The KISS principle

chrisp9au (Chris) · #1 24-01-2009, 11:43 PM

The KISS principle

I've been fiddling with my scope(s) for years, trying this and that, never really happy with the result, that's if I got as far as checking for a result! Usually I'd be half way through one idea when another idea would rise from the depths and take priority over everything else! A shed full of half finished mounts, equatorial tables, and who knows what else. The money I've wasted! If I'd stuck with the original 8" Dobsonian, everything might have worked out fine, but not this idiot!

I've had the dream of hooking my scope up to the laptop with stepper motors, bought Mel Bartels system, couldn't get the motors to go fast enough without stalling (yes, I tried flywheels). Motors screaming when tracking! Never finding the object in the eyepiece after slewing. I've tried the Bartel system over and over without any real success. I gave up the drink years ago, so thank God I never got to the point of sorting out PEC problems!

But today, this idiot tried something different!

Months ago I visited Rob Willet's website http://settingcircles.robertwillett.com:8000/ and managed to produce some setting circles with verniers, got them printed and laminated, and then, of course, sat them on a shelf while I pursued other ideas! Today I ripped the stepper motors off the 10" dob, all the cables and other bits and pieces, and fitted the setting circles and verniers. I also installed some red LED lights to read the verniers by. Set up the laptop by the scope, running HNSKY, and waited for dusk to fall.

As soon as I found Venus I calibrated the setting circles, and started to look for stars in the twilight.

Amazing! Every single star I looked for finished up in my new 18mm eyepiece! I was finding stars that were still invisible because of the twilight. When it got dark, the results were spectacular! Dialling up object after object, always in the eyepiece. I've seen things I've never seen before, just by using a simple system of setting circles. I've checked out NGC objects that have just been numbers until now. M1 clear as a bell, center of field, first time.

I didn't have to re-calibrate once. The LED lights need some re-positioning and some guards to reduce glare, but essentially, it's all systems go.

I now have one Bartell system for sale! I'll hang on the finder scopes, but I didn't use them once tonight, no need!

And for anyone thinking high tech is the only way to go, think twice! Setting circles are going to be a new way of life for me. Keep It Simple, Stupid! Save a lot of money, save a lot of time, do some actual star gazing!

Chris

Screwdriverone (Chris) · #2 24-01-2009, 11:53 PM

Very cool Chris,

I had a similar idea for the setting circles on the Az base after seeing a friend use his quite effectively, and thought of the same kind of red led idea for the "mood lighting" on the Az circle.

Sounds like you mastered it, with a Dob and the Alt magnetic scale and the Az circle, it really is a doddle isnt it?

Well done, now all i have to do is make up mine and buy the magnetic tiltmeter for my brand new dob.

Cheers

Chris

renormalised (Carl) · #3 25-01-2009, 12:44 AM

It'd be good to see piccies of your setting circles and such, might become inspirational

chrisp9au (Chris) · #4 25-01-2009, 01:17 AM

I'll post some in the morning!

Chris

Barrykgerdes · #5 25-01-2009, 11:21 AM

Ah Yes!

Electronic setting circles. Just think all the real astronomy ground work, algorithms, theories etc were all done with calibrated mechanical setting circles on telescopes that were sited and set up without the benefit of GPS or any other of the modern devices that "We just can't do without these days"

Incidently I went through the stepper motor business 20 years ago on my 8" Dobsonian. They are no good for fast slews. but I did manage to write a program in Basic to drive them, complete with a two star alignment routine.
Stepper motors were salvaged from old NFM hard drives. I found one type that would do 3000 steps/second

I just got it to work and along came my LX200 classic. The project is still sitting in a closet somewhere.

Barry

JethroB76 (Jeff) · #6 25-01-2009, 01:57 PM

Manual setting circles work very well indeed.

chrisp9au (Chris) · #7 26-01-2009, 04:54 PM

A couple of pics of my setting circles, revealing the depth of my woodworking skills, a lick of paint will fix it!
I hope to spend more time looking through the scope than at it, and who can tell in the dark anyway!

The pics are a day late, but when the wife points to the list of jobs to be done I know what my priorities are!
Azimuth circle is 460mm in diameter. Altitude circle is 230mm in diameter.
The azimuth circle can be adjusted within a range of about 20 degrees, so scope only has to be roughly aligned with North before leveling. Altitude is adjustable over a range of 360 degrees!
Verniers are mounted temporarily until I'm 100% happy with them, refinements will come in time.
Verniers allow reading of angles to an accuracy of less than 6 arc minutes.
In the pics, Azimuth reads 318 degrees 42 min. Altitude reads 11 degress 18 min. Plenty accurate enough.
I'm thinking of getting rid of the LED lights on the verniers, using my red flash light works just fine.
But the LED lights on the base board stay, they stop the grand kids kicking the scope!

Cheers
Chris

Barrykgerdes · #8 27-01-2009, 11:17 AM

The last pictures reminded me of my initial efforts on a Dobsonian.
I generated Alt/Azm scales to 6 arcminute precision in Autocad and printed them out on a 15 inch dot matrix printer, scaled to suit the base and Alt surfaces. They were carefully centered and pasted. They worked great I was even able to find stars during the day down to second magnitude. I could read altidtude to about 6 arcminutes and azimuth to 3 arcminutes.

barry

avandonk · #9 27-01-2009, 01:05 PM

Even though the Mel Bartels system on my modded EQ6 can theoretically be a GOTO or 'know' where it is I do not use it. I manually move the mount to roughly where I want to go and lock. Then I use my electronic finder with GstarEX video camera and 16 to 160 mm F1.8 lens as a guide to move the mount at a 'slow' speed to center the object for AP. This saves being light adapted and wear and tear on my mounts worms and wheels.

This works for me as I think I know my way around the sky. For really dim objects I point the setup at a bright nearby object and then type in the RA and DEC and then use the computer display of RA and DEC to move to the dim object.

There is no correct way only the way that works for you.

Bert

rmcpb (Rob) · #10 27-01-2009, 01:46 PM

Love the vernier scale on both axis. Mine have no vernier but work really well, so you are right about the KISS principle. Won't stop me continuing to have endless half done projects (including a vernier scale) and I bet it doesn't stop you either. Some of us are just like that

chrisp9au (Chris) · #11 27-01-2009, 02:28 PM

Sadly, you're right Rob! My lovely wife of 25 years said, 'so that'll be the end of all the tinkering in the shed then?' and walked away laughing!
Chris

rmcpb (Rob) · #12 28-01-2009, 09:22 AM

I always remind SWMBO that I could be smoking and at the pub spending buckets of money. This way its only cup fulls, I'm home and she is happy

DaveGee (Dave Gault) · #13 29-01-2009, 01:30 PM

Quote:

Originally Posted by chrisp9au

In the pics, Azimuth reads 318 degrees 42 min. Altitude reads 11 degress 18 min.

Hi Chris,
Nice clear scales!

Your vernier scales appear to be in decimal degrees and that means you have to convert 318.7 degrees to 318d 42m. I was wondering why don't you scale them to read in minutes directly,

say in increments of 5 minutes?

I'm also sorry to hear your heartache with the Bartels stepper system. I love my Bartelised GEM GOTOs. Is your board one of Mel's prepopulated boards? Anyway PM me to discuss a change in ownership.

Quote:

Originally Posted by rmcpb

I always remind SWMBO that I could be smoking and at the pub spending buckets of money. This way its only cup fulls, I'm home and she is happy

Rob, my SWMBO complained once of my shed time, I said it's Telescope Making or Drag Racing, your call sweety!

chrisp9au (Chris) · #14 29-01-2009, 02:17 PM

Dave, I'm happy with the 6 minute divisions on the vernier, considering the FOV on my 18mm eyepiece, it gives me very good accuracy, and it's the default when using Rob Willett's website to generate the circles and verniers. I don't think going to 5 minute divisions would make that much of a difference would it? I'm just happy to be able to see an object first time every time! I haven't turned on the Rigel Quickfinder since the circles went on!. The night before last I 'dialled up' NGC 2239, put the NPB filter (bought on IIS) on my 40mm eyepiece, and hey presto there's the Rosette Nebula! I'm now planning an evening to view a few more objects that will be visible with the filter, and easily located using the circles.
The Bartels board is the prepopulated version, I'll PM you with a picture when I get home from work.
Cheers
Chris