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Posts Made By: Dennis Freeman

February 26, 2006 02:49 PM Forum: Beginning Astronomy?

What type of telescope?

Posted By Dennis Freeman

My 9 yr. old son has consistently expressed interest in getting a telescope for some time now and over the years I've occasionally thought of giving it a try myself.

I think it important that we don't get something cheap from a dept. store or where the aperture is less than 4". I know from reading that we should not expect to see images like photographs, but I guess I want to impress my son to stimulate his interest.

Portability is a must. Our back yard is suburban Chicago and the view is blocked by large trees. I suspect anytime we want to use it we will have to travel. Also we go on family camping trips by car(probably great for dark skies) and occasionally fly out west. It would be great if we could bring the scope with us.

Budget is around $1000-1200, but this must include all the extras-case, extra eyepieces, barlow, etc. New or used, that is the question. Nice thing about used, you usually get a lot a ancillary equipment and can get a complete package for relatively low cost. New, you know what you're getting but can't get as much for the same money.

I think don't believe a refractor is doable because of the portability issue. I've seen a couple of 6"ers by Meade or Celestron on Ebay, but they look as big as cannons and definately not portable. I'm not sure if 8" reflectors are also too big (don't forget about all that camping gear).

That leaves me with SCTs, MCs, or 5-6" reflectors. Some level of GOTO would be nice, but I don't want something that totally takes the learning out of the cycle. I think it will be important to be able to be able to see alot without too much work/time between images to keep my son's interest going. Like most 9 years, his attention span is limited and like many people nowadays wants immediate gradification. I want to try to use his interest to help show him that if you want something you have to work for it, but not make it too ardrous (sp?).

Meade and Celestron seem to have the most selection and are the "big name brands" for the mass market. My impression of Meade is that they have good optics but cheap construction. Celestron optics don't get praised as much as Meade, but construction may be durable, i.e. more metal parts. Any opinions?

Any thoughts or comments are greatly appreciated. Thanks in advance.

March 10, 2006 06:30 PM Forum: Beginning Astronomy?

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

Posted By Dennis Freeman

Looking at purchasing either a ETX-125 or an Orion 8-10" dob(Already purchased one ETX scope, but sending it back for reasons unrelated to this discussion.).

Now I know that many of you will extoll the virtues of the Orion and it definately has a lot going for it. But for sake of discussion, try to be unbaised.

The two scopes are considerably different. One has a 1900mm focal length, the other 1200. One is around f/15, the other f/5. My question is this: What does this mean in practical terms to someone who doesn't yet understand all the physics?

Does one factor lend greater resolution than the other? What is the impact on eye relief (correct term?) or how far do you have to get to the eyepiece to see the whole view. (Some of the users wear glasses.) Does the lower f/number mean better contrast? What other things should I be asking, but don't even know about?

I guess what I'm seeking is a discussion about how the various numbers quoted in ads translate into practical considerations. Like, lower f/stops mean more light gathering ability so you can see deeper.

I've read some of the explanations on different sites, but I must be getting overwhelmed with all the technical details because when I'm done I don't understand all that much more than when I started.

I'm sure that I'm not the only one that can benefit from such a discussion. Your comments are welcome and appreciated.

March 24, 2006 12:22 AM Forum: Eyepieces

EP's for beginner

Posted By Dennis Freeman

Let me start out by saying that after reading these posts, I've discovered that dedicated astronomers are not only apt to get "aperture fever", but "eyepiece ache" as well.

I'm getting a 10",f/4.7 Orion XTi (based in large part on the comments here in the various forums-esp. Floyd's). This is my first scope and I'd like advice for eyepieces.

Don't want to spend big bucks for eyepieces until I know we're in this for the long haul. I can always upgrade down the road. Plus I won't trust my 9 yr old with $300-500 eyepieces. Sooo..what would you experienced guys recommend? Up to $100/pc.

Here's some info. you may want. I'm 53 and no glasses, although I'm nearsighted in one eye and farsighted in the other. My son's 9 and wears glasses . So does mom. Katie's only 4, I think we can forget about her for awhile.

Would like to get a nice spread for planetary and DSO's for a total of 5-6 eyepieces. FYI, I do plan on getting an Orion shorty-plus barlow. May have a moonlite CR1 on the scope.


May 11, 2006 12:56 AM Forum: Beginning Astronomy?

cleaning eyepieces

Posted By Dennis Freeman

Just purchased my first scope, a 10" XTi from a forum member. Don't have a problem yet, but with my 4 and 9 yr. olds looking through the scope I expect it won't be long.

How do you clean the eyepieces of oil, dirt, etc.? I know you can't use commercial window cleaners. Did a search for "Cleaning eyepieces" and didn't come up with a lot. Also didn't find anything in "Beginners" under reviews.

Any advice is appreciated.

June 13, 2006 09:31 PM Forum: Eyepieces

exit pupil

Posted By Dennis Freeman

I'm looking to purchase a 27mm or a 35mm Panoptic. grin The exit pupils compute to about 5.7 and 7.4 respectively.

Can someone help me out and explain the practical significance of this? I've seen a couple of comments in reviews that the 27mm is a better choice because the 35mm exit pupil is too large. Will the smaller exit pupil provide better contrast, brightness, etc.?

It will be used in a 10" XTi (f/l-1200mm , 254mm aperture).

June 21, 2006 01:49 AM Forum: Eyepieces

eyepiece collection

Posted By Dennis Freeman

Well, at the risk of being told I've made terrible choices, I like to solicit your ideas on my 1st stab at building up an eyepiece collection for my new 10" XTi f/4.7, f/l 1200mm. My budget is now spent and I'll have to live with these for awhile.

Total cost was $730, all used and in excellant condition.

7mm UO plossl
7mm Nagler Type 1
10mm Sirius plossl
8-24mm TV zoom
21mm Status
25mm Sirius plossl
35mm Panoptic
2x Orion shorty barlow

I bought the UO and then the Nagler came along at a price I couldn't pass up. The UO will be going. Eventually, I plan on replacing the Status with a 19mm Panoptic, getting something in the 12-14mm range, and supplementing the Type 1 with something that has longer eye relief.

Some considerations:

1. Two of the users wear glasses. (I just wanted the Nagler for myself. I know it's selfish, but after I saw the 82 fov I couldn't help myself grin ).
2. Since I have a dob, I want FOV as large as possible. (And no, I can't afford a bunch of naglers.)


Any comments/recommendations for the future?




July 5, 2006 09:59 PM Forum: Eyepieces

Barlow vs. high mag EPs

Posted By Dennis Freeman

I'm sure there are many experienced observers who can shed light on this question.

Are there any advantages/disadvantages to using a barlow or powermate with a relatively low power eyepiece to achieve higher magnifications as opposed to using an appropriate eyepiece alone to get the same level of magnification?

The only issue I can think of is the additional glass which will light throughput, but I'm sure it's more complicated than that.

Anyone willing to elucidate?


August 2, 2006 05:00 PM Forum: Equipment Talk

Home-made equipment

Posted By Dennis Freeman

I hope I'm not violating any policies on the forums. If I am I apologize in advance. I came across something that will be sure to interest many Astromarters.

There is a new Yahoo group just starting up that focuses on homemade solutions. The URL is:
http://groups.yahoo.com/group/astrotinker/

I know from reviewing the posts the last few months that many of you will be interested. In fact, this may be a good topic for a new forum here. It seems that many here are ingenious when it comes to solving problems in the hobby.



August 29, 2006 09:42 AM Forum: Equipment Talk

Eyepiece case

Posted By Dennis Freeman

I like to get some knowledgeable opinions about making up an eyepiece case. I'm sure all you guys with 50+ eyepiece collections have long since figured this out. smile

I have a large Dockucil case with the standard, open-cell foam "pluck" insert. Long-term I don't think the foam will hold up. As my eyepieces change so must the foam. I'm think of using the pink builders foam as a substitute. It's cheap, readily available, has different thicknesses, and easier to cut. I think it's poluyurethene based, but I'm not sure.

Does anyone know if outgassing is a problem? Is there a better substitute available that I'm overlooking?

Another issue. Is foam the best way to go? :S I've seen some cases that use cutouts to fit the barrel made of wood or lexan. Is this a better way to go?

Another question I thought of after looking at Floyd's cases. The case I have is very deep, any opinions on laying out the eyepieces vertically vs. horizontally? If horizontally, I can have two layers for the EPs.

Any pics that I can get ideas from is appeciated. Thanks in advance for your ideas and comments.

October 17, 2006 05:17 PM Forum: Beginning Astronomy?

SC vs. MC

Posted By Dennis Freeman

I'm looking for a pickup and go scope for around the house and on camping trips. Has to be small and relatively light (otherwise I'd bring my 10" XTi smile ). Since I've spent a bundle on nice lenses over the last nine months, to keep the cost down I'm looking at used scopes. I've got a couple of Naglers (7mm, 12mm, 17mm), several 68 degree lenses (8mm, 21mm, 27mm, 35mm), a few plossls (10mm,25mm), and a 7mm UO ortho. Oh, I also have a TV 8-24 zoom.

Anyone care to explain the issues in deciding between a Mak and a Schmidt? Pros and Cons? I believe the Maks have a longer cool down time and longer focal lengths for a given size. Cool down time is a non-issue since it would be outdoors in a tent and the shorter focal lengths of an SC means a wider field with a given lense-right? What other factors/tradeoffs should I be thinking about?

Go to capability would be nice but not mandatory. BTW, am I correct in assuming the white tube C5 was meant as a spotting scope and the orange for astronomy? If so, does anyone know if there is a difference astronomically?

Thanks in advance.