...improve my hitting the target!?

[Altocumulus]

Hi one and all,

I am, generally a daytime guy, imaging the Sun with Lunt 60 & William Optics 102 (WO). For a number of years each session sees me spending 10-15 frustrating minutes trying to target that great big ball in the sky - once I have it, though, tracking remains good.

This year I purchased an Astro Essentials 32mm f/4 Mini Guide Scope (GS). This last week I set it up directly on my losmandy plate with a 178mm camera and used the PA tool in Sharpcap to go from "Fair" to "Excellent" within 5 minutes; doing the procedure 2 times. Straight then +90; +90 then straight.

I then placed the GS on the WO and re-ran PA to find I was now scoring "Good" - Ok, 'scope and mount not accurately aligned, though it looked as though I could sneeze and it would improve. Slewed to the Moon and the GS missed it! So a hunt to find it it the GS was followed by 10-15 minutes hunting with the WO (178MC). [ Used SC (for GS) and Asicap (for WO) - if only Sc had a popup to show what it was seeing ].

Is this hunting always going to be there? Or can I hope to get close first time, one day! I ken some of it's an issue of fov, the GS way wider than the WO at f/6.9.

Ordinarily I sync target on CdC - but 'only' Sun & ( now ) Moon, which means little for the next session as I still miss.
Obvious question here would be should I spend time syncing stars - I guess so, logically....

My setup is permanent with a solid fixed tripod - the mount is an NEQ6-R. The losmandy plate holds the telescope/mini PC and Pegasus Ultimate. Everything locks in solidly, no flexing.

Geoff

[admin]

Hi Geoff,

If you're finding the target in your new finder scope, but then it isn't visible in the main scope, you need to spend some time aligning the two telescopes with each other. Get something like the moon centred in the main scope and then use the adjustment screws on the finder scope mounting to bring the moon into the centre of the field of view for your finder scope camera. Doing that should certainly help.

As for the accuracy of your GOTOs, and there are two main culprits when those go wrong in my experience – polar alignment being off and cone error (this is when the axis of the telescope and the RA axis are not parallel even when the declination axis is set to the home position). If you workout you have cone error then can correct it by putting in spaces at either the front or the back end of the telescope to move it slightly further away from the RA axis to ensure that the two can be made parallel.

Cheers, Robin

[Altocumulus]

Hi Geoff,

If you're finding the target in your new finder scope, but then it isn't visible in the main scope, you need to spend some time aligning the two telescopes with each other. Get something like the moon centred in the main scope and then use the adjustment screws on the finder scope mounting to bring the moon into the centre of the field of view for your finder scope camera. Doing that should certainly help.

As for the accuracy of your GOTOs, and there are two main culprits when those go wrong in my experience – polar alignment being off and cone error (this is when the axis of the telescope and the RA axis are not parallel even when the declination axis is set to the home position). If you workout you have cone error then can correct it by putting in spaces at either the front or the back end of the telescope to move it slightly further away from the RA axis to ensure that the two can be made parallel.

Cheers, Robin

Thanks Robin. Finder scope, though, doesn't have any adjustment options. So I guess what you're saying is that a good/excellent PA on guide scope should mean a quicker hunt. Much as expected, which means I have some work to do... Cheers.

[admin]

Oh, that's a shame… I was expecting it to be more like this product which has adjustments to allow you to align it with the main telescope

https://www.harrisontelescopes.co.uk/ac ... 32qrb.html

cheers,

Robin

[Altocumulus]

Oh, that's a shame… I was expecting it to be more like this product which has adjustments to allow you to align it with the main telescope

https://www.harrisontelescopes.co.uk/ac ... 32qrb.html

cheers,

Robin

Chuckles. Thanks Robin.

[Jean-Francois]

Hello,

I had similar problem for the alignment of my EQ8 mount with different telescope.
I have a finder (visual) and an electronic finder (guider).
It was one or the other ... but not necessary both at the same time.
The EQ8 mount alignment is much easier with a visual finder for the coarse movement, before that the star is centred in the main telescope.
The electronic finder (guider) is OK, but you need first install all the equipment with the computer for reading the guiding camera.

Also I have a lathe machine (in my kitchen ) ... I modify an old Meade finder and I connect a Vixen flip mirror to it.
I cut the tube ... you can see on the picture the remaining part.
I can now perform a quick visual alignment and then start (if necessary) the guiding with the camera ... simply flipping the mirror.
Note: for a stable pointing, I change the plastic alignment screws of the finder with metal screws.

Finder_visual_camera.jpg (49 KiB) Viewed 1125 times

Regards,
Jean-Francois

[Altocumulus]

I still have a problem which I hope to fix. I'll have a look at putting the GS into an adjustable holder - I have one that came with a Skymax.

But I am, also, guilty of a schoolboy error.

The PC on my mount doesn't connect to the internet, neither does my routine warm-room indoor laptop.............

Consequently, because it can't sync to time servers, the clock has drifted by around 4 minutes.....

[Altocumulus]

Thanks again, both.

On reflection I think my original point was missed.

The GS was clamped to the mount and PA was adjusted to "excellent".

It was the surprise that the WO, replacing the GS, was so far away from target - it took some hunting to correct.

Thanks, though, I realise I need to do some more hardware checking....