done something stupid now I need help

[rowan46]

I have read in many places that the takahashi polar scope for the em 200 is one of the best ever made so I bought one for a pretty reasonable price. Now how am I going to attach it to an eq1?

[gkec]

You're not!

[JamesF]

"With difficulty"

I can think of a few ways to do so and make it vaguely useful, but in most cases it would probably be cheaper to buy an EM200

James

[JamesF]

If you really want a polar scope on your EQ1, this is probably the way to go about it:

http://www.nightskyimages.co.uk/eq1_polarscope.htm

James

[rowan46]

The body of the eq1 is hollow, so I thought that maybe if I attached a shaped plate on the back using a star fangled nut and raised the hole for the finder about a centimeter above the ra gear that that might work?

[rowan46]

If you really want a polar scope on your EQ1, this is probably the way to go about it:

http://www.nightskyi..._polarscope.htm

James

I looked at that but its a red dot not a polar scope and I can't get my head around drift aligning. besides where's the fun in making something that works?

[JamesF]

You could actually get away without drift-aligning using a plate-solving system. A couple of SGL users have done that with cameras on EQ1 mounts.

However, because Polaris is not at the NCP but circumpolar it is necessary for the polar scope to rotate with the RA axis to get the correct time and date on the setting circles and the correct position for Polaris relative to the NCP on the polar scope reticle. That's going to be pig-awkward to do. Should you decide that it isn't necessary to be that accurate and that you can treat Polaris as if it were coincident with the NCP then the RDF solution is probably far easier and achieves the same goal.

But really, drift-aligning isn't that hard if you find a clear explanation of how to do it. Not unless you're planning on mounting a C14 on your EQ1, anyhow.

James

[rowan46]

the em200 finder comes as one unit so getting it all aligned shouldn't be that much of a problem

http://www.ebay.co.uk/itm/Takahashi-Polar-Finder-for-EM-2-/321134890557?pt=LH_DefaultDomain_0&hash=item4ac5218e3d

I figured if I was going to put a 17" planewave on an eq1 I may as well get a good alignment

[rowan46]

something like this I hope you get the idea I am not very good with computers

[JamesF]

It has to be correctly aligned relative to the time and date rings on the mount though. And to rotate as the RA axis rotates. Otherwise it's no better than the RDF.

James

[JamesF]

In fact I've just been and had a look at my EQ1 and it doesn't even have a date ring, so can't see that you can get any any better than the RDF solution at all.

James

[rowan46]

It doesn't need one its all built into the taks finder

[JamesF]

If it is then I can't see anything I recognise as such in the pictures for that auction. But, get to it, and post pictures when you're done. You'll need some method to make sure that the axis of rotation of the polar scope is parallel with the RA axis too, so I think one bracket is unlikely to work. You'll probably need something like a finder mounting to allow the axis to be aligned.

James

[rowan46]

Thankyou its these sort of things i hadn't thought of. here is the instruction manual for the em200 if you are interested

http://www.takahashi...00USDManual.pdf you may spot an error or 2 in my assumptions

[gkec]

I may be missing something but as an EQ1 mount doesn't accommodate a polar scope why buy one?

[rowan46]

2 reasons I want a go at wide field imaging but if I get a better polar alignment I can use a longer focal length and 2 I am on tramadol at the moment and may not be entirely rational

[gkec]

2 reasons I want a go at wide field imaging but if I get a better polar alignment I can use a longer focal length and 2 I am on tramadol at the moment and may not be entirely rational

ok -- fair enough. I expect members on here can deal with the first but the second might be a bit more challenging.

[rowan46]

I have come up with an idea that looks to be simi;ar to the astrotrac polar finder holder is there a place that does small commissions for machining at reasonable (cheap would be better) rates

The polar scope would be attached to the top hole by a threaded collar.

The bottom hole would attach to the eq1 body by bolt and star lug similar to the handlebar headset on a bicycle. As long as the thingummy is flat it should be orthagonal to the main gem body (excuse the drawing I am not good at using drawing programmes)