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Topics - wallnewsspheryz

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The filter feels like it wants to start cross threading about half way. Is this normal? It also will hit my baader prism so I had to 3d print a 7mm shim for it. CN won't let me upload STL files so here's a link to the 3d model if anyone wants it:
https://www.thingive...m/thing:2702830Attached Thumbnails




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Mainly posting this for curiosity and getting your thoughts. As I am asked for feedback on beginner GOTO scopes all the time i'd like to understand these two scopes below a little more. For the beginner quite a few people recommend a non goto dob or an alt az refractor, but given my better familiarity about cassegrain telescopes I am usually itching to recommend a cassegrain of some type and I think that is totally fine . Sure they have the disadvantage of them having a constrained slow f/ratio and you do have dew issues to figure out with the corrector being on the front, but overall i'm smitten with my Evolution C8, so when people at outreach events or new astronomers joining our area club ask me for a recommendation for something well under $1000, i'm usually itching to tell them to find a used C8, but lately i've wondered about 5" cassegrains (both MCT and SCT) for ease of portability as well as what one can truly see. The aperture is more than most decent refractors that can be had under $1000. They are great on planets which in many cases is what people like to see first and then dabble in more deep sky. And they come in packages with usable GOTO mounts with similar electronics as I have so I can help them through some of the initial newbie headaches to get them started.

One of my friends has a Levenhuk 105 Mak on a similar mount to the Orion Starseeker which is similar to the 127 SLT and it tracks very nicely. He uses it for EAA and some nice planetary stacked imaging. For the cost and size of that little scope i've been really very impressed. He even runs it on batteries quite frequently and gets decent run time.

I've seen a lot of recommendations for the 5SE which instead of a Mak-Cass it is a 5" Schmidt Cass, but what about the less expensive 127 SLT? Any love for the 127 SLT?

The aperture is the same for the two scopes below, but the focal length of the Mak 127 SLT is longer (1500 vs 1250 on the 5SE SCT) and the f/ratio is slower on the 127 SLT (f/12 on the 127 SLT vs f/10 on the 5SE). I've also heard that while you need to still collimate a Mak they are even less susceptible to losing collimation than comparable size SCT's. For the record my 8" SCT Evo purchased in Feb 2016 is still holding its factory collimation even after multiple tumble bumble trips in the car to the dark site, so this argument between holding collimation on Maks and Schmidts may be moot

To frame this a little better I'm interested mainly about the difference in real dark site or backyard experience between these two scopes-I really could care less about technical jargon or arc seconds of accuracy..we are talking 5" beginner scopes here-what's the real experience difference? I'm thinking of both beginners or as a grab and go for someone with a larger scope that would like something they could keep setup or "minimally" stored. For similar sky conditions and targets list including higher Mag objects like the Moon, Saturn, Jupiter, Lagoon and Orion Nebula, M13 and M3 and M11 what would the difference in what one actually sees? Is the 5SE really worth $250-270 more than the 127 SLT???

Both mounts use spur gear drives not worm gears, so i'm not sure that would make a difference. Both are alt/az Nexstar Electronics. Maybe the 5SE has a better tripod and stiffer mount, but on something like this would that really change the experience? Assume that both are setup on grass not concrete.

Head to Head Shootout!!!
Nexstar 127 SLT (Some suppliers have this as low as $439!)
http://www.celestron...rized-telescope

Nexstar 5SE (Usually sold for $699)
http://www.celestron...rized-telescope

Jon Thomas

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Just curious, what magnifications do other people use for starhopping with a manual mount? For me, 22x seems to be the best all around starhopping magnification. Once I get close to the target, 35x helps me verify the target and center it before switching to higher power. Magnifications over 50x are not as useful for starhopping, for me anyway. How about you?

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General Astronomy & Observing / Stars and sky brightness
« on: December 29, 2017, 02:34:53 AM »
I'm comparing two pair of binoculars... A pair of 8x42 I already have and a pair of 10x30.

When calculating quotient of light fluxes entering the eye, with and without instrument (using those formulas), I have the following results:

8x42

Punctual objects: 36
Extensive objects: 0.6

10x30

Punctual objects: 18
Extensive objects: 0.2

From those results, it seems that stars will be 2 times brighter in the 8x42 and that my light polluted sky will be 3 times fainter in the 10x30.

Since stars need to be "brighter" than sky to see them, I'm now wondering if I could see more stars in the 10x30 than in the 8x42 from my light polluted backyard. Yes, the 8x42 makes the stars 2 times brighter but the 10x30 makes the sky 3 times darker and thus better improve my ability to see them.

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Tomorrow I am purchasing an Orion xt10i (very excited!!!) but I have one concern. With winter creeping in, I'm worried about the mirror becoming foggy every time I go to set it up.
What would be the easiest and cheapest way to install a fan? I'm aware of computer fans being a cheap option but I don't know what to use for a power source. If anyone could help point me in the direction of how to set that up, that would be wonderful.
Also, if there's anything else I should know about owning a 10" Dob that will help me in the field, I'd greatly appreciate any advice. I have a small refractor but have never dealt with a dobsonian before.
Thank you!
-Sean

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Light Pollution Topics / Dallas Fortworth Dark sites
« on: December 28, 2017, 04:20:14 AM »
Hi,
I live in Dallas / Fort worth, and I've been searching for a close by Dark site. I my house is in the Yellow zone, and I want 3 Dark sites.
- A close by one that I can go 1 or 2 times a week

- One that I can go once/twice a month

-One that is far away and for prolonged school breaks.

Thanks in advance!

7
General Astronomy & Observing / Polaris starfield going faint wanted
« on: December 28, 2017, 03:57:38 AM »
I've had no luck finding a detailed starmap within 3deg of Polaris going down to mag 10-11. TIA if you can provide a link. The marked current position for the north celestial pole would also be helpful

Nytecam

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Eyepieces Questions & Recommendations / Good Kellners
« on: December 24, 2017, 04:02:32 PM »
Any excellent ones out there, particularly current or latest production?

Best Wishes,

Karl

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I am wondering just how these two telescopes would compare to each other from a performance perspective.  What are each ones strengths and weaknesses?

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