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Messages - Mark Richmond

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Totally agree with Jon regarding the refractor. I view sans electronics by choice, so am definitely biased that way, but would suggest for a first scope to keep it simple and easy. Learning to find things in the sky is fun.


This isn't a first scope. The OP already has a 3" scope. Makes more sense to skip to 8" in my opinion, particularly considering location.

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There's actually not much difference between the Synta and Celestron HC in terms of operation and the differences are mainly just syntax related. I suspect that the HDX110/Eq8 is a better mount than the CGE-pro because the Synta microstepping drive is inherently more accurate (Lower PE) than the servo motors used on most Celestron mounts. Orion will honour their stated specs of +/- 3 arc sec PE. Being able to move it manually while using the encoders sounds attractive but the trade-off is poorer pointing accuracy when using the goto system. To match the slewing/pointing accuracy of my AVX mount my friend has to turn off his encoders and then he gains a slight edge in accuracy.Yes the EQ-8 has a similar ASPA routine.

I agree that a large Newtonian has advantages in terms of AP and widefield viewing but it comes at a cost in terms of weight and size. A 12in F4 Newtonian:

https://www.astronom...ian_p20370.aspx

weighing in at 51lb and ~4ft in length.

However, from what I've seen an Eq-8 would carry it with no problem.
Not my experience. The tracking on the CGE Pro (servos) and the EQ-8 (steppers) is pretty much a wash. At any rate, the source of PE is not the motors, but the final gears.

As for the HC? The difference isn't "syntax," but features, and particularly the 2+4 alignment routine. The CGE Pro is dead accurate on gotos. The EQ-8? Fair. Encoders on or off, it's not up there with the NexStar HC in my experience.
You're probably right about the PE as the HDX110 has 8.6in 435 tooth worm gears while the CGE-Pro has 6in 255 tooth gears. OTOH, all things being equal one would expect smoother PE from a belt driven stepper motor because it can omit the reduction gear box required with a servo motor.

We did do a comparison goto test between my AVX (2+4)and the HDX110 (3 star) and with encoders off the HDX had a slight edge.

My point about the HC is that the Synscan is easy to use with only a small learning curve when coming from a nexstar.

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...just be prepared to explain that to the police when they track your beam down to you. They don't care if there are really any airplanes in the sky at the moment or not. GLP and red dot don't work well enough in the light polluted sky as thereare too often not enough stars close enough to the target to help with the accuracy. In the truly dark LPZ the lazer beam is too bright for the observer himself, obviously ruining the dark adaptation (the violet laser is much better, by the way). You don't have to go to your knees to point with the Telrad, that's just my personal preference helping me to stay fit all night long and without any neck strain.

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Beginners Forum / Re: What's the best telescope to 'do it all'?
« on: February 03, 2018, 12:26:21 AM »
Just my two cents but I think a 6-8" sct is a great all around scope. Decent light gathering for dso, very good on planets and more than adequate on clusters and doubles. Also portable enough to set up without a lot of hassel.

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Beginners Forum / Re: Are solar filters useful?
« on: February 02, 2018, 06:54:56 PM »
The sun's color index corresponds toa yellowish whitestar as seen from earth through our atmosphere, not a blue or white one. It is closer to Arcturus than Vega. And when we look at objects in the night sky with the same color index as the sun they tend to look somewhat yellow.

Overall brightness has some impact as well. Take a look at various very brightobjects that look quite white or blue, then look at them again with decreasing exit pupils and they begin to look yellower (the Moon for example.)

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Mounts Questions & Expirience / Re: Can someone explain this drift issue?
« on: January 31, 2018, 08:02:34 AM »
Does the drift occur in all regions of the sky, and is it always the same direction of drift? If it's flexure, it should be less severe in some area of the sky than in others, as the forces on the mount change with orientation. Also, how long are your exposures? I'd be shocked if you were getting noticeable flexure over the course of a couple minutes, the mount position just doesn't change that much in such a short period. Also, how long has the setup been in place before you start imaging? Perhaps what you are seeing is temperature equalization related, all the bits and pieces coming to ambient at different rates would affect the way they all fit together. You mention it happens most with wind, and wind would accelerate temp changes.

Just a few other possibilities to consider. Good luck.

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General Astronomy & Observing / Re: Astonomers and Sleep Deprivation
« on: January 31, 2018, 07:15:17 AM »
I am curious...tell me more about this thing you call "sleep"...I have heard of it but am not familiar with it.

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there are some very good people that can refigure your mirror to a very high standard for the fraction of the cost of a Zambuto - Ed Jones for example.

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Beginners Forum / Re: Getting more color and detail from scope
« on: January 31, 2018, 04:23:41 AM »
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Through my 16" DOB the only color I've detected (for all the reasons stated here) was a hint of green from the Orion Nebula and funnily enough - with averted imagination - some green in the Saturn nebula. Otherwise everything is pretty shades of gray!Phil


I wouldn't jump to the conclusion that your detection of color in the Saturn neb was averted imagination... I saw color in the Saturn neb very easily in a 10". With a 16" you undoubtedly really saw color in that object.

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General Astronomy & Observing / Re: Skeeter control...
« on: January 31, 2018, 02:52:02 AM »
I've evolved to wearing long pants (light weight longing pants if it's warmer than 75° F, a hat and using the Cutter brand, Lemon Eucalyptus, DEET free product in the pump spay dispenser.
I apply the Cutter repellent to my arms, back of hands, ears, neck, & face.

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Michael's experience is not out of the ordinary.
But, I believe, it is a bit telescope-specific.

I use two complete sets of eyepieces: Ethos and Delites.
And it's not uncommon for Ethos owners to have a set of narrower eyepieces too.

To wit: in a non-tracking scope like his 12.5" Discovery, an eyepiece like the Plössl is going to require a lot of nudging
and very little "drift time". A wider eyepiece might make observing a bit more user friendly.

On the other hand, in his 100mm refractor, a Plössl gives plenty of time to watch an object drift across the field,
AND, he has tracking mounts, where the field of view is largely irrelevant.

I found the width of the field in Delites to yield plenty of field and drift time in my 4" refractor, but not so much in my 12.5" newtonian dob.
In the dob, I prefer eyepieces of 100-120° to give me the "Wow!" factor and a lot of drift time.

But his points are well-taken. I had occasion to use some TV Plössls recently, and they are all he says they are, despite the eye relief below 20mm,
despite the lack of really short focal lengths (a 3-6mm Nagler zoom would be a good complement), despite the lack of field.
My concession was the Delites, which I found to be on a par with the Plössls (though slightly differing among the focal lengths because they're not scaled).
For someone who has used 100° and wider since '07, the Delites seemed EXTREMELY narrow until I adapted to the narrower fields, great contrast, super-sharp star images, and small format.
Sounds like Michael came to the same conclusions, only with Plössls.

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General Astronomy & Observing / Re: What am I doing wrong?
« on: January 30, 2018, 07:38:01 AM »
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An 8" isn't really that big of a step up, and now that my parents know I'm capable of making scopes they don't like it when I buy them (or just plain don't let me).
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My parents aren't into astronomy at all though, and dragging one of them to even that is difficult.
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You're still young, but the years will pass quickly, believe me. Soon you'll be your own master and can decide for yourself. If you have the means and tools to build a scope, instead of buying one, by all means grab the opportunity, especially when you're young. Finances can become very tight later on, when you're trying to settle down in a home of your own, so being able to make things (especially telescopes!! ) can become very handy and useful indeed.

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I don't really have any friends (IRL anyway) and definitely have none that are interested in astronomy
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Neither did I, when I was young. Nerds tend to have very few friends, if any. Relax, this will change, too, if you want it to. I go to a star party every year in September and some of the other long-time participants have become good friends. I only meet them in person once every year, but we meet online almost every day. They are closer friends than almost anyone my own age I had in my youth. For some of us, finding friends we really click with is quite difficult, but it's all the more rewarding, when it does happen.Clear skies!
Thomas, Denmark

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Reflectors Telescopes Forum / Re: Alt-Az mount for 6" reflector
« on: January 30, 2018, 12:23:26 AM »
That is some beefy leg, lol. Nice home brewed rings too.

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Beginners Forum / Re: Any help? Tasco Luminova... mount with the tremors
« on: January 29, 2018, 11:54:05 PM »
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On a great note, I finally took the 15 seconds needed to measure the OD of the EPs. They are 1.25". So, if I am not mistaken even if I decide to invest in 2" EPs, I can purchase an adapter to handle that difference. I am very pleased by that discovery. I just assumed they were the .965". I will start perusing the internet for decent deals on some quality, though not expensive, deals.
The next logical question to ask is what type of eyepieces your 60mm has and what type of eyepieces your 90mm has.

On the eyepiece there should a letter or two, such as H, R, K, MA, etc, next to the number that designates the focal length. Knowing this for the eyepieces you have should help. If details about the eyepieces associated with your 90mm are also available then that would help too.

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ATM, Optics and DIY Forum / Re: Mirror cell for 16 inch equatorial newton
« on: January 29, 2018, 11:25:22 PM »
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No. You just need better lateral support that works at any angle, and that's not that hard to do.

Maybe you could show a couple examples then?

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http://www.loptics.c...rorsupport.html
Yes, but of course, the mirror cell of a glass blank designed to work in an equatorial setup will need to have two additional whiffletree supports to cover the entire periphery of the mirror (8 points of equally spaced edge contacts completely surrounding the mirror). The principles shown in Mike Lockwood's article are a good start, and are the most state-of-the-art mirror edge support for dobsonian mounted instruments in existence today but they are insufficient for the application discussed here.

A second Caveat: in modern edge supports for dobsonian supported mirrors, the central pivots of the whiffletrees are located at +/- 45 degrees on each side of the mirror's center AND the weight of the glass is equally supported on four edge supports. On the other hand, in the worst case mirror position in an equatorial setup, all the mirror's weight may now end up supported only on two edge supports and, to make things worst, these are only spaced at +/- 22.5 degrees apart. I haven't seen any Finite Element Analysis of this situation nor any real life test results with a mirror mounted this way (except for Danny's Hubble mirror being grossly deformed when sitting on only one edge support). I would recommend anyone wishing to mount their thin, fast, large mirrors equatorially to first do a foucault or star test with the mirror resting on only two edge supports +/- 22.5 degrees apart, to make sure the figure is not distorted by this higher strain environment before undertaking construction of a new equatorial mounting they might regret.

Third Caveat: when the equatorial mounting moves across the sky and the mirror shifts from one orientation to another, the mirror will slide in its cell until the opposing whiffletree supports take up the slack. How much will that movement be and how tight will the edge supports need to be in contact with edge of the glass to minimize the amplitude of this movement? That problem always existed with equatorial telescopes in the past but the mirrors were thicker then and the focal lengths longer so the impact on the image was less pronounced. Oh, by the way, to minimize that mirror shift due to sliding of the glass, the pivot pins of each of the four whiffletrees will need to be really well machined bushings (or double ball bearings) because, in certain mount positions, the weight of the entire mirror will rest on that single, cantilevered whiffletree attachement point and it must not be allowed to significantly bend or move.

One last thing: there was an article in S&amp;T a few months back on an equatorial reflector which used four slings spaced 90 degrees apart to hold the mirror. According to the owner It worked. Anyone remember which S&amp;T that was (I'm on travel and don't have access to my library)?

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