Taken 13-Oct-12
Visitors 186


A quick and dirty Pacman nebula

This is a quick 60s exposure from my backyard. It is just a test shot with my new (to me) Takahashi Sky 90 II to check for optical defects - I don't see any.

Below is some info for those interested in the dry details.

Because of some unforeseen events (housing related), I ended up with some spare change in my pockets. This allowed me to upgrade my telephoto lens 4 months earlier than expected. Upgrading optics is no easy task, there are many many excellent options these days. I did what most people do: I made a matrix with all the available scopes, their specs, pros, and cons.

My matrix contained the following scopes: SV90, TMB92SS, AT90EDT, AT106, TV101, Tak-FSQ85, Tak-Sky90, Pentax 100, Borg 101ED.

I dismissed the AT and SV scopes as their focal lengths were a bit much and because they didn't have a dedicated FR. The TV was a bit on the heavy side, so that one was out. The FSQ, Pentax, and the Borg were impossible to get on the used market. Purely looking at the numbers in my matrix, I was left with the TMB, a well liked scope, and the Tak Sky 90 II, undoubtedly one of the most controversial scopes.

Given that the focus of my work is on narrowband imaging, I was not turned off by reports of the Tak showing more false color than the TMB. In fact, I was more concerned about spherochromatism and anecdotal evidence points towards the Tak beating the TMB in that department. Add the fact that the Tak is lighter and that it has a dedicated flattener and the Tak felt like the better choice for me.

Six hours after posting a wanted add on the used market Gary contacted me from New Zealand. His scope would come with the FF, FT focuser upgrade, and his images passed my criteria. And so I bought a used and controversial Tak.

First light
The scope saw its first light in my back yard where I wanted to verify that the scope was properly collimated. The scope was terribly out of collimation, and this was expected given that it was shipped from New Zealand. I set out to buy an eyepiece so I could collimate the Tak.

Collimating the Tak
Collimation is a pretty straightforward procedure. The Tak has a couple of screws that the user can adjust for this purpose. I made an artificial star out of a sheet of aluminum foil with a self made pinhole. As a light source, I used a red laser pointer. I spent 45 minutes adjusting the screws but I just couldn't get the star to look as it should. I was devastated. Did I get a lemon?

It was over dinner that I realized that my home made artificial star may have been junk. Pavel from the Yahoo Tak group recommended that I use an optical fiber. Of course! Why didn't I think of this? I stopped by the optics lab where I work and fished an optical fiber out of the sharps trash bin. Back at home, I set up my new artificial star, and I started adjusting the screws. Within 3 minutes, I had a text book image of a star - well this was easy.

Second light
Once again, I set up in my back yard to verify that everything was in order. Sure enough, the optics looked fine this time. The above image of the Pacman nebula was just a quick follow-up shot. No calibration images (darks, flats) were taken.

Consider me a happy Tak owner.
SBIG Camera

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A quick and dirty Pacman nebula