[GibbyTheMole]

Hey all.

I recently bought a nice 55-300 DA-L from another forum member that came equipped with a Tiffen UV filter. After shooting the same shots with and without the filter, I found the photos without the filter were much sharper than with the filter. After holding the Tiffen filter up to the light I noticed a light haze on the filter, so I decided to try another one to see if I would have better luck. I went out and did the test again with a new filter, taking the same shots with and without the filter & comparing the results. I thought it might be fun to see if you guys & gals can guess which were taken with the new UV filter in place. Here are the examples, all 100% center crops shot handheld with autofocus using center point at 300mm with a K-x at f:8 in Av mode at ISO 400. All are straight out of the camera, and all have shutter speeds 1/500 of a sec. or faster.

Example 1:



Example 2:



Example 3:



Example 4:



After enough people guess (either the top half, "1" or the bottom half, "2") which were taken WITH the UV filter in place, I'll pop back in with the results.

Cheers,
Bobbo :-)

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Last edited by GibbyTheMole; 07-11-2012 at 03:34 PM.

[JinDesu]

Example 1: Top clearly UV. Bottom none. Otherwise, you've misfocused.
Example 2:Top none. Bottom UV.
Example 3: Top none. Bottom UV.
Example 4: Top UV. Bottom none.

[rawr]

Ugh. You should warn users before you post 3MB+ of images in one post.

Anyway, it's well known that the Tiffen UV filter is no good:



From Lenstip's UV filter tests:
UV filters test - Introduction - Lenstip.com
UV filters test - supplement - Introduction - Lenstip.com

I don't know why you are bothering to use a UV filter on the 55-300 at all, to be honest. They do no good at all. Just use a hood if you want to protect the front element.

[GibbyTheMole]

I don't know why you are bothering to use a UV filter on the 55-300 at all, to be honest. They do no good at all. Just use a hood if you want to protect the front element.

Already using a hood. The hood doesn't keep dust off the lens itself though. Personally, I prefer cleaning a cheap piece of easily replaceable glass rather than the lens itself, when possible.

[m42man]

You'll see something very similar illustrated in this thread:

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/124056-impact-...ml#post1282280

The OP in that thread initially looked at the effect of a cheap filter, but later edited the post to include the effect of a decent (Hoya HMC) filter.

Conclusion: cheap filters won't be made from decent optical-quality glass and you'll get significant image degradation; but if you buy from a reputable manufacturer (Hoya, but I'd add Marumi and B+W, for example), you'll be just fine. Do note that the other thing to watch out for is flare, so, even if you buy a decent brand, make sure it's multicoated!

[ChopperCharles]

I honestly don't see any difference in using a UV filter. Those images look identical as far as I'm concerned.

Charles.

[Moo]

Conclusion: cheap filters won't be made from decent optical-quality glass and you'll get significant image degradation; but if you buy from a reputable manufacturer (Hoya, but I'd add Marumi and B+W, for example), you'll be just fine.

That's not quite the conclusion shown by the tests in lenstip tests, where reputable manufacturer didn't always mean good, and neither did high price. Some inexpensive ones performed very well too.

[GibbyTheMole]

One guess so far, eh?

[top-quark]

Not sure we can guess, actually. Problem is the "handheld" bit. I can tell, for example, the top image in the first pair is softer than the second, but is this down to the filter or to you missing focus a little?

To test this properly, you need to eliminate variables: which means on a tripod, one shot with, one without, don't refocus between shots.

From what you've given us here, your UV filter seems to be image-neutral: our eyes can't distinguish a 2% loss of light due to a filter in the optical path.

[GibbyTheMole]

Problem is the "handheld" bit. I can tell, for example, the top image in the first pair is softer than the second, but is this down to the filter or to you missing focus a little? To test this properly, you need to eliminate variables: which means on a tripod, one shot with, one without, don't refocus between shots.

I'm a pretty steady-handed guy and all shots were at 1/500th or higher, which I thought should be ok at 300mm, especially with shake reduction also on.

I refocused (with the autofocus locking on each time) in case the presence of the filter affected the accuracy of the AF.

I tested for my own benefit, because I'm planning on using this lens a lot at the long end, handheld. The Tiffen filter downright sucked, and I wanted to know if it was because of that particular filter, or a UV filter in general that was responsible for the poor image quality. Turns out, it was just the Tiffen filter at fault.

I can repeat the test with a tripod using whatever method is deemed "proper", but some will always say something is out of whack.

If you guys are done, I can pop up the results anytime.

Cheers,
Bobbo :-)

[GibbyTheMole]

Here goes:

The UV filter was ON in the following:

Photo 1: 2
Photo 2: 1
Photo 3: 1
Photo 4: 1

Bonus: The filter was a $2 Zeikos from eBay. I have several of those, and I've found them surprisingly decent. Though the ring is made in China, the glass is from Japan.

I actually have done this kinda thing with several lenses & different brands of filters before and surprisingly, some of the cheap eBay filters (Zeikos & Massa, for example) frequently test better than some filters that cost more. And it depends on the lens. My Tair 3M-5CA 500mm looks consistently a little sharper without the original Russian filter. (I haven't tried it with a different one, but I may.) On the other hand, my Tamron SP 23A 60-300 actually, quite surprisingly, produces slightly clearer photos with the UV filter in place. (I don't have an explanation for that, other than maybe the filter actually does filter out UV like it's supposed to.) With the other lenses I own, it doesn't seem to matter much either way.

My conclusion: If a lens produces noticeably better photos without the UV filter, I'll use it without. Otherwise, if it doesn't seem to make much, if any, difference, it's worth it to me to have on there to offer a little extra protection. In this case, at least for now, I think it's worth leaving on there.

[Marc Sabatella]

The major problem with your test - aside from not fixing focus, which is a problem too - is that none of these test shots are of the sort of scenes where a filter wpild be likely to cause degradation. It won't be primarily about sharpness when shooting at close range, but also flare and CA when shooting scenes with higher contrast and/or nearby light sources.

[GibbyTheMole]

Hey Marc. I can see where you might have a point about the flare & CA. I appreciate your input. :-)