Re: Saturn 2005-10-17


"Pete Lawrence" <pete.lawrence.nospam@xxxxxxxxxxx> wrote in message
news:3vb8l19fbs0463v7ghp8pdo7lrq0ut17pi@xxxxxxxxxx
> On Mon, 17 Oct 2005 23:23:41 +0100, "adm" <adm1@xxxxxxxxxxx> wrote:
>
>>
>>"Pete Lawrence" <pete.lawrence.nospam@xxxxxxxxxxx> wrote in message
>>news:ec08l195gah3m4par6g4jd8h1qi70gm69s@xxxxxxxxxx
>>>A bit of a planet fest last night. Saturn looked gorgeous visually!
>>>
>>> http://www.digitalsky.org.uk/saturn/saturn-20051017.html
>>> --
>>> Pete
>>> http://www.digitalsky.org.uk
>>
>>Nice one Pete.
>>
>>One question - how the f**k do you manage to focus so well with a 3x
>>Barlow
>>? Every time I stick my Barlow (new AE 2X "apo" barlow) into the mix, I
>>have
>>the devil's own time trying to get a good sharp image. I have a 10" LX200
>>GPS and Toucam Pro - so pretty much the same setup as you but a shorter
>>Barlow.....
>>
>>I'm using a homemade Hartmann mask and focussing in the Phillips VRecord
>>tool. Mind you, I have zero experience with astroimaging other than my
>>somewhat frustrating attempts since July this year.
>>
>>Any tips ? Other than getting the pier and dome completed now and not in 5
>>years time......
>
> I don't have any problem achieving focus - despite the fact that that
> Saturn isn't quite in focus (I was tired!).
>
> First up - are you using the default LX200GPS focuser? If so - ditch
> it - it's cr*p! Replace it with one of these:
>
> http://www.petersonengineering.com/SkyDiv/ez_focus_kit.htm

Funnily enough, I have exactly that kit sitting in my desk drawer right
now.....maybe it's time to do the install this afternoon !

> Second - make sure your scope is collimated properly. Learn how to do
> this with a star and replace the silly default hex bolts with Bob's
> Knobs.

Hmmm....also a little envelope with Bob's Knobs in the same drawer. OK- it's
telescope upgrade time today.....

> With the Peterson Engineering focuser you'll be able to approach
> focus, go through focus and (what you couldn't do with the standard
> focuser) move back through focus again.
>
> Of course it could have been just my focuser that was bad - I have to
> acknowledge that.
>
> Once you can do that, it's relatively easy to see where focus is on a
> laptop screen. Use a high frame rate - 25fps for example. Get things
> moer or less right.
>
> VRecord?! Ditch that too. Never trust a piece of software that will
> overwrite your hard work without even asking! Download the freeware
> version of K3CCDTools.
>
> http://www.pk3.org/Astro/index.htm?k3ccdtools.htm

Done !

> Ok - with all of these suggestions in place, rough focus using your
> new Peterson thrust bearing, smooth as butter focuser. Zoom to 200%
> display size in K3CCDTools. Use the electronic focuser of the LX200GPS
> scope to achieve focus. Even on fine it's pretty evident where focus
> is. Move through focus a few times to get a feel for where it actually
> is.

Presumably rough focus, then lock the mirror up, then fine focus ?

>
> Use the Haartman mask as a frisbee ;-)

My dog might be pleased with that.

>
> I had no problem focusing my 10" f/10 LX200 working at f/60 last
> night.
>
> Best of luck.

Cheers !

I think it's just that there are so many different bits and pieces to get
calibrated in this hobby that I need to practise lots more. Mainly during
the daylight to make sure everything is ready to go when the skies actually
clear. For example, I spent Saturday afternoon getting a Meade flip mirror
set up to be parfocal with the Toucam Pro and a 9.7mm illuminated reticle
ready for a run at Mars. Then as soon as that was all working nicely I took
the scope outside, went to align and of course banged the whole imaging
train on the fork mount as it slewed to the first alignment star !
(LX200>Peterson Eyeopener>Meade microfocusser>Meade 2" flip
mirror>Toucam/EP) I had a bit of a scare but nothing was damaged as I
managed to hit the power immediately. Of course, everything was then out of
alignment and fiddling with it all in the dark wasn't the easiest thing in
the world......

Then of course, I realised I needed the Barlow to get any chance of a decent
size image of Mars at all. By the time I added the Barlow I couldn't get a
decent focus on Mars, gave up in disgust and went to bed !

Sunday, I set the whole thing up again ready for the evening, but could not
get decent focus on terrestrial objects at all - although this was probably
more to do with rising hot air than anything else. By the time everything
was ready for Mars, it had clouded over and was about to rain. Pack up and
go inside again.....

Aaaargh ! Rather frustrating - but somehow also strangely addictive too. I
really, really see the need for a permanent pier at the very least, and some
form of scope protection (roll off shed perhaps) to make this all much
easier. It's annoying to have to keep setting up and tearing down all the
time.


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