Film-Tech Forum ARCHIVE: Hand Douser Question

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Posted by Matt Hollis (Member # 2954) on 03-21-2006, 08:55 AM:

How long does one recommend the hand douser be left closed with the bulb operating? We have a mix of Xenex I's, Xenex II's, and Xetron XHN's. Is the C/O douser strong enough to hold back light for a while (5 to 10 minutes)?

Posted by Bryan Fournier (Member # 264) on 03-21-2006, 09:11 AM:

Matt,

A properly functioning hand douser should be able to take a lamp's heat for that period of time. I've used the douser for up to 15 min when aligning a xenon lamp. The more important number is no more than 30 sec of raw light through a lens. BTW - I wouldn't use the C/O douser plate to block the light for more than 30 sec either. They're mainly designed to block the light for brief periods while the countdown leader is running through the gate. I've seen holes burned right through them.

Posted by Louis Bornwasser (Member # 3063) on 03-21-2006, 12:47 PM:

In studio applications, the lamp is not shut down at all between 20 minute reels. (The bulb is always darker when first struck). Not all dousers can stand this much long-term heat so special cooling fins, etc are required on the douser blade. Also special attention must be paid to the reflection off the douser and what it does to super-heat the bulb & reflector. Louis

Posted by Gordon McLeod (Member # 33) on 03-21-2006, 12:58 PM:

The Xenex1 and 2 have issues with heat so a better dowser is advised

Posted by David Graham Rose (Member # 1450) on 03-21-2006, 01:29 PM:

Greetings
How long does one recommend the hand douser be left closed with the bulb operating? We have a mix of Xenex I's, Xenex II's, and Xetron XHN's. Is the C/O douser strong enough to hold back light for a while (5 to 10 minutes)?

Hand douser = close with one's hand
C/O douser = close by means of an electromechanical switch.

My dear chap, it really is as simple as that.

From Cambridge

Goodnight

David

Posted by Monte L Fullmer (Member # 2797) on 03-21-2006, 11:48 PM:

Shoot, Cine V8(r) machines, mounted as a V-18 setup, had a dowser pretty thick to when the bulb was ignited, the bulb stayed lit for the entire day...we had vertical 2.5k bulbs in those side shooting lamphouses.

-Monte