? re: stacking/sealing holder for ND filters

Folks,

I'm working with the Cokin-P style holder for my 10 and 6 stop ND grad filters (obviously rectangular ones).  I'm interested to know if anyone is/has used this setup and how you were able to 'seal' the holder/filter setup such that NO 'stray' external light entered the lens.

Thanks for you input!

Bill

I needed to use BLACK tape...but I need a better solution than tape!

wgosma wrote:

Folks,

I'm working with the Cokin-P style holder for my 10 and 6 stop ND grad filters (obviously rectangular ones). I'm interested to know if anyone is/has used this setup and how you were able to 'seal' the holder/filter setup such that NO 'stray' external light entered the lens.

Well, that brings back some 1970s memories! Old problem....

If I cared, I'd 3D-print a holder with a clip-on top -- I've done 3D-printed filter holders before. I don't use Cokin filters now.

ProfHankD wrote:

wgosma wrote:

Folks,

I'm working with the Cokin-P style holder for my 10 and 6 stop ND grad filters (obviously rectangular ones). I'm interested to know if anyone is/has used this setup and how you were able to 'seal' the holder/filter setup such that NO 'stray' external light entered the lens.

Well, that brings back some 1970s memories! Old problem....

If I cared, I'd 3D-print a holder with a clip-on top -- I've done 3D-printed filter holders before. I don't use Cokin filters now.

I don't use Cokin filters, only their holders.  I am perusing some solutions, I think I can come up w/something....that 3D printer would be useful

Thanks/Bill

ProfHankD wrote:

wgosma wrote:

Folks,

I'm working with the Cokin-P style holder for my 10 and 6 stop ND grad filters (obviously rectangular ones). I'm interested to know if anyone is/has used this setup and how you were able to 'seal' the holder/filter setup such that NO 'stray' external light entered the lens.

Well, that brings back some 1970s memories! Old problem....

If I cared, I'd 3D-print a holder with a clip-on top -- I've done 3D-printed filter holders before. I don't use Cokin filters now.

Here's what I came up with: I used cardboard and made two 'inserts' (one for each open end of the filter setup in the holder) - used some small size adheasive-backed window seal material to provide the 'seal' between the cardboard and ND filter surface. The inserts are the same width as the 'slot' in the Cokin-P holder where one would insert a 'sprocket' type

Then use black electrical tape over the sides of the Cokin holder (they have slits in them), that together with my little sealing device works great, NO extraneous light enters the camera - tested at 2 minute exposures, looks to work well.

Next project is to stack two ND's and devise a way to 'seal' the gap between the two....I think that won't be difficult.

Bill

I dont have this system but have been working through in my head how to adapt one to my Rokinon 10mm with permanent hood.  I was thinking a black crafting foam stacked or maybe aplied to the sides of a Cd or plexi?  I am following this thread with interest.

thanks.

I ended up purchasing a Cokin-P sized holder from HiTech (a UK company).  With that aluminum holder I am able to place one ND filter virtually flat against the face of the holder, thus no light leakage.

To stack a second ND filter into the holder (I use 10 and 6 stop ND's) there is some 'gap' between the two filters.  I used some black tape to 'seal' that gap and tested at exposure times up to 8 minutes with the camera exposed to direct light (i.e. shooting about mid-day) and I get NO light leakage.  So this is workable.

I also contacted Cokin company last November (2015) as they advertise/sell a new ND grad filter for their P-sized holders that comes with a 'gasket'.  Cokin advised that the gasket would be offered for sale as a stand-alone item; I just sent them another follow-up email a day ago and await their reply.

I don't think I'll go back to using the Cokin plastic holder but on certain occasion I might; I have Singh-Ray sprocket mount polarizer that fits into this Cokin holder and it's possible that I many need both a polarizer and ND filter, tho not often.

On a different forum, I've seen one guy recommend an old black sock to put over the lens and holder to block the extraneous light.

I hate to reply to an old thread, but on the off chance anyone else is (still) dealing with this, here are a few more data points:

• I found a black terry wash cloth makes a good 'drape' to cover the Cokin holder. The only potential problem is washcloths are usually fairly thick (and thirsty!! ), so they're more difficult to "fit around" the holder, lens, etc. If you can find a black (or very dark) microfiber cloth, that can work well.
• I sewed up a black sock hoping it might make a good "bellows" to transition between the lens and the holder. Well, no. At least not my sock, by the time it stretched to fit, it was full of holes. Maybe a (much) larger sock? But now that I mention "bellows" I wonder if a properly-sized old set of bellows could be used? Hmmm...
• I also bought a square Cokin hood for the P Series holder. I put the hook side of adhesive Velcro on the outside and that helps give something the cloth can grab (or vice-versa, actually). The only downside is that now it sticks to everything inside my camera case.   Maybe I'll put it inside a small plastic bag (Ziploc?).
• Black gaffer's tape will cover the pointless slots in the side of the Cokin holder and help light-seal it.
• Again, gaffer's tape can be used to cover the viewfinder during long exposures, to help prevent light leak. I made a little cover from 1/16" thick ABS plastic that slides into the hot shoe and covers the viewfinder.
• With my holder and the Cokin CPL that fits in it, the clearance between the front (outside) surface of the CPL and the back (inside) surface of any filter in the rear slot is VERRRYYYY tight. I have to slightly flex the holder when removing the filter, so I rarely use that slot with the CPL. And, since the more gaps there are between filters, the greater the chance of light leak... I'm still working through that one. Maybe that's Yet One More Reason why folks buy Lee, NiSi, etc., instead of Cokin?

Anyway, hopefully that might help someone.