Why is one prime shooting blue

[chooser]

Sounds a bit of a strange question, but one of my primes appears to be deliverying a blue tint, i guess like simialr to a pale version of shooting tungsten stock in daylight. Its a cooke panchros. Just seems to come out a little (bit definitely can see) blue. Any ideas? thanks

[Chris Keth]

Sounds a bit of a strange question, but one of my primes appears to be deliverying a blue tint, i guess like simialr to a  pale version of shooting tungsten stock in daylight. Its a cooke panchros. Just seems to come out a little (bit definitely can see) blue. Any ideas? thanks

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Well, simplest explanation first (not to insult you), does it have a filter thread at the rear element and is there something on it?

[GeorgeSelinsky]

I have a Cooke Speed Panchro set for my Arri II, and my 25mm lens is colder than my 50 and 75mm. The 25mm is a Speed Panchro III, the other two are Speed Panchro II's. I assume they have different coatings. With negative film this problem is taken care of in timing. With reversal it sticks out like a sore thumb, you'd have to use a CC filter to fix it.

 

- G.

[Chris Keth]

I have a Cooke Speed Panchro set for my Arri II, and my 25mm lens is colder than my 50 and 75mm. The 25mm is a Speed Panchro III, the other two are Speed Panchro II's. I assume they have different coatings. With negative film this problem is taken care of in timing. With reversal it sticks out like a sore thumb, you'd have to use a CC filter to fix it.

 

- G.

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So the lens series is just like that?

[chooser]

BINGO ... exactly the same, what CC do you use to correct? ... thanks for that. ps: same series mix of II's and III's

 

PPS: would you also be so kind as o elaborate on "taken out in the timing" thanks

Edited January 18, 2005 by chooser

[GeorgeSelinsky]

I haven't experimented with filters yet, it probably makes more sense to warm up the one lens than cool down the other two. The correction should be slight. You really have to just shoot a comparison test and try several CC filters.

 

Taking it out in timing means that when the film is timed by the lab (color corrected) from negative to positive, or on the telecine, they will adjust for this difference thereby correcting it.

 

- G.

[chooser]

thanks for your help

[Bill Totolo]

You can spend hours, even days matching your primes at a large rental house.

 

Quick trick- take a toilet paper roll into a dark room and fix it over the rear element of a lens. Turn out the lights and shoot a Scorpion flashlight (or other portable high power light source of known color temp) though the front of your lens and take readings of the light exiting the rear with a color temp. meter. Check for inconsistencies.

 

Write down the serial numbers so you know the set you want. Even if they don't match entirely, you'll be dealing with a known quantity and have a better idea how to correct for their characterisitcs.

[andrewbuchanan]

True, true. I have a set of speed panchros too, the 75mm has a very, very slight yellowing to the glass. Perhaps it comes from age, perhaps it was always this way. When I rent a package and use my glass I set a peice of 100 IRE plastic/paper up and look through the lenses toward the paper... then I get the house's filters and balance out any differences. After doing this a couple of times, I have a good idea of what I need now ( filter wise).

[Nate Downes]

I have a Wollensak that is warm as well. It's quite humerous to see the differences.

[Stephen Williams]

one of my primes appears to be deliverying a blue tint, Its a cooke panchros. Just seems to come out a little (bit definitely can see) blue. Any ideas? thanks

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I have used a 75mm that is very yellow to look at! Apparantly the glass had some sort of long term radio active decay, I think all 75's are effected. The series II were made in the 1930's, the series III from the 1950's. However they make beautiful pictures!

 

Stephen Williams Lighting Cameraman

 

www.stephenw.com