Re: Konica 750 & filtered flash

[Joshua_Putnam <josh@xxxxxxxxxxxx>]

Clive Warren <Clive.Warren@xxxxxxxxxxxxx> writes:

>At 2:22 pm -0800 3/2/98, Joshua_Putnam wrote:

>>>According to Konica's technical bulletin No. Tech 015 "Konica Infra-Red 750
>>>has a sensitivity range from 640 to 820 nm in addition to the intrinsic
>>>sensitivity range of AgBr 400- 500nm. The peak sensitivity is 750 nm hence
>>>it's name".
>>
>>>So the answer seems to be - use HIE :-)   Which is a shame as I was using
>>>120 konica film on a rangefinder 6 x 7.  Guess I'm going to have to roll my
>>>own panoramic flash shots....
>>
>>Haven't tried it yet in my 6x9 rangefinder, but I shot a roll of
>>Konica 750 in my OM-4 this weekend, having only used HIE before,
>>and got good exposures using my T-32 flash on manual with an 87
>>filter.
>>
>>I bracketed through a relatively wide range (five stops) and
>>haven't yet decided which shot looks like the best exposure so I
>>can figure out a guide number for the filtered flash.  

>That's great, now try it with two sheets of unexposed, processed Ektachrome
>over the flash head, and no filter on the camera in the dark.

To clarify, that's almost what I did, except I didn't have any 
unexposed, processed Ektachrome handy, and did have an old 87 gel
that was too scratched to use in front of the lens, so I put a
strip of it on the flash.  (The T-32 handily has lips for holding
gel filters over the flash, originally intended for color
correction filters, so just think of an 87 as correcting xenon
to IR.)  No filter on the lens, only on the flash, and I was
shooting in a room dark enough that my wristwatch cast a visible
pool of light on the wall when I hit the light button to
illuminate the aperture ring on the lens.

Based on discussions I've had with other people who have done
filtered flash with HIE, I didn't try using the filtered flash
with TTL metering, just put the flash on full-power manual mode
and bracketed through five stops.  Since I know the stop used and
the flash-subject distance, I can just pick the exposure that
looks best and work backwards to get a guide number.  Haven't had
time for that yet -- the negs are hanging in my film dryer still,
haven't even had time to do a proof sheet.

*
****
*******
******************************************************
*  To remove yourself from this list, send:          *
*         UNSUBSCRIBE INFRARED                       *
*       to                                           *
*         MAJORDOMO@xxxxx                            *
*----------------------------------------------------*
*   For the IR-FAQ, IR-Gallery and heaps of links:   *
*  http://www.a1.nl/phomepag/markerink/mainpage.htm  *
******************************************************

------------------------------