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Fitting a Cokin filter holder to the DW-6 (GX100)

hiro

New Member
Elsewhere someone has written a webpage on how to make a DIY filter thread for the DW-6 using layers of magnetic strip and a sacrificed filter, however there is an easier solution if you are happy to use Cokin filters.

At 60mm, the outer diameter of the DW-6 is only 1mm less than the circular recess on the back of a Cokin-A filter holder. This means that if you reduce the diameter of the recess by 1mm you can simply push-fit the Cokin holder onto the DW-6. The obvious way to do this is to line the recess with a strip of thin card. This method dispenses with the usual Cokin metal adaptor ring entirely. (However you will no longer be able to fit a normal adaptor ring for use with the HA-2's filter thread, so you will need a second Cokin holder for that.) As you can see in the picture, the ring of card simply lines the circular recess and also serves to complete the circle at the bottom. The resulting fit is very snug when using the type of card used for cereal packets etc.

In use, the Cokin holder does not cause vignetting when positioned horizontally or vertically as long as you get it nice and square. There is a little vignetting if placed diagonally. I found the fit to be good and solid, with no chance of the holder falling off.



Method
You can probably figure the rest out for yourself but I'll describe it anyhow. (There are a couple of points to watch out for, such as choice of glue.)

First I would note that my Cokin holder is pretty old, if the design has changed in recent years you may need to adapt your approach accordingly.

You need to use 1/2mm thick card for this job, but luckily this is used by all sorts of packets everywhere. (I used a strip of card cut from the rim of an carton of supermarket Camembert, on the basis that it was already curved and so might be easier to bend further into a circle.)

Cut a strip of card 190mm long and 4mm wide, and fit it into the circular recess in the back of a bare Cokin-A holder (see pic). Trim for exact fit: I found that if the ends of the card overlapped at all, the DW-6 wouldn't go on. Since the fit is very tight, you should initially hold the card ring in place manually whilst checking that the DW-6 can be inserted at all, and if necessary try again with some different card. I found the DW-6 had to be rotated back and forth a bit to ease it into the ring, but this tight a fit does at least ensure the holder won't fall off of its own accord when in use.

Once you've got a fit, you might want to colour the card black with a marker pen for neatness, (although the card won't really be visible when the holder is on the lens). Don't use paint as this surface is going to be subjected to a lot of wear so it would rub off (and may ruin the fit)!

Then put some glue (I used UHU) on the outside of the card and press into place in the holder, wiping off any traces of glue that get on the inside. Allow to dry thoroughly before trying it out!

Going by my previous experience with this sort of lash up, UHU will not melt the plastic of the filter holder, but will nevertheless stick very well with no risk of the card coming off when pulling the holder off the lens. If you use a different glue, test it first for melt problems.

With UHU, I have found that if you ever need to remove a card gizmo like this, you can just soak the filter holder in hot water for a minute or so. The glue will soften such that you can scrape the card and glue off leaving the filter holder reusable.
 

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