Filter stops light

siejones

siejones

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I always considered it obvious I would loose a little light when using and UV or skyligtht filter but I never realised how much. I was doing some testing today with and without filters and found both my filters a UV and Skylight of different makes both stop the light by 2/3's of a stop. That's huge considering it's only a 3rd of a stop away from a full stop.

We pay huge amounts more for a lens that is capable of going one stop lower wide open then we dampen that by keeping these filters on for protection. My 70-200 F4 may as well by a F5.0 with the filter on. I don't think I need to go on about the disadvantages of this 2/3's of light loss. There were times I might not had to gone to that higher/noiser ISO if I had not had the filter on.

I am thinking maybe that I will keep the filter on for storage and carrage and for landscape shots and tripod shots but for the light crucial stuff I think it's gonna start coming off.
 
Notta lotta people know/appreciate that Sie ... ;)

I didn't for one ... always thought UV had no impact on light input ... DoH ... :eek:

Ta for the HU in that case ... :thumbs:




:p
 
Just read this and tried metering with a variety of lenses with skylight filter on and off and found no difference at all.
 
namllihs said:
Just read this and tried metering with a variety of lenses with skylight filter on and off and found no difference at all.
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I am hoping I am wrong but I tried this with both my lenses. I chose a scene and set my aperture to F4 and took note of shutter speed then took off the filter and watched it rise a couple of notches. Maybe the light changed that much (ambient light) while taking the filter off but for it to happen twice with both lenses kind of convinced me.

What lead me to the test was a test chart test I was doing on my 70-200 that had just come back from repair and I was just trying it without the filter and noticed the shutter speed drop when I had put the filter back on. I disregarded it at first but it happened a couple of times.
 
On further testing I think I was mistaken on the Hoya but on my jessops 67mm skylight produces the same 2/3'ds drop everytime.

I think the problem lyes with the jessops filters.
 
As far as I'm aware a UV0 is just about pure glass. It shouldnt the metering at all.
Whereas a skylight is slightly pink.

Any colouration is going to knobble some of the light passing through it.

Try it with a CircPL then you'll really see a 1 stop difference.
 
Have you tried cleaning them? :p

I thought and always accepted there was no appreciable light loss.... even in film days...
 
Agreed - you shouldn't see any exposure difference with a clear UV filter, but a skylight filter is usually pink as stated - sometimes described as 'straw'.
 
As has been said I always expected a little light loss but not anywhere near this extent.

The filter is clean.

I know that a CP can make 1-2 stop drop but never expected it from a Skylight.

I can point my 70-200 at a subject and move the filter in front of the lens and watch the meter drop by 2/3s of a stop
 
We shouldn't overlook the fact that modern lenses have numerous coatings on the various elements of the lens- even the elements cemented together. I forget the exact figures, but I'm pretty sure that a top end coated lens will transmit over 80% more light than an uncoated one due to the reduction in light scatter and diffusion as light passes through the lens.

Curiously, one of those many coatings is a UV one, rendering a UV filter redundant, apart from protection, which I appreciate is why people use them. I don't use them myself, I prefer to use a lens hood to protect against knocks. I certainly don't see the sense in sticking a real cheapo filter in front of an expensive lens unless you're in a particularly hostile environment when common sense dictates if it's cheap and cheerful it will have an adverse effect on your shots. :shrug:
 
siejones said:
As has been said I always expected a little light loss but not anywhere near this extent.

The filter is clean.

I know that a CP can make 1-2 stop drop but never expected it from a Skylight.

I can point my 70-200 at a subject and move the filter in front of the lens and watch the meter drop by 2/3s of a stop
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Does the skylight filter not have a filter factor number on the edge?
 
CT said:
Does the skylight filter not have a filter factor number on the edge?
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No all it say's is "Jessops Skylight 1A filter" andn I have no box as it came on the lens.

I appreciate what you are saying about using filters on the whole and feel it's a good point that you pay all this money for this exotic glass then stick a cheaper piece of glass in front of it. I have never been a fan of hood's but I may use one in future as protection as you said.
 
CT said:
We shouldn't overlook the fact that modern lenses have numerous coatings on the various elements of the lens- even the elements cemented together. I forget the exact figures, but I'm pretty sure that a top end coated lens will transmit over 80% more light than an uncoated one due the reduction in light scatter and diffusion as light passes through the lens.

Curiously, one of those many coatings is a UV one, rendering a UV filter redundant, apart from protection, which I appreciate is why people use them. I don't use them myself, I prefer to use a lens hood to protect against knocks. I certainly don't see the sense in sticking a real cheapo filter in front of an expensive lens unless you're in a particularly hostile environment when common sense dictates if it's cheap and cheerful it will have an adverse effect on your shots. :shrug:
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As you say I too agree - Use a hood. Protects your lens and helps control flare and stops the ghosting of colours (particularly in cityscape type shots). Filters in front of your glass reduce the quality (albeit perhaps very slightly).
 
id rather sacrifice a bit of quality than expose my front element to the mud and stones thrown up by rallycars. although for things like portraits i agree, its unneccesary
 
I suppose there's always the extremes :-) Hood in most cases though.
 
siejones said:
I appreciate what you are saying about using filters on the whole and feel it's a good point that you pay all this money for this exotic glass then stick a cheaper piece of glass in front of it. I have never been a fan of hood's but I may use one in future as protection as you said.
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I honestly think you'll see more benefit from using a hood than you will from a UV filter. The hood enormously assists the colour saturation and clarity of your shots due to eliminating a lot of the scattered light which is bouncing around in all directions. Think of the way you shade your eyes with your hands on bright days to aid vision - it's much the same principle.

Some lenses have the front element well recessed into the lens body and you could argue a case for sometimes not using a hood with those types of lenses. However, if you stick a flat filter right on the front of the lens, you're now losing all scatter protection but now with a large flat piece of glass catching any flare and diffraction, which will degrade your images anyway - quite apart from the optical quality of the filter, making a lens hood absolutely vital in those circumstances. :)
 
CT said:
I honestly think you'll see more benefit from using a hood than you will from a UV filter. The hood enormously assists the colour saturation and clarity of your shots due to eliminating a lot of the scattered light which is bouncing around in all directions. Think of the way you shade your eyes with your hands on bright days to aid vision - it's much the same principle.

Some lenses have the front element well recessed into the lens body and you could argue a case for sometimes not using a hood with those types of lenses. However, if you stick a flat filter right on the front of the lens, you're now losing all scatter protection but now with a large flat piece of glass catching any flare and diffraction, which will degrade your images anyway - quite apart from the optical quality of the filter, making a lens hood absolutely vital in those circumstances. :)
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SOLD :thumbs:
 
siejones said:
SOLD :thumbs:
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LOL Great! :thumbs:

If you think about the very recent deer pics too with the blue snow and blue colour casts ... that would have been the sort of situation to use your skylight filter to remove those casts, but as we saw in the thread, Photoshop editing gets the job done very well anyway.
 
CT said:
I certainly don't see the sense in sticking a real cheapo filter in front of an expensive lens unless you're in a particularly hostile environment
Click to expand...

I went through six 77mm UV Nikon filters last year at @ £60 each. Well worth the expense (to the tax-payer:lol: )...

And I just found out the 'old' 70-200 was scrapped by Calumet when its sent back to them for a re-furb. They were amazed I'd managed to keep it going so long. All the glass fell out when they dismantled it apparently...
 
Arkady said:
I went through six 77mm UV Nikon filters last year at @ £60 each. Well worth the expense (to the tax-payer:lol: )...
Click to expand...

Similarly ...
I had to replace the UV filt on the front of my 17-85 last year as I dropped the lens when changing it... filter took the impact. Lens still happy :)
 
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