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Star filter
Oct 8, 2012 11:28:10 #
beverett wrote:
TV broadcasters use star filters frequently at sports events and other night venues. I think the effect is annoying. I have one that I used with film cameras but haven't used it in years.
Sometimes atmospheric conditions give that look to street lights - very nice.
Oct 8, 2012 11:28:30 #
Oct 8, 2012 12:23:49 #
What is the difference between a Star Filter and a Cross Screen Filter?
Oct 8, 2012 12:47:03 #
Wabbit
Loc: Arizona Desert
Wil wrote:
What is the difference between a Star Filter and a Cross Screen Filter?
Hey Doc ..... they're the same, just using a different name
Oct 8, 2012 13:32:15 #
Wabbit wrote:
Hey Doc ..... they're the same, just using a different name
Wil wrote:
What is the difference between a Star Filter and a Cross Screen Filter?
Hey Doc ..... they're the same, just using a different name
Like Bill and William. :D
Oct 8, 2012 16:33:05 #
I have used a star filter on a few occasions and got satisfactory results. I have gotten better results by using a large f-stop like f/22.
I believe this is called Fraunhofer diffraction The straighter the aperture blades, the more pronounced the effect will be. Also, the longer the exposure, the greater the effect will be.
Another thing to note is if the lens has an even number of aperture blades, the star will have the same number of rays as the number of aperture blades: 6 blades, the stars will have 6 rays, etc. If there are an odd number of aperture blades, the stars will have twice as many rays as there are blades: 7 blades, the stars have 14 rays.
I believe the reason for this is that each blade makes 2 rays and on the even number of blades, they overlap and on the odd number of blades, they don't overlap. This is just my educated guess.
It takes a little practice but I feel you have more control over the appearance of the 'stars'.
I believe this is called Fraunhofer diffraction The straighter the aperture blades, the more pronounced the effect will be. Also, the longer the exposure, the greater the effect will be.
Another thing to note is if the lens has an even number of aperture blades, the star will have the same number of rays as the number of aperture blades: 6 blades, the stars will have 6 rays, etc. If there are an odd number of aperture blades, the stars will have twice as many rays as there are blades: 7 blades, the stars have 14 rays.
I believe the reason for this is that each blade makes 2 rays and on the even number of blades, they overlap and on the odd number of blades, they don't overlap. This is just my educated guess.
It takes a little practice but I feel you have more control over the appearance of the 'stars'.
Oct 8, 2012 17:18:36 #
You can get a star image by either using a small aperture, F16 or smaller, or a star filter and a very wide aperture, like F4 or bigger.
Check out Panorama section of our forum.
Oct 8, 2012 18:25:11 #
Oct 8, 2012 22:51:20 #
Oct 10, 2012 03:58:48 #
Brian in Whitby
Loc: Whitby, Ontario, Canada
Many years ago I read a tip getting stars. Place a piece of ordinary window screen between two filter reducing rings to produce a 4 point 'star' two pieces at an angle to each other produce an 8 point 'star' the best part is that there is no glass to otherwise affect your image.
Another advantage is the ability to easily adjust the angle(s) of the star points.
If you want to try this experimentally, just hold the window screen tightly to the front surface of the lens. I recommend you use fibreglass screen; it is less likely to scratch your lens.
Another advantage is the ability to easily adjust the angle(s) of the star points.
If you want to try this experimentally, just hold the window screen tightly to the front surface of the lens. I recommend you use fibreglass screen; it is less likely to scratch your lens.
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