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HMI's give color cast when aging?


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#1 Dennis Hingsberg

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Posted 28 July 2015 - 02:57 PM

I've only read this in a few places but wanted to know from others - is it normal for HMI's to give off any color casts as they age, bulb or ballast?

 

I had one shoot using two ARRI brand name 575w PAR HMI's and one looked yellow/orange compared to the other one. No gels, just a wide angle lens for the light and some barn doors. I never noticed until post.

 

Recently another shoot, three 1200w HMI's varying brands, and I have an obvious magenta cast from one of them that is picked up by certain objects in the frame. Again didn't notice it until post.

 

Would LOVE to hear from other folks on this,.

 

Cheers,

 


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#2 Stuart Brereton

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Posted 29 July 2015 - 02:25 AM

All HMI bulbs change color to varying degrees as they age. It's sometimes along the Red/Blue axis, sometimes along the Green/Magenta, sometimes both.


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#3 Simon Wyss

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Posted 29 July 2015 - 02:47 AM

Yes, bulbs age and change in colour balance. Physics


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#4 Mark Kenfield

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Posted 29 July 2015 - 04:10 AM

Bulbs change all the time, if you're working regularly with a particular gaffer/set of lights, it really pays to know the gel package each light needs to bring it to a neutral space.

Particularly when you're mixing sources like HMI, tungsten, LED or flouros in the same shot.

I bought a batch of 650w halogen bulbs recently, all of which seem to skew significantly warmer than 3200k.

It's where having a colour meter like the new ones from Sekonic really helps.
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#5 JD Hartman

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Posted 29 July 2015 - 06:00 AM

You really need to fire up all the rental HMIs side by side at checkout time and look for those with a major color shift and ask for a bulb changeout.  For most guy popping for a color temp meter probably isn't in the cards.  A cheap one.

 

http://www.bhphotovi...emperature.html


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#6 JD Hartman

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Posted 29 July 2015 - 06:01 AM

I bought a batch of 650w halogen bulbs recently, all of which seem to skew significantly warmer than 3200k.
 

 

What brand bulbs? 


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#7 Dennis Hingsberg

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Posted 29 July 2015 - 01:21 PM

Thanks for the replies, probably time to buy a good color meter.


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#8 Dennis Hingsberg

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Posted 30 July 2015 - 09:08 AM

Below are some shots to give you an idea, there is NO secondary color correction on these images and YES the talent is wearing some makeup that will likely not cause the skin tones on the face to match the arms - but look at the magenta seen on her arms, and the grey face of the actual appliance itself.

 

Any thoughts?

 

Shooting with two Sony F55's in slog3/sgamut3.cine mode with Canon PL cine zooms 15.5-47 f2.8 and 30-105 f2.8. (Full details of the shoot on blog www.hingsberg.com) Actually now that I think about it, I have to go check through footage to see if it was only present in one camera over the other..  maybe the lens or camera itself?

 

20059506085_570a76cf10_b.jpg

19871412868_0a3c18814e_b.jpg

 

19872824049_7a75c6dbeb_b.jpg


Edited by Dennis Hingsberg, 30 July 2015 - 09:13 AM.

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#9 John Holland

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Posted 30 July 2015 - 12:20 PM

I can not see anything wrong with these images !!! If you do ? just do a few tweaks in Post  .


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#10 Satsuki Murashige

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Posted 30 July 2015 - 07:13 PM

Her face does seem quite a bit more green than her arms, but like you say it could also be the makeup. I have seen this makeup phenomenon with Red MX and C300 sensors and HMI lighting, have not yet seen it with the F55.
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#11 Mark Kenfield

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Posted 30 July 2015 - 08:27 PM

 

What brand bulbs? 

 

They were listed as Osram, but appear to be a generic knockoff (bought them from eBay). Got tricked by the old "as Osram" wording on the listing.

 

Serves me right for trying to save money on things that matter. I've replaced them with proper Philips bulbs.


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#12 Phil Rhodes

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Posted 31 July 2015 - 03:53 AM

I've been using quite a bit of ceramic metal halide stuff recently and not seen problems. And the bulbs are only £10 each at 150W!

 

P


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#13 Dennis Hingsberg

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Posted 05 August 2015 - 09:09 AM

John the skin in these quick grades are quite on the yellow side, once I rebalance for the skin the magenta seems to pop right out more. 


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