tflak
Veteran
Sorry - password = vari
Vari ND Artifacts? Check the video
- Thread starter iflight
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Sorry - password = vari
you know. I just set up a DIY polarizer setup like yours and I have a Hoya Linear on top, which I tested with a Tiffen Circular Pola and also a 2nd Hoya Circular Pola on the bottom.
With both setups, I get the horrible Purple discoloration as you stop down. Since The common link between the 2 setups is the Hoya Linear (Which I believe is what you said you're using), I'm thinking that might be the cause of the discoloration.
I have done the DIY in the past with a Calumet Linear polarizer and an older version of a Hoya Linear Polorzier, and I don't remember it getting that purple color.
So yes, I might be trying it with a B+W linear in hopes that the purple will go away.
I have a Genus Fader and have had a Lightcraft, and both those just go dark without the purple. But, the image gets soft on any lens that is about 55 or above, so I just use those for the shorter focal lengths because, unlike the DIY fader and the Sigh Rays, you do not get any vignetting because they have the larger front element. I can use those on a Tokina 11-16 at 11 with a glass UV filter and still get no vignetting.
With both setups, I get the horrible Purple discoloration as you stop down. Since The common link between the 2 setups is the Hoya Linear (Which I believe is what you said you're using), I'm thinking that might be the cause of the discoloration.
I have done the DIY in the past with a Calumet Linear polarizer and an older version of a Hoya Linear Polorzier, and I don't remember it getting that purple color.
So yes, I might be trying it with a B+W linear in hopes that the purple will go away.
I have a Genus Fader and have had a Lightcraft, and both those just go dark without the purple. But, the image gets soft on any lens that is about 55 or above, so I just use those for the shorter focal lengths because, unlike the DIY fader and the Sigh Rays, you do not get any vignetting because they have the larger front element. I can use those on a Tokina 11-16 at 11 with a glass UV filter and still get no vignetting.
Interesting results. As it happens, i was by a friend of mine who just recieved his LCW Fader ND II and low and behold, the manual states: "If you rotate the filter beyond the MAX limit, it may produce varying degrees of off-color X-shaped patterns..."
The more research I've done, it appears that they are not designed to darken to max, and these variable ND's do have a limit. The "limit" (ie. the point after which you will notice uneven discoloration) will vary according to lens used, lighting conditions and focal length, but certainly with a DIY where we have no markings, we will have to be aware of the onset of these artifacts and just stop down to avoid them.
In the end, it appears that, according to LCW and even Singh Ray, from their site: http://singh-ray.com/varinduo.html
"The design of the Vari-N-Duo Filter may introduce irregularities when used with very wide angle lenses, especially on full-frame cameras. Adjust your focal length and reduce the filter density setting until the irregularities disappear."
Seems like this is par for the course and not a DIY failure. Proper use of vari-ND's seems to indicate avoiding "MAX" filtration to avoid these symptoms....
I feel better
stonebat
Veteran
Hmmm... I gotta play with my Fader ND filters more. http://www.clarkvision.com/photoinfo/evaluating_polarizing_filters/
The difference betweent the DIY (with the Hoya Linear Pola) and the LCW and the Genus Faders is that the DIY one turns Purple while the LCW and the Genus simply remain grey. Obviously it just turning grey is better because purple is just a really drastic and nasty color shift.
Has anyone tried the DIY with any other Linear Pola besides Hoya and NOT had the Purple shift? Hate purple... Grrrrrrrr......
Has anyone tried the DIY with any other Linear Pola besides Hoya and NOT had the Purple shift? Hate purple... Grrrrrrrr......
Hey shaveblog, were you able to find the Polaroid Vari ND in something larger than a 43mm or are you using step-up rings?
I bought a 55mm Polaroid vari-ND so it would fit my Canon FD 35mm f2. My LCW Fader-ND is 52mm, so it fits the thread of my FD 50mm f1.4 and with 46mm and 49mm step-up rings fits my 20mm pancake and Vivitar 28mm f2.8 respectively. To be honest I could have gotten a 55-52mm step-down ring and the LCW would work perfectly well on the FD 35mm without a trace of vignetting, but I was curious about the Polaroid and it was cheap enough to try.
Yeah, I was looking at the Polaroid Vari because of the good reviews, including yours, and the price. But the biggest one I can find is 43mm. Thanks for the info.
Thanks a lot! Polaroid's site didn't come up when I googled the filter.
I've finally got around to trying this myself and these are my conclusions
I have tried this with 2 CPLs (2 identical, top one reversed), and 1 LP and 1 CPL. With both combinations I get patchiness in similar shapes to the OP video when almost at full ND settings. Only with LP+CPL do I get the severe purple fringing(the 2 CPLs have it ever so slightly). Also with the LP+CPL I get less light blocking effect.
I suspect the last 2 observations are caused by the fact that the light loss is less on a LP than a CPL. This is also supported by when I've taken pictures with either of the LP and CPL alone and had different exposure, also commonly acknowledged on the internet. This is due to the more simplistic design on the LP due to the lack of a quarter wave filter. I've tried 2 LPs together though only holding them together (I don't have 2 identical sized LP filters) and I got less ND filtering than 2 CPLs.
Now the patchiness I suspect is caused by the distance between the 2 pieces of filter glass. I'm pretty sure if you were to decrease the gap between the 2 pieces of glass you would get less patchiness. Maybe if I was to use a slim line pro1d like CPL the distances would be closer.
I think for my environment and what I plan to shoot, the level of patchiness doesn't occur with the amount of ND filter I need. I took out the CPL glass on the back ring and place in it in a UV filter ring so I could get a more solid and slimmer profile.
Oh if you're going the DIY route and plan to use it on the 14-140mm kit lens I think you'll need at least 72mm filters, I used 67mm filters with a step up ring and get a bit of vignetting in the corners at 14mm, I have to goto around 16mm to get rid of them (you might not have this problem if you use a different step up ring or slim line CPLs like the PRO1Ds)
For my next step I plan to find a way to reduce the distance between the 2 CPLs, maybe try the thinner pro1D glass and try warming CPLs
Sorry for leading you wrong from the previous thread iflight
I have tried this with 2 CPLs (2 identical, top one reversed), and 1 LP and 1 CPL. With both combinations I get patchiness in similar shapes to the OP video when almost at full ND settings. Only with LP+CPL do I get the severe purple fringing(the 2 CPLs have it ever so slightly). Also with the LP+CPL I get less light blocking effect.
I suspect the last 2 observations are caused by the fact that the light loss is less on a LP than a CPL. This is also supported by when I've taken pictures with either of the LP and CPL alone and had different exposure, also commonly acknowledged on the internet. This is due to the more simplistic design on the LP due to the lack of a quarter wave filter. I've tried 2 LPs together though only holding them together (I don't have 2 identical sized LP filters) and I got less ND filtering than 2 CPLs.
Now the patchiness I suspect is caused by the distance between the 2 pieces of filter glass. I'm pretty sure if you were to decrease the gap between the 2 pieces of glass you would get less patchiness. Maybe if I was to use a slim line pro1d like CPL the distances would be closer.
I think for my environment and what I plan to shoot, the level of patchiness doesn't occur with the amount of ND filter I need. I took out the CPL glass on the back ring and place in it in a UV filter ring so I could get a more solid and slimmer profile.
Oh if you're going the DIY route and plan to use it on the 14-140mm kit lens I think you'll need at least 72mm filters, I used 67mm filters with a step up ring and get a bit of vignetting in the corners at 14mm, I have to goto around 16mm to get rid of them (you might not have this problem if you use a different step up ring or slim line CPLs like the PRO1Ds)
For my next step I plan to find a way to reduce the distance between the 2 CPLs, maybe try the thinner pro1D glass and try warming CPLs
Sorry for leading you wrong from the previous thread iflight
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Not at all Dazza. I appreciate the time you put into experiemnting on this. I've learned a lot through this process as well...interesting that the 2 CPL's gave you better results. As we've both discovered, i don't run into problems untill I enter the MAX filter range and I will just stop down a bit and avoid that problematic range in the future...no harm done. I love my Marumi Super DGH Slim CPL - i'd get another and forget the Hoya LP to avoid the disoloration it appears to introduce at higher filtration if i could figure out how to reverse the glass. The darn thing is so slim, i have no clue how to get it reversed. For now, i'll just stick with my Marumi CPL and Hoya LP and avoid the danger zone.
Thanks again for your experiments - very informative!
Polaroid seems to be licensing their name for a LOT of junk these days. There's tons of it on Amazon! There's even a "Polaroid" TTL bounce/swivel/zoom flash that should fit the GH1, for only $90, that seems powerful enough (GN 137). There seems to be absolutely no manual control over it, and I assume it wouldn't have the "FP" mode like the expensive Panny/Olympus FL50, but for the price it might be a good alternative for a hobbyist who doesn't need a $400 flash and doesn't want to mess with a more complex flash with manual controls. http://www.amazon.com/Polaroid-PL12...3IRI/ref=sr_1_2?ie=UTF8&qid=1300378750&sr=8-2
I haven't tried the Polaroid variable ND, but I've ordered a couple more variable ND's off eBay to see how they compare with the LightCraft Workshop one I have now. They all look like they were cranked out of the same Chinese labor camp.
I ordered this one from China: http://cgi.ebay.com/ws/eBayISAPI.dl...895815&ssPageName=STRK:MEWNX:IT#ht_2423wt_906
But it's been a month and 11 days, and it seems to have vanished into the global mail system.
I ordered this one for like a dollar more, which they claim ships from here within the U.S., and is supposedly of high quality. But again...we'll see. Hopefully it will show up in less than a month.
http://cgi.ebay.com/ws/eBayISAPI.dl...95537&ssPageName=STRK:MEWNX:IT#ht_3045wt_1032
Its pretty easy - unscrew the inner ring, revrese the glass, screw the inner ring back in place. I am using two Marumi CPLs as DIY variND and it softens the image, not very bad, but significantly. Single Marumi CPL seems to not soften at all.
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Wait - are you using the DHG Super Circular PLD? This thing is super thin and I cannot figure out where or how to unscrew it!
BTW, what artifacts/coloring to you get when you approach the MAX filtration level? Thanks.
rambooc1
Well-known member
They canceled my order after a week claiming no stock, can't be found anywhere else either. Seems very dodgy.
skiandbike
Member
Help with LPs
Help with LPs
Do two linear polarizers produce the same color shift artifacts seen with a circular and linear combo?
Is sharpness impacted with longer focal lengths with the higher quality polarizing filters in a DIY setup? I know the cheaper variable ND filters seem to have quite an issue with this.
Here is the idea rattling around inside my head: use a flexible filter system for run-and-gun outdoor use, with an adjustable polarizer for cutting through water glare (ex: shallow dof shot of someone fishing in a river on a sunny day at 200mm, while maintaining as much of the GH2's resolution as possible). Stills quality is important as well. The Singh-Ray Vari-N-Duo seems to solve this for $400. By all accounts, you get what you pay for.
I know I can get away with a linear polarizer on m4/3 due to the CDAF. How close would stacking two Hoya linear polarizers get me to the Vari-N-Duo, at 1/4 the cost? I need a polarizer for stills use either way. LPs are a bit more reasonable (and optically simpler) than comparable CPLs, but I could be convinced either way.
I have spent quite a bit of time searching here and other forums to come up with an answer and this thread seems like my best bet (going to ask on DPReview as well), mainly because the m4/3 system uses CDAF and by extension can handle LPs. Everywhere else online references CPL+LP attempts and the shortcomings at high ND levels.
Help with LPs
Do two linear polarizers produce the same color shift artifacts seen with a circular and linear combo?
Is sharpness impacted with longer focal lengths with the higher quality polarizing filters in a DIY setup? I know the cheaper variable ND filters seem to have quite an issue with this.
Here is the idea rattling around inside my head: use a flexible filter system for run-and-gun outdoor use, with an adjustable polarizer for cutting through water glare (ex: shallow dof shot of someone fishing in a river on a sunny day at 200mm, while maintaining as much of the GH2's resolution as possible). Stills quality is important as well. The Singh-Ray Vari-N-Duo seems to solve this for $400. By all accounts, you get what you pay for.
I know I can get away with a linear polarizer on m4/3 due to the CDAF. How close would stacking two Hoya linear polarizers get me to the Vari-N-Duo, at 1/4 the cost? I need a polarizer for stills use either way. LPs are a bit more reasonable (and optically simpler) than comparable CPLs, but I could be convinced either way.
I have spent quite a bit of time searching here and other forums to come up with an answer and this thread seems like my best bet (going to ask on DPReview as well), mainly because the m4/3 system uses CDAF and by extension can handle LPs. Everywhere else online references CPL+LP attempts and the shortcomings at high ND levels.