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Equipment Discussions >> Equipment

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Astro_Brucitor
member


Reged: 08/19/13

Using a Telrad for Locating Alignment Stars
      #6314188 - 01/15/14 11:29 AM

Hey Everyone,

I've done some research here on the forums and there are quite a few posts around the benefits of using a Telrad instead of a finder scope.

It seems the Telrad is very useful for "star hopping," and some people loosely mention its useful for finding alignment stars as well.

So I am curious how many people use a Telrad to find alignment stars, and how useful is the device for centering alignment stars in your eyepiece?

If you're reading this thread and never heard of a Telrad, here is a link to one on telescopes.com: Telrad Link on Telescopes.com


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epee
Pooh-Bah


Reged: 11/30/06

Loc: Suh-van-nuh, Jaw-juh
Re: Using a Telrad for Locating Alignment Stars new [Re: Astro_Brucitor]
      #6314201 - 01/15/14 11:40 AM

I use a Rigel Quickfinder (another version of reflex finder) for the same reason. Two-star alignmnet, especially with a "push-to" intelliscope, requires a speedy aquisition of the second star before the Earth's rotation changes the first star's position very much. I find a reflex finder helps me get the target into the field of view much faster than sighting along the OTA and using a telescopic finder.

On its own the reflex finder is not accurate enough for accurate alignment.


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Doug Culbertson
Post Laureate
*****

Reged: 01/06/05

Re: Using a Telrad for Locating Alignment Stars new [Re: Astro_Brucitor]
      #6314202 - 01/15/14 11:41 AM

I have used goto or push-to telescopes for years, and the Telrad is all that I have ever used to locate my alignment stars. Since the reticle in the Telrad is adjustable, I usually use a fixed object to align it with the view in my eyepiece. Once it's done, it usually stays that way for a long time between adjustments.

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Astro_Brucitor
member


Reged: 08/19/13

Re: Using a Telrad for Locating Alignment Stars new [Re: Doug Culbertson]
      #6314644 - 01/15/14 03:04 PM

Thanks Doug and Jim for the responses, now my second question is when the alignment star is inside the inner most circle, does that also mean the alignment star is inside the Telescopes eyepiece?

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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Using a Telrad for Locating Alignment Stars new [Re: Astro_Brucitor]
      #6314664 - 01/15/14 03:14 PM

If using a low power finder widefield, and you properly aligned the Telrad, it should be...

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junomike
Carpal Tunnel
*****

Reged: 09/07/09

Loc: Ontario
Re: Using a Telrad for Locating Alignment Stars new [Re: Astro_Brucitor]
      #6314671 - 01/15/14 03:17 PM

Quote:

Thanks Doug and Jim for the responses, now my second question is when the alignment star is inside the inner most circle, does that also mean the alignment star is inside the Telescopes eyepiece?




Yes, Provided you've previously calibated/aligned the Telrad with your scope.
I've used a Telrad and MRF for all my Star Alignments and find It easier than using a Finderscope due to the simple fact you really have unlimited FOV in a Telrad.

Being 1X's, you can just slew Telrad into the direction of the Star and when you get close, look at the "bull's eye" until the Star is centered.

Mike


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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Using a Telrad for Locating Alignment Stars new [Re: junomike]
      #6314686 - 01/15/14 03:22 PM

For the greatest astronomer in the world, the stars align themselves to his telescope.....

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Bill Kocken
sage


Reged: 08/07/04

Loc: Coon Rapids, MN
Re: Using a Telrad for Locating Alignment Stars new [Re: csrlice12]
      #6314752 - 01/15/14 03:43 PM

I use the Telrad to get the alignment star in my eyepiece. Then I switch to a high power EP or an EP with crosshairs to center the star precisely. I do not think the time it takes to find the stars and center the stars is crucial because your DSC's clock is running to allow for that. The only crucial time is the small amount of time between when you've centered the star and when you actually hit the "Enter" button on your DSC. That time is only a matter of a second or 2 and it isn't material.

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Astro_Brucitor
member


Reged: 08/19/13

Re: Using a Telrad for Locating Alignment Stars new [Re: Bill Kocken]
      #6314837 - 01/15/14 04:18 PM

Bill, Mike, and csrlice12,thanks guys for the input, I believe that answers all my questions about the telrad.

I also appreciate the fact the Telrad maintains its alignment with the main telescope. The finder scope on my 6" Newtonian is fine optically however the piece that holds and attaches it to the telescope is pretty shaky and needs to be modified in order to hold the finder scope still enough to not adjust.

Even then I'm still anticipating the finder scope will need to be calibrated over and over again. A little frustrating for something so critical, in the alignment process.

I think I will order a Telrad and give it a whirl. I have had success with the finder scope, but $40 to make my life easier is definitely worth it.


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Eddgie
Postmaster
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Reged: 02/01/06

Re: Using a Telrad for Locating Alignment Stars new [Re: Astro_Brucitor]
      #6314854 - 01/15/14 04:28 PM

I used them for a decade on all my Go-To scopes for alignment.

Even with my C14, I could get the alignment star near the center of my eyepeic field just using the Telrad.

I would even use them for rought polar aling.

I would just put the "Telrad Overlay" on my astro-program with the time and date and move the display to the NCP.

Then, I would note about where Polaris was in the program's display.

I would then go out and home position my CGE, then just use the azimuth adjsutment to bring Polaris into the same positino relative to the Telrad finder in the program.

I could get a pretty decent alignement this way, and slew to first alighment star was usually within a degree or less.

And once aligned, I would usually just turn it off.

I would use the Telrad sometimes for manual finding.

But mostly I only used it for alignment.

Worked great.

I no longer use traditional finders. Haven't for a very long time now.

With the Go-TO dob, I don't even use a Telrad anymore. Just the BB Gun sight. On for alighment, off for everything else.

The handset even reminds you to turn it off.. LOL.


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berobertsmd
super member


Reged: 09/28/09

Loc: Brandon, Mississippi
Re: Using a Telrad for Locating Alignment Stars new [Re: Eddgie]
      #6315841 - 01/16/14 03:50 AM

Just out of interest, I'm Left eye dominant and added the 2" riser base to my Telrad. I found it much easier to see the reticle and target area, and the entire unit is very steady.
Bruce


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dandabson
super member


Reged: 10/15/08

Loc: Dover, DE
Re: Using a Telrad for Locating Alignment Stars new [Re: berobertsmd]
      #6315891 - 01/16/14 06:17 AM

I use a Telrad on my 203/F4.9 newt. The Telrad mounting bracket has been mounted to the tube for more than 5 years with double sided 3m mounting tape. I have not had to realign my Telrad since mounting it on the tube. Once properly adjusted it should be fine between uses if you don't knock it out of alignment. If properly adjusted the Telrad will get your alignment star in the fov of a low power eyepiece. Just remember the alignment star is normally the brightest star shown in the vicinity of where it is pointing. I find I rarely use the 9X50 finder I also have mounted on the tube. I remove it every session and it has to be adjusted.

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Astro_Brucitor
member


Reged: 08/19/13

Re: Using a Telrad for Locating Alignment Stars new [Re: dandabson]
      #6316449 - 01/16/14 12:47 PM

Eddgie: I didn't even think about trying to polar align the scope with the Telrad thanks for info.

Bruce: Funny you mention being left eye dominant, because I'm also left handed and left eye dominant, so I'll check out getting the riser if it poses any problems, good to know there is a solution.

Dan: Thanks for the input, its always nice to hear another success story before I plop down some money into more gear.

I'm also having a similar issue with my finder scope, while I just leave mine attached to the OTA, it's not securely fastened enough within the bracket that holds it to maintain proper alignment with the telescope.

Then there's also the issue of getting the finder scope to properly adjusted to begin with.


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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Using a Telrad for Locating Alignment Stars new [Re: Astro_Brucitor]
      #6316534 - 01/16/14 01:31 PM

Truthfully, after collimating the dob, the next thing I do is tweek the finder and Telrad (rarely does the telrad need tweeking). But then I have to travel to use my scopes...

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Astro_Brucitor
member


Reged: 08/19/13

Re: Using a Telrad for Locating Alignment Stars new [Re: csrlice12]
      #6316718 - 01/16/14 02:56 PM

Yeah but I imagine the Telrad doesn't need adjusting after traveling right? Assuming you don't bump it excessively.

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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Using a Telrad for Locating Alignment Stars new [Re: Astro_Brucitor]
      #6316911 - 01/16/14 04:41 PM

Rarely does the telrad need tweeking, but it seems the finder needs tweeking every time.

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Astro_Brucitor
member


Reged: 08/19/13

Re: Using a Telrad for Locating Alignment Stars new [Re: csrlice12]
      #6318857 - 01/17/14 02:52 PM

By the finder you mean the alignment between the Telrad finder and the telescope eyepiece?

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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Using a Telrad for Locating Alignment Stars new [Re: Astro_Brucitor]
      #6318920 - 01/17/14 03:18 PM

Nope, have a 9X50 RACI and the telrad. The Telrad rarely needs touched except to turn it on/off...The RACI needs alignment tweeking most every time I take it out.

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Eddgie
Postmaster
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Reged: 02/01/06

Re: Using a Telrad for Locating Alignment Stars new [Re: Astro_Brucitor]
      #6319171 - 01/17/14 05:36 PM

I had a Telrad on my C14 and don't think I had to touch the alignment once.

I did transport it from time to time, but was careful not to bump into it though I did bump into it really hard with my head once. It hurt!!! The sharp corner put a big scratch on my forehead.

I relocated it further forward on the OTA and that never happened again. I was getting up out of my observing chair with the scope pointed near zenith and when I stood up, I was leaning forward a bit, and ouch!!!!


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berobertsmd
super member


Reged: 09/28/09

Loc: Brandon, Mississippi
Re: Using a Telrad for Locating Alignment Stars new [Re: Eddgie]
      #6325932 - 01/21/14 11:25 AM

There is another Telrad feature I find useful, not for alignment, but with fainter targets. In addition to the fader feature that give variable brightness, there also is an add-on variable pulse feature which allows you to have the control over the brightness and also have the reticle flash on and off at the speed you wish. The 2 controls operate independently for each other.
Bruce


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