balancing the optical tube

"you need to know if your optical tube is front heavy or rear heavy"

When i asked some questions with regard to the best possible setup for astrophotography, especially with regard to the final approach while aligning an object, i was told to make sure that the optical tube is properly balanced.

The nice people at cloudynights.com told me to remove the OTA and place it on a pencil with all the photography gear attached and to make sure that i mark the spot where the whole chebang is all nicely balanced.

So here we go with some pictures:

Step 1: Ask your wife to hold on to the OTA while you detach the OTA. My regular prism and eyepiece are still attached.

Step 2: Place the high tech balancing device (pencil) underneath the tube

Placing the pencil under the tube proved to be difficult because the whole setup was leaning to one side, towards me (due to the extra weight of the finderscope) and did not stay level on the table.

Step 3: Attach your photography gear and find the sweet spot

After some minutes of fiddling i think i found the sweet spot and marked it ( i had to get a second pencil : )) on the OTA. I first made a mark on the black rail that later "slips" into the mount and had to draw it again onto the tube because the mark of course got hidden inside the mount's base.

..and the result ?

Now that i have the tube back on the mount, i can see that it has moved quite a bit forward compared to before the balancing process. So it looks like it was quite a bit "rear heavy" before this procedure. The rail that is attached to the tube does not even stick out the end of the mounting base anymore. I'll add a picture that shows this later - my wife is waiting for me to watch another episode of Dexter together... ; )

here's the result. You can see that the tube has now moved quite a bit forward, leaving a gap.

just some boring pictures of the whole setup

New finderscope and red dot finder are installed

Now that i figured out how to attach the new equipment to the telescope, here are some pictures of the final setup. I've also included pictures of my other eyepieces as well as the crayford focuser which i had "left over" from my older 8" Meade LX10.

And here are the pictures of my accessories: 

40mm TS Super Plössl eyepiece and crayford focuser 

Set of three bushnell eyepieces (16.8mm, 10.5mm, 7mm) for planetary viewing, set next to the TS 40mm for size comparison: 

how to remote control your telescope - part 3

the neximage webcam arrives

shortly before i received the right angle finder i also got the neximage webcam i had ordered on ebay. It came in the original Celestron box and seems to be brand new. It came with a one page quick start instruction "manual" as well as a CD with a detailed manual and the Registax stacking software and a webcam capturing software.

I quickly installed the Registax software, the capturing software and was able to get an image from the camera. So i guess everything is working ok. I'll probably spend the next couple of evenings reading through the rather hefty Registax manual.

The version of Registax on the CD seems to be an older one. Registax is at Version 5 right now and this version is freely available for download.

Here's a picture of the webcam:

If you look closely you can see the image sensor at the "bottom" inside of the camera. (there's a protective cap that goes over the opening, which i removed for the picture)

Now i just have to wait for better weather to take some first shots of Mars : )

how to remote control your telescope - part 2

finderscope woes...

After alot of research on the web i ordered the antares 50mm right angle correct image (RACI) finder. This finder has a removable eyepiece and i'm hoping to use it as a sort of guide scope together with my neximage webcam. I also ordered a bracket for SCT telescopes but i failed to mention the size of my scope, thinking that it would be a "one size fits all" solution.

The Antares finderscope looks like this:

At first i could not get the crosshair eyepiece to focus at all. I then got some help from the nice people on the cloudy nights forums who told me to unfasten a tiny allen screw at the bottom of the finderscope so that the diagonal could be pulled out further. After i did this i did not have any problems getting proper focus.

once that problem was fixed, onto the next hurdle....

I then tried to attach the finder to my telescope. So i took the red dot finder off and tried to screw on the base. First surprise - the original screws were way too short. They did not even go all the way through the base. And the curvature of the base did not fit the curvature of the scope - it seemed to be just slightly larger. (it's actually a 8" curvature and should have been 7"). So down into the basement i went rummaging through my big box of nuts and bolts until i found two screws that were long enough.

In went the first screw, but the second one did not fit ! That's when i realized that the finderscope base did not lign up with the holes on the 6SE. Bummer. Only using ane screw

did not only look bad but was quite unstable as well. So off i went to get some more advice from the cloudy nights forums...

After alot of great tips i decided to drill a hole into the middle of the base. I then attached some dark sticky tape to both sides so that i would get a nice and flush fit. Here's a picture of the base with the new hole:

With the added sticky tape left and right from the center hole the base now sits nicely balanced and is rock steady. On the picture it looks like there's alot of empty space between the base and the scope - but actually it's only a milimeter or so.

here's another view:

So here's how the whole setup now looks like:

I've not had the chance yet to align it properly with the scope and i've also not yet figured out how to attach the remaining red dot finder back to the telescope. I did get some magnetic tape but it was not strong enough to hold the plastic red dot finder. Since i want to be able to put the scope back in the original box for transportation, i don't want to use sticky tape to permanently "glue" it to the scope.

I guess i'll have to visit the cloudy nights forums again to get some help with that one....

Red dot finder placement

As it turns out, it took me about an hour to realize that the red dot finder has a detachable base as well ! (slaps himself on the forehead - SMACK) I somehow thought that it was all one piece. So i now attached the base using extra strong sticky tape and am quite happy with it. I'll add a picture of the final setup soon.

how to build your own bathinov mask

while i'm waiting for my new finderscope to arrive, i tried to build my own bathinov mask

When i took those images of jupiter last summer, i had a heck of a time focusing the scope correctly. A bathinov mask should help get a correct focus, although (i think) it only works with deep sky objects.There are a couple of sites on the internet that offer free and downloadable instructions on how to build your own mask. So I downloaded a bathinov mask in pdf format and printed in on regular paper and then glued that onto some cardboard. But it's such an intricate pattern, that i immediately messed it all up : )

I've put the source file in my public folder at me.com. Here's the link: http://public.me.com/baierfamily - the password is "nexstar" and there's a folder called "Bathinov mask".

By the way, here's what the mask looks like:

Your're supposed to attach this mask to your telescope and take a couple of shots with your DSLR with different focus settings. Once the image appears like a concentric star, then the scope it supposed to be focused correctly. Here's how its supposed to look like:

I then read on cloudynights.com that someone had had the same problem cutting out the shape and instead printed the whole mask on a transparent sheet. So the next day i printed the mask at the office and just had to cut out a nice circle - which proved to be much less challenging : )

I then used some wooden sticks with added duct tape for extra thickness that went through the two holes on the top and that's how the mask looks "hung" over the optical tube:

And here's just the mask by itself:

The only thing that's missing now is to actually go out and test the thing. I hope that once it gets a little warmer or once i get my remote control setup up and running, that i'll be able to report on how the mask works.

Important addition: If you are planning to use your mask on a cold night where you'd use a dew cap then make sure you cut out your mask to be big enough to fit onto the dew cap. The particular mask that you see pictured here fit perfectly on the scope, but was to small for the dew cap - it "fell" inside when hung over the dew cap. So i had to print out another one of the suckers : )