Some recent telescope related developments

Although I haven't updated the blog, the last few months have been somewhat eventful.

First of all, I decided to complete my wonderful 4" refractor. I started with the lens cell. I tried a couple of places but could not find anyone that was willing to fabricate the cell to the tolerances and dimensions required. One place agreed to cast the cell and then machine it however, the price they quoted was above $500. I decided to instead buy a cell. There are very few companies who make/sell lens cells. Most telescope making companies only deal with mirror cells and not lens cells.

The current lens cell that I have is made out of two PVC pipes that were filed and hammered for a press fit. The lens was cushioned by a piece of paper. This setup in no way does any justice to the lens. The lens is a master piece and so I decided to update the setup so as to be more professional. Also, with the current setup, I was concerned about the axis of the lens not perfectly aligning with the axis of the focuser/diagonal/eyepiece. So to make the setup more professional, I decided to order a new lens cell.

After some looking around using the trusty Internet, I was able to find a company called, A. Jaegers, Jr. Optics, Inc., located in Lynbrook, NY. After a quick call and some poking on their web-site, I found that they make lens cells that hold lenses of 102mm and 108mm. I have decided to order the product that holds the 102mm lens as it would nicely and squarely fit the lens that I have. I would get 100mm of clear aperture with this cell.

Another recent development involves a mirror. I was able to obtain a 12" diameter mirror blank and a matching tool. The mirror blank is approx 2.5" thick and as such is very heavy. I have also been able to obtain large quantities of some grinding powders. I hope to start work on this blank sometime in the next 2 weeks or so. I was hoping initially to build a smaller mirror, say 8-10" diameter however, this blank came along at a ridiculously low price and I just had to have it. I will keep everyone posted about the progress of my mirror grinding work on this blog.

As regards the 6" mirror, I haven't worked on it since the last testing. I am afraid that the pitch tool is contaminated and would like to recreate a pitch tool. I am hoping to do the 12" and 6" pitch tools around the same time. The mirror has been tested and was found to be polished very well though somewhat under-corrected. It is currently at 1/2th wavelength while the generally accepted standard for this mirrors is 1/4th or better. The correction from 1/2 to 1/4 should not take more than a few minutes i.e. just a few circles around the tool using the W-stroke. Since however, I am afraid about the pitch tool being contaminated, I do not want to take the risk of ruining my mirror.


On a unrelated note, I have started studying for GMAT. I hope to give the exam sometime in March and then get admission to a decent business school in the fall. I am looking at part-time or executive MBA programs which will allow me to continue working while I study. This means that my mirror grinding is not going to be as fast as I would have liked it to be.