skylight filter - good or bad?

ancient_mariner

ancient_mariner

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When I started in film photography 30+ years ago I was taught that you always put a skylight filter on the your expensive lenses to protect the front element and to cut out haze.

On another forum we had a brief debate on skylight filters. It seems that they can seriously degrade image quality (there were with & without images to back up claims - in this case it was true). It was also observed that rather than protect a front element from damage, if a filter got broken then shards of glass were more likely to scratch the front element than if just the lens cap had been left in place.

So what's the current take on this: do you always put a filter on or are they a bad idea?
 
I think the only filters you'd need are Polarising and NDs now. I also think most filters will be worse than the quality of the lenses, especially expensive ones, unless you're also strapping an expensive filter on, in which case, do you want to smash it?

I don't think a filter is needed for protection.
 
I personally don't use them as in the past they have caused me to have serious focus issues!
I also tend to agree on image degradation!
If a lens gets broken surely that's what insurance is for!
 
I would say BAD, because they have a slight magenta cast. You may consider using high quality multicoated digital protector or UV because they are neutral/clear for protection purposes only

Don't forget to use lens hood
 
cotty332000 said:
I personally don't use them as in the past they have caused me to have serious focus issues!
I also tend to agree on image degradation!
If a lens gets broken surely that's what insurance is for!
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cheap / fake / crap filters maybe? I shoot full frame cameras and some expensive lenses and can't see any difference with and without even if I pixel peep

If lens gets a little broken, you are going to pay £200 excess. You may as well just send it in and get repaired probably for less, or have the filter+hood take some beating. Examples include flying food, sea spray and mud. Yeah, if you clean grit of the lens you will scratch it and insurance won't cover it, I'd rather bin the filter.
 
I had UV filters on all my lenses when I first started out with a 550D and it didn't seem to affect IQ much at all. They were good quality and fairly expensive, Hoya mainly but some others too, and I was happy with them. I eventually got a 7D and a Canon 100-400 L and was amazed at how soft the images were. I was on the brink of returning the camera when I went out without the UV filter on and again I was amazed at the difference.

When I'd got back I checked all my lenses with the filters on and off and from that moment on I've never used a filter, apart from the occasional time with a CPL, unless the elements are really against me. In pouring rain, dusty and sandy areas I'll put a UV filter on but it's very seldom. I hardly ever even have them in my bag anymore, I just make sure I've got the lens hood on and if I get a lens without one I make sure to get one. IMO they're far better protection than a thin piece of glass that degrades your IQ anyway.
 
Used to use daylight filters on colour film but have stopped using them on most of my lenses for the reasons given in the OP. I still use "clear" filters when there's a lot of airborne dust or spray around and on my Macro lens but generally leave protection to the hoods.
 
Thanks guys, this is useful. So the general consensus is that some kind of clear filter is good in a dirty environment but otherwise best to leave it off.
 
  • No UV/'protective' filter can improve image quality on a dSLR.
  • All UV/'protective' filters will cause some degradation in image quality.
  • The seriousness of this degradation tends to decrease as filter cost increases.
  • Good filters will cause degradation that is not noticeable under most conditions.
  • All filters, even the best, will cause noticeable degradation in some conditions.
 
skylight ones have a magenta cast on purpose, can be a nice warming effect, slight
 
hollis_f said:
  • No UV/'protective' filter can improve image quality on a dSLR.
  • All UV/'protective' filters will cause some degradation in image quality.
  • The seriousness of this degradation tends to decrease as filter cost increases.
  • Good filters will cause degradation that is not noticeable under most conditions.
  • All filters, even the best, will cause noticeable degradation in some conditions.
Click to expand...

Lets see some proof.
 
kestral said:
Lets see some proof.
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There's loads if you google. It's common sense regardless, you don't have to be a genious to understand why, basic level physics.
 
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Lets see the difference in two photos one with a filter and one without. Hoya would be good brand to try and prove this theory on. Please post the photos so we can see.(y)
 
kestral said:
Lets see the difference in two photos one with a filter and one without. Hoya would be good brand to try and prove this theory on. Please post the photos so we can see.(y)
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As it happens this test I did a while ago shows

No Filter - Hoya HD - NoName Cheapo

Filter%20Comparison%20100-400.jpg
 
kestral said:
Lets see the difference in two photos one with a filter and one without. Hoya would be good brand to try and prove this theory on. Please post the photos so we can see.(y)
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Not from me you won't. I don't own any skylight or "protective" filters for the reasons already stated.
 
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kestral said:
Lets see the difference in two photos one with a filter and one without. Hoya would be good brand to try and prove this theory on. Please post the photos so we can see.(y)
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You don't need physical proof. It's a mathematical certainty. If you add an extra element of glass to the light path, the image will be degraded.

The real question is not if it will be but by how much.
 
Thanks for posting those images Frank: pretty conclusive, even with the Hoya. I wonder how many images my use of a skylight has spoiled slightly.
 
ancient_mariner said:
Thanks for posting those images Frank: pretty conclusive, even with the Hoya. I wonder how many images my use of a skylight has spoiled slightly.
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Yes, if it weren't for the non-filter image to compare it with, the Hoya image looks OK. You wouldn't really notice that small loss of contrast otherwise, but it's always there.
 
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