Playing with a Star Adventurer mount....

[fwm891]

I've been playing with a Star Adventurer mount I got from FLO a few weeks ago and last night I put a 400mm lens on it to see if it would pick out M109. I shot 3x 100second subs, 1600 iso on a Nikon D5100 mono modified camera.

Not only did it pick-up M109 but a few others as well. Doing my head in with Uranometria 2000 trying to identify some of 'the others'... Result so far still plodding!

[FaDG]

100 seconds @400mm with a Star Adventurer without trailing? 

Was it guided or not?  If unguided, that's astounding (although high dec helps...) : I can't even get way less than that with mine! 

?

 

[fwm891]

No guiding. I've had circa 600s with it showing the barest elliptical star shapes. The key (I think) is getting the polar scope's reticule exactly centred in the polar scope - took me some time to adjust mine.

Like most I took mine straight out of the box and used it and had trailing. So I set to adjust the reticule - I did it in daylight on a distant chimney pot. Lots of fiddly adjustments but it's paid-off now.

[happy-kat]

I Google that word reticule and I had to giggle, its a woman's small handbag....none the wiser as to what you adjusted.

That's a lot of faint fuzzies.

[fwm891]

2 hours ago, happy-kat said:

I Google that word reticule and I had to giggle, its a woman's small handbag....none the wiser as to what you adjusted.

That's a lot of faint fuzzies.

Hi Happy-kat, When you look through the polar scope you see a small cross etched in the centre of view. Around it is etched a series of rings divided into smaller sections - this is the reticule, an etched clear plastic disc. Around the outside of the polar scope eyepiece are 3 small Allen headed grub screws, use these to adjust the reticule.

How?. First you need to mount the sky adventurer on a tripod to give it a firm base. Then you need to point the polar scope at a distant object (I used a chimney pot circa 200 metres away) do this in daylight it's far too fiddly to do in the dark.

Make sure you've placed the cross on the selected object, then rotate the RA axis by 180° (ish), watch what happens to the polar scope's cross. It will most likely describe a curved arc as the RA axis is rotated. You need to adjust the 3 grub screws until it remains pointing at the same spot as you make the rotation.

TAKE CARE: Use very small adjustments (± ¼ turn) slacken one and tighten the others then check again. Just keep making the small adjustments until the reticule is centred on the RA axis. If you try to make too bigger an adjustment the reticule may fall out of it's housing which then means dismantling the polar scope. After that follow the manual's procedure to complete a PA adjustment...

[FaDG]

22 hours ago, fwm891 said:

No guiding. I've had circa 600s with it showing the barest elliptical star shapes. The key (I think) is getting the polar scope's reticule exactly centred in the polar scope - took me some time to adjust mine.

Unfortunately in my case it wasn't polar misalignment, but plain old Periodic Error. 

Guided I have no issues with subs longer than 5 minutes, as polar scope is very accurately set. 

But due to high frequency harmonics there's no way to get above 45" @ 150 mm focal length.

It just trails in RA. And I tried several Star Adventurers. Seems like it's hit or miss. 

Fabio