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Topics - Christopher Hess

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Good Morning All,

I received my C90 and am impressed so far with it for Grab and Go Purposes for Land and Sky viewing. I am now wondering if there are any benefits(image quality) to be realized by upgrading to a set of different diagonals for Land and Sky use.

If so, can you recommend some models of diagonals to consider?

Thanks in Advance!


I'm getting ready to buy a fixed length focal length eyepiece or two for use in both a 140mm-f/7 refractor with a 980mm focal length and also in a 100mm-f/9 refractor w/ 900mm focal length and in research "exit pupil" size is referenced. Is that the same as the size of lens of the eyepiece? Is there an optimal exit pupils size and if so how is that figured out?

thank you!

Hi CN community again,

I have a son who will soon turn 5. I was planning on introducing him to the wonderful world of astronomy, and thought that it would be a wonderful way to also learn about optics. Does anyone in the community have experience with introducing kids this age to how these things actually work (I mean telelscopes etc.). What resources have you found to be useful for discussion of such topics?Update 2016-04-03:

Since I had the question in the beginning, I started looking as well. The wonderful world of the internet means that someone has thought of these things before and so ideas can spread quickly. Following, I am listing some sites I have found that may be useful for other parents who may do the same: That is to say leisurely and playfully teach optics to kids.

Websites with optics material for kids:

Khanh Academy:
This guy has never disappointed me. Hi is really good in explaining things.

Michael Biezen:
More traditional lectures which I am not sure is too kid friendly but IS cool refresher material for the grown-up kids.

ATM, Optics and DIY Forum / Polyeurathane and optics
« on: December 29, 2017, 01:35:29 AM »
Finished the new rocker box for my 22.5" DOB remake - looks nice and works well. However, now I need to seal and protect it with Polyeurathane and have never done this before. The only place I have available to do this in my garage. Would greatly appreciate guidance on the following points:

1) Do I need to worry about the fumes from the Polyeurathane damaging the optics of other scopes in my garage? What Im wondering is if the vapors in the air would settle out on the optics and leave a damaging residue? I'm envisioning something like the way dew settles out of the air and condenses on mirrors etc.

2) Spray it on or brush it on?

3) how many coats, and what sanding or whatever needs to be done between the coats?thanks in advance to all -


Beginners Forum / NEWBIE LOVES SATURN!
« on: December 27, 2017, 08:57:08 PM »
I know.....old stuff, but I just gathered first light with the new Questar. Saturn was up and beautiful as usual. Although hampered by a thin high haze and the atmospherics weren't too steady, I'll still take it. A lot different from the smaller and various scopes I have had in past years. I see a new learning curve ahead, but I plan to give it a shot. Thanks for letting me crow a bit!


ATM, Optics and DIY Forum / Please help me select pitch
« on: December 27, 2017, 01:31:58 PM »
I will be polishing and figuring an 18" f/4 mirror. My basement currently is running up to 71 -73 degrees while we have had low 80's F outside.  I have to run the dehumidifier normally b/c it tends to be humid (>65% RH) and the room gets warmer when it is on. I plan on using Gulgoz pitch. As I understand, Gulgoz #64 is good for 65-75 degrees.

My questions are:
1. Should I run the dehumidifier and what relative humidity should I set it to? Should I leave it off? Does humidity help?
2. Will #64 be good under these conditions for this focal ratio?



Eyepieces Questions & Recommendations / Expanding Eyepiece collection...
« on: December 26, 2017, 09:32:22 AM »

I have a 6mm Plossl, 9mm Kellner, 20mm Plossl, and 25mm Kellner who are absolutely excellent.  I have other eyepieces, but they're total crap.  I have 2 2x Barlows, that both may be converted into 1.5x.

I am looking into getting a 3.0millimeter Orion Planetary Eyepiece since I am frustrated with using a 2x Barlow with my 6mm.  I don't want to get an eyepiece I can't replicate with my Barlows, but in this situation I probably have to.

I plan to get an eyepiece between the 9mm and 20mm (Plossl naturally), what size between those would be ideal for viewing the entirety of the Moon or Sun with a 130mm f/5 scope?  What about with a 80mm f/6.25 refractor?  I am looking to a 12.4mm Meade Super Plossl or 10mm Orion or 15mm Omni...
I am eager to spend under $50 with this one.

Finally, I am getting a 2" widefield eyepiece, what size and brand under $120 would be most suitable?  I am looking at a Meade 2" 56mm.

These are all for the scopes listed in my touch, minus the FirstScope.


Beginners Forum / Extreme Cold and Z8
« on: December 24, 2017, 06:54:34 PM »
Hi Everyone,

A couple of newbie questions.

I'm a big science and science history fan, in my 50s, a computer consultant and ski instructor in Idaho, and with the support of advice here I have ordered a Zhumell Z8.

I live in Ketchum, Idaho and the skies are fairly dark.  But we really do have cold weather now, as low as 0 F. I know I need to let the telescope fix to outside temp, but do I need to worry about anything if it's real cold?

We've got a major snowpack, any issues with observing from packed snow --might not even see my deck until april.

What is everybody's favorite program to assist star jump?  I have 'Starwalk'.  What's going to help me stage this monster best?

I'm pretty much a complete ignoramus from the skies, though I have listened to astronomy podcasts for years.  Considering my place, what are the interesting things to start out searching for?

Thanks so much,

ATM, Optics and DIY Forum / Question about friction plates
« on: December 24, 2017, 03:43:57 PM »
So this is not really a telescope question but maybe someone can shine some light for me.  Working in my own bracket and thinking about the polar shaft pivot.  I've reworked the layout a bit although the changes aren't reflected in this drawing.  Imbedded steel bolts will be substituted for the timber displayed in the drawing.  But I'm thinking that, when these get locked down, the entire weight of this scope will be working against them.  Wood on wood might be subject to slippage under that load so I am working on a way to add some type of big lock or friction ring between the timber parts.  The place I am worried about is circled in red in this drawing:


I can't find any lock washers of this size I need (4-5" in diameter).  I've looked for big ridged washers and discovered one or two at the 4" diameter array but they are hideously expensive!  So I am looking for a resource for big lock washers or any advice on a different idea.  That is to use a clutch disk from something like a motorcycle.  These are easily available in the size range I need and are inexpensive to boot up.

Does anyone have any idea on how well this could work?

Thanx for any advice...

Subject explains it all.  This is the graph I am trying to add to my signature:

Http://www.cleardark...key.html#appearI tried using this code from that web page:

<a href=""><a href=; [/url][/url]
I can't seem to get the graph to show up, only the code.

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