Finally some observing!

The weather finally cleared up after several days of clouds and a full moon before that.  I lugged the AD10 out into the back yard to get some observing time in.  I don't have a lot of sky to look at from my small yard.  My house is right to the south, the neighbor is about 30 feet away to the north.  There's a tree to the west, and the neighbors on the east have bright lights shining all night.  Regardless, I pressed on.

Jupiter was pretty close to the zenith, so that's where I started.  It was extremely clear and steady, great seeing.  I was able to use my 9mm in a 2x Barlow, so about 278x.  With this I could easily see lots of detail on the surface.  Io was next to it and I could see the shadow of two of the moons, Io and Ganymede if I'm not mistaken.  This was also a good opportunity to practice tracking an object using the dobsonian mount.  It still feels a bit awkward, but I'll get used to it.

I tried to look for M97 and M108 in Ursa Major, but didn't have any luck.  Partly because of the lighting and partly because I don't know what I'm doing yet.  So I swung around to Auriga which was in a much better position.  I tried to locate a few things in the area, but still didn't have any luck.  I was using an old copy of Tirion's Bright Star Atlas 2000.0, but I found it hard to relate the small size of the maps to what I was seeing the scope.  Since I couldn't find anything in particular, I spent a while panning around with sky with my scope.  I spotted some double stars and saw lots of pretty, colorful star fields.

Now I'm reading up on how to star hop, so hopefully I'll be able to find some things next time.  I've got Cartes Du Ciel, which is a free program that can generate and print star maps, as well as Stellarium (another free planitarium software), and a couple of others.  I'm hoping that those, along with the Tonight's Sky observation planning web page, will give me the tools I need to star hop successfully.  I'm also planning to build a leveling base with setting circles for my AD10.  Along with the SkEye app on my phone, I should be able to find things.

Simple Apertura AD10 mods

While waiting for the full moon to go away and clouds to clear, I did a couple of quick mods on my Apertura AD10.  First, to display my mad sewing skills (yeah right), I made a cover for the bottom end of the scope.  As I currently store the scope in the garage, and the mirror cell is open at the edges, this will keep any dust and spiders out.

I first took a strip of 3/8" elastic and cut a length that would stretch slightly to fit around the tube.  Not tight, just enough to hold it on.  I sewed the ends of the strip together to make a loop.  Next, I cut a 16" disk from the back of an old t-shirt.  I attached the elastic strip to it at one edge with a few stitches, then at the opposite edge.  Then I attached it at the edge halfway between the first two.  I kept repeating this, adding a few stitches halfway between the previous, until I had the elastic attached every 1/2" or so.  By doing this, the elastic and fabric have room to move and stretch.

The other mod was to replace the collimation springs.  This is one of the mods that would have been included if I had purchased the "Tweaker's Dream Package" with my AD10, but it can be done very simply and much cheaper.  I haven't had my scope out enough to know the difference, but I've read many suggestions on the net to do this mod.  I purchased my springs from McMaster-Carr, part number 1986K117.  This is a 0.5" long by 0.5" wide stainless steel spring.  You can see the stock spring on the right and the new spring on the left in this picture.

The new springs are significantly stiffer than the old ones.  Replacing the springs is a trivial process.  First loosen all three locking knobs.  Then remove one of the collimation knobs, pull out the spring, slip in the new one, and reinstall the colliimation knob.  Repeat for the other two collimation knobs.  Be sure to only do one spring at a time.  When you're done, tighten all three collimation knobs then perform a normal collimation on the scope.  

One last thing I did was adjust the balance of my scope.  I originally installed the altitude bearings when the manual stated.  I've found that even with the 30mm 2" eyepiece, it's still tail-heavy and wants to swing straight up.  To stop this, I had to really tighten the grips on the altitude bearings, which made it more difficult to move smoothly.  I have now adjusted the bearing positions by loosening the mounting screws and sliding the bearings about 1/2" towards the bottom end of the scope.  This seems to be a good compromise in the balance of the scope.  

Straight rod barn door tracker

I'm moving forward with building my straight rod barn door tracker since I couldn't get good results with the curved rod one.  I found a couple of very good sites with lots of information.  ZZJ's barn door tracker provides a lot of information and good design theory.  He also provides a nice program in C++ to calculate delays for the loop.  The only problem is it's for an ATTiny85 MCU instead of an Arduino.  Rather than try to translate the code from one to the other and figure out the differences in timing, I went with a design based on another tracker by a user who goes by 0x05 on Reddit.  I based my design on the code he provided and added some additional functionality.  It took a bit of thinking to work out the math for my delay timings, but I think I've got it figured out.  

This one's got a 12" threaded rod which should provide me with about 2 1/4 hours of tracking before I need to reset.  For the motor mount and pivots, I found some materials at ePlastics, which is actually a local shop for me.  I used a 5/8" Delrin rod, for a 12" piece it was under $2.  For the blocks, I tried to find some nylon as others have used, but the shop didn't have any scraps and a small sheet was ridiculously expensive.  Instead, I found a 3"x6"x1" scrap of polyethylene for $2.  Perfect material for this.  It machines really well on a table saw and drill press.  Just don't try to sand it much, it gets very fuzzy.

 Yes, my prototype board still looks like a rat's nest.  In there I've got a SainSmart Nano V3 Arduino compatible and a breakout board for an A4988 stepper motor driver (similar to the one from Polulo, but for only a couple of bucks off eBay).  This driver allows 1/16 microstepping, which really smooths out the motor.  I've also hooked up a start/stop/rewind button, "fast" mode switch to run it at a much faster rate (possibly for drift aligning, if that works out), and a limit switch so when it's powered on, the tracker can rewind to a known position.

This all seems to work great at the moment, but I have come across one problem.  My tripod is too wobbly.  It's great for mounting just the camera, but the mount is pretty heavy, so any little touch makes it wiggle all over.  So, next I'll be building a nice, sturdy tripod for my mount.  I think I've come up with a nice design that I threw together in SketchUp.

It will be plenty sturdy and will provide fine adjustments for altitude and azimuth for setting polar alignment.

More pictures and info to come once I've build the tripod and get everything working.

Barn Door Tracker #3

Third attempt with the barn door tracker, this time using a 200 step/rev stepper motor and an EasyDriver stepper driver, which allows 1/8 microstepping.

I found that to get microstepping to work, I had to turn the current limiting pot all the way down.  Without doing that, the motor would always do full steps.  The pot on my EasyDriver is installed backwards, so I had to turn the pot all they way to the direction labeled max.  You can tell this by measuring the voltage at the test point TP1.  When you get minimum voltage, the pot is set to the minimum current.  I ran the Arduino on 7.4V and the EasyDriver and motor on 5V.

This still didn't give good tracking results though.  With my 135mm lens, I could expose for about 10 seconds max.  Any more than that and I would get short trails.  The trails were always consistent in length though.  Whether I exposed for 20 seconds or 5 minutes, they were always the same length, and they were also the same length as the ones I got with the cheap eBay stepper motor.  This tells me the motor and code aren't the issue.  I suspect the problem is my gears.  Maybe some imperfections in the gears or somewhere else in the drive train is causing the problem.

So for my next attempt, I'm going to build a different design of tracker.  This time with a straight shaft instead of a curved one.  Rather than a consistent stepping rate for the curved shaft, I will need to vary the speed of the motor with the straight shaft to account for the tangent error of the design.  I've found several sites online that cover the design, but I think the most complete and informative one is ZZJ's Barn Door Tracker.  He covers a lot of the details of the design, measurements, and calculations.  I will use most of the same components for the drive circuit and the 200 step/rev motor.

I spent the afternoon today cutting the wood and plastic parts for it, we'll see how it come out.

I picked up some new batteries for the laser collimator today.  One of the original cells was at 1.4V and the other two were at 1.1V.  I'm always suspicious of batteries that come packaged with something anyway.  With the new batteries installed, I was able to adjust my laser so when turned on my adjustment jig, the beam only moved about 1/8" when measured 20 feet away.  Close enough for me.

Before collimating the scope, I decided to do a couple of quick and simple mods.

I carefully removed the secondary by unscrewing the center screw and removed the metal washer.  Be careful when you do this and tip the scope horizontal.  There is a spring on the screw as well and you don't want that to fall on the primary.  I then traced the metal washer on plastic from a milk jug and cut out two duplicates.  The two plastic washers go back on the screw instead of the metal washer, then carefully put the secondary back on.

I also replaced the secondary collimation screws with M4 x 25mm allen head bolts, which are easy to adjust by hand.

After all of that, I adjusted my secondary position by eyeballing it through the finder opening.  I don't have a sight tube yet, so I can't adjust it very accurately.  I wanted to make a sight tube out a film canister, but good luck finding one of those in the digital age.  No one has them anymore.  YouTube videos helped out on figuring out how to adjust things.

I popped the laser in the finder and adjusted the secondary collimation get the laser's dot right in the middle of the center donut on the primary.

The spot from the laser isn't really a dot, it's more of an oval, so I used the "barlowed laser" technique described on many websites and videos.  You put the laser in a barlow, which diffuses the beam.  Rather than reflecting back the dot of the laser, it reflects an image of the center donut from the primary.

Loosen up the three white locking knobs on the primary before adjusting the black collimating knobs.  Center the image of the donut over the hole in the middle of the collimator.  First adjust things with the scope horizontal, then move it vertical to check that everything is still good.  Once you're satisfied, turn the white knobs so they are barely touching the back of the mirror cell.  Don't put any pressure on the white knobs or you could distort the mirror cell.

First light with the AD10

I finished putting together my Apertura AD10 today.  Assembly was very straightforward and the instructions are extremely clear.

One of the nylon screws on the finder was snapped off in the box, so I replaced both adjustment screws with 8-32 stainless steel allen head screws.

After assembly, I tried to adjust the collimation, but I found the included laser collimator was extremely out of adjustment.  I set it in a jig (piece of wood with four nails in it)

When turning the collimator on the nail heads and projecting the laser across the garage, it made a pretty large circle, over 6".  Problem was, as I was trying to adjust it using the three set screws on the side, the laser kept dying.  I believe it's just dead batteries.  By turning it off and back on multiple times, I was eventually able to get it pretty well adjusted.  The bad batteries meant I wasn't able to adjust the scope much though.

I pointed the scope at the farthest away trees that I could see from my location and aligned the finder.

Once it got dark, I dragged the scope out to the driveway to take a test drive.  WOW!  I didn't have any sort of observing plan for the night, just get out and look at some stuff.

First up was the moon.  Today it was first quarter.  I started with the 30mm SuperView.  The moon spanned about half the diameter of the eyepiece.  It was extremely sharp, although too bright to view for long.  Next I switched to the 9mm Plossl with the moon filter attached.  Very nice.  Extremely clear views and just the right brightness.  The dual speed focuser really makes it easy to dial in the focus.  The 9mm in the Barlow wasn't as nice due to seeing conditions.

After a little while I swung over to the Orion nebula M42.  Even with all of the lights from the neighbors' houses, I could easily see quite a bit of detail in the nebula through the 30mm.  I switched to the 9mm again.  What a great view.  

The kids came out and wanted to look at Jupiter, so we watched that for a little while in both eyepieces.  It was near the zenith though, so trying to follow it was a bit tricky.  I'm not used to the dob mount yet.

After that I went back to M42, but seeing was getting worse and the 9mm wouldn't focus well.  Instead I barlowed the 30mm and enjoyed that view.  While looking at M42, I even saw a satellite pass right through the middle of it.  

I tried to find a few other objects that I identified in Skeye on my phone, but I couldn't locate them, so I just panned around the sky for a little while.  I need to learn to read sky maps and star hop.

Next time I'll try setting up in the back yard where there is much less light from the neighbors.  

My AD10 is here!

Fedex delivered my Apertura AD10 10" dobsonian yesterday.  I had it delivered to my office and I'm glad I thought to drive my van, there is no way I would have fit the box in the back of the car.  The scope should fit in the car without a problem, but the box is significantly larger.

Last night I put together the base and today I'll get the rest of it put together and adjusted.  Hopefully tonight will be clear.

My new telescope and first attempt at processing

I pulled the trigger this evening and ordered an Apertura AD10.  I went with the basic scope, not any of the add-on packages.  I figure I can add flocking myself and springs, screws, and a knob can be found at the local hardware store or online for much less.  The secondary washers can be made from milk jugs.  I can also make a light shield myself.  As far as the eyepiece racks, I don't think I'd put the lower one on anyway.  I think it would risk getting dirt kicked into the eyepieces.  I can build my own leveling base and a setting circle can be printed and laminated at Staples.  One thing I expect I might buy is the Alti-Gauge digital level.  It has a nice red backlight, which will be useful.

I did order the Apertura 2" ED 2x Barlow along with the scope.  This will basically double my eyepiece selection.  I've also heard that using a Barlow makes laser collimation easier and more accurate.  We'll see how that goes.

I've also been playing around with some of the images I've taken previously with my original barn door tracker.  I found I did get a pretty good one of the M31 Andromeda galaxy region at 55mm.  It needs quite a bit of work on processing still, but here's a first attempt:

This was ISO 1600, 55mm, f5.6 on my Canon T3i with the stock 18-55mm lens.  It's a crop of about 1/4 of the full image.  I stacked 98 subs of 30 seconds each, 30 darks, 30 bias, and 30 flats in DeepSkyStacker.  I then played around with the curves and levels in GIMP 2.9.

I need to learn how to reduce the noise and gradient, bring out more detail, and bring out some color, but I think it shows promise.