UV filters (and how to choose them)

Usually, people get a UV filter to protect their lens from getting scratched and damaged. They serve that purpose nicely as they didn't really affect the picture quality. So you can put it permanently on the lens.. Or do they?

I now have a few lens in my collections but when I buy UV filters, I didn't pay much attention. I was not totally ignorant about it to get a cheapo generic ones though.. So I bought mostly the Hoya recommended by the shop.

Exception is that on my EF 50mm f1.4, there's a canon UV filter. I bought it off B&H together with the lens as I believed Canon will made the good filter for their lens. It may only half true.

I faced the problem when I was trying to capture the gig at the Sandwiches I posted earlier. In the low light condition of the pub, the filter was acting like a focusing screen.. I can see another image of spots and other lights faintly on different areas than the real image. Its totally distracting and its spoiling the image. In the end, I had to take off the filter and took the photos to eliminate those reflections.

When I got home, I started to look more closely into my UV filters I have. Most of them doesn't seems to have multi-coating.

Well, I should have known earlier. I was wearing glasses since I was 12. And I hated those early days when my glasses didn't have multi-coating.. Its very hard to see at night because of those extra reflections and glares. And when I was driving at night I have to pay extra attention because I can barely see the road when there's another car's head light or even bright lamp posts in my view. Only when I got my first multi-coated glasses, I can see clearly at night.

Its the same problem with the filters. I was putting a non-coated type UV filters and they are causing reflections and flares. You wont notice much until you started to shoot in very low light like me or pointing at a bright light source.

Here's some photo I took with Canon UV filter in front of my 50mm lens and without filter.
I boosted gamma a little in Photoshop to highlight the problem.

with canon UV filter

no filter ( bare lens)

So if you're getting a UV filter to protect your lens, try to get a good one if you intend to keep them permanently on the lens. Hoya made good ones and cheap ones. Those cheapest green color boxed Hoya filters are not multi-coated. I think you should get Hoya HMC Pro-1 for better quality protection. Or get B+W filters. Only thing is that they are expensive. But hey, that's why they said "You get what you paid for". I think its true here. well.. mostly..

I have a Marumi DHG UV filter for my Kit lens.. I bought it cheaply with my Kit lens. But when i check it , it have multi-coating on it. So, I put in on my lens and took this photo.

with Marumi DHG UV filter

As you can see, it's pretty good .. there's still a faint reflection.. but its not too bad.. And for a filter that cost NZ$20, its really good.

Well.. that's my findings on the UV filters.. I hope its useful for you. Untill I get a Heliopan or B+W one, I cant tell how good they are.. but I'll post again when I got one.

Cheers.