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Equipment Discussions >> Reflectors

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Carl N
super member
*****

Reged: 03/18/12

Loc: San Diego, CA
Re: Anyone with a Zhumell or similar try the new Halo? new [Re: edwinh]
      #5708167 - 03/02/13 03:52 AM

I hadn't seen that preinstalled setting circle before. I also hadn't noticed that they have added a stray light shield to the tweakers dream package along with stiffer primary springs. I think those ate both good additions. Especially since its the same additional cost I paid and I didn't get them

If I were getting one new I'd opt for the built in, but you still don't have leveling feet. Although, if you are putting it on a platform, that problem is solved.


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BigC
Carpal Tunnel
*****

Reged: 09/29/10

Loc: SE Indiana
Re: Anyone with a Zhumell or similar try the new Halo? new [Re: kfiscus]
      #5708525 - 03/02/13 10:45 AM

Zounds!

Methinks I will stay with my 4 foot carpenter's level and a handful of wooden wedges for leveling, or add some adjustable furntiure feet.

And thanks to Jon Isaacs hint, a Sears magnetic digital level with 1/10 gegree readout and built-in red laser pointer now sits on the Z12 tube close to the focuser.

Trying to figure out how to adapt the works from a Meade NGC-60 for push-to indicator.

Or a tall riser mount for a Celestron SkyScout unit.


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Cames
sage


Reged: 08/04/08

Re: Anyone with a Zhumell or similar try the new Halo? new [Re: Carl N]
      #5708846 - 03/02/13 01:31 PM

Quote:

(snip) The last point references the fact that the angle gauge really is the weakest link in the whole setup. Once calibrated the HALO is perfectly fine for getting within a 12mm crosshairs eyepiece. The alt cannot be adjusted though. If the angle gauge is 1 degree off after pointing to a known object, you can't replace the value it shows. So you have to "know" how far off it is. (snip)




Carl
Regarding the annoying Wixey Inclinometer discrepancy that you often encounter…
Try these few extra steps to compensate for the error like this:

1. Apply the Angle Gauge to your favorite location on the OTA
2. Level the OTA and ‘zero’ the gauge
3. Slew to a star whose current altitude you know and center it in the eyepiece
4. Note the altitude reading on the gauge
5. Subtract the reference star’s true current altitude from the reading on the gauge while observing sign convention (Example: gauge reads 47.5 degrees, SkySafari says it is now at 46.4 degrees; the math calculation is: 47.5° minus 46.4° equals 1.1°)
6. Push the OTA down until the gauge reads 1.1° and “zero” the gauge at that incline
7. Slew back to your reference star and check the reading on your gauge. It should now approximate the star’s actual altitude more closely.

Hint: zero altitude and azimuth devices only after you have completed collimation because the act of collimating changes the point at which the telescope is looking.

Try it and see if this helps.
------
C


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Carl N
super member
*****

Reged: 03/18/12

Loc: San Diego, CA
Re: Anyone with a Zhumell or similar try the new Halo? new [Re: Cames]
      #5709012 - 03/02/13 03:35 PM

Doh! I did all that and just kept making the adjustment mentally instead of calibrating it in as you ddo in steps 6&7. Guess I'm not a smart man, Forest!

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Cames
sage


Reged: 08/04/08

Re: Anyone with a Zhumell or similar try the new Halo? new [Re: Carl N]
      #5709115 - 03/02/13 04:43 PM

Carl
You have the right idea and your way is probably easier in the long run.

According to the directions, the Wixey gauge is very sensitive to right-to-left misalignment on the OTA. In order to be accurate, the long axis of the gauge has to be perpendicular to the axis of rotation between the altitude trunnions. Any right or left deviation from perpendicular will result in a degree reading that is less than the amount of elevation that one actually raises the OTA.

If you had a misaligned gauge (say to the left of axis), and followed my 7 steps for a star at 48°, then you might be able to get pretty close agreement on a target at 48° elevation but later on find that you are shy of your target by the time you reach for a target at 75° elevation. In fact, if you notice that you are losing gauge accuracy the higher (or lower) you go, there’s a good chance that the gauge is skewed either right or left of where it should be pointed.

So, you see, the problem becomes how accurately can one align that stubby gauge to be perpendicular to the altitude axis anyway? Using your approach, one avoids all the fiddling around with aligning and zeroing; and, simply adjusts the fudge factor along the way. It’s best to follow whatever procedure works for you.

Edit: By the way, the easiest way I can think of as a means to properly orient the long axis of the angle gauge is at step 4: Before you take the reading of your reference star elevation, slowly and carefully nudge the gauge to the left and right. Stop at the point where the angle reads the highest value. Take that value as your first altitude reading.
------
C

Edited by Cames (03/02/13 06:23 PM)


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Carl N
super member
*****

Reged: 03/18/12

Loc: San Diego, CA
Re: Anyone with a Zhumell or similar try the new Halo? new [Re: Cames]
      #5709234 - 03/02/13 05:57 PM

Your'e too kind.

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