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Posts Made By: Hugh Bartlett

March 6, 2006 01:30 AM Forum: Eyepieces

Lowest Power and FOV in a C-14

Posted By Hugh Bartlett
It is my understanding that you cannot use a 2" wide field eyepiece in a focal reducer without serious vignetting. The widest true field with the focal reducer and a 1.25" eyepiece would be about 0.75 degrees in your scope.

A slightly larger true field can be had using a 2" wide field eyepiece in a 2" diagonal. Something like the 41mm Panoptic or the UO 40MK70 would get you about 0.80 degrees, which would be about your maximum true field.

Hugh Bartlett

March 11, 2006 04:46 AM Forum: Beginning Astronomy?

Factors to consider-FOV, exit pupil, f/?

Posted By Hugh Bartlett
I'll make it simple for you. The three most important factors to consider in deciding on a telescope are: aperture, aperture, and aperture (not necessarily in that order).

I don't care if it's an Orion 125 mm Mak and a Meade 10" Dob, aperture is the determining factor in light gathering (not f-ratio) and in resolution.

I think the term you are looking for is exit pupil rather than eye relief, but both are parameters of specific eyepieces, not telescopes. Having said that, a smaller focal ratio will produce a greater exit pupil in an eyepiece, but I digress from what you want to focus on in your decision (the "a" word).

Longer telescope focal lengths limit the field of view available in a given eyepiece. As a result, the Mak is not only limited in aperture, but also in field of view! I am not trying to trash the Mak; it's a good design, highly portable, and can give sharp views, but it does lose some contrast due to the large central obstruction. It can make a great second or third scope, but is too limited to be your main scope.

To sum it up, get the largest aperture scope you can afford, that you can still physically handle and transport to your observing site without so much hassle that it prevents you from using it.

Hugh Bartlett


March 12, 2006 05:58 PM Forum: Beginning Astronomy?

Meade 10" Starfinder Dob locally available? ~$200

Posted By Hugh Bartlett
That's a good price, but proceed cautiously. Be prepared for spending another $200 or so in upgrades. I have a 10" Starfinder and have "been there; done that." The main thing is the mirror, which Meade is actually pretty good at getting right. Nevertheless, you want to check it for scratches or other signs of abuse.

The rest is mostly mechanical. Meade cheaped out on fitting out the scope to keep the price low. The original focuser is a piece of cow dung, and should go in the trash immediately(although I did see someone once advertise for one, I cannot believe anyone would pay $0.02 for a plastic focuser so poorly made). An Orion 2" focuser would be a great improvement.

The other thing I switched out immediately was the spider/secondary holder. I found it very difficult to adjust the secondary with the original spider. Since it is a f/4.5 scope, I (and would recommend you would want to also) check the collimation every time I use it. I got a curved vane spider from 1800 Destiny (an Astromart sponsor) that had hand adjustable screws. Switching a secondary from one spider to another is a non-trivial exercise, so pay close attention to how easy it is to adjust the secondary mirror, and whether this has been upgraded by the previous owner.

Hugh Bartlett

March 13, 2006 12:46 AM Forum: Beginning Astronomy?

Astromart classified personal info

Posted By Hugh Bartlett
Well, turn it around and put yourself in the seller's shoes. I'd like to be able to contact the party with whom I am dealing directly without having to rely on them checking their message mailbox on Astromart.

I believe you can preserve the privacy of your e-mail address by Private Messaging the other party (someone please correct me if I am wrong). However, I am always a little leary of transactions that happen that way because they occur outside the rating system. It makes me wonder if the responder sent a PM to avoid being rated.

Hugh Bartlett

March 13, 2006 06:45 AM Forum: Beginning Astronomy?

Need suggestions for grab-n-go mount

Posted By Hugh Bartlett
I second Peter's suggestion. Very smooth (you won't miss the slow motion controls) and very stable. I have one for a 4" refractor and love it!

Hugh Bartlett


March 13, 2006 07:02 AM Forum: Beginning Astronomy?

My first Scope!!!!

Posted By Hugh Bartlett
Not a bad price if it came with the tripod and backpack (although I did see one here today used without those accessories for $75).

The Discovery Store also has an 80mm f/5 ETX backpack scope, which would have been better in the same genre, but I'm sure it's more in the $299 range.

I would not count on doing astrophotography with that scope for a variety of reasons. In fact, it is quite limited in its aperture for visual use also.

In sum, I think I'd return it if you can, get an Orion catalog, and study the choices a bit more. Then get yourself to a few star parties and look through a bunch of scopes to see what does the trick for you. For the same amount of money, for example, you could get a used 6" Dob, which is a much better starter scope, IMHO.

My $0.02...,

Hugh Bartlett


March 13, 2006 07:14 AM Forum: Equipment Talk

Alternative to clamshell for Takahashi FS-78?

Posted By Hugh Bartlett
Borg makes a lightweight plastic clamshell tube holder for 80mm tubes. I've got one on my 4" refractor, and it works like a charm!

Hugh Bartlett

March 15, 2006 02:44 AM Forum: Beginning Astronomy?

When Mounting Secondary Mirror ?

Posted By Hugh Bartlett
I think by "shroud" you mean the thing that covers the edge of the secondary mirror. You are astute to note that the exposed glass edge will reflect unwanted light into your focuser.

I would use some silicone adhesive to glue a small strip of the darkest felt material you can find to the mirror edge facing the focuser. Protostar flocking material is what I used. Your spray paint idea is not half bad either. Just do something to cover the edge facing the focuser, and you will have done a lot to solve the stray light problem.

By the way, that silicone adhesive is great stuff, and can be used to mount the secondary to the spider. If you are concerned about it ever shaking loose, you should glue a short black nylon cord (e.g. shoelace) to the back of the secondary, loop it around a spider vane, and then glue the other end back to secondary to "leash" the secondary to the spider. Better to be safe than sorry!

Hugh Bartlett

March 15, 2006 05:12 PM Forum: Deep Sky Observing

messier marathon

Posted By Hugh Bartlett
I think you should do your own based on the star hopping patterns you use. I compiled mine from several sources, but the most helpful one was in Robert Bruce and Barbara Fritchman Thompsons' new book, Astronomy Hacks. He has a whole section describing how it worked in practice. The thing I really like about it is that he lists the times he logged each object. It made me realize that there are periods you can go really fast, and use binoculars to log a lot of bright open clusters, and other times when you need to spend longer to find things in the twilight. His order also put a few objects before M77 & M74 that become visible before the sky is dark enough to pick out those buggers.

Hugh Bartlett

March 31, 2006 06:18 PM Forum: Deep Sky Observing

Deep-sky objects in Scorpius -advice needed

Posted By Hugh Bartlett
On your way to the Bug Nebula (NGC 6302, which I am sure is on your list), check out Open Cluster NGC 6281. It has an interesting boxy shape. For me, it was one of those things I found on the was to something else that I enjoyed more than the object I was originally looking for. You cannot miss it if you are Star hopping over from the double star on the right side of the lower part of the "S".

Hugh Bartlett

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