Skylight filter question

Hi all

I've been given a skylight filter, a 77mm Hoya 1A, and I was wondering:

1) What's it for?? Is there any point using it?
2) Why is it brown coloured?? Only slightly, if you put a piece of white paper behind it looks distinctly brown

Cheers!

In a way, it can work as a UV filter, but it's not as effective. It's mostly useful to give a bit of warmth to reduce blue casts, especially in shadows.

Anon Ymous said:

In a way, it can work as a UV filter, but it's not as effective. It's mostly useful to give a bit of warmth to reduce blue casts, especially in shadows.

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Yes, especially if you use Ektachrome. Winter scenes are often blue and the skylight will help.

I think it is useful. Somewhat warmer effect for winter scenes. If it's free what the hell, use it.

Jeff

Yep, I tend to agree with the above comments. They do have a slight impact with color film, and there are certainly times when they can improve the results in the right conditions. Some people poo-poo putting anything so simple in front of the lens (UV, skylight, etc), but I've had some fantastic results from lenses that have severe separation, fungus, and other problems on the front element, so I find it difficult to believe that something like this would degrade an image so much as to override the intended effects. Take some shots of the same setting with and without it so you have a side-by-side comparison of the results and then you'll have a good idea when it works and when it doesn't...

- Randy

Lens protector.

Anon Ymous said:

In a way, it can work as a UV filter, but it's not as effective.

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As an UV filter, it is every bit as effective as an 'UV-only' filter.
It just ads a tiny bit of warming.

Q.G. said:

As an UV filter, it is every bit as effective as an 'UV-only' filter.
It just ads a tiny bit of warming.

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I've seen some transmittance curves and there's a clear difference. Of course, not all skylight filters are the same, so some might be every bit as effective.

If you are not using colour it is as good as a UV, it will cut more blue (generically), there is a 1b as well I think.

Noel

Right, I get it now.. Thanks chaps!

fotch said:

Lens protector.

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What he said and to slightly cut the haze.

Steve

Anon Ymous said:

I've seen some transmittance curves and there's a clear difference.

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Of course there is. In addition to cutting UV as effective as an UV filter, it also holds back a bit of the blue end.

It doing that, i'd say it definitely is more than just a lens protector that cuts haze.

Q.G. said:

Of course there is. In addition to cutting UV as effective as an UV filter, it also holds back a bit of the blue end.

It doing that, i'd say it definitely is more than just a lens protector that cuts haze.

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Eh no, I checked a Hoya booklet and there's a clear difference between UV(0) and skylight. The UV has a much steeper curve, effectively reducing UV better than their skylight. At 350nm the skylight filter allows 40% radiation to pass, while the UV cuts all of it. At 400nm, the skylight will allow about 90%, while the UV about 65%. From that point on, skylight's curve becomes flat, as opposed to the UV's curve...

Would love to see those curves.
(A steeper curve typically means transmission increases more rapidly, i.e. absorption drops faster.)

fotch said:

Lens protector.

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That's what I think too.

Q.G. said:

Would love to see those curves.
(A steeper curve typically means transmission increases more rapidly, i.e. absorption drops faster.)

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Sorry, no scanner

BTW, the curve becomes steep from about 375nm. At that point, transmission is approximately 10%. These are facts for the simple filters, the PRO1 UV starts transmission at 400 and has a nearly vertical curve.

Sounds like a filter to hang on to; all HOYA filters are excellent. A few points:

By way of nomenclature, Skylight is different to UV; two distinct filter types.

Skylight 1A and 1B (more pinkish) commonly used to absorb blue light in distant landscapes i.e.mountains, seascapes etc.

Any filter should be matched to the optical quality of your lens, as it will introduce more risk of flare and/or ghosting so look for multicoated filters (Hoya, B+W make excellent filters). This means don't put a $4.00 glass filter on a $1500 lens.

Avoid using a Skylight 1B or 1A particularly with Velvia 100F in early morning of evening light (when there are pink-mauve hues). 100F with its flashy, avant guarde palette a quite different to stalwart Velvia 50 and 100, exaggerating magenta, and a 1B filter will take it to quite an extreme and unpalatable level. I have exploited this once and once only and taken it to Ilfochrome. The client loved it. I hated it!!

A Hoya HMC-PRO Skylight 1B is resident on all my lenses 67Ø 72Ø, 77Ø, (interchanged with a polariser; never used together).