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Messages - frenafverbi

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Eyepieces Questions & Recommendations / Re: Astro-Tech Flat Field EP's
« on: January 18, 2018, 03:26:56 AM »
K5apl (also a ham-N7RMU), thanks for the info. Will check in that AT eyepiece. Sounds like a good one.

Had both, used the 24mm probably 90% of the time, even at the dark site. Mine were the older, nonwaterproof model..

General Astronomy & Observing / Re: New CGX Mount from Celestron
« on: January 18, 2018, 03:18:08 AM »
Would it be the same as the new Skywatcher EQ6R?
I saw it was belt driven also, didnt research it much, I'll let it be out for a year or two and let others be the beta testers.


Beginners Forum / Re: Travel Telescope
« on: January 17, 2018, 11:39:39 PM »
Hi everyone
i need some recommendations on what to buy. i was thinking of getting a celestron se 5. my budget is 1000$. what i want is a telescope that i can travel easily. in car and also hike for a little. i m not sure what to get. tbh i want something around 600-700 so i can buy some basic additional imaging accessories. i have a 8 dob which is impossible to move around with. i travel a lot so i was thinking of getting a travel scope. it could be a cheap refactor as well. cant decide if i should spend and buy something nice with go to mount or just get a small refactor just to do some planetary observation.
What do you recommend, help me with your expertise. i cant decide

Get a small scope, like a 6 inch SCT, or 80mm or smaller APO refractor. Slap it on a travel ready light Alt Az mount. And grab maybe 2 eyepieces and a barlow.

GoTo computerized mounts have weight, batteries, more bits & bobs, etc. I'd say keep it simple if you're going to be very portable all the time, and traveling a lot (where things take knocks all the time). Simple stuff will last longer and take more knocks. No charging batteries, no extra stuff, no wires. Totally simple.

Very best,

Assuming that theOmni XLT 150 you have in mind has a 1.25" focuser, I recommend replacing the stock 25mm ocular with a 24mm Explore Scientific 68 degree eyepiece, preferably when on sale, and adding an 8mm Paradigm Dual ED and a 2x Barlow lens for a minimalist eyepiece kit.

The Baader Planetarium Hyperion Mark III zoom offers very good performance.

Astronomics offers a discount for CN members.


Dave Mitsky

Light Pollution Topics / Re: This Can't Be Good News
« on: January 16, 2018, 11:27:44 PM »
Tesla wanted to do microwave power transmission.  He lost the war due to a number of factors (Edison and many other influential people killed his projects financially and with propaganda)....

Mounts Questions & Expirience / Re: vixen sxp discontinued?
« on: January 16, 2018, 05:44:41 AM »
You are very lucky to get that so congrats for the purchase. I only know of a couple places that have just the SX2 on final sale with Starbook. Yes I agree with your thoughts about weight. I miss my SX2 since it weighed less than the SXP and a touch quieter. It's really not bad though but I can feel it a tad when it's late out and I have to close up shop for the night. Let us know what polar scope it comes with. That was my bonus surprise although I don't use it anyway since I have a Polemaster.

Eyepieces Questions & Recommendations / Re: ES82 18mm - Why 2"?
« on: January 16, 2018, 01:32:04 AM »
Let's calculate maximal FL for 82-degree EP in 1.25" barrel with focal plane located at barrel/body connection. See attached chart.

FL<sub>max</sub> = d<sub>max</sub>*57.3/82, whered<sub>max</sub> = D<sub>1.25</sub> - L/FN, where

FL<sub>max</sub> - maximal focal length for EP without vignetting problems at FOV edge
d<sub>max</sub> - maximal diameter of effectiveFS
D<sub>1.25</sub>- clear aperture of EP enter in 1.25" = 27.3 mm (limited by filter thread)
L - length of barrel (in average 30 mm)
FN - focal rate (5 for F5 scope)

FL<sub>max</sub> = (27.3 - 30/5)*57.3/82 = 14.9 mm

To increase the FL we have to reduce barrel length, shift focal plane to open end of barrel, but even in this case more then 16 mm hardly ever could be done, especially taking into account existence scopes with focal rate more then 1:5.

Very good exlanations
I did some quick check about some AFOV for f4, it looks like this
AFOV max fl
 50 22.6
68 16.7
100 11.3
It looks like all the known max 1.25 AFOV eyepiece in the market will have some degree of vignetting in a f4 scope, so the following qustion is, how to determine the degree of vignetting in these EPs?

With the free reign businesses are about to have, it's going to get worse

Beginners Forum / Re: Astronomy in color
« on: January 15, 2018, 08:49:15 PM »
The mutation referred to involves an extra cone cell type, permitting to discern subtler color differences, like ducks do. Even if the density were very much higher (I doubt several orders of magnitude--implying of order 1,000 times more--for the the cells would have to be abnormally small to squeeze into the space available), this does not by itself necessarily confer greater sensitivity. As dictated by the chemistry, the same quantum efficiencybif 67% likely applied. More densely packed cells would permit pretty much only higher resolving power.

Given the not large number of colors for nebulae, which in any case are often enough found in pairs or triplets (from among, coarsely defined, 'red', green' and 'blue' and their admixtures), it would almost be surprising to find a neophyte not name some good possibility almost by chance.

And do not forget two almost insidious factors:

- These days almost no one has not seen images of nebulae in some form of media, with even subconscious bias being dangerous to discount.

- The red/green Illusion arising from intensity differences for colorless objects.

Eyepieces Questions & Recommendations / Re: Barlow or Eyepiece?
« on: January 15, 2018, 05:59:53 PM »
Also depends on the figure of your mirrors or glass.

Beginners Forum / Re: Help! My spider is bent!
« on: January 15, 2018, 01:29:20 PM »
I appreciate all the replies guys, and thanks for putting my mind at ease on this. I ejoyed the OCD jeers. I am not going to tell how late I was up last night working on that. Now I am ready to go out and it's cloudy.

General Astronomy & Observing / Re: Six Points of the Planets
« on: January 15, 2018, 11:34:10 AM »
© Pluto crosses the path of Neptune's orbit, so Neptune isn't a planet either.

Pluto was left out from the perturbation calculations, because its orbit
intersects the orbit of Neptune in the projection of the plane of the ecliptic,
"IN UPPER VIEW" only, but the two planets' orbits REALLY do not cross.

Mounts Questions & Expirience / Re: HDX110 or AP1100 for my Cave 10" f/7?
« on: January 13, 2018, 11:13:05 PM »
The 1100GTO is awesome...very portable for the weight class, optional pass thru cablingfor a clean setupand optional RAPAS is great. I've now set mine up about 70+ times and it just runs well. You pay more but get rewarded with a lifetime-like mount.

Best of luck with whatever you choose. cheers, DJ

Eyepieces Questions & Recommendations / Re: Beginner Optics?
« on: January 13, 2018, 11:43:48 AM »
Cheap, GSO Plössls (whatever the label on them) are just fine for your scope. Astronomics Value Line Plössl and Celestron Omni are the same eyepiece. Generally speaking, don't get anything shorter than 12mm. Get a GSO 2x Barlow (again basic Astro-Tech or Celestron Omni) for the higher magnifications. Start with 32mm, 20mm, 12mm. Then add the Barlow.

Note what Peter suggests is good for eye relief and is well planned spacing of the eyepieces

32, 20, 12

Add the 2X barlow you get

16, 10 and 6.

When planning a barlow into the mix you want to plan for this kind of spacing.  For example, adding a 10 mm would be redundant as your barlowed 20 mm is 10 mm already. If you did plan for another eyepiece it might be an 8 mm ( short eye relief) which would then barlow to a 4 mm.

Note also that a barlow works well is wide view eyepieces, should you buy some in the future.  It does not restrict the field of view.

Now, when you are observing use them alone for low to mid power observing. Then you put in the barlow for your mid to high power observing. 

Works similarly with a zoom eyepiece.  Without barlow for low to mid range. Add barlow for mid to high range.

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