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Re: (meteorobs) Info/help required for developing Leonid 99 film...



Hi Greg,

This is Steve Dearden.  Modern fast colour films from 400ASA upwards with exposures typically from a few (5) minutes to around 15min per frame (depending on sky conditions), tripod mounted with a cable release should get you off to a good start. As for hypersensitization with "Forming Gas": this is a non-exploseive mixture of 92% nitrogen and 8% hydrogren that is used to cause what is known as reduction sensitization of the silver halide grains. The film must be hypersensitized before exposure, usually by placing the unexposed film film in a metal tank, similar to a standard developing tank, and heating to about 50-60C for 24-48 hours.  The film has to be used ASAP after sensitization otherwise the effect wears off.   So you will not be able to hypersensitize your Fuji film now.  So could ask the lab to push process the film, but granularity will increase (should not be a problem for meteor shots).

Different films respond differently to gas hypersensitization.  Expect colour balance changes with colour materials.  One of the best B/W to try is Kodaks Technical Pan 2415.  Extremely fine grained.  Develop in D19.

For future meteor photography:
Try hypersensitized 2415, or if it has to be colour,try Fuji or Kodak 400/800 speed films but check out their reponse to gasc hypersensitization first (go to their Web sites - lots of technical info).
I know 28mm does not cover much sky. But short focus lenses can be expensive.  Try several cameras pointed in different directions.  Borrow a couple of cameras from friends for the evening.  Also consider a rotating disk to determine velociries, or perhaps a cheap diffraction grating in front of the lens to try and capture a meteor spectrum - now that would be something of scientific value.

Hope this helps.  Good luck,

Steve D

 
 
 

Greg Hudson wrote:

Hi everyone...

I tried my hand at photographing the Leonids (first time using an SLR) Using
Fuji 400 Slide film, Canon T4 with 28mm lens, F2.8 aperture, manual shutter
release cable, fixed tripod... I managed to shoot 36 exposures, some lasting
for a very short time (less than 30 secs), and others lasting up to 15
minutes (when there was no activity).

I wondered if anyone could give me any special instructions for getting the
images developed please?

I've read that some people 'hyper-sensitize' their images using gas & low
temperatures, but I'm not sure if this is done before or after the pictures
have been taken?

I also thought about getting the images transferred directly to Compact
Disc.  Any thoughts?

Also, what is the shortest exposure time I could reasonably expect to use
(next time I'm out observing) to get the background stars exposed? (Given
the above equipment)

I'm also curious to see what other people think about how I could improve
things... Here's what I'm considering:
1. Buying a piggy-back mount to allow me to lock the camera to the barrel of
my ETX-90EC telescope. This would at least allow tracking.
2. Purchase of a camera (SLR) with motor drive, that allows (for example) a
5 minute exposure, then automatically winds on to the next (5 minute)
exposure. (This would allow complete unattended operation). Does anyone
knows of a camera that allow such a function?
3. Purchase of a 20mm lens. Would this give sufficient coverage of the sky
without going to a radical fisheye? What I did notice was that a 28mm lens
simply didn't cover much of the sky, so it was just sheer luck that the
camera happened to be pointing in the general direction of a Leonid a few
times (well I hope it was anyway!).

Any info for a first timer would be greatly appreciated - Thanks.

Regards, Greg Hudson. (ghudson@hudsoft.com)

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