Cooke 20-100mm drop-in filters?

[A. Clint Litton]

Hi All,

I've got a Cooke 20-100mm T3.1, which accepts drop in filters at the rear of the lens. Does anyone have any idea where I can find/purchase filters that would work for this lens? I figured it would be nice to get some ND, possibly an 80-series filter for tungsten setups, thereby freeing up my puny 2-stage RRMB for bigger and better things...or nothing at all!

Any insight into this would be greatly appreciated.

Cheers,
Clint Litton

 

[Stephen Williams]

Hi,

You cut gelatin filters to fit the holder.

Stephen

Hi All,

I've got a Cooke 20-100mm T3.1, which accepts drop in filters at the rear of the lens. Does anyone have any idea where I can find/purchase filters that would work for this lens? I figured it would be nice to get some ND, possibly an 80-series filter for tungsten setups, thereby freeing up my puny 2-stage RRMB for bigger and better things...or nothing at all!

Any insight into this would be greatly appreciated.

Cheers,
Clint Litton

 

[Alexis Hanawalt]

Those free filter sample flip books are cut to almost exactly the right size too...

You can also apparently string a thread of filament across the filter holder which will "bling" when light hits it (haven't tried this yet.)

 

[A. Clint Litton]

Those free filter sample flip books are cut to almost exactly the right size too...

You can also apparently string a thread of filament across the filter holder which will "bling" when light hits it (haven't tried this yet.)

Yeah, I think I have a few of those laying around. I've read about the thread trick, too. It should be fun to get creative with the rear filter.

This raises a new issue...apparently, my lens came without a filter holder. there's a semi-circular clip that fits over the opening, but nothing into which to place the gels. Any ideas as to where I could find a replacement?

Thanks Stephen and Alexis for the insight...

 

[Alexis Hanawalt]

They aren't manufactured anymore - so it's very unlikely you'll find a replacement. I recommend just making one out of plain sheet metal or even cut up some cardstock paper.

Here's an image I scanned of mine. I brought up the details in the scan so you can see where the metal edges are - it's really just thin sheet metal with 3 little flaps folded over to hold a gel in place. Hopefully this helps!

 

[Raphael Varandas]

Very NIce Alexis... well done!
I have one of this lens too... a pretty look to me...very particular

 

[Stephen Williams]

Don't use lighting gels, they are not of optical quality & much too thick, that will effect focus.

Stephen

 

[Hans von Sonntag]

Don't use lighting gels, they are not of optical quality & much too thick, that will effect focus.

Stephen

Of course you are right but...

One can use lighting gels if the lens was collimated with a gelfilter in the rear filter slot. But then you need always a filter. I don't know if clear lighting gels are made.

I once used lighting gels and no shift focus was visible but I stopped dopwn the lens to 5.6 anyway

Hans

 

[Alexis Hanawalt]

With the resolving power of a typical Cooke 20-100, I think you're in the clear with lighting gels, but I do confess I have yet to ever make use of the rear filter holder... I may just try it out on my next shoot and report back.

 

[Stephen Williams]

One can use lighting gels if the lens was collimated with a gelfilter in the rear filter slot. But then you need always a filter. I don't know if clear lighting gels are made.

Hans

Hi Hans,

With the Cooke lens the gel filter is not at the back of the lens, it's between the glass elements. Using a proper filter does not effect collimation so I am not sure if that's correct.

Best,

Stephen

 

[Alexis Hanawalt]

I'm still not sure that any type of gel there should effect collimation - it's not adding any distance for light to travel.

Of note, the 18-100's use a different rear filter system with proprietary small glass filters that are inserted...

 

[Stephen Williams]

I'm still not sure that any type of gel there should effect collimation - it's not adding any distance for light to travel.

Of note, the 18-100's use a different rear filter system with proprietary small glass filters that are inserted...

Hi,

If it's behind the lens then the collimation is changed by 1/3 of the thickness of the gel. It's a real issue with fast wide lenses.

Stephen

 

[Sergey Afanasiev]

Now we produce drop-in ND filters for COOKE 18-100T3 lens! B&W glass.... We can offer 2 stops, 4 stops, and 6 stops ND... Produced on military optic factory in Hungary If somebody want it, please drop me e-mail producer@usa.net

 

[Nils J. Nesse]

Now we produce drop-in ND filters for COOKE 18-100T3 lens! B&W glass.... We can offer 2 stops, 4 stops, and 6 stops ND... Produced on military optic factory in Hungary If somebody want it, please drop me e-mail producer@usa.net

Are these compatible with the 20-100 as well?

 

[Clayton Burkhart]

Are these compatible with the 20-100 as well?

My question exactly.