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Messages - Jim Snyder

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1
Eyepieces Questions & Recommendations / Re: "Planetary" Eyepieces
« on: February 09, 2018, 11:36:41 AM »
Good discussion. However, what I am most curious about is objective optical performance, regardless of the other drawbacks, be they small FOV, tight eye relief, or rarity and expense. Obviously trying them out is the best way to evaluate, perhaps one day.

I have a good collection of EPs that are comfortable to use and good on axis. The type of people who read this forum, however (myself included), tend to be curious if there's any more tangible performance available. Would I find a contrast improvement in a 5.1mm XO vs my current 10mm XW + ES ED 2" Barlow? How about against a straight 5mm XW?

I've already improved my scope as much as possible. It's flocked, the primary has been tested and refigured, the secondary was replaced. I have an EQ Tech platform for tracking, and am dabbling with binos. More aperture (and correspondingly smaller CO) is in the future, but maybe a year or two away as I work with what I have and figure out what I want.

2
Beginners Forum / Re: Why do Maks have such a bad rep?
« on: February 09, 2018, 09:42:51 AM »
Who doesn't like a good Maksutov? I have owned 6 or 7 in the past and I impulse bought an Intes Micro MN55 just yesterday--should arrive next week. Sure that is a Maksutov Newtonian, but that still counts, right? Plus it negates the "Maks have a narrow FOV" argument. As another poster mentioned, all scopes have their own strengths and weaknesses. That is what makes them special. You just need to find one (or five) that meet your specific observing style and preferences. It sounds like you have. So enjoy the views.

3
Mounts Questions & Expirience / Re: Vixen Mini Porta?
« on: February 09, 2018, 06:46:45 AM »
OK thanks. I'd almost certainly carry the ST80 and the Vixen mount/tripod separately due to my disability. How would you say the original Porta, which I believe is roughly the same weight as the Porta II, compare in weight and transportability compared with a regular AZ3/AZ4 tripod? Is it much heavier to manipulate? Bearing in mind, I'm only really planning on carrying the Vixen in my garden.
Shorty Barlow,
I have no experience with an AZ3/AZ4 tripod.
Bill

4
Mounts Questions & Expirience / Re: Integrated WiFi - The Future?
« on: February 09, 2018, 01:49:38 AM »
Did you also contemplate how much Apple would charge for such a system?
David
Too much, which is why they won’t. Not enough money to make off of a bunch of geeks like me.

The astronomy market is small. That’s why we all need to put up with the quirks of companies like iOptron and Celestron, or spend a fortune on hand made stuff from companies like Astrophysics and Takahashi.

It is what it is.....

5
Quote
Quote

There's this this much longer thread started back in October...

http://www.cloudynig...5-mm-and-18-mm/

It contains this quote...

"I personally find these eyepeices excellent, and I sold all my Delites, and keept APM UFs"

Take what you read in this tread with caution.

Honestly not sure what to make from that quote, as the only two UFF's available are 18mm and 15mm which arguably would only replace one FL. I could see it replacing the Delite 18mm, but the 11mm and 7mm?
Denis will be able to answer better for himself, of course, but in case he doesn't see this thread... I believe Denis likes longer focal length eyepieces best and thinks they are better with a Barlow than shorter FL eyepieces, at least in the case of the DeLites. So he may be referring to his 18.2mm pair of DeLites he sold in favor of the APM UFF. He tried some of the shorter focal length DL and liked the 18.2 barlowed better. I know he really liked the 18.2mm DL pair a lot so for him to sell in favor of the APM UFF is quite something and got me thinking about the APM. If I recall correctly, he sold the shorter focal length DL before he tried the APM but I am not sure.

6
Beginners Forum / Re: Maksutov? Schmidt?
« on: February 08, 2018, 09:50:39 PM »
The EQ-1000, just a simple grab-n-go, circa 1900.

rms59--I assume that by the Mak, which you recommended over a SCT for reasons of less need to collimate, you were referring to a MCT rather than a Mak-Newt. Is this correct? And where does the simple Newtonian fit into the collimation scheme of things:  less or more than a catadioptric? My personal usages will require moving the telescope/mount for nearly all viewing sessions. Too much light pollution where I live, not to mention occlusive obstacles (trees).

7
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I have worked on number SCT over the years. I'm refiguring a Schimdt corrector for Dynamax 8 right now. I have thread in the Classic Telescope Forum about it. I can tell you, you'll see two types of zones in the corrector when testing via double pass, asymmetrical and symmetrical. Both of which you will not correct by rotating the corrector. When people rotate the corrector and say the image improves what they are doing is correcting for misalignment in the system. You can put the corrector in any position you want if the optics are mechanically centered and collimated you'll get the same results.
 If you want to test the corrector by itself, you can place it directly in front of spherical mirror and do a Ronchi test. You should see envyingly bowing lines like what one sees when testing a parabola.

        - Dave

What if both the corrector and the mirrors have astigmatism or zones?

8
The 24mm explore look good. This one seem to have a different looking upper body.

http://www.tringastr...mm-2-8931-p.asp

http://explorescient...roducts/82-24mm

9
Mounts Questions & Expirience / Re: iOptron ZEQ25 payload limits
« on: February 03, 2018, 12:28:40 PM »
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Depends on what you want to do.
The EC version is very good indeed for unguided work.
But at a substantial cost.
If you're going to guide anyway, the added value of the EC option is not used.
For field work you could guide with an MGEN (brilliant stand alone guider).
DSLR and MGEN are a perfect couple.
If you look at my Tripier, you'll see that the three solid spreader bars are replaced with small customized turn-buckles. This gives a lot more leveling space than the standard design.
Save the extra money on the EC mount (go standard CEM60) and spend it on the tripier, would be my advise.


These customized turn-buckles, are they bought from a store and then modifed? Or are they completely custom made?

cytan

10
I'm an almost exclusively visual observer, who occasionally throws my wife's DSLR in the mix for some quick (~30s) unguided shots, mostly just for fun, but also to bring out details in the faint fuzzies that I don't have enough aperture to see with my own eyes. My current EQ mount is the Orion-branded Synta EQ-3 (i.e. Orion AstroView). I used to hate it, thinking that the 150mm f/5 it came with was woefully undermounted (huge vibrations that take too long to dampen), but once I added the dual-axis motor kit (I got the Celestron version off of Craiglist; probably would have bought the Celestron version new since it's a little cheaper than the Orion one) my perspective on the mount totally changed. It still takes just as long for the vibrations to dampen, but once they do, whatever you're looking at stays dead center in the FOV for as long as you care to look at it. I am now a big fan of the mount, as it's relatively portable and offers decent performance for what I do. The one thing that really bugs me about it is that the RA axis has no clutch, so it isn't an easy matter to switch it to fully manual operation if for some reason I wish to do so.

Call me a luddite, but I don't like the idea of needing power in order to observe. I have no qualms with taking advantage of it when available, but I don't want it to be an absolute prerequisite. Batteries can run down, break, or neglectfully uncharged; any number of things can go wrong with motors and their control systems; I just like the idea of being able to easily fall back to manual. Even when everything is working, I like the idea of being able to center with the manual slo-mo controls, then tighten the clutch and let the RA motor track, and just letting the hand controller sit on the accessory tray and not having any reason to need to pick it up and fiddle with it.

I'm not actively in the market to upgrade my mount, but I know I will eventually, and like to sort of idly think about it from time to time. The obvious upgrade would be one of the many clones of the Vixen GP (or a used Vixen GP, since the Vixen AP just doesn't do it for me), all of which could be fitted with a dual-axis drive system with clutches to allow easy switching to manual slo-mo on *both* axes. But I'd like to know if there are any other decent options out there for manual-capable mounts. It sure doesn't seem like it. I'm guessing that the glut of inexpensive and reasonably capable EQ-5 type mounts makes it difficult for anybody else to justify making engineering the ability to use a mount with fully manual controls for the few of us who want that capability.

The EQ-5 type mounts that I have been able to identify so far are:

Astrozap AZ-3000 (it took me forever to realize "AZ" probably refers to "AstroZap" and not "AZimuth")
Bresser / Explore Scientific EXOS-2
Celestron CG-5 (no longer produced)
Meade LX70
Meade LXD-75 (no longer produced)
Orion SkyView Pro
Sywatcher EQ-5

And of course the original: Vixen Great Polaris and derivatives (no longer produced)

IIUC, these are all based on the Vixen GP design, and should all be reasonably compatible as far as motor options are concerned. They all look completely identical apart from color, with the exception of the SVP, which has more sculpted lines and has the setting circles in a different location. I believe some are made by Synta and some by Jinghua?

Anyway, I guess my actual questions are:

* I'm assuming not all of the above options are created equal, despite looking pretty much identical. For example, even though I've never actually used a Celestron CG-4, I sort of assume that despite it being pretty much identical to my Orion AstroView, the CG-4 would be slightly better just due to the fact that it comes with a more substantial tripod. Also, I hear the original Vixen mounts were made to tighter tolerances than their clones ever were, and I imagine there might be some variability between the currently produced clones as well. Do any of these mounts clearly stand out from their peers?
* I'm assuming I've missed some other, let's call them "GP compatibles". Have I? Which?
* I'm hoping that the "GP compatibles" aren't truly the only option for mounts that are both dual-axis and manual capable, where switching between the two doesn't require a screwdriver. Please tell me there's other possibilities. I'm intrigued by the Losmandy GM-8 and G-11 design, which as I understand uses friction clutches that let you just repoint by hand, but having never actually seen one, I don't have a good idea as to whether it's sensitive and smooth enough to be acceptable for fully manual use when the occasion calls for it. (I would sort of imagine tracking manually by just gently nudging the counterweight shaft to move in RA without moving in DEC, but worry that it would be hard to nudge gently enough to avoid overshooting at high power.) Any thoughts on other EQ mounts that can easily switch between motorized and manual control?

11
Eyepieces Questions & Recommendations / Re: Meade 8.8 UWA 5000 versions
« on: February 02, 2018, 11:12:59 PM »
Quote
Quote

Mel
no worries im all for you indicating your findings
my mini comparo was done at night while viewing i really concentrated on the feel mainly ER and performance
to me i wish the newer version 8.8 acted more like the 5.5 they would really have a winner on there hands
anyhow please post your findings
clear skies

All is well Tank! I will be sure to report back once I do the comparison.

Thanks,
Any updates on this one Mel ?

George

12
Light Pollution Topics / Re: Well I did it....approached the neighbors
« on: February 02, 2018, 09:49:29 PM »
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Matt, it looks like they are at least trying.  I would definitely make the gesture of inviting them over to look thru your scope.  It may help with them going even further (turning lights off sooner, etc.).  Never know until you try.Glad they did as much as they did!  How about a new picture showing the lights now?
+1Invite 'em over not just for a viewing, invite 'em over for supper/barbeque preceding the viewing.  By these people's lights, er perspective, they bent over to meet you more than halfway, even though from your perspective it's still only a bit better than half...um, moon.  But flies attract honey better than vin...oh, fuggetaboutit youknowaddimean  You never know...the result might be even lead to further progress over time in reducing their inclinations toward being quite so lit-up so much of the time.

13
ATM, Optics and DIY Forum / Re: Focal Ratio of Older Meade Lightbridge 16"?
« on: February 02, 2018, 01:31:55 PM »
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Don & Jon:

My exercise was to confirm for myself that all of my current EP combinations would work at what appears to be my final pole length.

<p class="citation">QuoteDo you mean the new focal plane due to the Paracorr

[/quote]

I was thinking of your measurement of the actual focal length of the mirror. The Paracorr eats up about 0.5 inches of inward focuser travel. If you are measuring focuser height with the Paracorr in place, the actual focal length would be about 1/2 inch longer.

In terms of determining the pole length, there are a number of ways to do it. The last time I did it, I found the focuser height with a known eyepiece, the scope focused with 41 mm Panoptic without cutting the poles.

Then another telescope, I measured the relative focuser heights for various combinations of the Paracorr, my Eyepieces and a Barlow and using the 41 mm Panoptic as a reference height, decided how much to cut off based on the inward focuser travel required.

Jon

14
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A 115-mm refractor is pretty big, probably weighs about 3X as much as a comparable 80-mm, and accordingly requires a hefty mount. It's big enough so that the cooldown time is substantial, though still much shorter than a comparable reflector or catadioptric. It's long enough so that the range in eyepiece height depending where the scope is pointing is quite large; you almost certainly need an adjustable-height chair to use this scope.


I'm imagining the three stooges getting bopped in the head as someone slews the camera around and says "Oh, look at that big red spot on Jupiter." "I'll put a big red spot on your forehead!" "Nuk Nuk Nuk!"

All kidding aside, it sounds like the larger one has more of my wish list on there....but the 80mm sounds so much more useable. The other aspect I'm running into is that when I simulate a telescope with Stellarium that the binoculars are more than enough for studying constellations. Even the 80 with about 20x magnification is way too much for that...so the telescope would definitely be more for smaller objects (or the moon as you said).

I may heed the more practical side of me which says: enjoy the visual side, don't get more telescope than you can transport it. Cool, thanks for the feedback on the size and associated nuances (like the height adjustable chair). I may end up with a 8-10" Dobsonian andthe smaller 80mm refractor...that's my thoughts now. I'll see how it refines itself between now and whenever I decide to make my first purchase. In the mean time, I'm going to spend some good quality time with my binoculars.

15
Light Pollution Topics / Re: LP Map (new to us)
« on: January 31, 2018, 12:04:26 AM »
the area southwest and northeast of madrid looks really attractive. especially considering the current prices of spanish real estate. and the lovely spanish weather.

my wife and i drove through there several years ago and it's beautiful country, gently rolling plains of wheat and graze, very sparsely populated, a relatively high plateau. (madrid is at 650 meters.)

unfortunately, the map is strongly skewed to high luminance areas and makes the dark areas appear more attractive than they are. in the conventional map france seems much less attractive, but spain still looks very interesting ...

http://www.lightpoll.../pages/fig4.htm

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