[LargeFormat] Leonid Meteor Shower
Michael Briggs
largeformat@f32.net
Sat Nov 17 12:40:00 2001
On 17-Nov-01 Clive Warren wrote:
> As for technique - yep and thanks for the advice. I am hoping to use
> a 7" aero Ektar on 4x5. This has an aperture of f2.5 and is corrected
> for infinity - probably performs very well wide open. This is one of
> those times that not having a shutter is an advantage in the dark -
> just take the lens cap off :-)
This should work. I wonder whether a f2.5 Aero Ektar delivers more light than
a modern f5.6 lens. The Aero Ektars must be uncoated and the rear glass has
turned brown from self-induced radation damage. I am doing a historical and
labortory study of the Aero Ektars. Two of the rear elements contain Thorium.
>
> As for film - B&W 400ASA pushed one stop. As you seem to know a bit
> about astro photography, what do you think my chances are? I
> understand that the meteors will probably be as bright as the the
> brightest stars but will be very fast moving.
You approach sounds good. You can develop one sheet and adjust the time.
Since it is not a pictorial scence, the criteria for developing are different.
I have used high-constrast developers like D-19. I don't know what the best
choice would be, perhaps Microphen or XTOL.
One thing, base your exposure time on the sky brightness from light pollution.
If you are near a city you will have to keep the exposures shorter, of the
order of a minute or two, I can't say exactly. With truly dark skys, much
longer exposures will work. You can stop the exposure when you think you have
a bright meteorite, or you keep going for longer star trails and possible
additional ones.
Good luck with the weather.
--Michael