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Messages - Jim Snyder

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31
Beginners Forum / Re: My first Telescope.
« on: January 22, 2018, 09:20:49 PM »
Also,The 8-900$ is for the scope only, but I don't have any more money for accessories.I will rely on the supplied accessories of the scope until I have enough to buy a basic set!

Thanks again!

32
Reflectors Telescopes Forum / Re: I just ordered a Z12
« on: January 21, 2018, 02:56:18 PM »
Enjoy! I have certainly enjoyed modding mine. Making the scope my own has been half the fun.

33
Mounts Questions & Expirience / Re: Any NEGATIVES to a Paramount MX+ ?
« on: January 21, 2018, 12:09:41 PM »
When are you guys going to mention the hand controller? That thing used to be the bee's knees...
Clear skies,
Bill

34
ATM, Optics and DIY Forum / Re: Making a Mak
« on: January 21, 2018, 12:07:39 PM »
Quote
By the way Cumberland Optics who has been making the optics for Questar since the very early 1960's which is a Gregory type design aspherizes one of the surfaces of the Mak. optics they produce to address this issue and better correct the wavefront vs an all spherical system.

Dave,

I have a Questar and have always been curiuous. Do you know which surface is aspherized? There are R1 and R2 secondary Questars. Mine is the older R1. Optical quality is impressive. I have unfortunately not looked through the newer R2 Questar.

I am not sure how one would aspherize only a sharply defined central portion of a spherical concave surface (R1 Questar) or convex surface (R2 Questar). So that leaves either aspherizing the whole corrector rear surface or front surface, respectively. Or a sharply defined other portion of the corrector outside of the area occupied by the secondary etc. Or the primary mirror.

I always wondered if the double passage of light through the corrector for the secondary reflection in the older R1 instruments was used as some kind of extra correction for aberration. But that would make the later move to R2 a bad idea, unless that was made primarily for contrast issues. Perhaps the prism diagonal helps too.

Still, From a manufacturing point of view, claims of aspherization in the Questar always sounded to me, to say the least, somewhat unsupported by evidence. It would be nice to hear from someone knowledgeable whether they are true, or only lore. Regards,

--Christian

35
Mounts Questions & Expirience / Re: The best program for polar alignment
« on: January 21, 2018, 08:35:48 AM »
Looks neat, I don't have the required software but thanks for the work regardless.

36
ATM, Optics and DIY Forum / Re: .99999964 Strehl Mirrors
« on: January 21, 2018, 04:48:34 AM »
The huge news is this set of mirrors can see gravity . I think this is so cool /   New type of telescope  .

37
General Astronomy & Observing / Re: What has happened to Meade
« on: January 21, 2018, 04:20:42 AM »
Thanks all for the comments. I guess I really missed all the action. I remember the LX200 well and dreamed of owning one. Well, I've just bought a used Celestron 5se and so far really like it.

PS: Maybe the DSLR and astrophotography will get people back into the hobby... like me!

38
I don't know what to say, but i do have a filter that is called Contrast booster, it is designed for killing the fringe or minimize that Achro color issue, and from its name it supposes to increase the contrast, in addition i also have moon&skyglow filter which is called Neod. filter.

I said i wasn't much care about quality, i saw that Jupiter and Saturn without the filter, and also the moon, so i have to give it another try with the filters and see what i can expect.

I want to learn more about masking the scope down, how to do that?

39
seems like a good project for a 3D printer

40
I hate to break the news to you, but it's a left handed mount.
That's why every picture points left.
Now you need to find a left handed telescope. Hard to find indeed.
If you need a good home for it, you can send it here.I'm fairly convinced my next one, (if ever) will be an iOptron.
Congrats and ENJOY!

41
ATM, Optics and DIY Forum / Re: Motorized Equatorial Mount
« on: January 18, 2018, 10:03:14 AM »
Check out the yahoo group "OnSteptelescope". Howard has done the firmware and a user, Steve, has designed boards which he sells for a reasonable price, saving the work of wiring up components. Number of people using it on their scopes. A Utube of one of Howard's scopes slewing is here:

https://www.youtube....nYdNQvLyrD9y8Ew

Howard is using 0.9 degree step motors. The drivers/firmware are capable of 1/32 stepping which is used for tracking, and switched to faster stepping for slewing. Slewing is typically ~ 2 - 3 deg/sec. He also has sky planetarium software which works with the OnStep boards for goto, and has an Android app to run it.

Even if you prefer to do your own you can learn a lot from the site.

42
Reflectors Telescopes Forum / Re: Question about 100% illumination
« on: January 18, 2018, 04:21:27 AM »
Quote
Quote

Your observing habits should factor in the decision. If you are primarily a planetary and lunar observer, a smaller fully illuminated field with lesser CO are beneficial. If your observations tend to involve eyepieces with larger field stops the smaller fully illuminated field will tend to provide a less bright image.
Which is more valuable is your call.

A calculator for field illumination:http://www.bbastrode...om/diagonal.htm


That's certainly true in theory. However, my own experience is that the difference between a 24% versus 20% central obstruction is not noticeable when it comes to fine lunar and planetary detail, even with scopes of superb optical quality. And that's the other thing, if the Coulter's mirror is a stock primary, I doubt it's very useful for fine lunar and planetary work, let alone being able to actually see a relatively small difference in central obstruction.

Thanks for the link. Most useful.

Jeff
Yes. What I did not mention in my original post was that I sent the primary down to Steve Swayze for re-figuring. He found it is quite undercorrected among other things. I always thought something was wrong because I would really have to strain to pick out more than a couple bands on Jupiter.

I was in a hurry to leave for work this morning!

I digress... My other scope is a mostly home made 8" f/7 that has a Ostahowsky Optics primary. The one in my avatar. There is simply no comparison on planets. Jupiter through the 8" is VERY detailed with the swirls and festoons that you see in pictures. I have had it up to 307x (4.7mm) and it could probably go higher. The Coulter with the stock optics can't really be used above about 150x, but I must say it was the only scope through which I've seen the Orion Nebula as green.

Tim

43
Beginners Forum / Re: Advice for small portable telescope
« on: January 18, 2018, 04:18:04 AM »
Quote
Thank you for your replies. I am also including binos, but we (my son and I) want also a little portable scope.
The AWB scope is awesome, but perhaps on the big side of what I am thinking. I like the idea of a little mak, like ETX90 (without tripod) or the Orion Starmax 90 tabletop.
What do you think of the Starmax 90?

60 Day review of the Meade ETX 80 – Cloudy Nights
http://www.cloudynig...0/#entry6855822

Video overview of the backpack version – same scope, different package
https://www.youtube....h?v=zjsD69fPg6Y

44
Mounts Questions & Expirience / Re: CG-4 solid enough?
« on: January 18, 2018, 03:50:28 AM »
Kinda big for that mount.

45
Beginners Forum / Re: Questions on dewing
« on: January 16, 2018, 11:00:06 PM »
What about dewing on a Truss Tube? I have a light shroud for my LB, but I'm wondering how well that will work, would moisture be absorbed by the shroud? We are expecting rain here this Friday and Saturday am, but clearing out Saturday pm and clear {supposedly} for the whole night into Sunday. Like Tony said, I keep the 2 most used EP's in my pockets.

Thanx, David

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