# UV filter sharpness frustration



## icefox (Sep 4, 2009)

I was shooting the beautiful full moon with my Canon 70-200 f4L on 400D. I realize that my UV filter is degrading the sharpness significantly. See the enlarged (original size) pictures w/o and w/ the filter.







You must be thinking the filter is a $5 ebay crap. Sorry, but in fact it's a Hoya. I trashed my last cheap UV filter when I found it reduces sharpness in a similar test. But I never thought a Hoya would do no better; in fact it is even worse.

This is quite frustrating. Do you guys think this level of reduction of sharpness is normal? Would you recommend buying an even more expensive filter, or leave the front element naked? I'm thinking of latter. Note that sharpness reduction is most severe when shooting far away objects, so if you want to test your own filter, do shoot the moon with a telescope.


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## Pure (Sep 4, 2009)

Personally, I only use UV filters when shooting in dirty/dusty places where particulate can enter the lens.  Other than that, just a hood.


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## icefox (Sep 4, 2009)

Pure said:


> Personally, I only use UV filters when shooting in dirty/dusty places where particulate can enter the lens. Other than that, just a hood.


 I guess I'll do so as well in the future.  I never thought a single layer of glass can blur the image so badly.


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## soze (Sep 5, 2009)

ouch, I'm going to have to test this out as well.


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## Garbz (Sep 5, 2009)

icefox said:


> You must be thinking the filter is a $5 ebay crap. Sorry, but in fact it's a Hoya.



Which Hoya, there's about 5 different kinds, and 3 of them are ****. The SHMC and Pro1 series of filters give no visible difference zoomed in 100% in my tests. The rest of them ... yeah.


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## Sw1tchFX (Sep 5, 2009)

this is why i don't use UV filters unless the conditions are going to be SERIOUSLY bad. Which is almost never here in oregon.


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## HeY iTs ScOTtY (Sep 5, 2009)

I NOTICED THIS AS WELL. I ALSO NOTICED IT MAKES THE COLOR LOOKED WASHED OUT. I REALLY ONLY USED IT FOR LENS PROTECTION SO NOW I ONLY USE IT WHEN THE ENVIRONMENT CALLS FOR IT LIKE WHEN I'M AT THE BEACH. I DIDN'T NOTICE IT AT FIRST BUT AFTER A FEW PHOTO SESSIONS I NOTICED MY PICTURES LOOKED A LOT CLEARER AND COLORFUL WHEN I FIRST GOT MY CAMERA. I THOUGHT I MIGHT OF MESSED WITH THE SETTING OR SOMETHING. I STARTED SHOOTING ON THE VIVID SETTING FOR A WHILE BUT THEN I REALIZED ITS THE DAMN FILTER. :er:


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## Phranquey (Sep 5, 2009)

Garbz said:


> icefox said:
> 
> 
> > You must be thinking the filter is a $5 ebay crap. Sorry, but in fact it's a Hoya.
> ...


 
That's why for the filters that I do use, like the CP and neutral densities, I buy good ones....crap ones do affect quality.  Like most, I do keep a UV filter on the lens for protection in bad conditions or if the cap pops off in the bag, but 99% of the time it comes off for shooting.


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## Dwig (Sep 5, 2009)

icefox said:


> ...Do you guys think this level of reduction of sharpness is normal? ...



Yes, its in line with my expectations and experience.

It should be noted that you used the correct term, "sharpenss". "Sharpness" is something that does not exist in the real world. It is a mental opinion that you get when your eye/brain sees a range of image attributes including detail level (~=resolution) and various aspects of contrast.

Given that shooting the moon against a black sky is a massively flare inducing situation, the addition of two glass to air surfaces (rear of filter and front of lens) to the optical path can cause a noticable increase in flare even with modern multi-coating. Also, even the best multi-coating isn't enough. The edges of the glass disk must be ground and blackened, just like the elements in a good lens, or their will be additional internal reflections that the coatings can do nothing about.

Additional optical problems can be introduced if the filter isn't perfectly flat and perfectly perpendicular to the optical axis. Warping is not uncommon when atmospheric pressure and/or temperture changes and when the filter is torqued onto the lens too tightly. In ancient days, Nikon took steps to avoid the warping issues. They used a hard bronze for the metal band and the filter was held in with a spring clip. This kept the glass from being put under stress. They also edge blackened the glass flat to avoid the internal reflections.


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## icefox (Sep 5, 2009)

thank you guys so much for the careful explanation!  I'm a relative newbie in photography and your advices do help a lot.

Now if only someone could show me how your more expensive filter would affect shooting the moon at 200mm focal length.


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## Derrel (Sep 5, 2009)

That's Hoya Quality for ya!


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## cfusionpm (Sep 5, 2009)

icefox said:


> Now if only someone could show me how your more expensive filter would affect shooting the moon at 200mm focal length.


 
That would be interesting to see.  I can't stand using UV filters as they just don't do anything to help the image.  I use a lens hood for protection and only put on a filter if an application calls for it.


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## KmH (Sep 5, 2009)

HeY iTs ScOTtY said:


> I NOTICED THIS AS WELL. I ALSO NOTICED IT MAKES THE COLOR LOOKED WASHED OUT. I REALLY ONLY USED IT FOR LENS PROTECTION SO NOW I ONLY USE IT WHEN THE ENVIRONMENT CALLS FOR IT LIKE WHEN I'M AT THE BEACH. I DIDN'T NOTICE IT AT FIRST BUT AFTER A FEW PHOTO SESSIONS I NOTICED MY PICTURES LOOKED A LOT CLEARER AND COLORFUL WHEN I FIRST GOT MY CAMERA. I THOUGHT I MIGHT OF MESSED WITH THE SETTING OR SOMETHING. I STARTED SHOOTING ON THE VIVID SETTING FOR A WHILE BUT THEN I REALIZED ITS THE DAMN FILTER. :er:


Well, you figured out what the problem was.​


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## icefox (Sep 5, 2009)

i think i understand it now
no filter in the future unless necessary


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## icefox (Sep 5, 2009)

did another test
a $100 canon uv filter is much much better
but still visible
I'll keep the filter off untill environment calls
thanks all for help


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## Garbz (Sep 7, 2009)

icefox said:


> thank you guys so much for the careful explanation!  I'm a relative newbie in photography and your advices do help a lot.
> 
> Now if only someone could show me how your more expensive filter would affect shooting the moon at 200mm focal length.





cfusionpm said:


> That would be interesting to see.  I can't stand using UV filters as they just don't do anything to help the image.  I use a lens hood for protection and only put on a filter if an application calls for it.



Side by side comparison of Hoya Filters here, nearly every series: http://www.thephotoforum.com/forum/...100830-more-hoya-filter-comparison-tests.html

Note the quality of the cheap ones, and that there's no visible difference in the good ones, except for that 1 ghost which will be present on any filter. Get a good UV filter, know that if you shoot into the light the flare will increase and then take it off when you do so. 



Derrel said:


> That's Hoya Quality for ya!


You could say the same thing about Nikon what with them actually having rather crap Coolpix cameras on the market, or any other company manufacturing any other product :er:



icefox said:


> i think i understand it now
> no filter in the future unless necessary


Then you have already lost. The filter is always necessary 1 minute before you decide to put it on. Same goes for anything used as protection. You may as well not buy one.

Again I tell you don't get turned off by crap filters. There are plenty out there that will produce no visible difference to shooting. Go try a Hoya Pro1 or Hoya SHMC for example. Try a B+W protector filter. I'll give you an example with your beloved moon tomorrow if I remember. Today is horridly overcast and raining


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## icefox (Sep 7, 2009)

Garbz said:


> icefox said:
> 
> 
> > thank you guys so much for the careful explanation! I'm a relative newbie in photography and your advices do help a lot.
> ...


 many thanks, waiting to see a moon pic, and your recommendation for a properly priced non-quality-compromising protection gear.

I know if I throw $200 I'll get a perfect filter that does not affect quality, and with 5% chance will protect my $600 lens in its entire life, but it doesn't sound like a good deal.


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## Garbz (Sep 8, 2009)

True and ultimately this is a decision you have to make. I don't have a filter on my 50mm lenses either. It's not much more to replace the lens than the filter, and it's only minor protection. Something serious is likely to break straight through the filter and lens element.

Still overcast tonight. We haven't had clouds all year before this thread, you should change your nickname to rainman :lmao:


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## Garbz (Sep 11, 2009)

Sorry about the delay. The results are in. The moon was up, and so was I.

Methodology:
Took the camera filter off, fired a few shots at the moon to get settings and focus right. Flicked to manual, took photo, put on filter took another photo that easy.

Settings: f/5 1/500th ISO250 Hand-held. D200 with the excellent Nikkor AF 80-200 f/2.8. Shot in RAW and worked with default settings editing only white balance which is the same on both photos.

Images:
These are blown to 100% and cropped. The left is filter less. The right you can probably just see an every so slight colour shift and a very tiny loss of contrast. But no blur which means that any quality loss can be easily offset by by changing your default settings in Lightroom or whatever you use from 25 sharpening to 30 (which is probably too much anyway  and the colour cast is below the standard error for which you'd need a grey card to correct anyway)









The filter:
Hoya HMC Super (S-HMC) 77mm UV(0). This is NOT Hoyas best and most expensive filter, and Hoya is no where near a name of top quality. There are 2 more Hoya series above it, the Pro1 and Pro1D which I both have but won't buy anymore because the ever so tiny difference in quality is not worth paying twice the price for. 

It costs me a whopping $39.95US of ebay


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## Derrel (Sep 11, 2009)

Shooting at 1/500 second with a 200mm focal length risks negating any sharpness benefit you might get by using a filter or not using a filter. At the size shown, the two moon shots give us no real idea of the quality of the shots. Without a 100 percent pixel-level crop, even a terribly out of focus shot will look reasonably sharp.

Look at this shot from the new EOS 7D at web size
IMG_4923 on Flickr - Photo Sharing!

and then look at the original size--the focus is TOTALLY off. But at at web size, it looks like a sharp shot.


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## dhilberg (Sep 11, 2009)

Derrel said:


> *Without a 100 percent pixel-level crop*, even a terribly out of focus shot will look reasonably sharp.





Garbz said:


> These are blown to 100% and cropped.



:scratch:


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## Garbz (Sep 12, 2009)

a) they are 100%
b) 1/efl in this case is 1/300 which I am relatively certain I can in the absence of coffee easily get a tac sharp photo at. This is 1/500th. Trust me it doesn't get any sharper than this on this camera.


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## cfusionpm (Sep 12, 2009)

So basically, what this shows is that if you spend a lot of money on a UV filter, there will be no visable difference (or maybe just a tiny tiny bit) compared to no filter.  And buying a cheap filter will result in plenty of problems and IQ issues.  So again, what benefit does the UV filter have if at its absolute, most-expensive best, it does nothing visually?


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## Garbz (Sep 12, 2009)

The benefit is:
- when a horse kicks mud onto my filter, I can wipe it off with a dirty shirt and not scratch my front element.
- when my camera falls to the ground and lens hood snaps and lands lens first on a rock, the filter is cracked and not my front element.
- when a 6 year old at a wedding decides to stick his yoghurt covered fingers down the end of my spare camera I can take the filter off and wash off the resulting mould, and not send the lens in for a cleaning. 
- in a sandstorm my front element won't get sandblasted
- at minus 50 degrees when my filter freezes over i have nothing against licking it to try and melt the ice (I got a very weird look from a friend for this one). This didn't work so I got a stick and scraped the ice off the filter got a couple of wonderful shots, and then threw away the filter a few days later.

- Oh and when image quality is paramount, there is only a 3 second twist to remove said filter.

All of the above have happened to me, and there is now a medium to high quality filter on every lens of mine worth over $500. 

Oh and before someone else chimes in, no a filter will not protect your camera smacking full speed into the corner of something very sharp that ends up going straight through the filter and into the element. It's only a single layer of protection, and if something is strong enough to crack the filter and cause that to scratch the front element, chances are it would have screwed the element anyway.


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