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Messages - Milan Gainer

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Beginners Forum / Re: So my Z12 turned into a Z10
« on: February 09, 2018, 10:57:10 AM »
You're enjoying the 10" awesomely at the moment, and going from 10 to 12 isn't big enough of a jump for the effort. Keep the 10 and keep enjoying the hell out of it. 10" can be a lifetime scope for some people. Someday in the future, evaluate whether you can handle a 16" and then go for it if so. If not, just keep enjoying the 10.

ATM, Optics and DIY Forum / Re: Synta Secondary Assembly Mod
« on: February 09, 2018, 04:47:58 AM »
I have another question. Do you have enough adjustment range to account for the thickness of the washer or did the washer push the secondary down too far in the tube preventing proper collimation?

<p class="citation">Quote
One possibility would be a jpastrocraft 16" f/4 "Sweet Sixteen." I find this excellent. Seated viewing even at zenith. Wheels for transport, just tip and roll. Scope doesn't move as eyepieces are changed. Expensive but worth every penny, a lifetime scope. Superb construction. Use a Parracorr. Use a Zambuto or Lockwood mirror. My most used eyepiece with this scope is a 13 Ethos.


That's exactly the scope I had in mind when I suggested the 16 inch F/4.


Thanks for the link Jon, the Sweet Sixteen looks awesome

Clear Skies,

ATM, Optics and DIY Forum / Re: Mirror grinding machine-runout
« on: February 04, 2018, 01:35:53 PM »
<p class="citation">Quote

Can I use the machine to rotate the mirror at 25 rpm and hold a grinding stone at 45 degrees to the mirror edge to redo the bevel. Or is this too risky?

I like my edges rounded, its really cool when its finished, just a totally different look, doesn't make a difference but its nice.[/quote]That's what I do as well, though I use diamond cloth. Some people have called anything but a sharp breakable 45 degree bevel "unprofessional looking."

FWIW, I can carry the SW 100 Pro Ed, Twilight II mount and tripod from one part of the yard to another fully set up. I'm 51, 5'4" height, and in fairly typical middle aged shape

Does anyone know if new (2017+) Losmandy G11GFT mounts come already with the one piece worm upgrade that everyone seems to be buying for older G11's, or is the OPW upgrade still necessary to buy even for new G11GFT mounts? Thanks!

This is the specific mount i'm asking about: https://www.bhphotov...rial_mount.html

ATM, Optics and DIY Forum / Re: Not for me
« on: February 02, 2018, 07:25:21 PM »
can't sneak anything past an IF

Reflectors Telescopes Forum / Re: Solutions for balancing a Newtonian OTA?
« on: February 02, 2018, 05:00:19 PM »
One problem with placing the longitudinal counterweight is that the closer you position the weight to the altitude bearing (the fulcrum), the heavier the weight will need to be. Little children can discover this on a seesaw. If you sit closer to the end of the seesaw, your weight has more effect on the child at the other end. Remember Archimedes' saying, "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world."

So it makes sense to position the longitudinal counterweight as close as possible to the primary mirror end of the OTA. Placing this weight below the OTA partially compensates for the transverse weight of the focuser/finder when the scope is pointed toward zenith.

For the transverse counterweight itself, when the OTA is pointed to zenith, any position along the longitudinal line opposite the focuser/finder will do the trick for transverse balance. So it would make sense to place this weight closer to the altitude bearing to reduce the effect on longitudinal balance when the OTA is not pointed to zenith, and so that a somewhat lighter weight would be required at the bottom of the OTA.

However, the problem is finding a place for the transverse weight. My Dob mount does not allow much space between the OTA and the backboard.  This is why I place the transverse weight opposite the focuser/finder, where I have room.

Remember, my Dob mount does not have retention springs, does not have a tension knob nor any other detention mechanism, and I doubt if I can add one to it. If the OTA is not balanced moderately well, it will move on its own. That is why I add a compensatory weight or two to the OTA near the focuser, and why my default balance is for the heaviest setup. When the setup is lighter, I just add a weight beside the focuser.

This is also very convenient, since I am right there at the focuser when observing. I keep a small bag of weights attached to the edge of the Dob mount.  IME, while observing at the focuser, it is a PITA to get up and place an additional weight toward the bottom of the OTA, where I am not observing.


General Astronomy & Observing / Re: Enough with the clouds/rain already...
« on: February 02, 2018, 02:55:46 PM »
According to one of the local television weathermen, it's been mostly cloudy or overcast 85% of the month so far in my area.
Dave Mitsky

Reflectors Telescopes Forum / Re: Star collimation test - debris?
« on: January 31, 2018, 09:14:13 AM »
wipe them down with acetone and cotton balls.

What ever you do, please do not do this!

Coated mirrors should be cleaned in warm, soapy water - with lots of running water. You may use a cotton ball but do not apply pressure. Make a final rinse with distilled water.

GOLGO13: I can't reply to your post for some reason, so I'll just say this. I can't see the Little Dipper from my location, so I would use the Southern Cross instead. If I can easily see Epsilon my skies would be okay, and if I can see the Jewel Box then my skies would be very good. Also, I may have just, just seen the Orion Nebula from my location. So maybe 4.0 would be my limiting magnitude. I don't know as the area is awash with lights.

Beginners Forum / Re: Hello ....
« on: January 31, 2018, 03:50:24 AM »
Welcome to this family.

ATM, Optics and DIY Forum / Re: Coring Zerodur
« on: January 31, 2018, 03:25:22 AM »
Really?Its still an abrasive cutting process subject to the Twyman effect.
Yes, of course, but coring does generate a lot of heat even at slowest speeds, which is an added factor. The Twyman effect can be prevented or minimized after the coring. Eliminating the heat by water jetting is a major improvement over traditional methods.M laden
Etching is an alternative to polishng to remove the damaged layer formed by cutting.However the required etchants are a little nasty.Twyman effect measurements:

Light Pollution Topics / Re: Outdoor lighting war
« on: January 31, 2018, 01:59:59 AM »

Look up your local county code and see if it is illegal or if you think its illegal then go to the police and ask them to have a look

The sheriff's department isn't interested in doing anything about it in this rural area
Nope. It's a civil matter.

Moreover, even if he is violating some zoning code, it would be the building department (or equivalent) that would enforce the code, not the sheriff.

Spare counter weightsAttached Thumbnails

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