Larger zoom lenses and filters

[canders2]

I have a 150-600 zoom and noticed that when I screw a filter on the front, the picture is a little blurry at higher zooms. Is this a characteristic of the larger zooms or do I just have a cheap filter. It did come with the lens. It’s a vivitar multi-coated CPL filter. The lens is a Sigma sports lens.

[Kayaker72]

If photos taken with the screw in filter are noticeably less sharp than without the filter, it is a cheap filter. I own the 150-600S, but is the one lens I own where I haven’t added a filter. I just figure the lens hood is massive and sufficient protection.

[Busted Knuckles]

I had a cheap CPL on a kit lens back when I started and it totally destroyed the image quality. My bet is poor filter quality - try just holding it in front of another lens and shoot through it and see if it crashed the IQ

[neuroanatomist]

It’s a vivitar multi-coated CPL filter.

Vivitar...not the first name that comes to mind when I think of quality filters. Nor the second. Actually, it doesn't even make the list. I'd say it's the filter.

[Lars]

Well, I had a vivitar lens (400mm) for my Canon A-1, decades ago. Don't think a bad filter would make any difference in the image quality with that lens .

Lars