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Messages - latorika

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1
The dob market in general seems to suffer on the resale market... not just the ones with electronics
that may not be reliable but simple, manually only scopes as well. They were an excellent value when
new but almost unbelievable values when resold at half price and a few upgrades already made.

Knowing what I know now, if just starting out, I would buy a used dob in the size I want.

2
I am simply going to move, dome and all, to a better site.  Set to close on the new place late this week.  No covenants either.  Have you ever thought of moving?  Sometimes that is the better solution.

3
ATM, Optics and DIY Forum / Re: Polishing pads questions
« on: February 08, 2018, 07:00:26 PM »
You can always go waywayway old school and use deer skin

4
Thanks for all the great photos of your setups with the MI 250.
I am anxious to use that mount as soon as my observatory is built.
I only have one 8" SCT for now, but may purchase a triplet refractor soon.
Of all the forums I use, this one is my first choice (all CN forums) for info.
All the members are generous with their knowledge and time and I hope I can "pay it forward" sometime.

Clear skies to all.

Fivel

5
ATM, Optics and DIY Forum / Re: Why Glass? (Stupid Question?)
« on: February 03, 2018, 02:32:09 AM »
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OK... I am reading all these threads about people grinding their own glass mirrors. As a maker, I totally get why one would want to roll their own. But it seems like once all the grinding is done, the mirror still needs to be coated with a reflective surface. So, the reflective surface is what makes the mirror a mirror, right? Otherwise, its just a very flat piece of glass? So... why does it have to be made of glass? Why not granite or steel? Why not thick plexiglass? I might even ask, why not a stable piece of wood? Or a cast ceramic? Please keep in mind that I am a woodworker, not an astronomer, an engineer or a physicist, so hails of derisive laughter, while maybe justified, might obscure the seriousness of this question.

You want the material to not change shape or size with temperature swings likely to be encountered.
That rules out most metals and plastics.
You want it to not change shape due to humidity changes, which rules out wood.
You want it to be polishable to small fractions of a wavelength on the surface, which rules out stone, most plastics, most ceramics, wood, etc.
That still leaves a number of glass, metal, ceramic materials.
Of all the appropriate materials, glass is the cheapest.
The best in terms of weight and stiffness is SiC, silicon carbide. You don't want to know how expensive the material is.
Some composite materials might be OK if made by very elaborate processes, like Boron, or carbon.
But though there are metals with coefficients of expansion that would be reasonable, they usually suffer from great difficulty in working into a mirror surface.
I've read about techniques to use lasers or diamond polishers to work beryllium or even magnesium, but these would not be optimum materials:
https://en.wikipedia...ermal_expansion
Note the coefficients of expansion for various materials, then look for what is lower than borosilicate glass (pyrex, for example):
Fused quartz is an excellent material and often only 2X to 4X the cost of glass.
Invar would be fantastic, but would require entirely different techniques to manufacture into a polished mirror, leading to very high cost.
Just about all the materials other than glass or quartz are prohibitively expensive. Imagine paying 50X as much for a 12.5" mirror than the current price
of a high end mirror.
The usual requirement is that the geometric form of the mirror not change significantly during temperature changes. This is minimised if the ratio of thermal expansion to diffusivity (smaller value is better) is the principal determinant of shape distortion during temperature changes and the ratio of thermal expansion to thermal conductivty (smaller value is better) for static conditions. In this regard aluminium is far better than Pyrex.
Invar is notoriously unstable and its shape and size change with time.

Overcoated Beryllium is widely used aerospace telescope (eg JWST primary). However it best avoided as berylliosis due to inhalation of beryllium dust is usually fatal.
Aluminum definitely loses its heat far faster than glass, it's true.
However, it changes shape more than glass per degree of temperature change.
And, though aluminum loses its heat fast, it depends on the conductivity of the material next to it which is, in this case, air, which is a poor conductor.
I don't see why fans wouldn't work on Aluminum as well as they do on glass.
And polished aluminum wouldn't need to be coated with a reflective surface material.
Corrosion would require refiguring, though, so a reflective overcoat might be practical.
Making an aluminum mirror wouldn't be a cheap amateur process, for sure.

6
Beginners Forum / Re: Im finished with all this and never coming back
« on: February 02, 2018, 10:24:00 PM »
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As a few others have been willing to imply to one degree or another and I'll come right out and say, if today's host of newcomer hobbyists bothered to learn the sky thoroughly in the first place there would be little need for today's GoTo and too often electronically fickle telescopes/mountings. I regard it as down right pathetic when I attend occasional star parties and witness hobbyists rendered all but helpless because their scope's electronics/power sources have failed them...while I cruise from object to object using a no frills Dob and a few simple paper charts. A good familiarity with the sky negates all the fussing with a scope/mount/power cord and makes all your time under the stars eyepiece time. It is time for a great many hobbyists to return to learning basic astronomy again, rather then relying on just punching buttons on their scope's key pad. If a major portion of your evening's "observing" time is really "scope set-up" time, then it is time for you to move on to another simpler and less potentially frustrating hobby than amateur astronomy.

BrooksObs


Your 18th century approach to astronomy is your own choice. Other people make different astronomical observation choices and theirs are equally as valid. I have a limited view in my backyard and add the light pollution on top of that and there isn't alot of enjoyment in star hopping as I can only see about 20. So my modern 21st century goto gem mount allows me to slew to targets that I cannot see and using another electronic marvel called a camera, I am able to enjoy the night sky.
If all I had was a manual telescope, I would have given this hobby up in less than one month.

So, we learn to make all of the electronic conveniences work together, which some of us consider a major part of astronomy and then as time goes on we also learn the sky. Our goals are the same. our approaches differ to meet our needs and interests.

I for one, am a computer geek, and when I found that there was so much electronic paraphernalia that can be used to augment the basic telescope, I was hooked.
I have tried starhopping, although there is some satisfaction in it. I am bored after about an hour.
Look at a galaxy or cluster in a computer monitor and I am fascinated.

John

There's a difference, though, and that is that your hobby is astrophotography, a much different beast than simple visual astronomy. Getting really good shots in astrophotographyrequirestechnology. Tracking, timing, capture. Lots of pieces there.

For visual astronomy, in even modestly dark skies, star hopping is a fantastic, simple, and more importantlysatisfying process. You can go out on any given night and, within a few minutes, find and identify major points of interest. Even if you don't bring out your telescope!

And this is coming from another computer geek (both professionally and as a hobby!). I've been engrossed in computers and electronics for 30 years, and star hopping is another skillset that I was happy to learn, just as JS, Ohm's Law, soldering, and operating systems were.

It's simply worth the time and effort, because the payout is huge.

My₺0.06. Of course, ymmv.

I agree. There is lots to learn and I wasn't implying that one way is better than another. But, I do enjoy a little sarcasm. I think everyone should learn the night sky as well as they can. Also, I would love to look thru a big dobsonian at a dark site and see what I have been missing.

John

7
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Jim:

I was going to recommend the restaurant at inn at Tsegi Canyon, it's between Kayenta and the turn off to the Navajo National Monument at Black Mesa.. A good place to get Fry Bread.. But I was Googled it and found it that it had burned down last November. 

Probably the best Fry Bread is at turn off to Gouldings off the 163. There's a wide spot in the road where people setup and sell stuff. There's a guy with a truck and towing a trailer, they BBQ stuff and make Fry Bread. Only there two or three days a week. The Pulled Pork with Fry Bread is amazing.

Jon

Ahéhee' Tʼáá íiyisíí ahéheeʼ, Jon!
- Jim

8
I owned a couple Radians for about a year. I didn't like the Instadjust. One of the reasons was that every time I reached into my eyepiece case to remove a Radian from its hole, the Instadjust would expand like a Slinky toy. Something else to be careful of and fiddle with when trying to observe.

I like the eyecups of the Delos and DeLite much more than the that of the Radians. But the simple twist-up/down eyecup of the XW's was fine for me and I preferred it.

I usually keep the eyecups all the way down so I can observe with glasses. So for me, probably any method that allows you to keep the eyecup down without it coming up too easily is OK.

Mike

9
I got a 7mm 2" eyepiece from him. Its excellent all the the way through to my eye on my 10" dob. It was worth it for the price to not pay 4-5x more for something I cant make full use of in my current location. I plan to get the 12mm next.

10
Also, it may be hard to fit the eyepiece in your existing case. I needed to
get a bigger case when I bought the Lunt version.

11
Beginners Forum / Re: First Timer with a Evolution 9.25
« on: January 31, 2018, 09:33:27 AM »
Hi all,
I do love this scope. It’s the perfect beast for me. I have had it a year and it gets used a ton. I did recently pick up another refractor as the 9.25 at 65ish pounds is not an ideal grab and go size, but it still gets a ton of love.

A few thoughts…
On the dew heaters: Are you traveling to dark sites? If so invest. However I view from my home patio, and my dark site is a family ski house in the NY Adirondacks so I have the luxury of an outlet. That means instead of a $250 anti-dew system I have a $25 extra quiet Conair hair dryer which does the job wonderfully. 3 minutes with the Conair and I am good for another 20-30 at least, even in the soupy NJ spring and summer humidity.

On the chair: I am 6’3 so I have a bit more range than most, but I need 2 chairs. A regular wicker I use for everything except things really low on the horizon. Then I switch to the stool. Something comfortable and adjustable to sit on is huge. This is a Zen hobby that requires extended periods of physically relaxing yourself to not move. Get comfy!

On the eye pieces that came with the scope: They were pretty bad. When I bought the Evo I was lucky enough to already have the 14mm Delos and I bought the 24mm Panoptic. At 98x and 167x there really isn’t much I couldn’t accomplish. Since then I have added the 2” diag and the 31mm Nagler. The Celestron 2” diag is a great value buy. I really love it. Far superior to what comes with the scope. I do see some field curvature with the 31mmT5. None with the Pan or Delos. The optics that come with the Evo are not Celestron’s best. Those would be the EdgeHD OTAs. However the Evo is very good. There have been LONG nights where I used nothing but the 24mm Pan because I just didn’t need anything else. The Nagler is an experience. The powermate is amazing on planets and the Delos is a great all around EP at middle power. My point is simply this… If you get a chance to invest in a couple premium EPs it will bring out the best in this scope. They are another investment, but also transferable to other scopes.

Starting out:
Get Sky Safari Pro. I bought it on sale for $20 (down from $40) but would 100% pay the full price. Would you balk at a hardcover book for the same price full of images and a real research tool? No.

For alignment I always do a 1 star. Then I use the hand controller’s arrows (HC for short) and add a couple more stars in the area. I do this because my viewing area has tons of trees etc. I can view most all of the sky, but not from one spot. So for me I generally work with “areas.” That being said I have found this technique to work really well and be very accurate.
I am one of the rare folks that likes the red dot finder. I don’t know why this scope would need much more.
It’s a great scope. I connect my iphone to the scope via USB. I only do this because SkySafari is a battery hog, and this way the Evo actually charges my phone. I have gone 6+ hours with no power issues. You can monitor your battery reserve in the app so no surprises! Iphone in one hand, HC in the other and I spend all my time at the EP.

I never plan my sessions beyond 2-3 targets like Orion, planets, Andromeda, etc… with SS (Sky Safari) you don’t need to. Once you are aligned you can see where your scope is pointing on the screen. From there you will see all the goodies in your area. NGC objects, Messier lists, comets, satellites… everything. Your phone/tablet is a road map and all you need to do to see things is point and click ‘goto.’ Some have said a goto doesn’t teach you the sky. For me it was the opposite. I would pick a constellation and view everything from DSOs to doubles. Some stuff is impressive. Some stuff you can barely see at all. It’s all part of the fun
If you have any issues don’t hesitate to PM me.

12
Mounts Questions & Expirience / Re: AHHH! Broke my CGEM
« on: January 31, 2018, 08:54:54 AM »
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Well, yes of course that is the board. Did you open the link?That was my point! Not to spend $342 to replace a $2 connector.

Stan

It is worth noting that Celestron does not sell parts directly outside of the US and the web site knows this.  So for those of us outside of the US such as orlyandico and I that link shows a picture of the board but no price.

Thus the confusion.

13
You want high strength plywood not high density plywood.
Baltic birch, Appleply, and other solid hardwood core plywoods.

14
Slightly better as Dave said. The NPB is my most used filter. If you want to add the OIII to your toolbox, keep an eye out for a used one.

15
Beginners Forum / Re: Setting UP My Orion 150mm Go To Mak-Cas
« on: January 30, 2018, 04:04:18 AM »
Jeff,

I did have that thought too. Since I got some time under the warrenty I'll use it through the summer and see what happens.
Burned out AZ motor perhaps?
It seemed like it went through two sets of AA batteries quickly so I bought a new Celestron Li-ion battery so I'll just let the motors do the work. That and GOTO is what I bought the mount for anyway!

Thanks,
Scott

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