Recently Browsing 0 members
No registered users viewing this page.
By GiL Young
Hello all. Thank you for taking a moment to read this & offer your suggestions/ advice. I'm sure my basic question has been asked many times: "In your opinion or experience, what are the first, most important, necessary accessories I should add in order to maximize the the use and ease of a newly acquired Celestron Nexstar 127 SLT ? I have a power supply adapter, 9mm,10mm, 25mm eyepieces, 2x Barlow and 90 degree diagonal mirror adaptor. With a modest budget and a 2 week deadline, I've researched numerous reviews and narrowed some choices to additional Plossl eyepieces, an assortment of filters or a dew shield. All of and these can probably be purchased within my budget but I'm even willing to take the plunge on an upgrade to a better mount, which I have no idea where to start. Any and all suggestions, advice and opinions are gladly appreciated. Thank you all, from across the pond in northeastern US.
By Astro Dave
I recently decided to give the SynScan app a try on my new Orion XT10g.
Now using the hand controller I was familiar with the "Brightest Star" and "Two-Star" alignments methods, indeed I always use the Two-Star method.
With the app however I see that the Two-Star has been replaced with the level north two star. What is that? And since there's no manual for the app, what precisely does level north mean? I'm guessing that you level the OTA and point north but with what precision? Any idea why that replaces the Two-Star method from the hand controller?
OK, so fine. I did the Level North alignment. I noticed that as it goes to each of the two stars and stops, while waiting for you to center the star, a couple of the directional buttons are flashing. What's interesting is that the ones flashing are not the ones for the direction that the scope needs to move to center the star. Again, what's up with this?
Finally, after aligning and doing a Goto (reasonably accurate), once it arrives at the target again, one of the directional buttons is flashing and there's a message above the object name that says that I'm to center it. Huh?
Can someone help me make sense of all this. And, is there a manual for this app ??
By The Admiral
I recently took delivery of this mount, having until now only used an Alt-Az mount for imaging. So this is a whole new experience, and as such I’m not really in a position to give a meaningful performance review. Nevertheless, here are my first thoughts.
I wanted a mount that could be set up for each session, and light enough to allow my ageing frame to be able to carry it from inside the house to outside. It also had to be able to successfully carry a load currently around 6-7kg without complaint. So this is what attracted me to the GEM45. I bought the version with the case and tripod, non-EC. I don’t guide it as yet, so I can’t quote chapter and verse on its guiding performance.
Here's the set up raring to go! I've left the tripod trousers on!
It seems a solidly built, well finished, precision machine, unlike what one would expect from a mass-produced object. The axes move smoothly and I haven’t noticed significant backlash either by ‘free play’ or other than instant response to commands when lining up objects. However nice the looks, performance is everything of course, though it does give confidence.
The first thing I needed to do was to swap the latitude adjustment from the low position to the high position, as I live in the UK. It is worth noting that for where I live, ~51° N, I need to wind back the altitude to ~40° with the altitude adjuster (not re-set the setting from high to low, fortunately), each time I need to get the mount into the foam cut-out of the case.
Initially I had trouble locating the bolts with which to bolt the mount onto the tripod, the Azi Locking Screws. Thanks to FLO that was simply resolved, but I found that one of the bolts was slightly bent, enough to bind a bit in the thread, again resolved by the excellent services of FLO. Also, these bolts are meant to be used with the provided washers, but only one could be located. These are little perishers, as it’s easy to drop them when assembling the mount, as I discovered. My wife’s eagle eyes managed to spot it on the patio; try doing that in the dark! It’s a pity that the bolts don’t have a winged- or star-head for finger tightening to make life easier with repeated setting up, but there isn’t room beside the mount to allow that.
The bolt shown here is a make-shift arrangement and is not the proper bolt and washer.
The same could be said for the Lat Locking Screws, since they have to be slackened off and re-tightened before and after setting up/Polar aligning. However, these could reasonably be replaced with hand operated bolts, rather than rely on the Allen key, as there is ample room.
A note re. the tripod, is that it has an alloy top plate and I do wonder how resilient it will be to the repeated attachment of the mount. However, I also bought the Mini-Pier and the threads on this are inserts pressed into the alloy and look to be made of a more bolt friendly material. I plan to leave the Mini-Pier on the tripod.
As I said I don’t guide so I can’t offer any figures. So the best I can do is provide some subs from my recent tests. You’ll need to bear with me on this as I’ve not many examples to date. My first examples are of M3 showing different sub durations of 90s, 120s and 150s. Unfortunately I was having trouble with my optical train and have got out of shape stars towards the edges anyway so that may confuse. Here they are for what they are worth:
My second offering is a sub from an attempt at M81 shot at 90 seconds:
The full image is posted here https://stargazerslounge.com/topic/352345-m81-m82-with-gem45-unguided/.
In summary then:
The iPolar is a doddle to use, though does need a laptop to be set up for the alignment process, but that can be put away afterwards. Far better than kneeling on the floor and craning one’s neck.
I’ve found tracking to be good enough for me up to about 1½ minutes, though possibly beyond that to 2 minutes or more, without guiding, with a FL of ~560mm and load between 6-7kg. Depends on how purist one wants to be about ‘round stars’.
It’s quiet whilst tracking but slewing is by no means silent. I’m always concerned about disturbing neighbours so perhaps I’m being unduly critical. It’s quite difficult to judge how loud these things are in the middle of the night when you are standing next to the source. Then again, I’ve not used other mounts to compare it with.
The hand controller seems fairly logical to use.
Assuming I’m setting up everything correctly, I’ve found that the homing in on alignment stars to be somewhat ‘out’, and have always needed a significant correction to align. I do a 3-star align and I find this to be the case for each star. However, when I come to align on my target I found that it centred the object very well. May be I have significant cone error which will only be corrected for after the 3rd align, if I understand correctly.
The need to reset the altitude setting to around 40° in order to replace it into the case.
Fiddly washers beneath the mounting bolts which are easy to lose. A touch of grease might help them to be retained by the bolt.
Having to use the Allen key on the Lat Locking Screws.
When aligning, the stars offered are in magnitude order, which from one point of view is logical, but is a bit of a pain when one wants to find particular stars. It would be good to be able to change your preference on star order.
That's it for now, and I hope that it's been of some use.