Variable ND filter

[motor]

OK now is the time to show your age and experience ( obviously I am showing mine...... Young and dumb ) I am taking a long trip to the a place where there are tons of waterfalls, rushing water and flowing streams. In the mornings it will be foggy, afternoon very bright and evening beautiful sunsets. I have a few bucks to blow and I was thinking about trying to make a Variable ND filter. I have read about them but don't know if it is worth it. I currently have a B+W MRC circular polarizing filter (77mm CP) and have been doing some research. I only have a B+W .6 (2 stop) ND filter which does work at times with the CP to create very silky/ soft shots of moving water but I am limited with only one ND filter. (max 4 stop combining both) I have a great carbon tripod that I can carry anywhere. If I attempt to make my own variable ND to my understanding all I need is a linear polarizer filter ontop of my CP filter correct? How good does a homemade VND filter work as in performance? (good, satisfactory, not worth it?) Has anyone tried this? I have good glass and don't really want to cheapen it. Is it even worth trying or just buy a couple more ND filters? Final question does it matter if the Linear polarizing filter is multi coated or can it just be a basic one? B+W makes both some $40 difference one with MRC other regular. Is it worth getting the B+W MRC linear or can I just get a cheap Tiffen for 1/4 of the price. My feeling is good glass good filters. I don't know though...... I am still young and bumb ( inexperienced I should say to filters ) Photoshop, viveza, fog-it have spoiled me!

Any comments or suggestions?

Motor

[Javelin]

Singh ray has one thats highly regarded. ND2 -ND12 I think.

[Lonnie Utah]

What lens will you be taking the shots on? It's its very wide, you start to get vinegetting stacking filters.

If you want to make those galssying looking stream pics, set on your lowest ISO, stop down all the way, and the add a CP and ND. With just those two you will most likely be OK. Don't forget to take you UV filter off so it's only a 2 stack and not a 3 stack.

That's why I love my sigma 24-70mm. It stops down to f32. I got 8 seconds out of this shot at ISO 200 with only a UV filter...

[WaltKnapp]

Singh ray has one thats highly regarded. ND2 -ND12 I think.

I have the Singh Ray Vari-N-Duo, which combines polarizer and variable ND in one. 2 2/3 to 8 stops ND. It's 77mm diameter but 17mm thick, so not going to work on wide angle lenses much. There is a thin version at 14mm thick too.

Very nice tool for playing with water and some other uses.
http://www.singh-ray.com/varinduo.html

Walt

[motor]

Lonnie this is exactly I am looking for. Perfect picture! There was a post that started about 3 weeks ago about "leaving things behind......." I think David started it, well for this trip I have the opposite problem. As soon as school is out and the kids are done I am hooking up my 32' fifth wheel and taking off for the Eastern Coast of US. We are heading to Niagara Fall, Letchworth falls and state park and Eastern NY. Then we are heading to the White Mts in NH and then Vermont. Then traveling to Washington DC for the 4th or July and then down to the Smokey MTS NC,TN area ( site currently under water right now ) We are then heading to Atlanta and then making a long swing back. I will have room for all my equipment and MORE! I have the Tammy 17-50, Km 28-75, sigma 24-70 HSM, 70-400 G, 70-200G, 11-18 and then I plan to take my old 18-70 and 75-300 on the maid of the mist so that if something happens to those lenses no biggy. I have a set of extension tube, 50 1.4, 30 macro and 2 telecoverters, tripods and heads. I am going to be shooting waterfalls, landscape, mts, memorials, fireworks, zoo animals, aquarium, city and night ambiance. So to answer your question when I get there I will decide on the lens for I will be at each site for at least 4-6 days others more. I am planning on doing most of my falls with the tammy or sigma and Niagara falls with my 70-400 from the distance also. I have step up and down rings to fit everything so the 77 filters will work on everything. (67-77mm) My biggest fear though is late June and all of July the sun is really bright in washington DC and the smokeys. This is why I was thinking of making a Variable ND filter and trying it. I may or may not even need it. I use my .6 ND very little and the B+W CP all the time so to buy another one I would rather I'd like to just play around with a VND if it's cheap but if it decreases the quality majorly then I wouldn't try at all. I will bump the exposer lite to -2 or so if I have to with the CP and all should be fine.


Walt I have seen the singh-ray. It is in high regards and would be an awesome filter to have but if I am going to spend $400 on a filter I'd rather put it towards a lens (Tokina 11-16 2. Sing-ray is how I got the idea of the Variable filter though. A guy at a local camera shop said he had read about making a singh-ray once and when I looked it up he was correct. (CP then just a LP filter on top) I just thought it would be fun to try and if I was out $20-$50 no biggy. I am just afraid of the over brightness, space between the lenses and foggy images so I thought I'd give it a whirl to see if anyone else had ever tried making one or done this with the two filters


If anyone has and CP and a linear polarizer filter give it a try and let me know how it works. (place the cp on the lens first, then put the Linear polarizer on the outside and rotate. I remember from Highschool doing this exact activity and the results of the lenses getting darker. I am still interested in the results on a camera. It could be a fun little tool to have since everything is soft anyway.


Thanks all

Motor

[David Kilpatrick]

Way back in 1977 or so, Cokin, Vivtar, Izumar and others introduced two types of twin polarizing filter. You can make a variable density filter using nothing more than two cheap linear pols. Vivitar at photokina 1978 gave all the press a slimline polarizer (I chose 55mm) together with a dichroic polarizing non-rotatable. This gave a graded colour change from roughly daylight to artificial conversion, to artificial to daylight, but there was no real neutral midpoint! It always seemed to have a pink cast.

I had an Izumar deep purple - colour density changed with the polarizer. And a B+W set with a whole stack of dichroics.

You could put chemical crystals between the two halves of the pol/dichroic and get amazing micro shots with colour polarised crystals against a vividly coloured background, with just white light. I used this for photomicrographs of minerals and cenospheres (hollow ash particles from extreme temperatures in power station combustion) in the 1980s for a calendar. Even old plain sugar crystals look great.

David

[WaltKnapp]

Walt I have seen the singh-ray. It is in high regards and would be an awesome filter to have but if I am going to spend $400 on a filter I'd rather put it towards a lens

Well, in my case I cheated through my usual discount house (ebay) and did not pay anything like full fare. It is really good.

Many years ago I had my one chance at a solar eclipse. I used crossed polarizers for my filter for that. All went well until just as totality approached a tiny cloud also approached and I got no totality photos

A friend gave me copies of his slides taken about a mile away. So all was not lost. The lead in and out were fine with the crossed polarizers on a 400mm lens.

Walt

[motor]

David,

When I looked it up on the net the same words were used " CHEAP linear lens". Does the linear filter NOT have to be of good high quality glass or do you mean cheap as in price? Are you saying I could use a simple Tiffen $15.00 or is it more sensible to get a $40-$60 Hoya or B+W linear filter? I don't think that it needs to be MRC version ($78). ( multi coated) Does the quality of the linear not matter when the circle polarizer is of high quality? I just assumed that if you want a good quality you have to use good quality glass, and since this is a "Jery-rig" Idea my biggest fear is that the space between the filters will reflect or refract light making streaks in the picture of dark and light areas. This is why I assumed you needed a good linear polarizer filter. My local shop has hoya but they are packaged and they are not to keen on the idea of opening one for me just to experiment and then return it. I do see on e-bay and amazon some inexpensive ones I could buy to try.

Motor

[David Kilpatrick]

For cross polarizer micro effects for fun, big sheets of cheap linear polarizer are the best buy (using a high quality polarizer on the camera). I think they mean that all linear polarizers are cheaper than circular pols.

What you do need is perfect colour neutrality. For that, go for Hoya not faked up brands like Tiffen who just buy anything from anywhere then brand it and claim it is the best. Hoya is an original manufacturer and generally their glass matches itself. If you get two unmatched polarizers, they can go blue or brown when you cross them to get the extra density.

So my answer would be you need to try, test ideally, two identical slimline linear polarizers and they should be good quality.

For the best result, buy B+W Kasemann type linear polarizers but the result is a rather thick assembly.

Coating is important, multicoating obviously will help a lot.

David

[David Kilpatrick]

I just tried some combinations:

Minolta circ pol on camera - Vivitar linear pol in front - powerful ND but deep violet/blue cast
Reversed - no effect, except marginal warm-up in maximum position
Hoya linear pol with Vivitar linear pol - useless, intense blue-violet cast
Hoya linear pol with Minolta circ pol on camera - excellemt, total extinction possib;e, no colour cast, massive density range
Two Minolta circular polarizers - no appreciable density change but rather useful colour balance shift, looks like the shift equivalent to an 81C warm up one way, and similar bluish cool-down the other way
Vivitar linear in front of Vivitar Chromo Blend Blue (non rotating) - from pure ND to roughly 80A blue conversion

I'd still go for two Hoya polarizers, but you can use one circular on the camera, and one linear in front

David

[motor]

Thanks David. Good stuff

If you say that the results were good with the Hoya linear polarizer ontop of the Minolta CP then that is what I was looking for. I have a good 77mm B+W mrc cp already so I am going to make take advantage of the local camera shop and send a friend into there to buy a hoya linear polarizer. Then if it DOESN'T work as well as I like I will just have her return it and she can play stupid and say she didn't realize it wouldn't work on the digital camera. I might have an opportunity to try out a B+W MRC linear polarizer next week. A studio Photographer I know might have one stashed away that he doesn't us anymore. He thinks it is only 67mm though, but I have a step down or up ring to make it work and if I like the results I might still want to keep like manufactured glass if possible. The blue tint I read about came from opposing glass and unlike cuts. (again back to different types of glass manufactures) That is what I was afraid of to start. I am just glad to hear that my theory and what I have read does work. I might not even use it but it is a quick fall back if I ever need a darker ND lens and only have the .6 with the CP max.

Thanks again

Motor

[Lonnie Utah]

1 Sec. F32 Iso 100 24mm

[Dr. Harout]

Beautiful.