider would be an external flash. The built-in flash is fairly weak, and has an effective useful range of about 10 feet. Light drops off significantly beyond 12 feet. The built-in flash can also be a drain on the camera's battery, when used a lot. An external flash would have greater range, and use its' own battery.
Speaking of batteries, buy a spare battery, or two. Figure out how you're going to recharge them before you leave on your trips.
09-16-2017 03:01 PM
" I was trying to get one lense for when ..."
Don't we all? Trouble is IQ and large zoom ratios are at opisite ends of the scale. One or the other. Take your choice.
The best choice for you is the Canon EF-S 17-55mm f/2.8 IS USM Lens. Nice zoom range, very sharp and a fast constant aperture. It is as good as it gets.
If that zoom ranger just doesn't do it for you you might consider the Canon EF-S 18-200mm f/3.5-5.6 IS Lens. It is a pretty decent lens and most people like it a lot. But you will be giving up the better IQ and faster aperture of the above.