Mounting rings and guiding

[PhobosPhil]

Hi all,

I'm after some advice.

I have a Meade 5000 80mm Apo and a HEQ5 Pro.  I try my hand at astrophotography (DSLR rather than CCD), but i'm not very good at setting it up so generally end up with a blurred DSO surrounded by lines rather than points of stars.  I was wondering if using an autoguider would help keep the startrails at bay.

However, if I were to go down the route of getting a guidescope and guidecamera, what would be the best way to join a guidescope to the 80mm?  It's the one with the L bracket dovetail thing.

Any suggestions would be much appreciated.

Kind regards

Phil

[ollypenrice]

You could use a mini finder guider which could go where the guidescope goes at present...

I do an initial star alignment quite easily by holding a green laser pointer along the dovetail bar. This gets me close enough to then centre the star in the camera image for star alignment and I don't miss the finderscope.

Olly

[PhobosPhil]

Thanks Olly, that looks ideal, however, the 5000 80mm doesn't come with a finderscope and as far as I can tell, there isn't screw holes or anything to attach it to.  I always assumed that was by design and I was supposed to use a 30mm eyepiece to find stuff.

[ChrisLX200]

Well you could use a second set of scope rings turned the other way up with a short bar joining the two (or you might even get away with a single ring if it's sturdy enough and the guidescope is lightweight). You still need to improve the polar alignment to reduce the workload on the guider, it's only supposed to correct minor irregularities not correct for mis-aligment.

ChrisH

[PhobosPhil]

Ah right, thanks Chris, I didn't know that.  Hmmm, maybe it's back to the drawing board rather than pay extra for an alternate fix!f

[PhotoGav]

What kind of sub length do you expose currently and get the star trails?

[PhobosPhil]

It can very, the last time I tried it was about 20 seconds.  But since last August i've had sessions where it was about 45 seconds, 1m 30 and the best was about 2mins.  It may also vary depending on where in the sky i'm looking, but i'm not 100% sure about that as by then frustration has set in and I haven't analysed the photo's afterwards.

I think it's my polar alignment technique.  The goto doesn't get anywhere close to center on the stars during alignment.  If I view through a 30mm eye piece the star is in the field of view, but it isn't in the 12mm one with the crosshairs.  I'm sure I read somewhere that taking too long in between alignment stars stops it working properly, so it probably gets worse as I go on.

[ollypenrice]

Star alignment for GoTo has nothing to do with tracking accuracy unless you are using a polar alignment routine which involves slewintg to stars, adjusting the mount axes and repeating. Such systems do exist but don't confuse GoTo with tracking. They are not normally connected.

Olly

[PhobosPhil]

After the goto has, er, gone there - isn't it supposed to track the object you've told it to go to?  And if you haven't polar aligned properly the object drifts from the center of view?