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Messages - Matt Gibbs

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1
Beginners Forum / Re: Compare Telescopes Please
« on: February 08, 2018, 06:11:22 PM »
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Yes, your right, I should not condemn all Dobs based on a lemon, but I really don't like the entire design. ...

I grew up in the muscle car era. ... They are wonderfully simple and you don't need any special tech to use them. However, I do think you make some sacrifices, as with any design, and for me I don't like what is sacrificed.

I think Dobs are the best scopes for beginners BUT not hands down.  I do like how easy it is to track planets with my EQ mount. The DOB
has to be "bumped" and at high power it can be a bit of a struggle. With even a simple polar alignment on my EQ, I can walk away for 15 minutes to
take care of the kids, come back twist the RA knob and I'm back in business. With a DOB I may have to re-starhop. For a beginner, an EQ mount gives you fixed stellar coordinates that never change. a DOB has Alt-az which means you will need a tablet with astro software in order to slew the scope to the right place.

I think some of the DOB problems can be solved with a little bit of carpentry and tinkering, if that is appealing to you. For some it it not.

I like the celestron CG4 mount for beginners with a 6" reflector or 4" refractor.  It is my winter quick peak setup. Larger DOBs
have a cool down time, which I don't always have my DOB pre cooled.

2
Beginners Forum / Re: Optimum Messier Program Telescope
« on: February 02, 2018, 06:49:06 PM »
I don't disagree with those who say Dobs are especially suited to star hopping and love mine but if I owned an 8SE I think buying an 8" Dob would be tough for me to do. There are different ways to star hop but I primarily use a RACI finder, paired with a red dot or other unit finder when possible, and only look through the scope when I am in the area of the subject - so max field of view doesn't make a huge difference for finding objects*.

Personally, I'd lean toward using the C8 and adding a RACI 50mm finder, Telrad or red dot finder, and a good manual alt-az mount. A good mount will not cost much less than you'd spend on the Dob so the choice comes down to which gives less overlap in your opinion.

*This isn't to say I don't love wide views for their own sake.

3
Good deal!

Here's my encoder story. I've got the geared ones, and not the glass disk mounted on the shaft ones. I'm kind of happy I ended up with those. The glass ones are sexier, but I can replace an encoder with this setup if one goes bad, or even up the number of counts. With the glass disk you are stuck if it breaks. I haven't seen any for sale for a while. You may have to resort to begging (i.e. Wanted...).

http://www.greschke....e/20160410.html

4
Reflectors Telescopes Forum / Re: Need advice on Mid-Size Newtonian
« on: January 31, 2018, 10:40:54 AM »
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It is optimised for use as a visual scope as I can't reach focus with it using my DSLR -
There are two suppliers that I'm aware of -http://www.altairast...-telescope.htmlhttp://www.teleskop-...tical-tube.html
Cheers,
Mick
OPT sells the scope under TPO (Third Planet Optics) name<a class="bbc_url">http://www.optcorp.com/tpo-6-f-6-imaging-newtonian-ota-6-6n.html[/url]
It's optimzed for photography but includes an extension for visual use.
I'm very happy with mine
Astronomy Technology Today had a review of it in Volume 10 issue 3 2016

5
Lawn darts? My brothers and I had bow and arrows when I was in the fourth grade. We're just lucky we didn't kill ourselves or someone else. Ever shoot an arrow in the air to see how high it will go? Whoops! Can't see it anymore! Run! Well, that was stupid.
Then there was the time we were shooting targets in our large backyard in Kent, Ohio. The backyard was separated from the house to the rear by a high hedge. One of us managed to accidentally send an arrow over the hedge. Luckily, no one was on the other side. Often wondered what the neighbors thought when they found an arrow in their yard.
Stupid kids!
I had a small cheap reflector in the eighth grade. Didn't come with a solar filter, fortunately. I would have probably used it without reading the instructions. I wasn't the sharpest tool in the shed, obviously.
Btw, that was one of those notorious scopes that turn kids off to astronomy. And, it did until Iwas much, much older.

6
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I like the way Rob has solved the "lateral slop" problem with his dobs by making the Teflon altitude pads wider so they extend inward to make contact with the tube cradle box on both sides at the same time.

I copied this on my custom setup.

A simple and elegant solution to a pain in the a$$ problem.

It works, though I suspect not without a free lunch. Pad contact with the finished mirror box wood must be thinning the stain through time.

I have a couple of wish list items:

* Firmer, less squish-prone rubber feet on the ground board.
I QUICKLY REPLACED MINE WITH HARD PLASTIC PUCKS TO REDUCE THE WIGGLES.

* A durable contact surface for those teflon pads that gets placed over the rocker box wood where they touch (such as cell phone type thin adhesive backed tempered glass shield material.
THIS SOLUTION FOR LATERAL MOVEMENT OF THE MIRROR BOX IN THE ROCKER BOX IS A SORT OF GRADE B SOLUTION. A GUIDE AROUND THE OUTSIDE OF THE TRUNNION WOULD HAVE
BEEN BETTER BECAUSE IT WOULD AVOID HAVING THE MIRROR BOX EXIT FROM BETWEEN TWO OF THE PADS AND THEN COME BACK INTO CONTACT WITH THEM AS THE SCOPE MOVES UP AND DOWN.

* CLUTCH ON THE ALTITUDE AXIS! All Dobs should have elegant, simple, and invisible friction clutches that let you lock the scope for eyepiece swaps. But hardly anyone does so.
AGREED. WHEN YOU GO LOW, AN EXTRA COUNTERWEIGHT OR VIRTUAL COUNTERWEIGHT IS NECESSARY. CHANGING EYEPIECES THEN REQUIRES REMOVING THE COUNTERWEIGHT AT THE SAME TIME.
A CLUTCH IS SO SIMPLE YET SO NECESSARY IN A 10-18" DOB. HECK, IF THE ORIGINAL MEADE LIGHTBRIDGES COULD DO IT, SURELY TEETER CAN. I ONLY WOULD FIND IT NECESSARY BELOW 40° ALTITUDE, THOUGH.
DO YOU ACTUALLY NEED IT HIGHER UP?

* hoop ring type primary mirror cover (to keep the primary freer of dust between uses); it would look like a picnic pie/cake cover. Heather of the famous shrouds could easily cook something up.
i PUT A PLEXIGLASS CIRCLE ON THE MIRROR CLIPS IN BETWEEN USES TO COVER THE MIRROR CLOSER TO THE MIRROR. IT DOESN'T PREVENT DUST ENTIRELY, BUT IT HELPS.

* more durable coating/finish on the brass lift handles; on my older Teeter the finish came off, they oxidized, and I cleaned them but they are now matte rather than shiny.
TRUE THAT! MINE NOW HAVE THE PATINA OF OLD BRASS (BROWN).

* (related to the point above) all of the bright metal work should be of the same metal using the same finish treatment, rather than merely the same color.
BUT NOT BRASS SCREWS! THEY ALL SHEAR OFF. I'VE HAD TO EASY-OUT SEVERAL OF THEM. ONE OF THESE DAYS I'LL REPLACE THEM ALL WITH STAINLESS STEEL.

* add an over the top super-premium materials build, featuring better wood (maybe pretty Obsession style Appleply rather than Baltic Birch, fancy(ier) joinery, fancy marine bronze (custom cast?) fittings - handles, screw caps, box corner protectors, counterweight hanger, collimation knobs, etc.
AND A BETTER STAIN THAT RESISTS UV-INDUCED FADING.

* hidden, in-mirror-box variable counterweighting system.
A VIRTUAL COUNTERWEIGHT SYSTEM WORKS IF ALL YOUR EYEPIECES HAVE SIMILAR WEIGHTS, BUT THESE FAIL WHEN YOUR EYEPIECES VARY BY AS MUCH AS 30 OUNCES (WHICH MINE DO)

* better cable routing for non-Servo Cat models, for DSC cables; in pole routing of secondary dew heater wiring, etc.
I RE-RAN MY WIRES IN SUCH A MANNER I COULD CUT SEVERAL FEET OFF THE WIRES. THE ORIGINALS WERE WAY TOO LONG.

* Rough ground "BIG WHEEL" wheelbarrow handles using high quality sealed bearing bicycle wheels and rough(er) terrain hybrid tires; larger diameter wheels would allow you to roll the bad boy much further over lumpy ground, and also might help with little curbs and steps, even.
ON 16" AND LARGER SCOPES, FOR SURE. 16" KID'S BIKE WHEELS, FOR EXAMPLE.

A cheap 16" BMW wheel as an example. https://www.danscomp...ront_Wheel.html

None of it material; I really like his business model and his structures.
YES, INDEED.
-DON- Jim

7
If you have a smartphone download Procompass. It has a magnetic and separate true north markings. Very helpful to see that your GEM is pointed in the right direction to begin with. Once the movie not is set up then begin your PA and ensure it’s dead on. Then do your 3 star alignment.

8
ATM, Optics and DIY Forum / Re: Advice from 'oldtimer'
« on: January 31, 2018, 05:09:35 AM »
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I don't often get the opportunity to spend $$ on materials, and with job, family, church, etc. I don't have a lot of spare time to futz around in the shop. So I'm a bit risk-averse. Before I ever cut wood / metal I always spend days to weeks turning a project over and over in my mind, trying to visualize every step, anticipate every obstacle or weakness in my design, and generally fabricate the whatzit step-by-step in my mind many times before I ever attempt it IRL. I find that not only does this weed out weak ideas, it also gives me a chance to identify ways to improve on my original idea, and it makes me more efficient when I do get to the shop, since by then I know EXACTLY what I'm going to do next.

Thats my excuse too, and its a shocker.

9
Light Pollution Topics / Re: Google Maps meets Light Pollution
« on: January 31, 2018, 02:49:02 AM »
Greetings,  Great work Jon, I found your app. a while ago and added 6 sites myself. Albers had compiled a list of about 400 dark sky sites with Lat/Long. Several years ago, using ArcMap9.2 I converted the list to a .dbf and overlaid it on a georeferenced layer of Cinzano's light pollution zones in the US. Currently with the NPS, I am producing In-Situ Light Pollution Hemispheres from data taken by the Night Sky Monitoring Team. We are in the process of re-processing the data, so that it will also show JUST the light pollution, from most of the National Parks in the US (~300). It would seem to be a very good idea to link all this great data on LP, to help reinforce our case and implement solutions. A web-ring of sorts?  Dark Skies!! Shield and point those lights down.   Several of these preliminary hemisphere models have been post on the in-Situ LP Hemisphere thread.

Attached Thumbnails


10
Mounts Questions & Expirience / Re: Regreasing AVX Dec axis
« on: January 30, 2018, 03:47:48 AM »
Hi Quinnn,

Use a non-flammable citrus degreaser like Zep or similar. Outdoors. Wear Nitrile gloves! Trim down a toothbrush so that the bristles are about half-height, if you want to get really western on it have at the gears with toothpicks. I hope you're using one of their NLGI #2 grease formulas rather than the high viscosity oil.

Good luck and clear skies,
Bill

11
ATM, Optics and DIY Forum / Re: Tile tool frustration
« on: January 26, 2018, 03:37:41 AM »
Another idea is Portland cement, unlike plaster you don't need to seal it and can use it the next day. The downside is I can only find it in 90-100 lbs bags around here but it is cheap at $15/bag.

12
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The question posed at the beginning of this thread asks who is responsible for causing light pollution. Secondarily, what laws, ordinances, regulations, codes, etc., would need to be enacted not just in the cities, but in the suburbs, exurbs and especially rural areas to reduce, control or eliminate it.

Obviously, rural areas are the last stand for dark skies. When someone says there are no more dark skies left east of the Mississippi, that means that the rural areas are the most at risk and that little is being done there.

Well, it's a good question. It's not always the other guy's fault. Even if we are somewhat conscious of our lighting and have some idea of what it means for a dark sky (something others may not even consider), we still drive into lit communities to buy milk. We need light as much as the next guy. I think the trick is to share responsibility. Ask our neighbors to be considerate, then be responsible to block any direct trespass light that cannot or will not shield.If they think you're a vivisectionist, they might just comply.

I guess every municipality may have some form of laws on the books about being obtrusive in some form or another, beit sound, light trespass. And it;'s likely not all municipalities will nor will they be the same if they do. I am not directly aware of any state or federal laws, but some internet research or a trip to city hall may turn up some in your area.

I try to explain and share responsibility with my immediate neighbors, then shield what's left. Hard to do much about the city glow in the north as that would take a concerted and prolonged effort with local city hall and a lot of money they are not willing to spend fixing the problem just for me. You may be right, maybe there is not much outcry in rural areas where it's still kinda dark. So, not much gets done and light encroaches unregulated as communities grow. Maybe start early with city hall to enact some ordinance and require the property owners to pay for specific lighting requirements.

13
Light Pollution Topics / Re: What to look for when buying a new House?
« on: January 25, 2018, 04:03:15 PM »
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<p class="citation">QuoteAlso keep in mind that trees grow. That view you had a few years ago might just be lost due to tree growth. Many trees can grow several feet a year.

Yes, but that is why there are chainsaws!!!  Remember a tree is just a wannabe stump. [/quote]

If they are your neighbors trees they may not be amused!

14
All good ones listed so far. I also like the Little Gem (NGC 6818), the Needle (NGC 4565), Omega Centauri, Centaurus A, NGC 7331, the Silver Dollar (NGC 253), Hubble's Variable Nebula (NGC 2261), Rosette Nebula (NGC 2237), Cat's Eye (NGC 6543), Blue Snowball (NGC 7662), Tau Canis Major cluster and and NGC 2438 (maybe cheating - it's the PN embedded in the cluster, M46).

- Jim

15
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I am considering purchasing my first "real" eyepieces...

1. Is/are there eyepiece designs that function "equally" well across several different scope designs?
2. What AFOV should I be looking for to "fit" my scopes?
3. What focal lengths?
4. What would you consider with a ~$1000 budget?

Current scopes:
•18" f/4.2 Newtonian
•14" f/10 SCT
•Tak TOA-130

PS. I do not wear eyeglasses (yet).


Since different telescope designs have different focal plane curvatures, it would be nice if eyepiece manufacturers had models "tuned" to each type of curvature. But that would be a marketing disaster for them, so we try and churn on Astromart. Great customer service model.

As for the other questions: AFOV is more of a personal choice and preference. It's ok to buck the marketing and peer pressure.

Focal lengths are bound (generally) by exit pupil on one end, your typical atmospheric conditions (and scope thermal performance) on the other end. With scopes ranging from f/4.2 to f/10 you have a lot of ground to cover for $1000!

Likewise, you are somewhat limited in choices by the faster scopes. You'll most likely need the higher correction levels (more money). Eyepieces like Pentax XW, Morpheus, Ethos, Nagler, Delos (to name a few). Maybe a zoom like the Baader or Leica. Don't be tempted to save a few bucks with the bargain wide fields.

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