why do we need polarscope for alignment?

[bambuko]

Another one of those stupid newbs questions?

Why do we need polarscope for alignment?

(visual only question)

Can I instead set the main scope aligned with mount's RA axis and use main finderscope to do polar alignment (for visual observing only - I am anything else would require far more precise methods).

Providing that the telescope is indeed parallel to the axis that should be good enough? and I guess easier than trying to see it through "polar scope view port" (yes, you guessed right - I do not have polarscope in either of my two mounts).

[Astro Imp]

For visual observing aligning Polaris in the EP is quite sufficient, it's what I have always done and find I can keep objects in view with just an occasional tweak of the Dec. controls.

[baggywrinkle]

For visual work you are correct, you can make minor adjustments as you observe.

But for long exposure work in astro photography a good polar alignment is essential as the Pole Star is not quite at the Celestial Pole and rotates around it.

Even usinga polar scope some will go to the added work of doing drift alignments or using guide scopes to ensure proper tracking of their mount.

[Mav359]

Remember its the mount your polar aligning not the scope, the better aligned you are the less time you'll spend correcting and can just enjoy the visual session then

[bambuko]

Yes indeed!

What I am suggesting will only work if the scope at the time is aligned with mount's axis (as I mention in my original post).

I suppose it will be no more inaccurate (ie using finderscope for polar alignment) than peering up "polar scope view port" ?

(remember I do not have actual polarscope).

And also: I say again "visual only"

[jambouk]

Using the finder scope on the telescope will be fine for a rough and ready polar alignment, as long as:

- the finder scope is well aligned with the telescope

- the telescope can be easily aligned with the RA axis of the mount

For an easier rough and ready alignment, you could just use a compas, and have the north leg of the tripod pointing north, and adjust the elevation to your latitude. That would probably be fine for visual.

If you have no polar scope in the mount, you could just look up the hole in the mount and line Polaris up in there.

James

[bambuko]

...If you have no polar scope in the mount, you could just look up the hole in the mount and line Polaris up in there...

Thanks

I know I "can" do it, but it is just as painful for me to do it as is using straight through finderscope

(probably even more so, since I use my scope fairly low down in a seating position).

I am 6'4" and the polar scope would be less than 30" from the ground in this arrangement

So I have invested in RACI  finderscope to solve one of my problems.

Now I need to sort out polar alignment (compass is not really accurate enough even for visual).

[ronin]

If the scope is well aligned with the mount and for visual only then no great problem.

Just remember that whatever will not remain central for as long so you will have to readjust at times, especially if you go for high magnifications.

Is there not a polar eyepiece to put in a scope?

That would then leave the scope-mount alignment the question area.

[bambuko]

Yes, I can organise cross-hair eyepiece to center things nicely through either finderscope or even the main scope.

The only thing it leaves than is the tube/mount alignment (should be easy).

I am not keen on getting down on the floor to either look through polarscope or the polarscope view port.

[jambouk]

It depends how well polar aligned you want to be for visual. Using a compass will go a long way towards polar alignment.

The other option would be to attach a web cam to the polar scope and view the image on a laptop and make adjustments that way. I made a right angle adaptor for my polar scope, i'll share the link later. I can sympathise as i hate looking up the polar scope when using my newtonian as like you the mouth is at its lowest setting, and i'm reasonable tall and have a knackered back.

James

[jambouk]

Here's the link:

http://www.eastmidlandsstargazers.org.uk/topic/5751-right-angle-polar-scope-viewer/?fromsearch=1

James

[bambuko]

That's very good link indeed - thank you!

I have spare 6x30 finderscope ... hmm

[Alien 13]

Yes, I can organise cross-hair eyepiece to center things nicely through either finderscope or even the main scope.

The only thing it leaves than is the tube/mount alignment (should be easy).

I am not keen on getting down on the floor to either look through polarscope or the polarscope view port.

I use a right angled camera viwfinder just held against the polarscope you can get them cheap off e-bay

[bambuko]

Just discovered this trick in the previous post by jambouk - I am off to ebay now

thanks guys

[jambouk]

Here is my home made polarcam:

James

[jambouk]

Just make sure you get left and right, up and down, the correct way around as any right angled system or web cam may change this.

I set the mount up aiming north with my compass; I have set my RA setting circles up so at 0 degrees the small polaris circle is at the 6 o'clock position (transit) and i use the hour angle to rotate the RA to the correction position when polar aligning (i don't alter the elevation bolt between sessions) and then attach the right angle polar viewer, and just use the azimuth and elevation bolts to centre polaris in its small circle... No wet knees, and can even do it sitting on a chair behind the mount.

I cannot claim any credit for either the right angled viewer or polarcam ideas, as ii have just adapted other peoples ideas. I can't even claim credit for making them as my mum made polarcam for me, and my astro neighbour kindly made most of my right angled polar viewer!

Good luck.

James

[bambuko]

Polarcam, whilst interesting is not for me (trying to keep pc away while in the field in the dark night)

Your instructions on setting up got me lost slightly, but that's maybe because I only have EQ3-2 and you are (I am guessing) referring to EQ6 ?

[jambouk]

Polarcam isn't for me either for exactly the same reason. My laptop is a pain in the ar&e at the best of times, let alone in the dark, on battery and in the damp, hence right angled polar viewer

I have an AZEQ6 which is very similar to an EQ6.

Does your RA axis have a setting circle on it? If so, can you adjust the position of that setting circle? At some stage you will need to look through the polar scope with your eye; you can do this by getting the mount to it's maximum height and then lowering the elevation to it's lowest and just look through the polar scope whilst standing up (minimal back bending needed). In this position, rotate the RA axis until the small Polaris circle is at the very bottom in the middle (in the 6 o'clock position); lock the RA clutch. Rotate your RA setting circle (not the RA axis) so the notch or marker on the mount matches up with 0 degrees on the setting circle; lock the setting circle in place (never move it again). Now you can put the mount back to a normal elevation ready for night time use.

Now when setting up, if you know the Hour Angle of Polaris (either handset if GOTO mount, or off the internet), you can rotate the RA axis so the notch or marker point on the mount matches up with the relevant Hour Angle on that setting circle (it is a time in a 24 hour clock). Once you have rotated the RA axis to that time, the small Polaris circle will be in the right place in the polar scope. Then all you need to do is look through the right angled polar viewer, and adjust the knobs to get Polaris bang in the middle of the small circle. Bang on Polar Aligned, and not a wet knee or stiff back in sight

James

[baggywrinkle]

Here's the link:

http://www.eastmidlandsstargazers.org.uk/topic/5751-right-angle-polar-scope-viewer/?fromsearch=1

James

Very neat idea, I have one of those for my old Canon which did not have a flip screen live view.

[jambouk]

I'm looking at the Canon 6d, and thoroughly disappointed it doesn't have a flip screen like my 600d

[bambuko]

well... I am going to have to face this one day and it will mean some reading and trying

I will use your advice (amongst multitude available on interweb )

but... not tonight