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Messages - blacosticna

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Mounts Questions & Expirience / Re: iOptron StarFi
« on: February 03, 2018, 11:38:09 AM »
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The iOptron mounts, however, I have become soured on, so I'm going to be selling mine. The mount doesn't work for my style of use, but it works fine for other people. Ironically, I haven't decided if I'm selling the StarFi in case iOptron gets their act together and makes a better mount that I can use it on in the future.

Michael


Michael, can you be more specific about why your style of use isn't compatible with iOptron mounts?
Yes, I can do that. I'm limited on observing time, so I need to have the mount set up and ready to go in my house. I usually have the counterweight installed, and the mount head on the tripod (no scope). When I carry the mount outside, the weight shifts and bumping the counterweight/shaft the wimpy worm tension spring fails to hold the worm on the ring gear, and it slips out and drags against the ring gear. All of the iOptron equatorial mounts use this design, so I won't be using iOptron again unless they solve this design and manufacturing issue. I like the StarFi, and I wish it worked on other ASCOM mounts so I could use it on my Celestron/Meade mounts.

Michael

Ouch! Yes, that's an issue. You don't want to be stressing the mount like that with counterweights dragging the worm on the wheel. I would go one extra step and recommend you don't stress ANY mount like this. While the iOptron might skip teeth and cause damage, other designs without spring loaded worms aren't going to do well with this stress, either. It only takes a couple minutes to take the weights off and put them back on. Or you could release the clutch. and sling the shaft over your shoulder to carry it. Regardless, stressing a locked counterweighted mount around like that will end badly no matter which mount you have.

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I am quite happy living in San Diego. The city itself has plenty of light pollution but the seeing is generally quite good so my backyard is well suited for observing the planets and enjoying close double stars.

San Diego county is about 4200 square miles and includes just about every sort of environment possible, every possible micro-climate, there's the coast with it's beaches and mild weather, there's foothills and real mountains with snow in the winter and there's deserts where it's hot in the summer but mild in the winter. The back country has reasonably dark skies and there is plenty of open land for observing, about half the county is either a state park, national forest or BLM land, it's open. And truly dark skies are with a day's drive.

Add in the year around fine weather, the lack of flying insects, the clear skies in the mountains and deserts, the moderate to dry humidity... Most people live where the climate and weather is governed by large scale effects. If it's cloudy and you drive 100 miles in any direction, it's probably still cloudy. In San Diego, with the varied terrain and micro-climates, you might drive 5 miles and it will be clear.. A couple of years ago a couple of friends from the midwest were visiting our place in the high desert.. Their hotel was by the bay and it was solid overcast when I picked them up. They wondered if it was even worth driving out to the mountains because of the clouds. I assured them it was worth the drive.
The skies are not the darkest, the seeing isn't perfect but as a place for an amateur astronomer to live, it's tough to beat.

Jon
Out in eastern and southeastern San Diego County along the Campo Road and along old U.S. Highway 94 (the really old stage coach route from San Diego to Yuma) -- its pretty isolated country with really dark areas.

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Years ago, before I knew of CN, I considered getting curved secondary holders because I mistakenly thought that they eliminated diffraction. For DSO observers like me, that hardly ever look at anything bright, curved vanes are not worth the trouble or expense.

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Reflectors Telescopes Forum / Re: SECONDARY MIRROR VISUAL AID
« on: February 02, 2018, 07:40:02 PM »
No comment on post #17?

I did your thought experiment as requested--it was tricky. Your 7-inch minor axis "see-through and reflective" secondary mirror almost made it possible. It's basically a 3-degree tilted lowrider. If you don't get fixated on the "squared" focuser and instead use the primary mirror axis as the reference axis, it makes sense. It will need to have the front aperture expanded 2-inches on the side opposite the focuser.

Do a drawing--you'll see! I promise--I'm not trying to fool you or bait you--do a drawing. Extend the secondary mirror the full 7-inches at 45-degrees, 3 1/2 inches either side of the OTA center line. Extend the focuser line down until it intersects the secondary mirror. Then draw a line from the center of the primary mirror to the point where the focuser line intersects the secondary mirror. Now erase the OTA center line and draw a new OTA that's centered on the "tilted" primary mirror line. See what happened? The secondary needs to be a bit larger (another inch is about right).

Do a drawing.

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Eyepieces Questions & Recommendations / Re: Recommendations for 7" f/15 Mak
« on: February 02, 2018, 07:17:53 PM »
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That scope puts you in a very enviable position - complete eyepiece freedom.Due to exit pupil considerations, I would not go wild acquiring eyepieces of less than 15mm focal length. Maybe one or two for double star work. A barlow might be a better and more cost-effective option to really "ramp it up".
Personally, I wouldn't worry about eye piece focal lengths less than 15mm. The OP stated his high magnification targets of choice are the moon and planets and they are plenty bright enough to provide pleasing views with less than 1mm exit pupil.

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Beginners Forum / Re: High-power eyepiece for planets? Or Barlow?
« on: February 02, 2018, 06:28:23 PM »
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Casper Dad,

I've looked for the weight of the Z130, don't see anything on it. Any idea, I'm thinking at least 18 lbs. maybe more?

Did you get the simple flat collimation cap, looks like a focuser cap with a small hole in the middle? I've only been able to find these at Agena Astros website. If you got the flat one, where did you get it from?

Looking at one of these for my nephew, the Z130 or Z114 seems they don't include the collimation caps. He is young, 5 1/2, the Z130 seems a bit big for him, but when Jupter and Saturn are out it seems the Z130 would be good for that, not to mention the moon, Orion Nebula, Pliedes, and just scanning the sky. Of course theseeing conditions make a difference.

Also looked at Orion's Funscope (too fast, want more aperture, very cute though and portable) and the Orion Sky Scanner- a tad bigger at 100mm/f4.

But looking at the parabolic mirrors in the Zhumells, that might be the way to go. I have Orion's XT4.5, great scope-my first, easyto collimate, their dobs come with collimation caps, handy and necessary. I don't need another 'scope but the Z130 is very temtempting


I'm not sure of the weight but if I had to guess I'd say 12-15 pounds. My son is about the same age as your nephew, and he's really enjoyed looking through it. I can put the scope right on the ground and the eyepiece is just the right height for him to lean over and look. That said, with the short attention span of 5 year olds, he doesn't last more than a few minutes, and I'm not going to try to show him any fainter objects until he's a little older. I might try to show him the Orion nebula or the Pleiades once they start coming up earlier in the evening, and depending on how good the view is through the scope.

It didn't come with a collimation cap and I haven't ordered one yet.

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6mm Pentax smc ortho or Brandom 6mm.

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Any reason you are not looking at the Sky-Watchers? They are clearing out their non-goto models in the larger class. I have the 14" and love it. If you use binoviewers, or have any inclination to try them, the SW has a nice feature: the upper cage can be set to a lower position to accommodate the longer light path of the BV. This means you can reach focus without using a barlow.

A few concerns regarding the Sky-Watchers:
1) With only three tubes, it seems to me that adding a shroud would impede on the light path.
2) I have heard from others that collimation is constantly required, even during sessions.
3) Collapsing the tube keeps it as one unit, and I have back issues and need to be carful not to strain it. So I am looking for something that breaks down into lighter pieces.

Since you have one, maybe you can dispel my concerns.

On the plus side, it looks like the base has hand-tightened hardware with retention bolts that are made to come apart easily, is that right? That would be a plus for portability/ break-down. In comparison, the base on my Z8 does not have this feature, requires tools to take apart and is not made to do repeatedly (think screws in chipboard).

I have seen deals on these. How are the mirrors, accessories, hardware? Any weak spots that you corrected or that persist?
Thanks for you time and input.
Jason
Shroud is not a problem at full extension. The Astrozap has two plastic belts in the fabric that keep it from sagging into the light path. With the cage lowered to bino-height, however, mine did sag. There are probably a number of ways to fix this. What I do is use a piece of cardboard (from the scope's packaging) which I worked into an arc and cut to fit the gap between tube sections when in bino-mode. I would be interested to hear what others do.

Collimation.... I am not fanatical about precise collimation as some CNers seem to be. What I can say is that even between sessions collimation remains quite close according to my Glatter tools. I am not in the habit of checking it every hour to see if it has shifted. On the occasion I have checked during a session I have not needed to re-collimate.

Back issues I think would lead one towards the ES or similar types for large scopes. For your reference, carrying the 14" SW tube is about the same as carrying the fully assembled 8" Zhumell dob (tube + base). The base for the 14" breaks down nicely, no tools required, but the bottom of the base - the "lazy susan" part - weighs 33 lbs and is a bit awkward do to its size and shape. Carrying that has actually put my back in more jeopardy than carrying the ~50 lb tube because the tube's weight distribution is better balanced for hoisting.

My guess is the large SW dobs won't be best for you, but if your 8" Zhumell dob base is straining your back you might consider the 8" SW dob with the white base as a replacement. I think that white base model is only available in goto version now for the 8" but you might keep an eye out for a non-goto version on the used market.

So, um...eh-hem...yeah.....High Point Scientific had the SW 14" for $1167......and I ordered one. Compared to the other 14" I was considering, the Orion XX14i, which would have been more portable, came with cases, push to computer, etc...at twice the price of the SW. So, yeah.

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Keith,

You restated the question as follows:"does the RV that we measure assume we are a fixed point in space or does it include our half of the RV contract?" RV means radial velocity. As I said before, there is no radial velocity per se. The effect is supposed to be a result of the expansion of space between any two fixed points in space, and the redshift, is supposed to be caused by the expansion of the space such that the wavelength of the light is stretched out as it moves through the expanding space. In my opinion the use of radial velocity is misleading and goes back to the historical usage that the redshift was due to a recessional velocity. As I said above that is not what cosmology books say causes the redshift.

The idea that each and every point recedes from every other point in space, pairwise, is an assumption. There is no proof that it is true since the phenomenon is only known to us from earth observations. The assumption is known as the Cosmological principle and there are different versions of it. Recent evidence is not consistent with the cosmological principle since the surveys seem to show that the universe may consist of spherical shells. That would imply that the assumption is false.

http://gsjournal.net...s/Download/3621

The uniform expansion of space relative to every point pairwise presents a problem in conceptualization of how it could be real. The usual explanatory concept is to say that space is a two dimensional expanding balloon, where the surface expands so that every point is receding pairwise from every other point. As I said above this analogy requires a four dimensional space for a three dimensional "surface" to expand as required. The other way is to say space expands like a raisin bread baking. The baking bread idea is not very good since the baking bread has boundaries, and the universe is not supposed to have boundaries. That tells me that the other possibility for visualization is that the universe is an infinite Euclidean space that is expanding or dilating equally in all three dimensions and there are no boundaries or limits of the space or its expansion.

Some commentators have tried to say that time being the fourth dimension explains the supposed expansion of space in the required manner. This doesn't make sense to me since time is a parameter of the expansion. I am open to opinions regarding that, but it doesn't make sense to me that time as the fourth dimension allows the expansion to be pairwise uniform as a function of time.

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Mounts Questions & Expirience / Re: WO EZ Touch mount with big Refractors
« on: January 31, 2018, 08:52:27 AM »
the EZ takes alot
i recently had my 178 ED on it just to test out
yes its not meant to hold that much
but it did enought for me to test it out
i also had 10" meade SCTs on it and worked great
on the one side i bought a adm mini dual saddle which holds everything D and V

counter WT helps but anything under 30 lbs you should be fine without counter

last thing to add i love my WO EZ

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Mounts Questions & Expirience / Re: Fornax Lightrack II First light
« on: January 31, 2018, 07:44:26 AM »
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Hi guys,

I sold my Astrotrac and got the Fornax lightrack. I will be testing it this weekend hopefully and I will let you know my results.

Here is is a picture of the setup which consists of the Fornax mount and wedge, Astrotrac head/counter weight system and polemaster adhered to the Astrotrac head.

Cheers!

How do you like the Fornax Lightrack as compared to the Astrotrac?

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Beginners Forum / Re: Confused Newbie
« on: January 31, 2018, 06:52:58 AM »
I hope you find a great scope that works for you. Your enjoyment of the scope will invariably be connected to your familiarity with the finding your way around the sky.

Getting oriented in the sky might be made a little easier by locating a prominent constellation or grouping of stars, and go from there. In winter, you might start with Orion, and then at your own pace, move out from there. In summer, perhaps the Summer Triangle (Vega-Deneb-Altair) would be a suitable anchor.

How can you find your anchor? I recommend using planispheres as they are simple, inexpensive, lift-over-your-head portable, and are a sort of "living" star map that adapts to whatever date and time you'd like. As soon as you get accustomed to the scale and configuration of the constellations that are plotted on the planisphere, and how they actually appear in the sky, there'll be no stopping you.

When I was in my teens I could not, for the life of me, find the Great Square of Pegasus, despite the fact it contained some of the brightest stars in the sky and was almost right overhead. I lay in a snowbank, and searched in vain. Then it suddenly revealed itself, hiding in plain sight. It was a lot larger than I thought it would be. You'll have moments like this and I can assure you they are very satisfying and rewarding and, as you can see, they will likely remain with you for a long time.

Also, I have heard it said that learning the constellations is easier in urban areas because you are less likely to be overwhelmed by the sheer number of stars that would otherwise be visible in a darker sky. Seeing the stars from a truly dark site may take you back to school!

Best of luck,

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Is it possible that the lens attached to the focuser tube was a 2x barlow lens? Just thought of this.

In that case, would that "change" the focal length?

Sam

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I have been in this hobby for near 60 years now and still don't qualify myself as an expert. That said I would never recommend a Schmidt Cass or Maksutov to a rank beginner. The narrow field of view they produce just makes it harder to find things for beginners. I strongly advise the 8" dob with 'push to' electronics. With low power 2" eyepieces it can produce 2 degree fields of view and with shorter focal length eyepieces still be a very good planetary scope.

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Just a question that came to me. Thanks for any answers!

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