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Using a Telrad for Locating Alignment Stars

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#1 Astro_Brucitor

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Posted 15 January 2014 - 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

#2 epee

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Posted 15 January 2014 - 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.

#3 Doug Culbertson

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Posted 15 January 2014 - 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.

#4 Astro_Brucitor

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Posted 15 January 2014 - 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?

#5 csrlice12

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Posted 15 January 2014 - 03:14 PM

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

#6 junomike

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Posted 15 January 2014 - 03:17 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?



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

#7 csrlice12

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Posted 15 January 2014 - 03:22 PM

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

#8 Bill Kocken

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Posted 15 January 2014 - 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.

#9 Astro_Brucitor

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Posted 15 January 2014 - 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.

#10 Eddgie

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Posted 15 January 2014 - 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.

#11 berobertsmd

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Posted 16 January 2014 - 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.
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#12 dandabson

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Posted 16 January 2014 - 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.

#13 Astro_Brucitor

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Posted 16 January 2014 - 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.

#14 csrlice12

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Posted 16 January 2014 - 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...

#15 Astro_Brucitor

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Posted 16 January 2014 - 02:56 PM

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

#16 csrlice12

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Posted 16 January 2014 - 04:41 PM

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

#17 Astro_Brucitor

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Posted 17 January 2014 - 02:52 PM

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

#18 csrlice12

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Posted 17 January 2014 - 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.

#19 Eddgie

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Posted 17 January 2014 - 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!!!!

#20 berobertsmd

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Posted 21 January 2014 - 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

#21 Dakota1

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Posted 21 January 2014 - 11:47 AM

+1 for the variable pulse unit. It should come standard.
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#22 Astro_Brucitor

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Posted 21 January 2014 - 12:10 PM

Thanks for the input guys, I ordered a Telrad and it should be coming in on Friday so hopefully I get a chance to play around with it and get it adjusted.

#23 petrus45

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Posted 21 January 2014 - 11:00 PM

I have a Telrad on my Z10, and use it exclusively, going directly to wide field EPs. I can find what I am looking for usually in a matter of seconds. I don't even use the finder scope any more.

A nice mod for a Telrad is to put flexible adhesive fridge magnets on the bottom. Then you can take it off, put it back on, and move it around very easily. I have it calibrated so if I push it up against the focuser block, and forward against the lip of the OTA it's ready to go.

One of the biggest improvements for the overall enjoyment of the scope - and for not much money.

#24 Dan Finnerty

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Posted 21 January 2014 - 11:07 PM

I have a Telrad on my Z10, and use it exclusively, going directly to wide field EPs. I can find what I am looking for usually in a matter of seconds. I don't even use the finder scope any more.

A nice mod for a Telrad is to put flexible adhesive fridge magnets on the bottom. Then you can take it off, put it back on, and move it around very easily. I have it calibrated so if I push it up against the focuser block, and forward against the lip of the OTA it's ready to go.

One of the biggest improvements for the overall enjoyment of the scope - and for not much money.


Does not work very well for my aluminum-tubed refractor. Instead, I got a roll of double-sided velcro tape. Cut two strips long enough to go around the tube with several inches of overlap. I put them on soft-side down to avoid scratching the paint. Works great, holds alignment all night, no issues and I can reposition the Telrad or easily move it to a different OTA.

#25 ThreeD

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Posted 22 January 2014 - 12:43 AM

The real power of a telrad is when used under relatively dark skies in conjunction with telrad charts. One moves the scope to the position shown on the star chart, look in a low power eyepiece and, voila, the object is there just like it wold be with DSC. It can also be used to star hop under dark skies.

In light polluted skies it can really only be used to find the brightest stars, like you would do to align DSCs or to star hop using a magnifying finder like a 9x50. If this is the only intended use then a red dot finder is all that is needed so you can save some money and weight. As others have said, you used the telrad (or RDF) to quickly locate the bright star, then move to an eyepiece or magnifying finder. If aligning, I always use relatively high power to increase accuracy.






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