Testing filters

Nanobot

Nanobot

Nanobot

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18 Sep 2008
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I'm wondering if there is a 'method' for testing filters properly from a new DSLR user's point of view. Have finally got my filters - a Pro1D UV filter (for protection as already mentioned in an old thread) and a circular polarising filter.
I dont seem to notice much difference from the UV filter, and I notice from the CP filter that its slightly tinted and darkens images as I appreciate that it would!
I know the CPF has a mark on the front ring which allows me to turn, but I dont seem to notice any change in image no matter where I turn the marker.
From what I have read, I need to be 90 degress to the sun etc.
Am I missing something really obvious from the UV and CP filters - sorry if it sounds all too naive, I'm still learning (and waiting for my books to arrive! ;))
:confused:
 
depending where that point is, the reflections will change. I only really notice it when taking pictures of cars. I generally do a few with it pointing one way, and a few the other way. that way you get sidewindows or windscreen showing clear.

Img_8140_edit_small.jpg


ie in this shot the pointer was pointing right, but if i had it left/up the windscreen would be clear.
 
The UV filter wont change anything, its not designed to. It's purely to protect the front lens when on the beach etc. LEave it off the rest of the time unless you are just not messing about and don't care about image quality.


The polariser can be used in many different ways. It can be used to remove reflections from glass and water, although rarely is this really advantage except on water when it can make the water bluer. Better use is on reflections on objects you want to photograph.

The most common use for the polariser is to remove haze and glare which results in stronger colours for landscapes.

have a look here http://www.ephotozine.com/article/Polariser-guide
 
D.P. said:
The UV filter wont change anything, its not designed to.
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Technically it is designed to do something and does. It cuts down the UV rays entering film, and increases contrast. But on digital cameras, the hot filter already cuts UV and IR light so you won't see any additional effect. So your right in saying on digital cameras they only serve to protect the front element of the lens, but they are infact actually doing something. It's just that what they are doing is also already being done by the camera.

Oh, and the easiest way to see the effect of a CPL is to point it at a TFT monitor and turn the filter ring. :)
 
Messiah Khan said:
the easiest way to see the effect of a CPL is to point it at a TFT monitor and turn the filter ring. :)
Click to expand...

+1

This is the best demo, LCDs emit polarised light by there very design, so turning you polarising filter will result in the image varying from looking normal, right through to no light visible form the screen (it is all filtered as the waves are perpendicular to the filter's current direction)
 
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Ah ok, that explains things. I was aimlessly taking shots around the house the other day, one of which was an LCD desk clock. The LCD digits were visible and not affected, but the background was 'pearlescent' like what you get when you press and apply pressure on LCD and it ripples and runs.
Is that the effect I'm looking for?
I've took more shots of the LCD clock and tried turning the CPL 90 degress, but just realised that if I was pointing directly at the middle of the clock display, then it would have looked the same whichever angle I turned it. See, I told you I was new! :o
Thanks again for the advice.
 
Nanobot said:
Ah ok, that explains things. I was aimlessly taking shots around the house the other day, one of which was an LCD desk clock. The LCD digits were visible and not affected, but the background was 'pearlescent' like what you get when you press and apply pressure on LCD and it ripples and runs.
Is that the effect I'm looking for?
I've took more shots of the LCD clock and tried turning the CPL 90 degress, but just realised that if I was pointing directly at the middle of the clock display, then it would have looked the same whichever angle I turned it. See, I told you I was new! :o
Thanks again for the advice.
Click to expand...

Not quite the test that was suggested, What was being refered to was a LCD TFT panel (TV/monitor) the 'lcd' panels in alramclocks dont work in quite the same way.
 
No, If you pointthe polariser at the LCD clock, at a certain point you will be abl to see the digits. Rotate 90 degrees and you won't be able to see the digits..

Good tip on the LCD screen as well.
 
Hmm, I've just tried the CPL filter on its own without DSLR as have put it away with UV filter back on, was about to turn in for the night. Curiousity got the better of me so just decided to try CPL on its own and I can see the effect now! :D I think the desk clock I tested is some cheap duff as it wasnt really doing much other than streak. Just tried it on one of those better clocks/temp/weather station things and it does indeed turn the whole screen black - so feeling a lot more relieved now... Thanks for your patience. :cool:
 
Messiah Khan said:
Technically it is designed to do something and does. It cuts down the UV rays entering film, and increases contrast. But on digital cameras, the hot filter already cuts UV and IR light so you won't see any additional effect. So your right in saying on digital cameras they only serve to protect the front element of the lens, but they are infact actually doing something. It's just that what they are doing is also already being done by the camera.

Oh, and the easiest way to see the effect of a CPL is to point it at a TFT monitor and turn the filter ring. :)
Click to expand...

This is mostly true, however a lot of cheap UV filters don't even filter UV rays any more, and some have a slight color cast even.
 
D.P. said:
This is mostly true, however a lot of cheap UV filters don't even filter UV rays any more, and some have a slight color cast even.
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But surely then it's a clear filter? I'm not saying your wrong, but I would consider that as misadvertisement. And on a related issue.. a skylight filter is just a UV filter with a slightly warm colour cast. :)
 
Well I have been looking at what lenses to get next and it slightly annoys me that other lenses will need different sized filters and hoods and therefore add to the expense. I would think that things would become a bit more compatible these days given that if the mount can be compatible with same bodies, why not filters and hoods?!
Sorry, rant over with...
 
Messiah Khan said:
But surely then it's a clear filter? I'm not saying your wrong, but I would consider that as misadvertisement. And on a related issue.. a skylight filter is just a UV filter with a slightly warm colour cast. :)
Click to expand...

just what i've seen in some reviews. UV has a long wavelength range, so a UV filter may filter out over a certain frequency which is within the UV spectrum but not the whle UV spectrum.

The end result matters little for DSLR users.
 
Nanobot said:
Well I have been looking at what lenses to get next and it slightly annoys me that other lenses will need different sized filters and hoods and therefore add to the expense. I would think that things would become a bit more compatible these days given that if the mount can be compatible with same bodies, why not filters and hoods?!
Sorry, rant over with...
Click to expand...

Just by 77mm filters, this is the standard for pro glass and most lenses uses 77mm or less. Then just buy a set of cheap step down adapters for a few bucks each.


The reason the filter size differs is due to physics. A faster lens will need a larger end glass to let more light in. A longer focal length will need a larger front element to let the same light in.
 
D.P. said:
Just by 77mm filters, this is the standard for pro glass and most lenses uses 77mm or less. Then just buy a set of cheap step down adapters for a few bucks each.


The reason the filter size differs is due to physics. A faster lens will need a larger end glass to let more light in. A longer focal length will need a larger front element to let the same light in.
Click to expand...

Thanks DP, I wasnt sure if there were adapters so thats good to hear. Off to do some googling.
 
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