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Messages - grountentaybrig

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Beginners Forum / Re: Must Go To Amature Astronomy Event
« on: February 09, 2018, 10:54:26 AM »
Well, there is camping at Stellafane.

And it is possible to camp on other weekends.

Alex we pull in I can be all "wow hunny look at all the campers who brought their telescopes"

One radical option I had been poking once - the "lay along" mount. Which is basically a narrow bed with the scope mounted in parallel above it (eyepiece down) on a motorized Alt/Az mountwith ellipticalAlt rails. But might be too comfy to resist sleep all night...
Oooooohhh ! NICE.
For these cold winter nights, you crawl into a sleeping bag, just in case you do nod off.
No doubt someone will object to body-heat thermals; for that you cover the bag with a space blanket !
Last problem would be the people standing in line to try it out (Hey when do I get my turn !!! Is that snoring I hear in there ??! )

Seriously I like it, it solves all the issues of observing comfort I can think of, One heck of agiant leap past standing on a ladder
Not sure about portability, but you do have me thinking

Mounts Questions & Expirience / Re: Weight Limit for AVX
« on: February 03, 2018, 01:00:55 PM »
Bob - tell the truth - do you work for my 4th grade reading teacher?

Seriously though thank you for the recommendations!

So much to learn.....

Panoptic, ES68, GSO Superview
None of >80-deg. eyepieces


I recommend the 31 Nagler. It has 19mm of eye relief, plenty for me to view when wearing glasses. It is also one of the finest wide field eyepieces ever made. https://www.astronom...iece_p3301.aspx

31 mm Nagler with glasses? No way!
In glasses I could see no more then 70% FOV in the EP.

Yes way!   In practice, ability to take advantage of eye relief can vary quite a bit among individuals. I can keep my eyeglasses on while observing through the 31 Nagler and still see the entire FOV. 100%. No problem.


ATM, Optics and DIY Forum / Re: Ross Null
« on: February 03, 2018, 05:55:53 AM »
When you say the Ronchi lines flow right off the edge is that with the Ross Null or using the Ronchi grating without the Ross Null lens ? Remember with the Ross your looking at the figure as it referenced to the parabola you want so what looks like it is OK at the radius of curvature test doesn't mean the edge is good when your referencing it to the parabolic figure you want.
 In the Ross null software you can check the box that will allows the program to calculate the maximum spacing error for the lens to mirror spacing for a given tolerance in the Optical Path Difference. So I used your 139.0" ROC, a diameter of 11.875" and testing wavelength of 465nm and the default specs for the Ross Null since you have a Ceravolo unit and got 119.1667" +/- 0.472" for 1/10 wave. Remember that is if you achieve a perfect null.

     - Dave

Ronchi grating without null lens looked textbook to me. At least at the edge....  I need to get my video cam working with the null lens, it doesn't want to focus now. I need to move it back I think. My eyes aren't good enough to see without some sort of magnification. Then I can see whats going on for sure. Its a work in progress, I had just gotten Foucault / Ronchi to work real good, now I added a new variable.

Eyepieces Questions & Recommendations / Re: High-power eyepiece advice
« on: February 03, 2018, 12:45:21 AM »
Well, thanks to the excellent advice here, I thought it had my next purchase figured out. A used Nagler t4 22mm would give me a wide field, good magnification, exit pupil within my range, not too heavy for my small scope. BUT, I'm now seeing ER quoted as 17mm, 20mm, "around 18mm" depending on the site. Since that is the crucial feature for me with my glasses, I'm not sure buying one used is a good idea. Anyone know why the range is so unclear? Personal experience with this eyepiece and glasses?

Think maybe a Delos or Delite 6-7mm + barlow may be the later purchase. Thanks again to everyone for the amazing depth of knowledge and the willingness to share it.

Eye relief claims should be taken with a grain of salt. Throw in other factors, like how recessed the eye lens is, or the shape of the eye lens, and one eyepiece's 17mm will beat another's 20mm. What IS out there, and quite frequently too, are claims that you can use the type 4 Nagler with glasses, particularly the 22mm.

Ray, whose in new Zealand, uses onestep, he went thru a lot of motors and voltages and driver boards to get his movements smooth. He also uses a driver wheel against the ground board.

I'd rather use a soft durometer wheel against the edge of plywood.

With his 20" trad dob , his pics of Jupiter look better than Hubble.

But his mirrors, he made, are way better than a standard zoc. Plus his seeing.

Eyepieces Questions & Recommendations / Re: eBay scammers for ES 30mm 82*?
« on: February 02, 2018, 10:49:48 PM »
It's all over Amazon too. Here's one example...

Mounts Questions & Expirience / Re: Moved up the iOptron line to CEM-60
« on: February 02, 2018, 09:32:11 PM »
Just watch out to clear the alignment models. The new iOptron mounts (CEM25, ieq45 pro, CEM60) all will not platesolve if you have a pointing model in the mount.

I don't know why you concern that much about GOTO accuracy when imaging with SGP, just plate solve and move on. You could just be chasing cone error in this case that your ieq45 didn't have as much of.

ATM, Optics and DIY Forum / Re: Plans for a Portable a 6" F/8?
« on: February 02, 2018, 05:09:49 PM »
Maybe...for a reflector forum...

And it is an old site.

Why are you keep this OT going.

Reflectors Telescopes Forum / Re: Mirror coating question
« on: February 02, 2018, 02:42:58 PM »
<p class="citation">Quotechange over to 3 vein curved spider holding

I would suggest a 3 vane spider, using a 3 vein spider can be tricky, if
the vein gets abraded it can tear and spray blood all over everything.
Veins don't spray, they just kind of ooze. Now arteries are a whole different story.

ATM, Optics and DIY Forum / Re: Polishing a 6" mirror on an 8" Lap?
« on: January 31, 2018, 12:37:51 PM »
I suppose for the purist, or someone who has worked through many mirrors, and has a pile of lap/disk bases, or materials to whip up a plaster one, one must use a lap with the exact radius as the mirror. For those who use thin layers of pitch, this would make a difference. For the occasional glass pusher who makes a common 1/4" thick pitch lap, the effect would be far less.

I've made laps on flat discs, and encountered no trouble, though most of my mirrors have shallow radius.  Alan Mackintosh says he's more attuned to using stroke action for his figuring work rather than relying on lap conditions.

How do you warm press a small mirror on an oversize lap? Is this your final decision to use the oversized lap?  Put the lap in warm water for a few minutes. A clean thumbnail indentation should tell you that the pitch has softened. Put polishing solution on the lap, and with the mirror work the solution to cover the lap. Move the mirror out so it overhangs the edge of the lap, and apply hand pressure for a few seconds. advance the mirror around the edge repeating presiing all around. Keep gong around until the lap has cooled. You should be able to gauge lap contact through the back of the mirror. If poor contact, keep repeating it. While polishing, make sure you're passing the mirror over the edge enough to keep it true.

To stay out of trouble on this, why not just build a dam to make a 6" diameter pitch lap, or cast squares and stick them on, or cast an 8" lap and chisel off the excess. .


About 1.2 arc sec/pixel. Not large, not small.

Mounts Questions & Expirience / Re: Orion 16" Pier Extension
« on: January 31, 2018, 12:08:36 PM »

One thing I've noticed with storage that has higher sides ... dew can often accumulate enough to cause a little pooling of water. Sometimes it wasn't enough to notice on a single night but after a few consecutive nights I've noticed some accumulation (likely because the sides prevent air flow that might normally dry it out when it's sitting during the day). To prevent it I just have to remember to wipe any areas like that out after each night.

I get quite a bit of dew. One thing I plan on doing was having a wrap (think something like a bathrobe) that I can simply wrap around the pier extension above the EP rack. That way everything is under cover, yet still easily accessible.

General Astronomy & Observing / Re: Magnitude Discrepecies
« on: January 31, 2018, 09:56:59 AM »
Like this?:
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