Hi,
Today I finally have a little bit of time to dedicate to Oly posts, so
here's "an old cow being dragged out of the ditch" - to use a Dutch saying
;)
> Now a few questions:
> - -I decided to push the Provia 100F to 400 ASA, as it was mentioned to
> me that this gives better results than simply using the 400 ASA
> Provia F film.
>
> The planets and the moon are very bright! Use the sharpest film you can
get!
> To estimate the exposure time you can use the following equation:
(F)^2/(C*ISO).
> F = F stop
> C = a constant, with Mars C=70
> So with Provia and your F36 bazooka you must use an exposure time
> of about 36x36/(70*100) = 1/5 s, with a 1000 mm F11 -> 1/60 s!
Great information, thanks a lot Erwin!
So with 100 ASA film it wouldn't even be necessary to push the film to 400
ASA. Well, as you'll have read by now, in the end I didn't take any picture
as Mars still showed up waaaay to small in the sights of the 2400/36
tele-bazooka. Still this is very useful information, especially for taking
moon shots; mind telling me what the C constant would be for moon shots
(I've been told that spot metering the moon and then bracketing a bit seems
to work very well, but what does the formula say)?
> - -What type of magnification would be needed in order to get a, say,
> frame filling shot of Mars? Obviously this falls well within the
> telescopical range, but I'm wondering just what type of magnification
> would be needed.
>
> This falls in the NASA range.
> You will need a telescope with a focal length of about 300 to 400 *meters*
> the have a frame filling shot of Mars...
Darn, that doesn't fit in my attic ;)
> However, the resolution of large telescopes is limited by the atmosphere.
Funnily enough, after posting the original message I came across an article
in a Dutch popular science magazine, and this was mentioned there too.
> Even with "adaptive" optics it is very hard to increase the resolution
> beyond 0.1" (remember: Mars = 20"!). That's why it is worth to spend
several
> billion to get a telescope in orbit, or better: send a probe.
Yes, that does make sense... Hmmm, would Olympus.... Naaaahhh ;)
> - -Did any of you shoot pictures of Mars using telescopes? Acer? Matt?
> Anyone else?
>
> Nope. Only Jupiter, Saturn, Pluto and of course the moon.
> (and with an ordinary 200 mm lens the stereo photo of Uranus and Neptune:
> http://members.nbci.com/_XMCM/photovoogt/astro/uranep.html)
Hmmm, I'm trying to access that picture right now, but the Xoom server
doesn't reply. I'll have to check that at a later time...
> But the selftimer MLU of the OM4 & OM40 is fine too. The ST-MLU will not
work with B, so
> then the OM1 is better. The OM40 eats batteries at B. Best camera for
pictures of the
> planets through a telescope: a $40 webcam!!!
A webcam beating our beloved OMs, who would have thought that...:(
>>Perhaps it's better to remove the cheap converter...
>
> Yes. Use only 1 good converter and a sharp film.
Unfortunately the moon is still a bit small for my likings at 600mm, so I
might experiment with 1 and 2 teleconverters, and see which results are more
to my likings.
> Again: the moon is very bright!
> With the OM4 you can use the spotmeter to estimate the exposure time. Do
not
> forget to bracket!
Yes, that's what I've heard before. Thanks for the advice!
[Joe added]
>Robert Reeves has an excellent web sight on wide field astrophotography.
>The link below covers tests he did on print and slide film.
A most interesting page, I'll have to read that in detail. Unfortunately I
couldn't find Provia 100F in there :(
> One way to overcome reciprocity failure is to "hyper" the film. This can
be difficult
> and dangerous depending on the method used.
This doesn't sound like something that should be attempted at home; I'll
just stick to commercially available film if I'm going to do some tests ;)
>If you search his web site you will see that you can get some great shots,
using off the
>shelf film, with exposures of 15 minutes or more.
>His book is also very good.
Thanks again, I'll check it out!
More tomorrow...
Cheers!
Olafo
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