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Cooke 18-100mm rear filter question

George A

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The Cooke 18-100 does have a filter slot that accommodates 2 types of filter holders, gel filters or glass filters.






The 2 types of holders





I am most familiar with the 30.5mm glass filters and holder as I used that the most. Gels can be slow, and get messy when you are in a hurry! I have 2 glass filter holders so you could preload a 2nd filter pack to change filter requirements quickly.



The glass filters were mounted in a metal ring that screwed into the holder.







The Cooke glass filter holder




With Filter





Top view of holder w/o filters




Holder with 2 filters screwed in




In the States, the 30.5mm filters were sold through Les Zellan's ZGC. They were Tiffen filters that were ground down to fit the very thin metal rings that was required to fit into the opening on the 18-100. I believe you could buy the mounted filters through Tiffen also, but that was years ago. But, thanks to Ira Tiffen, I was able to acquire some blank metal rings from Tiffen so I could mount nets on them. They also ground down (thickness) a couple of specialty filters for me, one being a 1/2 value Enhancement filter. Not many shooters remember the Enhancement filter these days.


One word of caution, while Cooke claims that "no degradation of optical performance or shift of back focus", I found that you had to be careful when using "effect" filters, not N.Ds, 85s, 85NDs, or EFs etc. With one filter on the holder no problem, but when you added the 2nd filter, well, sometimes there was a slight change on the focus scale. Different thickness of the glass filters, or the type of "effect" filter could cause slight changes. So, I'm not dissing Cooke, but it's the type of glass you put into the "optical path" that mucked things up.


For table-top shooting, the rear filter holder in the 18-100 was a very welcome feature, no big matte box to hold 6.6 X 6.6 filters!


This could lead to a debate, is an effect filter better in front of a variable focal length lens when the magnification is changing on the effect filter, or is it better in the optical path after the image has been formed, whether it's wide or tel? Film or digital, doesn't make a difference, in my opinion.



The 20-100 has a Gel Filter holder as shown here





Also, the 18-100 has a very nice look on both 35mm and 16mm. The close focus helps also.








George, it's best to use your full name on the forum. Da rules.

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