PMW-EX1/3 IR solution

A

asafb

Active member
Hello,
I just spoke with a guy at Abel CineTech based in New York and he has tested a Tiffen IR filter that correctly solves the IR contamination problem of bleeding reds instead of properly displaying blacks when it comes to indoor shooting with tungsten lighting, bright lights, etc...

Apparently he tested the Schneiders and none worked succesfully, some had a green tint. I am trying to get Tiffen/AbelCine on the phone to find out exactly the model number - apparently he said it is "NOT the hot mirror one, you want to get the IR absorption filter" -- will find out if it's a mattebox or 77mm screw-on.

I am obviously cautiously optimisitc since I want to test this myself.

Stay tuned GuyB! :)

Asaf.
 
I don't know for sure if the internals don't cut far red well or much, but I don't think they do. What happens is the EX has an internal hot mirror which cuts around 700nm, most NDs seem to only cut up to 680nm or so. So when you put an ND on the lens, say an .9, that cuts light hitting the sensor down to 12.5%. The problem is you still get 100% of the far red coming through most NDs, so what is normally overwhelmed by the visible spectrum becomes dominant. The EX sees it as a dull red color.
The Tiffen IR ND seems to block this far red with the yellow-green dye in proportion to the normal ND coating, so it doesn't overwhelm the visible spectrum. Hence, if you put a normal ND on as well as an IR ND, your allowing more far red through to the sensor.
This is only one part of the issue though, some people get far red problems without any NDs. Usually from tungsten lights. Personally I think that has to do with radiated heat, as tungsten heats black objects pretty well. Radiated heat is part of the IR range. Perhaps Tiffen can release a filter with just the dye in some light grades to cope with that.
 
Last edited:
I only care about that last part of IR contamination, the one you get with no ND in concerts and stage productions. I need black costumes to be black, not muddy red. I also see it inside on some grooms clothing as well.

Normal daytime shooting etc I don't see any problem that worries me in the least (so far).
 
GuyB said:
I only care about that last part of IR contamination, the one you get with no ND in concerts and stage productions. I need black costumes to be black, not muddy red. I also see it inside on some grooms clothing as well.

Normal daytime shooting etc I don't see any problem that worries me in the least (so far).
Click to expand...

Same here. Therefore, what we need is a IR filter like the Tiffen - not a Hot Mirror, but without any ND component either - so that other ND filters, either internal or external, could be used with it (should need be - very unlikely in stage production where low-light is typical).

Piotr
 
shiny4 said:
look here:
test with all filters for ex1/ex3
http://provideocoalition.com/index.php/aadams/story/ex1_ex3_ir_filter_shoot_out/
Click to expand...

Yep - there, but also the other two artilces by Art Adams (on the F35, and RED).

The conclusion is what I said in my previous post: unlike the RED (which requires Hot Mirror type of filters), the whole CineAlta series (F35, and the EX camcorders) do NOT need extra Hot Mirror-ing; just some IR cut to fill the hole between 680 and 700 nm...
 
ahhhhhhhhhhhhh.... does the Tru-Cut 680 even exist? i can't seem to find it anywhere. not even on schneider's website. tried googleing and results showed ProVideo Coalition test. where can i buy this product?

thanks.
 
moldcad said:
The closest thing I found is this one:
http://www.bhphotovideo.com/c/product/572940-REG/Tiffen_45650IRND3_Neutral_Density_0_3_ND_.html

- just one stop light loss, but even that's too much for low-light. AND you cannot use it along any other ND filter in bright light, so... Not quite what we need!
Click to expand...


yeah, the tiffens seem find for day exteriors, but you'd need the whole line of them depending on what your stop is. from reading the provideo test you can't use other NDs with this IR filter. meaning if you need to cut 6 stops of light then you'd need to use a 1.8ND IR. it doesn't seem practical when they retail at about $350 for a single 4x5.65. the Schneider Tru-Cut 680 seems ideal but where can you find one?

still shopping.......
 
You must log in or register to reply here.
Back
Top