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Topics - Douglas Preece

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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.

Asking partly out of nostalgia; partly thinking about scopes that got away.

I have a wonderful 7" Starmaster dob, which has a tube cradle, large side bearings, and its focuser on the *right* side (as you look from the back). It works superbly-- it is simply a matter of placing the scope onto the mount; nothing to watch out for; just "plop-and-drop" into place. It swiftly and confidently moves right into place on the cutouts of the top sides of the rocker box -- and you are good to go!

The focuser location is especially good for me as I am left-eye dominant.

Used to own -- and remember well -- Discovery dobs which had the right-side focuser, too, but almost everything I see advertised these days has a *left*-side focuser, along with tiny bearings (which Discovery also suffered from. though strategically placed felt solved that problem), and the dobs almost all have things to fiddle with just to get the scope in place -- tension bolts, washers to thread, etc. and things to beware of -- hitting encoders, tension bolts askew blocking the lowering of the tube into position, etc.

Wonder why the tube cradle seems to have gone the way of the Dodo... it's great for tweaking the rotation and the scope's balance, though that's rarely needed.  The tube cradle and large bearings mean that there is a large sweet spot for the tube's position and there isn't a need for rebalancing even with 3x Barlow, large eyepiece, and camera in the focuser! Focusing is rock solid, too.

Also, wonder why makers switched the focusers to the left side! While a 10" dob looks tempting, not sure if I could buy a current dob without large bearings and a right-side focuser!

Oh, well! Next, I'll start reminiscing about when we used to walk five miles to school through 2 feet of snow; the Great Red Spot was actually RED; milk was delivered fresh daily in returnable bottles, a 6" scope was considered a LARGE one; Norton's Star Atlas was the cat's' meow (and still is great to look at); and Edmund Scientific made a great adjustable Barlow that one simply pushed the lens up or down in its tube to change the magnification!

Beginners Forum / Viewing Comets with a small scope
« on: December 31, 2017, 04:23:10 PM »
Hi all,

From a noob standpoint- will something like a Celestron 5se or 6se be able to locate and view comets? This may be a dumb question as I imagine that viewing comets is one of the more difficult aspects of the hobby. Thanks in advance for your reply =)

Beginners Forum / Newbie decisions.
« on: December 30, 2017, 04:36:59 AM »

I received an Orion XT6 for Christmas. I am enjoying it very much. I've got the stock 25mm EP and bought a 10mm Celestron Luminos EP. I really like the Luminos. It has an extendable eyecup and wide FOV.

About my question. When I first setup the telescope, I had to collimate it. It was not perfect when it arrived. I adjusted the secondary mirror, then the primary mirror, so that the dot from the collimation cap was in the center of the round circle (reflection) from the primary.

After doing this, however, I am not seeing a perfect "solar eclipse", if you get my meaning, when looking through the collimation cap. I am seeing a portion of the side of the plastic tube that holds the secondary mirror, a small sliver. The secondary mirror holder seems like it is angled a bit and not pointed directly at me when I look through the cap hole.

Does this make sense? Do you think this is a problem?

When I do the "star test", focus on a star, then unfocus, it turns into a round, fuzzy circle, so things seem like they're setup right.

Thanks for any help.

ATM, Optics and DIY Forum / Focus at, or through a mirror?
« on: December 29, 2017, 02:28:18 AM »
OK, my brain can't figure this, so thought I'd ask.

Lets say you set up a normal flat big mirror at the back of your yard. If you point your scope at it and bring the reflection into focus, would focus be..
A) at the mirror glass or
B) actually at the distance of the object in the reflection?

Does that question make sense?

Here is what I want to do, but before I go through all that, this question is the deciding factor.
My yard isn't deep enough to do a false star test, but was thinking, if I put the false star like right by me and my telescope, then put a mirror in the backyard pointing back at me, then it would double the distance to the false star as it would be from me, to the mirror then back to the false star. Like this. would that work?

Attached Thumbnails

Beginners Forum / Thank you
« on: December 28, 2017, 08:16:18 PM »
Just wanted to thank my CN friends for all your support since I came back to
the forum this summer. Not only did I get some good advice, I got help with
getting connected to my local astronomy club, and being able to join it. And best of all,
Through the efforts of 3 CNers, who shall remain anonymous, I got not one, but
threetelescopes to enjoy the night sky!! You guys are the best!!

Light Pollution Topics / LP from fracking: Is the end in sight?
« on: December 28, 2017, 12:05:25 AM »
Fracking has been an ongoing concern for amateur astronomers in recent years, as these operations utilize drilling rigs that (primarily at the behest of government bureaucracy) are veritable light towers, and cause a great deal of light pollution in their areas of operation. With the price of oil in the $100 range, it became profitable to utilize this method of oil and natural gas recovery; with the recent drop in prices of both these commodities, this may no longer be the case in the future.

It would appear that the recent drop in oil and natgasprices is likely going to have a negative effect on much of the fracking industry in the U.S.; while the breakeven full-cycle prices for the Marcellus wet shale plays are in the mid-to-high $30's per barrel, others are not nearly as well-situated: much of the Bakken, for example, as well as the Marcellus dry plays, have their BEFC prices pegged in the $50 to $70 range; other smaller regional plays are also within this range, and would be similarly affected. Both Brent and WTI are hovering below and around $50 and may well go lower, with natgas dropping below $3 per MMBtu; if this trend continues, the majority of current fracking operations in the continental U.S. may well prove unprofitable sooner or later. While these operations would not cease immediately, they could only hold out for a limited time without substantial capital inflows, which, depending upon the global oil outlook, could be difficult or impossible to acquire.

If the price of petroleum products remains depressed for the foreseeable future, shrinking or collapse of the fracking industry seems likely; while this would doubtless ill-affect those economies dependent upon this industry, the potential for reduction in light pollution seems just as certain.
(Please be advised that nothing in the foregoing is to be construed in any way as investment advice.)

Reflectors Telescopes Forum / Springs vs. Knobs
« on: December 27, 2017, 01:41:54 AM »
I really don't know if this topic belongs here or below "Mounts", but here goes...

I'm getting close to buying my very first telescope in roughly 30 years.  I discovered a used XT8 (roughly a year old, seemingly in good shape) and have been comparing it to some new AD8 from Highpoint Scientific that, per another thread, will probably be available next week.

The biggest question I have is regarding the differences (and similarities) between the motion, balance, ease of demounting that the OTA, etc. between the spring tension system of this XT8 and the friction knob system of this AD8 or Z8.  Even though I have found remarks about the two approaches in multiple articles, I have not seen a definitive, knock-down-drag-out conversation detailing the pros and cons of both systems.  I would really like to see what the CN community needs to say on the subject.

FWIW: I am leaning toward the AD8 because of the 8x50 finderscope and dual-speed focuser.  Either way, I don't ever see myself "tricking out" the scope; maybe buy some better eyepieces and accessories.


Beginners Forum / Another "Which Accessories" Thread...
« on: December 23, 2017, 10:58:54 PM »
I have been enjoying my Zhummel Z10.  LOVING IT.

I have been really stoked about this forum also - you guys are the best source that I've had in navigating this new interest and I love it.

The Zhummel includes two eyepieces:2 in.  30 mm, 1.25 in.  9 mm.

My birthday is coming up late next week (37 years down).  People are asking me for gift ideas for my bday and Christmas.

I primary use the range on my back porch (there's definitely suburban level light contamination out there).

Any tips for lens updates, new lenses, filters, or other things?

I'm thinking that I may want to get a barlow, but that I don't know where to start with that.  I'm also thinking about purchasing a nebula filter.

Any thoughts?  Any good places to start?

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