Aligning to north and more questions

[PaulR]

I have a 6" Orion reflector on an equatorial mount but I've never really bothered to use it in anything but alt-azimuth fashion. I'd like to start using it 'properly' now that I'm getting interested in astronomy again

I'll probably want to move the scope around the garden once or twice in an evening (to see round the neighbouring houses and trees!!) and realise it'll mean re-aligning. So far as I can tell getting the mount pointing bodily in a northerly direction will be the trickiest (/sweatiest) bit. I have a large desk compass that I can use to find N but an obvious solution would I suppose be a small compass on the mount itself?

I've also yet to use the levelling bubble and fear it might be problematic if the scope is on grass!

I'd also at some point like to have a go at some constellation photography with a (cheapo) camera piggy-backed on the scope (just using the scope for guidance) - I'm not thinking of huge exposures so is 'hand-guided' likely to work?

Does anyone have any tips?

TIA

Paul

[CELESCOPE]

If you can get it fairly close to pole Paul , you should be able to do 45 to a min exposures ,with thecamera piggy backed .

Rog

[blinky]

I suppose a compass may be OK for getting you close to North. Have you got a polar scope on your mount? I find now that I have done it a few times it only takes a couple of mins to align to North.

[PaulR]

Cheers Rog, I'll have to give it a whirl (no pun intended)

Blinky, the mount has got the hole (technical term there) for one but it didn't come with one. Do you think it's worth buying one and if so are they a standard size or 'mount specific' (and what's it likely to cost)?

Thanks for the replies

EDIT: Ignore that last question, I've just found one on the net...

http://www.pulsar-optical.co.uk/prod/skywatcher/generalaccessories/polaralignmentscope.html

[blinky]

I think it may be worth getting the polar scope, as I say it does allow me to get pretty decent north alignment in a few mins.

[MartinB]

Paul, don't try hand guiding for star photography, it wont work. You can hand guide when using a web cam to image very bright objects such as the moon, mars, venus, jupiter and saturn because you are using lots and lots of short exposures. Without moving your mount it will be around 15 secs before trails start to appear using a 50mm lens. That should be enough time for the brighter stars to show up.

If you can see polaris then point the mount at that. If you can't then use a compass. you will also need to adjust your latitude. If you know this and your mount has a scale you can set that way. Or, you can line your scope up with the mount and adjust the latitude until polaris is centre view. Job done. Obviously you only have to adjust the latitude once. For visual use don't go to any more trouble than that. It should take you 20 seconds then just look at stars.

[barkis]

Hi. Paul.

You said you would like to piggy back your camera to the scope, but you did not say if the camera is a digital, or a film SLR.

If it is a point and shoot, would you get a long enough exposure.?

If it is a film camera SLR, then when you find the target for your shot, cover the mouth of the scope with a large piece of card, press the release cable to start the exposure, once the shake in your scope has died away, caarefully remove the card, and time the exposure.

When you reach the amount of time for the shot, carefully replace the card over the scope mouth, then close the camera shutter.

This procedure helps eliminate any unwanted image movement to to the scope vibrations when operating the camera.

The same can be done if it is a digital SLR too.

Ron.

[saturn5]

=

[PaulR]

Thanks for the tips all

I think I'm going to get a polar alignment scope and make life easy. Possibly!

As I understand it for an observing session I'd need to:

Adjust the latitude 'wedge' - done that

Balance the RA and DEC axes - no problem

Level the mount - easy with the bubble

Point roughly north - towards polaris

Set the DEC to 90

Use the polar scope in conjunction with the latitude and azimuth fine adjustment to get Polaris centred

I realise the the celectial North Pole is offset a bit but I'll learn to deal with that later!

Have I got the procedure right? (No chance of trying it for real with the weather as is!).

[Kaptain Klevtsov]

Thats more or less it Paul. The polar 'scope should have a small target offset from the centre to show you where to put Polaris.

Kaptain Klevtsov

[Astroman]

Procedure looks good, Paul. One small thing though-if you're using an equatorial mount and doing a careful polar alignment, you don't need to level it. Sure, leveling makes all the altitude dials read correctly, but the act of aligning sets the scope to revolve around the proper axis, and as long as the rotation axis is correct, id doesn't matter if it's level. It matters for an alt/az GOTO, but not a simple tracking equatorial.

Hope that doesn't confuse things.

[PaulR]

Cheers Kaptain K. Doh! I actually read up on the polar 'scope yesterday and saw a diagram of the target - my mind is really going!

Astroman: Do you mean "...makes all the declination dials read correctly"? Once I've got it sorted I want to try finding objects by their RA/DEC so I'd need it set up pretty well.

Thanks for the help

[Kaptain Klevtsov]

No Paul, he doesn't. On the altitude adjustment there is usually a scale that you set to your latitude to get the correct evevation. If the base isn't level, but the axis is polar aligned, the scale will read wrong is all.

Kaptain Klevtsov

[PaulR]

Ah, ok latitude/altitude/elevation = the same scale. I thought I was a scale short somewhere LOL!

[Astroman]

Thanks, KK, that's exactly what I meant. (And exactly why I apologized for confusion in advance.) 8)

[The Warthog]

I'm glad you and KK both said that. I had thought so, but never actually figured it out or looked it up.

[Astroman]

It was a pet question of my mentor, Prof. Nidey. "Figure it out and get back to me" was what he'd say. So I did.

Aligning an eq mount places the rotational axis of the scope parallel to the rotation axis of Earth and perpendicular to the direction of rotation. As long as this is true, the angle of the mount is irrelevant. As KK said, the numbers on your latitude scale may not agree with your actual position, but the scope will track accurately anyway.

My head hurts. I'm going home.

[Kaptain Klevtsov]

This is precisely the reason that I can't see the point in making the mounting plate on a pier adjustable. If you sit the head on the plate, you can do all the aadjusting you need with the alt/az adjustments. The mounting plate doesn't have to be level to any degree of accuracy.

Kaptain Klevtsov

[Astroman]

My guess KK, is it's a matter of aesthetics. If you walk into a dome and see the scope not level, it may "tweak" someone's sensibilities. Out in the field, especially if you've seen my field mount, you may not notice it as much, but in a dome you'd expect certain things.