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mrpete Dec 19, 2009 7:48 PM

Filter questions
I am buying some filters for for my Sony a200 kit lens. I have a few questions.

First, would a UV filter negatively effect my photos? I want to use it to protect my lens.

Also, do Macro filters work? And wouldn't a +10 automatically be better than a +4 or a +6?

And does the brand of the filter matter? I have seen many (non-chinese) UV filters on eBay for $2. It seems like a nice deal. Same goes for macro.

Thanks for all your help in advance.

TCav Dec 20, 2009 4:25 AM

Adding optical elements to an already complex optical device will degrade image quality to some extent. Good filters will not degrade image quality in any perceptable way.

I don't know for a fact that the $2 filters you're looking at would not be good, but my guess is that they would not.

"Macro filters", or close-up lenses work, but they are the least good way to do macrophotography. The best is with a macro lens, but naturally it's the most expensive. Extension tubes are the next best way, and since extension tubes don't have any optical elements, they don't degrade image quality all by themselves, but they do magnify the imperfections in the lens, so that lens should be quite good. Close-up lenses are the least good way to do macro work, but they are simple and the least expensive.

Also, your kit lens goes to 18mm at the wide end, and a filter can increase vignetting at wide angles. If you use a filter on that lens, you should get a wide angle or "Thin" filter so as to not increase the vignetting too much. The problem with wide angle filters is that they often don't have the screw threads that the lens cap attaches to, so you may not be able to use the lens cap when the filter is in place.

shoturtle Dec 22, 2009 5:24 AM

A lens hood it a good way to protect the lens. I do not like UV filters, as even multicoated filter can give you ghost images and ruining your shot. I have used hoya multicoated filter and I find that they are a pain to clean in the field.

In dusty, sandy, or sea spray environments I use a tiffen haze 1 filter to protect the lens. It is uncoated glass so it is simple to clean in the field. It also serves me as a ND filter, as it warms up the shot when I need it. If you want a easy to clean multicoated filter, the tiffen HT's are good, but they will cost an arm and a leg, at 100 dollars.

If you do a search of the board, you will find couple of thread about the uses of UV filters.

mtngal Dec 22, 2009 11:01 PM

While a good UV filter will be fine outdoors without a strong light source, it'll cause ghosting when you have a bright light (i.e., city lights at night, indoors with a strong light, like from a window). So I tend not to use them unless I'm in a harsh environment and want the extra protection.

As far as your macro question - I once had a macro lens that did 1:2 on its own and came with a matched adaptor that allowed it to take photos at 1:1. The adaptor didn't degrade the picture at all, so I'm not totally adverse to add-on macro filters. In photography, though, you get what you pay for - so cheap dioper filters will degrade the picture enough that I think they would be a waste of money. The more expensive add-on lenses can be quite good, but even with them, there's a certain amount of degradation. They work all right when added to a good, sharp lens, but suspect they'd have mediocre results if you were using a kit lens. TCav's suggestion of using extension tubes would give better results since there's no extra glass to cause ghosting or extra distortion. There's disadvantages to using them, but that's another topic entirely.

shoturtle Dec 22, 2009 11:11 PM


What camera were you thinking about putting these filters on?

mrpete Dec 23, 2009 1:53 PM

I was planning on putting them on my Sony A200 I just bought to protect the kit lens (55mm diameter). It appears that a wide angle filter would be more appropriate. The intent originally was just to protect my glass.

This was the sort of thing I saw on eBay:

My kit lens is able to do enough macro that I am happy without a macro filter.

shoturtle Dec 23, 2009 2:02 PM

Actually I have a friend that used the filter you are looking at from the same ebay seller for his canon xt lens only different is he got a 58mm instead. He seems happy with them. But he said it just takes a bit of care clean as it has the same problem as the other multicoated filters. The coating require more care when cleaning.

He was happy with the seller, he got his item in 3-4 days.

mrpete Dec 23, 2009 2:09 PM

Thanks. Maybe I should just get a clear filter for protection?

shoturtle Dec 23, 2009 2:19 PM

I am not a fan of putting UV filter infront of a lens for protection, a lens hood will be better and will not impact the image, it will do more to reduce flare then any filter.

mrpete Dec 23, 2009 2:29 PM

Ok. I was thinking of fingerprints and scratches though, because it's much easier to replace a filter than a lens.

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