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SteveL

Report: NS8GPS on a wedge

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Great capture Steve and in the reduced format.

Can't wait to get settled in so I can start moving in this direction.....

What Off-Axis are you using?

You must be well chuffed!

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Great reporting Steve, really informative. Shall be going the wedge route myself one day soon and have found this thread very helpful, great pic too.

M2

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Thanks Steve.

forgot to ask - are you using any counter-weights? Do they/Will they make much difference?

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No I`m not, yes I should, as it will extend the life of the motors and clutches. The whole counterweight/balanceweight issue will need some money because it it will then be compulsory for me to add an ED80 or similar on top for wide field work ;-)

That reminds me, I really must sell my ETX90 setup....

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Excellent work Steve, you have done really well with the guiding. Focal length of 2000mm is a major challenge.

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After using (and now selling) the Baader laser collimator, its no good for SCTs... it made it far far worse :wink: So I had to go and do it the hard way.

Or did I... :cool:

I used a program called MetaGuide ( http://www.astrogeeks.com/Bliss/MetaGuide/index.html ) which not only does guiding, but also allows the use of a webcam to help with your collimation. It stacks multiple frames together to reduce the bad seeing and then display that on screen. It has some other funky stuff that worth looking at, but lets just say I`m mighty impressed with it. Just look at the results from nights of similar seeing conditions.

Jupiter from before collimation (26th June)

20070626_jupiter_plus_moons.png

Jupiter After collimation (6th July)

20070707_jupiter_001.jpg

Next report will be about PHD autoguiding, which will be short because it really is very very easy to use, almost fool proof.

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Next report will be about PHD autoguiding, which will be short because it really is very very easy to use, almost fool proof.

Thats good, considering I'm a fool :wink:

Peonic

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Your no fool.... just keep asking all the right questions like you have been so far

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At the mearest remotest possibility of a clear night, the OTA was outside at 6pm last night to cool down. It was hazy, and expected to vary from reasonable to more hazy over the course of the night.

I did the usual alignment stuff, then got all brave and decided that imaging was going to be a non-starter so I had better get my Bob's Knobs installed. I dont know why I had ummed and aahred about this before, it was 3 minute job to install, and another 10 to get it recollimated better than it has ever been before. Seeing wasnt great, so there is more tweaking to be done another night.

OK, what else is there to do? Ah yes, train the PEC. Now, there is the hard way, and the easy way.

The hard way is to select PEC Record, find index, move to a star, and then spend the next 8 minutes keeping the guide star in the middle of the eyepiece.

The easy way is to let the autoguidng system do it for you :( Unsuprisingly, I chose this option.

Using my Meade DSI straight into the back of the NS8 OTA, and plugging the laptop into the hand controller, I was away:

phd_training.jpg

I turned off guidng the DEC, as I was only interested in training the PEC on the Az motor. After it had completed one training session (8 minutes), I used the Celestron PECTool to download and save the current PEC profile to disk.

pectool_single.jpg

+20" to -10" variation of the course of 8 minutes. Not great, but could be a lot lot worse. The PEC graph is a bit ragged, but the PEC Tool allows you to download multiple PEC runs to disk, average them out, and re-upload a single smoothed graph.

pectool_average.jpg

It was just after finishing 5 PEC training sessions and uploading the averaged PEC info into the mount via the hand controller than the hazy clouds rolled in again. What with that, and the bright moon bleaching the sky out, I decided to call it a night, and packed up.

I`m expecting my ADM counterweight rail next week, so i`ll post about that when I get it installed, then I can get to work on piggy back autoguiding my images (no more faffing around with the OAG at funny angles :) )

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More rambings of a madman...

Got the William Optics Piggybacked, the ADM counterweight rail installed now (first real light for the WO6 later this evening)

ns8gps_wo66_002.jpg

Doesnt that look great :( Not sure the wife will agree... yet...

The ADM counterweight rail comes with a single 3.5lb balance weight, and after balancing in both directions, and the weight being about as far down the threaded rod as I dare, I now know I need another weight to get the total weight closer to the centre of gravity (you can just see the weight under the OTA in the following picture)

ns8gps_wo66_001.jpg

So, its out, set up, and cooling. Laptop out, cables connected, second screen attached (8" touchscreen, left of laptop, so I can run PHD on that while watching the images being spat out on the main screen

ns8gps_wo66_003.jpg

Sky is looking kind of hopeful, some thin high level cloud right now. Looking forward to guiding with the WO66 and imaging with the NS8... or vice versa for some wide field shots (M31 for example). Am hoping that I dont experience much (or any) differential flexure between the OTAs while guiding, but I guess I`ll find out later.

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Fantastic read, Steve, you are about 6 steps ahead of myself and it's great to see someone progressing down the path I hope to follow myself. After faffing around with lesser kit I've now invested in the similar 8" Celestron CPC and my next stops are a wedge, an Atik16 camera and either an OAG or a piggyback for my now mountless Orion ED80. I hear OAGs are sometimes very difficult to get right, what with problems of finding guide stars and focussing, etc. Then again I'm not sure about mounting something like the ED80 and loads of weights on my shiny new 8 incher.

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You can mount an ED80 on an NS8 as long as you are sensible about slewing and balancing, I've done it without too much of a problem. I do would work out the positioning of the counterweight for good balance in advance then remove ED80 and counterweight. Then do the alignment. Go to a decent star for focussing near your intended target and mount the ED80 and weight (a mag 4 star is about right). Then do a short slew to target. Alternatively go to the target before mounting everything up - I just like to do a focus on a decent star.

The NS8 will cope easily with the tracking. It will slew ok at normal rate but I do worry about the motors with the bulky ED80. With a ZS66 I slew with the scope piggy backed, doesn't seem to be a problem at all.

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Steve, that must be one of the most comprehensive reviews, I've had the pleasure of reading, on any forum.

Detailed, informative, and with lots of pictures to support it.

BTW, don't be too disappointed at the engineering build quality (or lack of it :D, of the Celestron 'wedge', its not unique to Celestron.

I paid £500 for my Meade Superwedge, and had to carry out a lot of engineering improvements, to bring it up to a useable standard.

Dave

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Hasnt the weather just been utterly carp recently? 2 weeks without a single clear night...

Anyway, the forecast says clear tonight, so i`m going out :D I will have a couple of pics to show after I painted some parts of the wedge with white Hammerite to help me with the dark/black sky initial alignment.

Also I discovered something on the NexStar mail list today. I was always amazed at how I managed to do my 2 star align and then North EQ wedge align and it then needing almost no drift alignment..... weird! Anyway, the reason why the NS8 requires a 2 star alignment before the wedge align is this: The wedge align routine points the OTA at where it knows polaris should be... and its aware of the calculated offset from true celestial north pole. Its obvious really, but would totally explain why when i go to drift align afterwards, the wedge hardly needs any tweaks at all (some nights, it didnt move... at all... now I know why).

Also, tonight could well be the last night I use my Canon 350D as my primary imaging camera, as I am collecting something new tomorrow. News on that soon (well, after the first clear night!)

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Hasnt the weather just been utterly carp recently? 2 weeks without a single clear night...

Anyway, the forecast says clear tonight, so i`m going out :D

Shhhhh!!! Him upstairs will hear and it'll be blanket cloud!

Fingers crossed though! I'm itching to get some scope time in!!! Another new toy is awaiting it's maiden voyage...

Tony..

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I painted some markings my wedge and OTA as shown below:

ns8gps_markings.jpg

#1 -Vertical and Horizontal markings n the back of the OTA so I know which way is "up" when its positioned at some strange angle.

#2 - Lines across the edge of the wedge base and angle plate to align the back of the OTA flat against when finding south during polar alignment

#3 - painted the front spurs of the wedge to help when I am aligning the base plate north/south.

Used to great affect last night :D

I have another new toy I have been playing with since yesterday afternoon, and will provide a writeup on it after I have had a chance to use "it" in anger.

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I leave my NS8GPS alone for 10 minutes, and it appears it was assimilated by the Borg :shock:

ns8gps_20070827.jpg

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