Discussion in 'Photography Equipment & Products' started by abraxas, Jul 18, 2007.
Anybody have any thoughts on or experience with the singh ray vari nd filter?
nope, but someone did put up a thread about a diy variable nd filter. i'll try to find it. . .
That would be me.
From a previous post:
"I have a fast 50mm that I like shooting wide.... even in daylight. All I have is a 3 stop ND filter but I needed some flexibility. Next step... a collection of ND filters but that just seems like more junk to pack. Singh-Ray makes a Variable ND filter but at $350-$400 I think they are a bit expensive.. Someone mentioned two polarizers... but adjusting is a pain since both stacked polarizers have a tendancy to turn together instead of seperately. They are also a bit thick which can mean some vinetting can occur.
So today I went to the local camera show today (unfortunately it is pretty much dying out now due to the popularity of modern digital) and picked up two same brand 67mm circular polarizers and one plain jane UV. Three of those filters plus a step down ring cost only $35... not bad eh. Popped out the glass of the UV filter and replaced it with the glass of one of the two polarizers. The modified UV (now polarized) filter is stacked on the other polarizer. There you have it.... the same behavior as the Singh-Ray Variable ND for 1/10 the cost in a nice package. If you do the same, just make sure the filters purchased will easily allow you to remove the glass.
Now I just need to take a paint marker and measure the points for 2, 3 ,4 ,5 etc.. stops. "
Unfortunately, I haven't had time to shoot with it all week so I can't give you any input other than it seems to work with test shots from a digital camera. From my meter it looks like it goes from 3 stops to 8 stops (could never get it light enough for 2 stops). The guy who sold me filters at the camera swap is a photography professor who seems to be an expert in filters and their applications (he has 4 tables FULL of hundreds of filters) also said that he has used two polarizers in the past.. the issue is the thinkness of two stacked polarizers can possible vinette at the corners. I went through the trouble of popping out the polarizer glass and placing it inside a UV filter ring in hopes to prevent vinetting. My setup doesn't seem to be any thicker than the Singh-Ray Vari-ND. The guy also mentioned that he will not carry nor use Singh-Ray filters due to past experience with them.... apparently they use to make filters with hard plastic instead of glass. Don't know if thats still the case.
I guess I'm not understanding the difference between polarizing and ND filters, where 2 circular polarizers = nd?
I have a tiffen 67mm circular polarizer already, would screwing a (warming?) polarizer (or nd filter?) on top get me to where I'm thinking I want to go?
You are not too far off.... I'll try to explain but I have to admit my knowledge in this area is limited... (anyone correct anything I'm saying incorrectly)
polarizing filters are different from ND filters. ND filters reduce the light passing through uniformly. Polarizers convert unpolarized light into uniformly polarized light. Two polarizers at 90degrees of each other will filter out all the light. Two polarizers at varying degress of 0-90 will let some light depending on their direction.
If you want to experiment, take two polarizers and stack them on top of each other. Shine a light through it and rotate the front polarizer (holding the rear one steady). You will see a similar effect to that of the Vari-ND filter video that Singh-ray has on their site. In my setup, I essentually remove the rotating ring out of the rear polarizer in my two polarizer stack. This allows for less thickness infront of the lens (prevent vinetting) and makes it easier to rotate the front element without the rear polarizer also spinning.... easier operation.
I haven't been able to experiment yet, but this has brought me back around to using the circular polarizer again, which has been producing some interesting results. Once the grand-kids are sent back home and I have some time, I'll get another polarizer and check it out. Thanks!
I've got the Singh Ray Variable ND filter. It's expensive but it does exactly what it claims to do. Excellent quality and no hint of any unwanted tones to it. I got one in 77mm and use step down rings for my other filter sizes.
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