Archive for February, 2014

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Guest post: David DeLano’s ultimate Galileoscope quest, Part 2 – The Easy Solutions

February 24, 2014

Welcome to the second post in David’s series on hot-rodding a Galileoscope. The rest of the posts in the series are here.

There are several easy modifications that can be made to the Galileoscope to make it more usable. This post is going to be short, but I decided to break these off separately and document them as a group, because they do need to be documented.

Daisy finder

The first mod is to add a finder. Track down one with a 3/8″ rail. The BSA Daisy BB Gun Site works well, and is relatively inexpensive, but whatever you have on hand or can dig up will work. Fit it onto the front sight, and make sure it’s on as flat as possible. This probably means centering the sight between the screws that hold the finder to the rail. Tighten it snug, but so that it will slide back and forth. Slide it back and forth a few times, making sure to maintain the position on the sight. This will give you a bit of a groove for the rail cleats (I don’t know what else to call them) to ride in. Tighten it down a bit and repeat, a couple of times. Now tighten it as much as feasible, and it should stay firmly attached.

This next step is optional. Remove the sight, and take a nail file or a small saw and deepen the groove that you started on the sight. I highly recommend this, as it will give the finder a bit more grip and prevent it from coming loose, or tilting during use.

The Galileoscope kit does not come with a cover for the objective. It does have a nice dew shield, which also holds the two halves of the tube firmly around the objective, but no cover. I originally found that a plastic cap from a shipping tube, probably a 2″ size, fit nicely into the dew shield. However, I eventually figured out that a 70mm binocular cover is exactly the right size to go over the dew shield. The ones I use came from Agena Astro.

O-ring reminder v2

While you are still in mod mode, replace the O-rings that hold the tube together. In reality, the O-rings aren’t absolutely required, but because there is some stress in holding everything together, use the O-rings. I replaced mine with a bit of a heavier duty version measuring 1-5/8″ ID, 1-7/8″ OD, 1/8″ thick. They are a bit more difficult to install, but should hold up better over the long haul.

Be careful with the 1/4″-20 mounting nut on the bottom of the scope. If you over tighten when fastening to it, the nut will start to pull out of the tube halves, splitting them apart. This is one reason I recommend using the O-rings, as they are closer to the center of the scope. However, I highly recommend using finder rings instead. For one, if you are going to use the GS as a finder, you need to be able to align it to your telescope. Beyond that, it is a much more secure way to mount the GS. Be careful when tracking down the rings. You would think a 50mm to 60mm set of rings would work, but they are almost impossible to get over the front or rear sights, along with the block where the mount nut is located. Go with a 80mm to 90mm set, making sure that the minimum tube they can accommodate is around 55mm.

IMG_0806

I’ll add this mod for Matt. I didn’t do this, but you can also blacken the edges of the objective. I believe Matt uses a black permanent marker. This might reduce any internal reflections in the lens. (That photo is actually from my Celestron TravelScope 70 overhaul, but the procedure would be the same for the GS.–Matt)

And lastly, use a Plossl EP instead of using the ones from kit. Go ahead and make and try out the ones from the kit for the experience, but if you really want to use the GS for viewing, use a better EP. You don’t need an expensive one. Something in the 20mm to 25mm range is probably the most useful, though I have had a 4mm in the GS viewing the moon, and other than the moon moving rather quickly, it was an interesting view! The 4mm I used was from a Celestron Firstscope reflector, another nice scope to play with if you can track one down. The Plossl EP can be used in the GS without any modifications if you can put up with the push-pull focus and having no diagonal.

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Guest post: David DeLano’s ultimate Galileoscope quest, Part 1 – Introduction

February 18, 2014

I’ve been fortunate to have my electronic pen pal and sometime observing partner David DeLano contribute several guest posts in the past (sun funnel, diagonal comparo), and I wrote about one of his early Galileoscope hacks way back when this blog was only four months old. But now he’s pulled out all the stops, and written a multi-part epic explaining in detail how he evolved his stock Galileoscope into the hypertuned monster it is today. The best thing I can do at this point is shut up and get out of his way!

I have owned a Galileoscope (GS) from day one.  I’ve also been on a quest to make the GS better from day one.  I hit a stale point in the quest, though, when Matt set me off again.  I was using the GS3 (third iteration, though I’d be hard pressed to figure out what GS1 and GS2 were at this point) as a finder.  Matt was working on the question of why finders cost so much, when something like the GS could be had for half the price.  So, I was off again to make the GS better.

GS box

I don’t want to reiterate the Galileoscope history. Instead, refer to http://galileoscope.org/. Also note that there are now vendors that carry the kits, so you don’t have to buy them directly and pay shipping that increases the cost by 50%. I recently ran across them at http://www.scopestuff.com/ss_gscope.htm. There may also be some interesting additions for the GS at http://www.leosciencelab.com/, though the site appears to be down at the moment, maybe permanently, and the last time I visited the site, you couldn’t buy anything.

When I first received my GS (well, one of the Galileoscopes from a case that I bought and distributed to family and friends) I found it interesting to build, but frustrating to use. I immediately picked up on a few modifications that made it useful. There are three shortcomings to the design that needed remedied: the gun sight finder was difficult, if not impossible, to use in the dark; the focal length was too short to use a diagonal; the push-pull focusing was very frustrating to use.

GS box contents

The finder update was the simplest. A very inexpensive Daisy BB gun RDF clamps nicely to the front of the gun sight.

The focal length was relatively easy to fix, though the solution had it’s drawbacks. I bought a diagonal, a Barlow, and while I was at it, a 25mm Plossl Eye Piece, since that is what the scope kit came with, from OPT.  The Barlow needed to have a removable lens, which was removed and screwed onto the end of the diagonal. This extended the focal point into the drawtube, and gave enough in-focus to make the design work. I was up and running with a working scope, and could verify that the objectives in these scopes were very well made. In fact, during design, the objective was where most of the effort and cost went. I got lucky in that all the parts I ordered from OPT fit together. I’ve since learned that this is NOT always the case, and many of the dead ends I ran into were because threads didn’t match.

Now I had a working scope, but one that was still difficult to focus (though I think with my current level of experience I could likely make it work better). So I set out to solve the problem of focusing. I’m still on that quest for the perfect focusing solution, but I can now at least suggest some ways to solve the issue. The focusing issue is tightly coupled with the diagonal issue, and invariably lead to focal length being the issue.

GS main parts

My hope with these posts is to give an update with off-the-shelf, readily available, parts. However, with the information I share, anyone with spare parts on hand might be able to put together a workable solution. In the end, the tube halves, the dewshield, and the objective are the only parts of the kit that I used, the objective being the important part.