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Messages - unmoharib

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16
Beginners Forum / Re: best scope for $1500
« on: January 26, 2018, 12:06:04 AM »
12" with setting circles on an EQ platform and top-end EPs (all bought used). This is my set-up other than the setting circles. I like the hunt and my buddy and I are good at it.

Scope retails around $1000 (got mine for $360 picked up), EQ platform ($300 picked up), EPs in signature all bought used. $1500 went away in about a year in about 4 chunks...

17
My TMB Paragon is my most-often used 40mm because it just plain rocks in Newts, Schmidt-Newts and 'Fracs. I do slightly prefer the views offered by my Meade 4000 SWA smoothie, but it is such a heavy monster compared with the TMB, the TMB wins hand-down.

The Paragon 30mm is not quite as nice, so my Meade smoothie wins that drag race.

18
Mounts Questions & Expirience / Re: New ES Mount coming to market?
« on: January 25, 2018, 06:55:47 PM »
Based on that S&T ad they've introduced a new goto system called PMC-Eight (powerd by Open GOTO.) It contains "ultra-quiet" steppers and the system is "programmable."

Interstingly, they've rotated the RA worm 90 degrees about the RA axis. Not sure if this is a Losmandy redesign or something they requested. Also, it looks like they've eliminated the gearbox entirely, so the stepper is driving the worm directly.

If the the PMC-Eight is a good system and they sell it independently as an upgrade to the G11, I might very well make the leap and try it out.

Mark

19
Quote
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Unless you are viewing from a very dark site, as the exit pupil increases so does the brightness of the background causing a decrease in contrast. Exit pupils are 4.0mm for the 30, 4.5mm for the 34, and 5.3 for the 40. I'd go with the ES30 for this reason and because it is 82 degrees.


For extended objects, the change in brightness of the object and the brightness of the sky are proportional, the contrast is the ratio of the two and does not change.  Stars, being points of light, more ore less, do not change in brightness so increasing the magnification darkens the sky and the contrast increases.

Jon

I read statements like this a lot but I have to wonder: when you say point sources do not change brightness, does that account for exit pupil? Because my eyes tell me that stars are brighter at larger exit pupils. [/quote]
Astronomics, the owner of Cloudy Nights, addresses this herehttps://www.astronom...t-pupils_t.aspx[/quote]
Yeah, I'm not buying that.

Edit: (by "that" I mean: "Stars do not get dimmer as a scope’s power increases and the exit pupil gets smaller.")

20
Beginners Forum / Re: Beginner Eyepieces for Dobsonian
« on: January 25, 2018, 02:24:19 PM »
Also...

"...the 'ortho' is not particularly well corrected..."

...is it not, rather, that an orthoscopic cannot be corrected for use with fast Newtonians of apertures greater than 6"?

21
ATM, Optics and DIY Forum / Re: Ideas for a 2 speed Crayford focuser mod?
« on: January 23, 2018, 06:14:55 PM »
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Rapier looking at what you did there gave me an idea. What about using a large diameter whip focusing knob? Similar to the knobs used on the RA/DEC adjustments.

I wonder if a whip type knob would also eliminate or at least reduce telescope movement when focusing?


I wouldn't do that. In addition to the reason that Jon Isaacs gave, in reality all you would be doing is extending the focuser knob shaft further away from the focuser and that's not really a solution.

Working from the basic idea that I introduced with a larger knob, you could conceivably fashion a detachable lever thereby giving your focuser knob a much larger radius. I don't know your mechanical capabilities so I can't begin to guess what is or is not within your abilities.

Think of it like this: take 12 inch long clothes pin and grasp the focuser knob axle with it. The longer the "clothes pin" the larger the radius, and therefore the greater the reduction in focuser tube travel. The trade off with any idea like this, though, is that you will have the unintended consequence of introducing more spurious momentary wobble in your scope, making focus a little more difficult, momentarily, because you won't be able to see past the wiggling image. But you will probably get better at using it with time.

22
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For me it depends on how dark it is. Really dark, a 31 Nagler is hard to beat.

But most of the time with moderate darkness (say green zone), I find around 20-25 is about as low as I want to go. The 24 Explore Scientific 68 is my most used low power in my 80mm F6.

Dark site only. I am 100% mobile. Skies are sqm 20.7 - 21.8 at my two sites

23
When I first started I wanted a barlow but the budget was really tight. I hopped over to e-bay and found a low cost option. Well, for $10 with shipping I decided to give it a try. I have been using it now for 15 months and have no plans to replace it.Name: - Datyson 2X barlow - I believe this Datyson is a 3 element design. - $10 with shipping
http://www.ebay.com/...506&rk=1&rkt=1

Features:
This Barlow features an air-spaced, Apo design with fully multicoated optics.
The housing is precision machined from aluminum stock and black anodized to a hard finish.
The lens edges and inner barrel are blackened to provide maximum contrast.
The Barlow body includes a safety undercut on the lower barrel and a brass compression ring so that your eyepiece barrels are not marred by the captive set screw.
Specifications:
Barrel size: 1.25"(31.7mm)
Height: 65mm
Magnification factor: 2x
Coatings: Fully multicoated
Material: Metal + Optical glass
Weight: 43g
Color: BlackUsing this with a Meade ETX 80, F5 refractor and an Orion XT8i F5.9 Dobsonian

Works quite well. Have compared it to barlows in the $30 to $50 range and it seems quite comparable.Compares quite well tomy 2" GSO barlow when used with 1.25" eyepieces.I have the 3X version as well. Works OK but not quite as good as the 2X. The 3X seems to have a bit of distortion at the outer 10% of the image. I use this one in the ETX 80 exclusively.

24
Reflectors Telescopes Forum / Re: Crazy collimation
« on: January 23, 2018, 12:21:19 AM »
Not sure which way to go. Also, perhaps I should simply buy a new tube? Any recommendations? I don't have the time for elaborate fixes. My solution has to be quick, and ultimately, not too expensive. A couple of three tube rings for an 8", along with two pieces of wood running down each side of the tube rings should secure it from the outside, no? This is a troubling fix for someone who just wanted a dob. Now I've got a freaking project. It is intriguing, but I have scads of home projects, too.

25
General Astronomy & Observing / Re: What to do during bad weather
« on: January 22, 2018, 09:17:51 PM »
Yep....build stuff and then build some more stuff. SkySafari is a good Astro play toy too.

26
Reflectors Telescopes Forum / Re: Goodbye cursed diffraction spikes
« on: January 22, 2018, 08:37:40 PM »
The exit pupil is the key. Refractors and Maks have darker background skies than Newts with spider vanes? Maybe that's because they tend to have slower f/numbers. Observers should make sure they compare perceived sky brightening among telescopes at the same exit pupil.

You put a long enough focal length eyepiece in a slow refractor and you'll get a bright, washed-out sky. I know because I've seen it. 

Mike

27
Beginners Forum / Re: Must Go To Amature Astronomy Event
« on: January 21, 2018, 08:46:40 AM »
One thing to keep in mind about theRiverside Telescope Makers Conference (RTMC) is that it always takes place at the end of May so the Moon phase can be a consideration if you're interested primarily in DSO observing. The Moon won't be a problem next year at that time.

There's a description of the event posted athttp://ephemeris.sjaa.net/0207/c.html

Dave Mitsky

28
Quote

Macro mode with the flash turned off should work.

29
Beginners Forum / Re: Planning my eyepiece purchases
« on: January 21, 2018, 01:23:55 AM »
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Hello all!

I'm a relative newbie currently using an old Orion SpaceProbe 130EQ I bought in 2003 (it's been in storage for much of the intervening time). I live in Atlanta with pretty bad light pollution and I have a lot of trouble finding things, or knowing what I'm looking at one I've stumbled upon something.

I'm considering upgrading to a 10" Dobsonian, likely an Orion Intelliscope. The SkyWatcher collapsible GoTo dob looks good too, but costs a fair bit more. If you have opinions between these two scopes or would suggest a different 10" dob with either PushTo or GoTo let me know... I know the Zhumells are supposed to be a great value, but I feel like I really need the PushTo or GoTo to help find objects since it's so difficult to find things in our sky here, plus it will save time and let me get in more observing.

Additionally, I'm going to want to get some good eyepieces. Right now I have the 25mm and 10mm eyepiece that came with my SpaceProbe, a TeleVue 8mm Plossl, and a Celestron 2x barlow. My understanding is that the included eyepieces can be improved on a lot, and while the 8mm plossl seems good, it has poor eye relief which makes it a distinctly un-luxurious experience to peek through. Maybe my eyesight was better 13 years ago, who knows?

I've been reading about different eyepieces but a lot of them have notes that they do not work well in faster scopes such as an f/4.7 dobsonian. So, I want to plan ahead and make sure that anything I purchase will work well in both scopes. The eyepieces should have decent eye relief, and I'd like a nice field of view as well if possible.

A few that I've been looking at to give you an idea of price range:
 Celestron X-Cel LX
 Zhumell Z Planetary
 Celestron Ultima Duo
 Celestron Luminos
 Baader Hyperion
Baader Hyperion Zoom (replacing several individual eyepieces)

I've specifically heard that the X-Cels do work nicely in faster scopes, not sure about some of the others.

The Baader zoom is intriguing, if it's really as good quality as several prime lenses, but the field of view seems lower than the others I've been looking at. I've also heard that it never goes obsolete because even if you have super-fancy eyepieces people use the Baader to find the desired size, then switch to a higher end eyepiece of that length.

I don't really care that much about having all my eyepieces match, although a parfocal set does sound kind of nice. I expect that most likely I'd stick with one main line and then maybe have a specific highest-mag eyepiece that could be from a different set and same on the wide end where I might have one super-wide eyepiece that doesn't match. I am planning to get 1-2 eyepieces first (or the Baader zoom) and get the dob later.

Does being in a heavy light pollution area have any effect on eyepiece choice?

On focal lengths... The SpaceProbe is 900mm, the eventual dob would likely be 1200mm. What do you think are the most important eyepiece focal length ranges or widths for:
 1. Saturn/Jupiter (doesn't need to be wide-angle here)
 2. DSOs in general
 3. Casual browsing around the sky

Thanks!

OK, now that we have all told you what we would suggest you buy, What's wrong with your current scope? 
Doesn't work?
Not enough aperture?
Money burning a whole in your pocket?
Baader Hyperian zoom gets very very good reviews.  Not as wide view as the ES 82 eyepieces but wider than the typical Plossl.
If you go to the bigger scope with the longer FL the eyepieces will produce higher magnification which will be well supported by the larger aperture. So I think whatever you get for the 130 mm should play nice with the 10".
I think I saw that you want to plan AP into this somehow.  So the Intelliscope is out. You will need tracking of some kind.

Photography?  What level?

Attach your smart phone or compact digital to the eyepiece - take pictures - any scope
There is webcam based for planets - need some kind of tracking but AltAz would work fine
There is video astronomy - I just ordered a Reveloution Imager 2 beginner kit - Again tracking is recommended
Then there is digital SLR - here you are talking long exposures and now you want a good (expensive) eq mount with tracking

So, what do you mean by AP?

30
ATM, Optics and DIY Forum / Re: Schief Telescope
« on: January 20, 2018, 09:56:38 PM »
Quote
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Quote
<p class="citation">Quote


Ed,
Could this Newt-setup be made using a larger mirror and of course using OTS lenses...?

I was also thinking, what if the lenses were not smooth enough, maybe they could be re-polished..? Advantage working this way is skipping al that grinding work.
Do not misunderstand, I have no problem grinding/polishing, but small lenses is another story.


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