[Nim]

Hi
I bought my husband a fairly decent entry level telescope for his birthday.  He's got it all set up and working but could do with some advice on the best viewing times etc.  He had a look at joining the Sheffield Astronomical Society, but the photo on the website put him off (he's not old or grey enough, and has too many teeth).  Does anyone know of any slightly more "hip" astronomy type clubs/groups in the Sheffield area? 
I realise this is a slightly rhetorical question, as astronomy is, in itself, nerd-ville central  , but I know some of you are astronomy-minded (Stu?).   Any advice very welcome! 
Thanks in advance
Nim

[underground]

Norton College has (or at least had) an observatory - and ran an evening class, GCSE Astronomy, once - I say once because I did it back in '93. This fella ran it, but has obviously moved on since then...

I'd still give the college a ring though, it was a nice course.

[Stu Littlefair]

Mexborough and swinton astronomy society are a decent bunch.

There's a slight nerdish tendency to most astronomy clubs though. If he wants to go it alone, sky and telescope magazine and website have a guide to what's good to look at each month.

[Tiberius]

There's no real substitute for being shown how to observe the sky by the nerds, sorry. A bit like having a sensible climbing instructor, then go take your top off, wear a beanie and do some bouldering...but get the basics first, it will make a hell of a lot of difference to his enjoyment.

A friend went on an open uni course in Spain and was really surprised how close to the big boys the amatuer can get.

[slackline]

A friend went on an open uni course in Spain and was really surprised how close to the big boys the amatuer can get.

On this front, another plug for AndiT's astrophotography.

Most recent shot...


 

[SA Chris]

Oh my God. It's full of stars!

[Nim]

That's a great photo! 
Thanks for the advice - really appreciated.  I'll get him to look at the Mexborough group, even if it means growing a beard 
Have to admit, I am almost tempted by the whole "looking at the stars" thing.  I spy plenty of trips to Sedbergh in the near future (with down jackets)!
Thanks again
Nim

[r-man]

Dunno if there's another thread for this, but...

Green fireball just been sighted apparently. Anyone see it?

https://twitter.com/VirtualAstro

Definitely a very large green fireball in northern skies spotted by many,

[lagerstarfish]

apologies

a) if I have posted this before

b) it is a very poor quality pic

c) my composition skills suck

I was very excited to get this pic of Jupiter and moons from our back yard - for some reason I find it amazing that I could take a photo of another planet using household technology

I'd gone outside with binoculars to have a look - bit wobbly - so I  thought I'd try using my wife's SLR on a tripod with long lens and laptop as monitor

it worked pretty well and I even managed a photo - I was surprised just how fast the earth spins - exposures of more than a second or so resulted in streaked stars - I tried using a long, weak elastic band to pull the tripod head round at the right speed, but didn't manage to get it to work

only 3 moons visible that night - the other is obviously obscured by the enormous black monolith floating out there

Canon 500d with cheap Tamron 300mm lens - and then cropped and cropped some more

[Johnny Brown]

Google barn-door mounts Lagers. You point the hinge at the pole star and then wind the handle at the right speed (very slowly).

[lagerstarfish]

my technique was to aim the centre shaft of the tripod at the pole star by adjusting the legs' length and angle (Manfroto 055xPROB), used my fluid video head with the handle extended with an old alu tent pole and pulled the end of the pole with long laggy bands at various speeds - adjusting the drag on the head till it seemed right

this wouldn't get the right curve, but over short arcs a straight line would be good enough

trouble is that I was trying to move the head at imperceptable speeds through a tiny angle and the whole thing wobbled a lot - didn't work
 - 300mm lens moved by a long stick pointed at an abject a very long way away and a long exposure? - what did I expect

I think it might just have worked (after a few thousand goes) with a really long extension and some angle markings to enable me to judge how fast to go and weight the whole thing down with a sack of sand and got lucky - basically a lot of trouble

taking loads of photos with shorter exposures and stacking them in some clever way would be a lot easier - am I right in thinking that people do this already?

[slackline]

taking loads of photos with shorter exposures and stacking them in some clever way would be a lot easier - am I right in thinking that people do this already?

I think thats how AndiT gets his excellent shots of nebula etc..  Attach a web-cam to a telescope mounted on a tracking device that rotates so the camera stays focused on the same spot, then use software to stack all the frames together.

[SamT]

I bought my husband a fairly decent entry level telescope for his birthday

Brilliant - I was going to start a thread today and someones done it for me...

Shorty No1 announced last night that he'd like a telescope for his forth coming birthday, (they are doing a lot of stuff about space at school) and I was going to ask folks advice re getting an entry level one.

So - Nim - what did you get (and would it be too expensive for a 7 year olds birthday)

Any general advice on what to get a 7 year old.

[Stu Littlefair]

taking loads of photos with shorter exposures and stacking them in some clever way would be a lot easier - am I right in thinking that people do this already?

Lagers - look at some software called 'enfuse'. This will do what you want (align and stack) without getting into specialist astronomy software.

[SamT]

Oops - just seen original date 

[Stu Littlefair]

Any general advice on what to get a 7 year old.

Generally speaking I recommend this for a 7 year old who's a bit impatient/violent with his toys

http://www.amazon.co.uk/SkyWatcher-Infinity-76P-300-Telescope/dp/B003CXMOAQ

and this for a kid who's a bit more careful (it has the same specs, but a proper finder and better eyepieces)

http://www.amazon.co.uk/Sky-Watcher-Heritage-Mini-Dobsonian-Telescope/dp/B002PNJCCW

If you want to blow the bank, you could step up to one of these

http://www.amazon.co.uk/HERITAGE-130P-FlexTube-Dobsonian/dp/B0039ZM14Q/ref=sr_1_4?s=electronics&ie=UTF8&qid=1359626091&sr=1-4

The larger aperture means you could see fainter objects.

Whatever you get, make the most of it by buying this

http://www.amazon.co.uk/Turn-Left-Orion-Hundreds-Telescope/dp/0521153972/ref=sr_1_1?ie=UTF8&qid=1359626230&sr=8-1

[SA Chris]

Sam T - Golt asked a similar question late last year.

http://ukbouldering.com/board/index.php/topic,21063.0.html

Any feedback Golt?

Lagers, surely you can cobble something together using some old rollerblades?

[SamT]

Spot on Stu & SA Chris   

thanks

[Johnny Brown]

Worth a read of this thread too.

taking loads of photos with shorter exposures and stacking them in some clever way would be a lot easier - am I right in thinking that people do this already?

Lagers - look at some software called 'enfuse'. This will do what you want (align and stack) without getting into specialist astronomy software.

I already have enfuse as a Lightroom plugin, which I use occasionally for exposure blends.

Any one fancy writing a quick and dirty guide to camera settings? I'm guessing use as fast a lens as possible (pref. prime), close to wide open, check exact focus first, then what? Base ISO, or a bit faster? Optimum shutter speeds? Optimum gap between for sensor to cool? How many frames?

[Stu Littlefair]

Johnny, you could write a book about that. Still, here goes

Exposure length depends upon the lens you are using. The longer the focal length, the less time you can expose before you start to get star trails. As a general rule (increase exposure times by a factor of ~4 if you're not too fussy).

Longest "Practical" Exposure (sec) = 250/Focal Length (mm)

So you can see that even with a 50mm you're limited to 5-10 second exposures.

At these exposure times, you're going to want high ISOs. I'd start with something around 2000, and experiment from there.

Use the fastest, widest lens you've got. Try to avoid using it wide open since this will cause pretty horrible abberations in the stars.

Don't worry about cooling the sensor, just take a string of images. As many as you have patience for, but more than 9 for sure.

The image below was taken using this method. A sequence of 9x10s exposures using my 85 1.8 @1.8, ISO 5000.
The nasty purple halos around stars are the result of shooting wide-open, but you can see you get good results.


Small Magellanic Cloud and 47 Tuc by stulittlefair, on Flickr

[Stu Littlefair]

One last tip:

if you're taking photos of constellations, the bright stars don't stand out as much as you'd expect, and you tend to lose the colour.

Try taking two sets of images, one with some sort of diffusion filter in front of the lens. Process them seperately then blend as two layers in photoshop, with the diffused image on top,  at an opacity of ~50%

[Johnny Brown]

Nice one, that's just what I was after. I know its a big topic, just after the basic considerations...

[lagerstarfish]

Longest "Practical" Exposure (sec) = 250/Focal Length (mm)

interestingly, the shot I posted was at 0.8 seconds with 300mm lens (250/300 = 0.83333)

[Johnny Brown]

I'm not an expert on Astro stuff obvs, but it looks way over-exposed to me. I'm guessing you can get away with much shorter exposures when planets are involved. Have taken a lot of pics of the moon over the years, and to avoid blowing out you often need daylight exposure values - e.g. 1/125 @ f/4.

[SA Chris]

Also if that's a straight JPEG, you can probably get more out of the image shooting in RAW and doing some post processing.