Re: Astro reports

Chris Street said:

I think at some point the three of us anre going to have to meet up
for a lens comparison session and general pointing at the stars
session.

Sounds good. Somewhere in North Wales would probably be most convenient
for us.

Quoted message said:

When's the next expedition then?

Who knows, maybe we should just arrange a date and place amongst
ourselves then tell everyone it was an expedition when we get back?

Paul
--
http://www.wilderness-wales.co.uk

In article <[email hidden]>, Paul Saunders
<[email hidden]> writes

Quoted message said:

You could set the shutter speed and then use the exposure meter to
determine the aperture, but I find that the exposure meter isn't very
useful for twilight or night exposures anyway, not that I ever trust
auto as you know. Best to make a test exposure using the exposure
meter, then adjust accordingly.

Quickest way to determine the correct exposure is to set the ISO to
maximum and use a fast shutter speed for the test exposures, then adjust
accordingly for the main picture. Taking 30 second test exposures can
waste several minutes, and during twilight the light level changes quite
fast, so by the time you determine the correct exposure, it may have
changed!

I once bracketed three long exposure shots during twilight (back in my
film days), something like 2, 4 and 8 minutes I think, and the longest
exposure came out the darkest!

Ok, thanks Paul, I think you mentioned the above when you posted your
Llyn-y-Fan Fawr pics. I was expecting you to tell me how you used the
division of 600 by whatever focal length lens you used to determine the
actual exposure you would finally use.

If you could e-mail me the details it would save space on the NG.
--
Bill Grey
http://www.billboy.co.uk

W. D. Grey said:

Ok, thanks Paul, I think you mentioned the above when you posted your
Llyn-y-Fan Fawr pics. I was expecting you to tell me how you used the
division of 600 by whatever focal length lens you used to determine
the actual exposure you would finally use.

It doesn't determine the exposure, just the shutter speed.

Paul
--
http://www.wilderness-wales.co.uk

In article <[email hidden]>, Paul Saunders
<[email hidden]> writes

Quoted message said:

It doesn't determine the exposure, just the shutter speed.

I'll not argue such an academic point but of course the shutter speed is
invoved in the exposure!
--
Bill Grey
http://www.billboy.co.uk

W. D. Grey said:

Quoted message said:

It doesn't determine the exposure, just the shutter speed.

I'll not argue such an academic point but of course the shutter speed
is invoved in the exposure!

Obviously it's involved, but the formula is not for working out the
exposure, it's for working out the maximum shutter speed to prevent star
trails. You can use any combination of shutter speed, aperture and ISO
that you want for the exposure, but if you exceed the maximum shutter
speed you'll get trails.

The rule doesn't say that you have to use that shutter speed, only that
you shouldn't exceed it, you can use any faster shutter speed that you
want. But for night time shots, it's more likely that you'll want to
use the slowest speed possible, so that formula tells you what it is.

Working out the exposure is another thing entirely. Trial and error is
as good a method as any, checking the histogram after each shot. What
you'll find is that as it gets darker, you can make a reasonably
accurate guess as to what the next exposure might be, based on the
previous one.

Paul
--
http://www.wilderness-wales.co.uk

"Chris Street" <[email hidden]> wrote in message
news:[email hidden]...
| On Sat, 8 Jan 2005 19:07:24 -0000, ste® wrote:
|
| > "Chris Street" <[email hidden]> wrote in message
| > news:[email hidden]...
| >| On Fri, 7 Jan 2005 23:09:21 -0000, ste® wrote:
| >
| > <snip!>
| >
| >| Before you splash out on a lens I've got a Sigma 18-55 f2.8 DG coming -
| >| I'll post you some sample images if you like.
| >
| > Yes, sure! Email or post away when you get it. I am sure Paul has
| > mentioned this lens to me before too.
|
| See my reply to Paul up one post.

Thanks Chris - 85.4mb no less! :-)

Ste

"Chris Street" <[email hidden]> wrote in message
news:[email hidden]...
| On Sat, 8 Jan 2005 19:07:24 -0000, ste® wrote:

<snip>

| See my reply to Paul up one post.

....Just to add that the look on the bag-piper's face is a classic!! :-)

Ste