Posts Made By: Rod Nabholz

One of the things that I enjoy about forums like this one is seeing what people come up with by taking a common item and finding a unique Astro related use for it. For example, a 35mm film canister as a simple sight tube.

So if you have found, made or adapted something that answers a need, saved you some money, or otherwise made your Astro life easier, please share it with all of us.

Anything you can do to help all of us understand what you have found or done would be a bonus, links, pictures, diagrams etc. But if you don't have these, don't let that stop you from posting.

Might I suggest that responders edit the subject of the response to reflect the idea? ie: Eyepiece Case from Toolbox

Thanks for playing along.

This Bluebird was competing for this perch with a Kingbird. They went back and forth for about 20 minutes, and I kept shooting.

Canon D30, Canon 300mm 2.8 with 2x converter

This is the nemesis of the Eastern Bluebird of my last post. They really were going at it for a while. The Kingbird is holding the prize perch in this shot

Canon D30, Canon 300mm 2.8 with 2XII converter

I have just published a page with some information on a home built Downward Looking Binocular Mount.

It is pretty simple and straight forward, borrowing ideas from some others I have seen out there.

Those interested can see more at:

http://www.indytel.com/~rnabholz/downbino/

Thanks

I have added a page to my Home Built Astronomy Projects Site. It is an observing stool that I built.

It is an easy, inexpensive project and it really works well.

If you would like to find out more please go to:

http://www.indytel.com/~rnabholz/stool/

Thanks

I have recently come to possess a Edmund 4" f15 tube. Unfortunately, this one met with some misfortune, and it's objective was broken.

I have always been interested in owning a long focal length refractor, so I have a new project.

I have been looking around and have found two possible sources of replacement objectives. Antares (through their dealers) and Apogee Inc.

The Antares line claims to be sourced from the suppliers of objectives to Vixen, I would infer that it is likely to be a quality product.

I do not know what the source of the Apogee product is.

The Antares set at approx $350 is about $100 higher than the Apogee set.

I am more than willing to pay that price if the quality is there.

So, I guess I am looking for real experiences with either of these objectives, or any other sources or considerations I should examine.

Thanks!

With a tip of the hat to Eugene Artemyeff and his great Comet Couch design, here is a version that I recently completed.

It is a GREAT way to observe.

I plan on writing up some construction notes when I have a little time, but your thoughts and questions are welcome.

Thanks again for a great design Eugene!

Well Guys and Gals, I could use some help.

You might remember a recent thread in which I sought some opinions on a 4" f15 project I was thinking about undertaking. Well I dived in and now find myself at a point that I could use some help.

I was lucky enough to be offered an Edmund 4"f15 tube that had a broken objective. After considerable research I ordered and received an Antares 105mm f14.2 objective with an adjustable cell.

After some lathe work on the cell, it now fit the tube, but despite trying to match the objective to tube distance on the new cell, their must be enough difference in the cell and objectives to give me a focus problem.

I cannot reach focus with a diagonal in place with my Televue plossls, not enough in travel If I remove the diagonal, I can reach focus with the 1.25" focuser racked out 2" of it's 6.25" travel. That seems to measure very close 60 inches focal length, as expected.

I obviously need to shorten the tube, so being that the thought of a mistake in cutting the tube is making me a little nervous, I am seeking counsel here. These are my questions.

1. The tube is nicely baffled in three places. If there is an error in the placement of the objective introduced by the new cell, I believe it to be that it is too far forward by less than an inch. It therefore seems to me that the best course is to shorten the tube at the back so as not to change the light cone and cause a problem with the baffles. Do you agree?

2. By shortening at the back, is there a chance that the long tube of the 1.25" focuser may vignette?

3. I was able to achieve focus with no diagonal using my TV 32mm Plossl and my 13mm TV plossl. Those were the only two that I tried because the focal point was unchanged between them, so I expect that the others will focus nearby. Would it be prudent to plan for the shortening to place the focus point at mid point of the focuser travel?

4. I use plossls almost exclusively right now, but if that changes in the future how does the focal point of TV Plossls compare to others like orthos or wide field types? Does using these plossls as the model make sense?

5. Does adding Barlow affect this calculation?

6. So assuming my thinking is correct the amount to cut from the back would be:

Current Tube Length - (Length of the Light Path of the Diagonal - 2 inches) - Half of the Focuser Travel)

OK I thank you for coming this far, Now Please Help me not screw this up!

Thanks

Thanks to those to responded to my recent questions about this project. With your help I was able to get my newest scope operational and out for a couple of sessions and am really enjoying it.

I have come to call it Frankenscope because for a refractor, it came together from so many different distant sources with components that were made over so many years.

The tube is an old Edmund Scientific tube. The objective is a new Antares. The cell is a Synta. The finder is a GS. The mount is a Tal, and the tripod is an old Birns and Sawyer Motion Picture Camera Tripod.

I thought it interesting the number of countries involved in the manufacture and distribution of the components too. USA, China, Russia, Japan, and Canada.

I use a Pocket PC at the telescope to provide real time Altitude and Azimuth coordinates which applied with an azimuth dial and altitude scale makes for a simple and affordable setting circle system.

Since implementing the system on my 13" I have worked to try and improve the accuracy of the system. I recently replaced my hand drawn azimuth dial with a computer generated dial and saw an improvement in accuracy. The altitude system still needed work. I have been using an inclinometer which I was able to make work pretty well, but the small size of the dial made making fine adjustments really difficult. I was often able get close with the dial, sometimes right in the one degree field, but often had to scan a little to pick up the target.

I was on the look out for a way to improve the accuracy of the altitude system when I came across an advertisement for an electronic level that was accurate to 1/10th of a degree. This might be just the ticket, that kind of accuracy would be excellent.

I ordered one of the units. I devised a simple mount using a short piece of aluminum angle. I attached the mount to one of my struts with 2 1/4 20 thumbscrews into threaded holes in the strut. I placed springs between the mount and the truss. The level attaches to the mount with velcro.

I have been out with the new system for 2 nights now.

The level is very accurate. As I worked my way through my observing plan, object after object was placed in the 1 degree field of view of my 32mm plossl. At one point, I had 15 consecutive objects in the field, and they were spread all over the sky.

In the event an object was not seen in the field, a half a degree scan in azimuth turned it up immediately, so altitude placement was accurate. After a "miss", I center on the object and simply reset the azimuth dial to the match the expected setting and things are back on track

This is a big improvement in this system. The resolution of a tenth of a degree offered by this device is all I had hoped for and makes using the system a real joy.