UV Filters

[33dollars]

I purchased a Ø 37mm UV filter online from Ebay because Ø37mm isn't easy to find here in Australia. It was also cheap inexpensive.
So it got me thinking, is it any good at that price? I've never heard of that brand before. How can I test it?
This is what I came up with.
One shopping receipt from local supermarket. Two paper weights to hold it down. A UV filter to test. Full sunshine with UV, from the Bureau of Meteorology (UV Alert: 9:20 am to 5:20 pm, UV Index predicted to reach 10 [Very High])That should do it. 3 hours in the sun.With the paper weight removed & no sun light, it is my control.
I think at the end of my test (And it's not that scientific) The UV filter did stop some of the UV radiation. But I baked it in direct sunlight for 3 hours at 48°C (118.94°F). I prity sure it will do the job.

Now I'm off for a siesta.
All the best to you all for the New Year

 

[BillBingham2]

This is what little I know about UV light. There are two different frequencies UVB and UVA. For years Nikon made two different UV filters L-37 and L-38. My father always said I wanted the 37. Not sure why but as he was the professional photographer working for Kodak I trusted him on this info. Your UV paper might be sensitive to A and your filter might block B, or reverse, I have not idea.

There are at least two different perspectives that come to mind when you talk about the quality of the filter. I think of the optical flatness which I've never come up with a good test that was easy to do. I've heard different issues with the filter being mounted correctly, too tight twists the glass and too loose allows it to tilt (same results different root causes) and the filter goes out of alignment with the lens.

Part of me wants to say find a wall that has very even painting on it. Take five different pictures with the filter on and with it off (10 shots total). Focus on infinity when you are say 3 foot away from the wall, then at 10 feet, then on the wall, then at 2 feet then at 6 inches. Repeat this with the filter and without. Look at the pictures for any waves or disturbances in all the pictures. If you see something when the filter is on vs off, then you might have an issue with the filter. Make sure there are no shadows and the lighting is even across the area of the wall you are capturing.

Best I could guess for testing. Outside it depends upon how much water is in the air and haze and stuff.

Interesting that your top weight did not do as good a job at blocking everything as the big round one did.

Hope this helps.

B2 (;->

 

[odklizec]

Interesting and useful test Phil! But in my opinion, there seems to be very little (if any) difference between the UV "protected" and unprotected area? Is the UV filter made by any known brand? Unfortunately, ebay is full of very cheap and often useless imitations And maybe it's just a bad luck with different UV frequency as suggested Bill?

 

[rui fernandes]

That's an interesting test, Phil!

From what I've read about, UV filters can be more helpful to protect the lens than anything else. Of course that an experienced photographer on the right conditions will show you the real difference, not me ;-)

Maybe this is a useful reading for you, as it was for me. Unfortunately I didn't read it before buying my UV filter, the Tiffen Haze would be a good choice and not expensive at all :shock:
http://photo.net/equipment/filters/