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Re: Astro reports

Started by Paul Saunders · · Last activity · 47 posts · 1,149 views

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General fitness, health and nutrition
Published
5 January 2005
Last activity
15 January 2005
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Paul Saunders
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  1. ste® said:

    Thanks for that Chris, though I'll take your word for it because I could
    personally join up any of those dots and still can't recognise anything! It
    takes some skill.

    Yes, I was looking in roughly NNW.

    You amongst others...

    Quoted message said:

    Ste

    requote 98 lines to add 5 ??

    Getta grip y'all !!!!

    How about following accepted protocol and requoting /just/ the content
    you are replying to?

    I know its hard, life's a biatch and all that but... needs must?? ;-)

    SteveO
    --
    NE Climbers & walkers chat forum;
    http://www.thenmc.org.uk/phpBB2/index.php

    NMC website: http://www.thenmc.org.uk

  2. I noticed that Message-ID: <[email hidden]> from Paul
    Saunders contained the following:

    Quoted message said:

    and as you know, depth of field is extremely narrow with a
    long tele so accurate focusing is critical.

    I suspect that at astronomical distances it turns out to be quite large,
    but I know what you mean. ;-)

    --
    Geoff Berrow (put thecat out to email)
    It's only Usenet, no one dies.
    My opinions, not the committee's, mine.
    Simple RFDs http://www.ckdog.co.uk/rfdmaker/

  3. Chris Street said:

    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.

    I'm keen to hear more about that too.

    Quoted message said:

    It apparantly is exceedingly good glass and at 2 stops faster than the
    Canon one it'll be handy for night work.

    My thoughts exactly.

    Quoted message said:

    I just need the money to get a 10mm rectangular prime and I'll be
    happy.....:-)

    Surely no-one makes one?

    Sigma do an 8mm fisheye don't they? Perhaps there's some software to
    de-fish it?

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

  4. SteveO said:
    Quoted message said:

    Should be possible if you crank the ISO up, I managed it. Remember
    the 600 rule, divide 600 by the (equivalent) focal length for the
    maximum exposure time in seconds to prevent trails.

    huh? 600/gazillion miles = still gazillions
    ;-)

    Focal length, not distance to the stars!

    600/480 equiv (300mm on a 300D) = 1.25 seconds
    600/88 equiv (55mm) = 6.8 seconds
    600/27 equiv (17mm) = 22 seconds

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

  5. Geoff Berrow said:
    Quoted message said:

    and as you know, depth of field is extremely narrow with a
    long tele so accurate focusing is critical.

    I suspect that at astronomical distances it turns out to be quite
    large, but I know what you mean. ;-)

    Yes, if you focus on the moon then the stars will be in focus too, but
    that's not much use if you've focused on the tree 10m in front of you.

    Manually focusing a 300mm lens (480 equiv) requires a lot of care in
    daylight, it's extremely difficult in the dark, especially when turning
    the focusing wheel just 1mm can make a huge difference to the focus
    point.

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

  6. SteveO said:


    You amongst others...

    Quoted message said:

    Ste

    requote 98 lines to add 5 ??

    Sorry 'bout the mini-rant y'all, it was nothing personal, well it was
    but it wasn't IYSWIM. If the whole mesage is re-quoted it makes it
    nigh on impossible to see where/ what you're replying to :-(

    </petpeeve>

    SteveO
    --
    NE Climbers & walkers chat forum;
    http://www.thenmc.org.uk/phpBB2/index.php

    NMC website: http://www.thenmc.org.uk

  7. Paul Saunders said:
    SteveO said:
    Quoted message said:

    Should be possible if you crank the ISO up, I managed it. Remember
    the 600 rule, divide 600 by the (equivalent) focal length for the
    maximum exposure time in seconds to prevent trails.

    huh? 600/gazillion miles = still gazillions
    ;-)

    Focal length, not distance to the stars!

    <doh!>
    ;-)

    SteveO
    --
    NE Climbers & walkers chat forum;
    http://www.thenmc.org.uk/phpBB2/index.php

    NMC website: http://www.thenmc.org.uk

  8. Paul Saunders said:
    Quoted message said:

    Thanks for that. I'll have a look on the next clear night and see if
    I can make it out.

    Well tonight's the night. Try to get a pic if you have clear skies.
    Look south at 9pm, SE earlier, SW later.

    Did either of you (or anyone else) get a clear sky last night? I
    picked up a "red alert" on auroa watch last night, did it translate
    into high aurora activity?

    SteveO
    --
    NE Climbers & walkers chat forum;
    http://www.thenmc.org.uk/phpBB2/index.php

    NMC website: http://www.thenmc.org.uk

  9. ste® said:
    Quoted message said:

    Nice pic too.

    Yes, that's what yours should have been like! ;-)

    Indeed. Lend me a few grand for a decent computerised telescope plus a
    good quality CCD and my next effort will be! ;-)

    Quoted message said:
    Quoted message said:

    Pray tell, how do I focus on infinity with a cheapo lens that has no
    distance scale?

    When I took my star photos, I auto-focused on the moon then switched
    it to manual focus. I'm pretty sure that was your advice too.

    No moon.

    Quoted message said:

    On a
    moonless or cloudy night, I would have tried to have focus on the
    most distant object I could see (assuming there was something light
    in a distance).

    That's the problem. I was taking the photos from my back yard, which is
    completely enclosed. This has the disadvantage of a very restricted sky
    view, but the advantage of completely blocking out all street lights.
    This also means that there are no distant objects for me to focus on, I
    have to go through the house and outside to get a distant view of
    anything, and that'd be a pain in the [censored] doing that every time I
    change the focal length, which tends to throw the focus out.

    Quoted message said:

    I'm surprised that you haven't yet prepared a table of infinity marks
    against temperatures! You could go out and focus on the moon and
    note the temperature and focusing position! Hard work though... ;-)

    Way too much hassle and too imprecise. How would I know the temperature
    of the lens? It's one thing knowing the air temperature, but how
    quickly does a lens drop to that temperature after leaving a warm room?
    I know that my 10-22 lens was pretty cold at Llyn y Fan Fawr since there
    was frost forming on it. Perhaps lenses should come with internal
    thermometers? ;-)

    Quoted message said:

    Yes, I realise why it's a problem. This is where a viewfinder
    magnifier would also come in handy, to help manual focus on distant
    and small objects.

    Yes, that would be a much better solution. A faster lens would help a
    lot too. In case you hadn't realised, the maximum aperture of the lens
    determines how bright the viewfinder image is (along with other
    factors - I think the 20D viewfinder is a bit dimmer than the 300D,
    which is dimmer than the 10D). That's another good reason for using an
    f2.8 or brighter lens for night shots. F5.6 at night is not good.

    Quoted message said:

    Oh well, like you've said before, you're never going to get great
    astro-photography without some a specialist setup.

    No, and it's not a priority so I can't see me spending real money on
    what is only a minor hobby, not until I have money to burn anyway. ;-)

    Quoted message said:
    Quoted message said:
    Quoted message said:

    My only way of finding the North Star is...

    Quoted message said:
    Quoted message said:

    I'd recommend the Collins Gem Guide - TheNight Sky,

    Quoted message said:
    Quoted message said:

    a small pocket sized book, if they still make it, or
    something similar.

    Quoted message said:

    Yes, don't worry, I'll sort it out. It's going to at least be
    important for me to find the north star and see sky charts to work
    out its position in relation to nice landscape scenes.

    You don't need star charts for that, all you need is a compass, a cheap
    one will do! How high is it? Simple, whatever your latitude is, that's
    how high the north star is, in your case roughly 53.5 degrees.

    Quoted message said:

    to work
    out its position in relation to nice landscape scenes.

    No working out needed for the north star, just point your camera north!
    The north star is always in the same position, north! No matter where
    you are! So all you need to find is some north facing compositions.
    Just get hold of a cheap compass, even a button one will do. Use that
    to aim the camera. Tilt it up at 53.5 degrees to get the north star in
    the centre. You'll need a wide angle to include the ground in the pic.
    Aiming up at say 25 degrees may give you a decent composition with
    ground at the bottom and the north star at the top, depending on how
    wide your lens is of course. Try your 18-55 lens at 18mm.

    Quoted message said:

    Possibly a good lens, but nooo, not another lens! :-) I'm now
    working on the assumption that in order to buy more camera equipment,
    I must make money from the hobby first. We'll see!

    That's the problem. Easy to get hooked on buying lenses, but at the end
    of the day it's a hassle to carry them and a hassle to change them, so
    if you buy too many you'll end up leaving most of them at home.
    Consider your lens choices carefully, buy lenses that you really need
    and which you'll use a lot. It's a big expense initially, but can be a
    good investment over time. Before I went digital I was using the same
    lenses that I bought between 1986 and 1989. No need to keep upgrading
    them like digital camera bodies, once you've got a set of lenses you're
    happy with.

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

  10. SteveO said:

    Did either of you (or anyone else) get a clear sky last night?

    No.

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

  11. The message <[email hidden]>
    from Chris Street <[email hidden]> contains these words:

    Quoted message said:
    Quoted message said:

    OH, bog off.... why do some folk /persist/ in requoting the entire
    post they are repying to, to add a line and a bit??

    Quoted message said:

    Don't bloody read it then - I don't care.

    Your choice but I for one routinely skip posts from those who do not
    have the courtesy to edit out irrelevant repetition.

    --
    Roger Chapman

  12. "Chris Street" <[email hidden]> wrote in message
    news:[email hidden]...
    | On Fri, 7 Jan 2005 23:08:54 -0000, ste® wrote:

    <snip!>

    | > Thanks for that Chris, though I'll take your word for it because I could
    | > personally join up any of those dots and still can't recognise anything!
    It
    | > takes some skill.
    | >
    | > Yes, I was looking in roughly NNW.
    |
    | It was actually easy once I looked at the second shot - the trails give a
    | clear idea of where the north axis is and then I can easily see which
    | direction it is in. Given an almanc and some time I could probably nail
    | your exposure time down to a few minutes and also the duration on the
    | second one.

    Sounds very 'big brother' to me, you'll be telling me what underwear I was
    wearing next! ;-)

    | But I did do Astronomy at Uni which helps.....

    Ahh yes, that would help! :-) Thanks again, and if I take some nice photos
    in the future of stars or star trails, I'll be sure to come back to you for
    help in keywording the constellations correctly.

    Thanks,

    Ste

  13. <SteveO> wrote in message news:[email hidden]...
    | On Sat, 08 Jan 2005 02:51:23 +0000, SteveO wrote:

    <snip!>

    | >requote 98 lines to add 5 ??
    |
    | Sorry 'bout the mini-rant y'all, it was nothing personal, well it was
    | but it wasn't IYSWIM.

    By your standards, that was quite a tame rant, I've seen much worse...

    | If the whole mesage is re-quoted it makes it
    | nigh on impossible to see where/ what you're replying to :-(
    |
    | </petpeeve>
    |
    | SteveO

    I'm usually quite good at snipping, but I do slip from time to time. But
    rest assured, I don't do it to deliberately wind yourself or Roger up
    though, and I will snip harder in future! ;-)

    Ste

  14. "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.

    | It apparantly is exceedingly good glass and at 2 stops faster than the
    | Canon one it'll be handy for night work.

    Yes, should be good. I found the 50mm lens (80mm equiv on 20D) to not be
    wide enough to get a lot of the night sky when I did that photo. As you're
    a bit of an astronomer, I'll look forward to seeing some of your night shots
    too! ;-)

    | I just need the money to get a 10mm rectangular prime and I'll be
    | happy.....:-)

    As I've started out with zero lenses, my initial purchases have been for
    lenses that offer me something different, like telephoto zoom, or macro,
    etc. My only gap at the moment is a wide-angle lens, like the Canon EF-S
    10-22 which Paul and Bill have.

    I've currently got:

    EF-S 18-55
    EF 75-300 IS USM
    EF 100 2.8 Macro
    EF 50 1.8

    My plan is to save up and get a good wide-angle lens, then look at replacing
    the existing lenses above with better versions (i.e., like you Sigma).

    What other lenses have you got? If you're interested in testing, then Paul
    has a good test chart he could email you and some interesting results from
    his lenses. I keep meaning to print the chart out and do my own tests, so
    will share the results when I do this.

    Ste

  15. ste® said:

    if I take some nice
    photos in the future of stars or star trails, I'll be sure to come
    back to you for help in keywording the constellations correctly.

    Thing is, you really should learn them yourself, because if you just
    point the camera randomly at the sky you could find yourself
    photographing 5/8ths of a constellation or parts of two different
    constellations thinking that they're the same one. If you really want
    to sell pics of constellations, you should include the whole
    constellation and crop appropriately.

    It's not that difficult, really. All you need is a pocket book of
    constellation maps, a small torch (with a red filter if possible, to
    prevent losing your night vision), some warm clothing (don't forget the
    wooly hat) and a calm, clear night.

    Start with Orion, then spread out from there.

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

  16. "Paul Saunders" <[email hidden]> wrote in message
    news:[email hidden]...
    | ste® wrote:

    <snip!>

    | Indeed. Lend me a few grand for a decent computerised telescope plus a
    | good quality CCD and my next effort will be! ;-)

    But what about the old saying, "nice photo, what camera have you got?" I
    know many photographers don't like that! ;-)

    <snip!>

    | > I'm surprised that you haven't yet prepared a table of infinity marks
    | > against temperatures! You could go out and focus on the moon and
    | > note the temperature and focusing position! Hard work though... ;-)
    |
    | Way too much hassle and too imprecise. How would I know the temperature
    | of the lens? It's one thing knowing the air temperature, but how
    | quickly does a lens drop to that temperature after leaving a warm room?
    | I know that my 10-22 lens was pretty cold at Llyn y Fan Fawr since there
    | was frost forming on it. Perhaps lenses should come with internal
    | thermometers? ;-)

    I like the way you dismiss it - not because it's a bit over the top, but
    because it's not quite accurate for you! :-) Something tells me that if the
    lenses did have internal thermometers, you'd soon have your table in your
    pocket! ;-)

    | > Yes, I realise why it's a problem. This is where a viewfinder
    | > magnifier would also come in handy, to help manual focus on distant
    | > and small objects.
    |
    | Yes, that would be a much better solution. A faster lens would help a
    | lot too. In case you hadn't realised, the maximum aperture of the lens
    | determines how bright the viewfinder image is (along with other
    | factors - I think the 20D viewfinder is a bit dimmer than the 300D,
    | which is dimmer than the 10D). That's another good reason for using an
    | f2.8 or brighter lens for night shots. F5.6 at night is not good.

    Yes, I did already know about the lens max aperture determining the
    brightness of the viewfinder image. Likewise, I've also read the same thing
    the brightness of the viewfinders for the 10D, 300D, and 20D - though I read
    that the 20D is still better for manual focusing because it has a grainy
    texture on the glass. However, I've only really noticed this texture when
    out on a bright sunny day! ;-)

    I know the Angle Finder C is £150, but you can pick them up for a *bit*
    cheaper on eBay, though still expensive. I initially didn't like the
    thought of this because it would only really be suited for macro work and
    floor work, but after noticing that I am often bending down to take my
    landscape shots anyway (because I've got a small crappy tripod), it might
    actually suit this type of photography better than first thought.

    | > Oh well, like you've said before, you're never going to get great
    | > astro-photography without some a specialist setup.
    |
    | No, and it's not a priority so I can't see me spending real money on
    | what is only a minor hobby, not until I have money to burn anyway. ;-)

    I don't know much about astronomy, but it would be really cool to have some
    8 megapixel photos of galaxies, stars, etc, with all them bright colours..
    But as you say, you'd have to spend real money on that and be dedicated to
    make it worthwhile. ...so I was thinking about contacting my local
    astronomy club (wherever that may be), to see if there's any chance of
    coming along with my camera one night to take some photos through their
    telescopes. That way, I'd hopefully have no expense (though I'd be unsure
    what I'd need to connect my camera to the telescope), will have access to
    good equipment, can rely on someone elses expertise to find something
    interesting in the sky, and can then snap away. What do you think, and
    would you do something similar by where you live?

    <snip!>

    | You don't need star charts for that, all you need is a compass, a cheap
    | one will do! How high is it? Simple, whatever your latitude is, that's
    | how high the north star is, in your case roughly 53.5 degrees.

    Easy when you know how. Okay, that sounds quite simple, I can guess 53.5
    degrees and I know which way north is when I go out to local locations. I
    was thinking of going to the beach for some night photos, but it's that
    windy around here that I'd be too worried about getting all sorts of sand in
    the camera. It'd be a good walk though if I can bear to leave the camera at
    home and just go for the fun of it! :-)

    <snip!>

    | No working out needed for the north star, just point your camera north!
    | The north star is always in the same position, north! No matter where
    | you are! So all you need to find is some north facing compositions.
    | Just get hold of a cheap compass, even a button one will do. Use that
    | to aim the camera. Tilt it up at 53.5 degrees to get the north star in
    | the centre. You'll need a wide angle to include the ground in the pic.
    | Aiming up at say 25 degrees may give you a decent composition with
    | ground at the bottom and the north star at the top, depending on how
    | wide your lens is of course. Try your 18-55 lens at 18mm.

    I'll try it Paul, thanks. No need to get a compass though as I know my
    local locations/directions; and I've also got a GPS if needed. I was
    reading an article by David Noton in one of the magazines a month or so ago,
    and he recommended a watch with a built-in compass. Might be a good idea as
    it'd do two jobs in one and save carrying something else in the bag.

    | > Possibly a good lens, but nooo, not another lens! :-) I'm now
    | > working on the assumption that in order to buy more camera equipment,
    | > I must make money from the hobby first. We'll see!
    |
    | That's the problem. Easy to get hooked on buying lenses, but at the end
    | of the day it's a hassle to carry them and a hassle to change them, so
    | if you buy too many you'll end up leaving most of them at home.
    | Consider your lens choices carefully, buy lenses that you really need
    | and which you'll use a lot. It's a big expense initially, but can be a
    | good investment over time. Before I went digital I was using the same
    | lenses that I bought between 1986 and 1989. No need to keep upgrading
    | them like digital camera bodies, once you've got a set of lenses you're
    | happy with.

    My LowePro backpack is quite heavy with all my lenses now! And I've only
    got about 4 of them and a flash! Saying that though, when I wear the
    rucksack over both shoulders and tie the clip across my chest, it doesn't
    feel that heavy at all. In fact, I'm currently carrying a surplus 4 stone
    around my belly anyway, so what's a few lenses...! :-)

    The lens plan is to eventually (and this might be a few years down the line)
    have a few high quality zoom lenses, nice big white ones! :-)

    | Paul

    Ste

  17. ste® said:

    | Sorry 'bout the mini-rant y'all, it was nothing personal, well it was
    | but it wasn't IYSWIM.

    By your standards, that was quite a tame rant, I've seen much worse...

    hey... when I were a lad!!
    ;-)

    Quoted message said:

    I'm usually quite good at snipping, but I do slip from time to time. But
    rest assured, I don't do it to deliberately wind yourself or Roger up
    though, and I will snip harder in future! ;-)

    yurra gent!

    <ouch!>
    hey, careful with those scissors!!

    ;-)

    --
    SteveO

    PPP
    rr |\ _,,,---,,_
    zz /,`.-'`' -. ;-;;,
    |,4- ) )-,_. ,\ ( `'-'
    '---''(_/--' `-'\_)

  18. In article <[email hidden]>, Chris Street
    <[email hidden]> writes

    Quoted message said:

    I picked the nearest hills to the capital towns, then realised that Cardiff
    wasn't that far west and more people seem to be nearer Swansea than Cardiff
    (or I've totally got you Fran and Bill G's home locations mixed up)

    Excellent Chris - this info will do fine - thanks.
    --
    Bill Grey
    http://www.billboy.co.uk

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

    Quoted message said:

    Should be possible if you crank the ISO up, I managed it. Remember the
    600 rule, divide 600 by the (equivalent) focal length for the maximum
    exposure time in seconds to prevent trails.

    Glad you repeated this Paul, I couldn't remember what you divided 600
    by!

    Can you e-mail me the full monte re aperture/focal length /ISO etc,
    Or do you get to the aperture for the right exposure length by trial and
    error?
    --
    Bill Grey
    http://www.billboy.co.uk

  20. W. D. Grey said:

    Glad you repeated this Paul, I couldn't remember what you divided 600
    by!

    Can you e-mail me the full monte re aperture/focal length /ISO etc,
    Or do you get to the aperture for the right exposure length by trial
    and error?

    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!

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

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