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#1 Terry Dactile

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Posted 21 January 2013 - 05:23 PM

I keep reading about how easy it is to find objects with a Terad finder. I have an 8" Newtonion on a DOB mount with a 9 X 50 right angle finder scope and I am having more trouble than I thought finding things. I've found a few and I know the finder scope and the telescope are aligned properly. It just seems like I get lost in the sky when looking through the finder. Do you think the Telrad would help in that regard? Also do you guys think it would be advantagous to have both the 9 X 50 and a Telrad mounted on my scope?

How about a laser pointer for pointing at items for finding. This brings to mind another thought. Lasers used for astronomy seem to be green. Is green better than red? I ask because I've taken my 5mw red laser pointer outside to try and point out objects in the sky and could not see the beam at all. Would I have been able to see the green beam?

I would really like to see more Messier objets. I've found the few in Orion but seem to get lost looking for others.

Thanks in advance for your thoughts and advice.

#2 neotesla

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Posted 21 January 2013 - 05:42 PM

Telrads are non magnifying so for myself personally I find it easier to find things. That being said for small objects the other finder will help. Use the Telrad to get in the vicinity, and the 9X50 to fine tune it.

Red lasers are not that visible, green is very much so.

#3 panhard

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Posted 21 January 2013 - 05:43 PM

Terry I use both. How is the light pollution in your area? The more light pollution you have the less a Telrad will help you. Can you see the big dipper. At our clubs viewing site I can see the big dipper and most of the little dipper a Telrad is very useful there. It is also easier to keep track of where you are in the sky with the Telrad. You can use this to find out how dark your skies are. link

#4 neotesla

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Posted 21 January 2013 - 05:47 PM

Telrad charts for Messier objects really help as well...

http://www.atmob.org...aps_jsmall.html

one example. There were links in the stickied section of the beginner forum for these, but the site appears to be dead. Google or Bing search for it.

#5 dpwoos

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Posted 21 January 2013 - 06:15 PM

You can see a lot of the messier objects with ordinary binoculars, and once you find something that way it becomes a lot easier to find it in your scope. I don't have magnifying finders on any of my scopes, but rather use a Quickfinder or Telrad to get in the ballpark and then move the scope while looking through the eyepiece to actually locate whatever. Sometimes I will start with a (much) lower power eyepiece if I am less certain of the location. You can learn a lot about how to do this by observing with your local astro club.

On the laser pointer topic, you will need a green laser to see the beam projected into the sky. Some folks mount a green laser on the scope and then use that as a finder. I have a green laser (Glatter) that I regularly use at outreach events to point at stuff, but I don't use it as a finder.

#6 csa/montana

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Posted 21 January 2013 - 06:21 PM

Telrad charts for Messier objects really help as well...

http://www.atmob.org...aps_jsmall.html

one example. There were links in the stickied section of the beginner forum for these, but the site appears to be dead. Google or Bing search for it.


There are several links for Telrad charts in the Equipment Sticky here:

Link

Sadly, Link #1, & #3 are dead, and since I'm no longer a moderator in Equip; I cannot edit them.

#7 Mike4242

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Posted 21 January 2013 - 06:50 PM

Yes, a Telrad will indeed help. It can be difficult to tell exactly where you're looking with a RACI sometimes. You can use the Telrad to get in the correct area and then use your optical finder to star hop.

#8 lamplight

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Posted 21 January 2013 - 06:58 PM

Telrads are non magnifying so for myself personally I find it easier to find things. That being said for small objects the other finder will help. Use the Telrad to get in the vicinity, and the 9X50 to fine tune it.


And then to get BACK in the right area if , like me you find your scope movements were a little too aggressive. And oops.. You're in another constellation :foreheadslap:

Like some people said I've found i need both due to inability to starhop on stars I can't see.. I see someone mention only using a telrad and low power eyepiece.. I guess that would work too , but I'm finding I'm really finding my groove using a telrad (or Rigel) for general orientation of the scope,, finder to look for some orienting markers to starhop, then finally the eyepiece. It's been another layer of lifted frustration for me personally.

Depending on the difficulty of the object I'm looking for, I can bypass the finder sometimes but often not.

#9 RogerRZ

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Posted 21 January 2013 - 07:00 PM

I have had a fleeting relationship with much of my astro-gear, but one piece I've had since day one, and is here to stay, is my Telrad. 25 years and counting with it.

Cheap, simple, efficient...

#10 Terry Dactile

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Posted 21 January 2013 - 07:02 PM

Terry I use both. How is the light pollution in your area? The more light pollution you have the less a Telrad will help you. Can you see the big dipper. At our clubs viewing site I can see the big dipper and most of the little dipper a Telrad is very useful there. It is also easier to keep track of where you are in the sky with the Telrad. You can use this to find out how dark your skies are. link

Sadly I live in the orange zone, closer to yellow than the red though. My problem lately has been wash out from the moon, but I can see the dippers on good seeing nights.

#11 Terry Dactile

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Posted 21 January 2013 - 07:11 PM

Thanks for the replies so far. From what I gather from you guys a Telrad would be a definite asset to my scope and help to not get so lost in the sky. Also sounds like a combo would be of a benefit as well.

I found the links in the sticky for the Telrad charts. Very nice tool.

So I wonder why a green laser has a visible beam outdoors and a red one does not?

I love this forum, I have learned so much by just reading through the various posts. Thanks again for the replies to my questions so far.

#12 Pharquart

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Posted 21 January 2013 - 07:31 PM

Your eye is significantly more sensitive to green light than it is to red, whether in regular vision or dark-adapted vision. See this:

http://www.ndt-ed.or...ntTest/Intro...

If it's really dark, you can see a red laser as well, just not as well as green. What you're actually seeing is the laser reflecting off dust particles, insects, and water droplets in the air, and you can only see it if you're relatively near to the laser source, looking along the length. At least for the power of lasers consumers are permitted to own legally.

I have a green laser on one scope and a Telrad on the other. Both scopes also have a 8x50 magnified finder. I use the Telrad/laser to get me started, then the finder scope to move around. In my opinion, you need a "unit power" finder (laser, Telrad, red dot finder, or simple sights) AND a magnified finder.

Brian

#13 newtoskies

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Posted 21 January 2013 - 09:22 PM

I don't own the Telrad but like the others have said, it is a good aid. I will be getting one for my dob and a Rigel for the XLt102.
Here is the link to the Telrad Charts . glad I booked marked this one.

#14 GeneT

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Posted 21 January 2013 - 09:23 PM

do you guys think it would be advantagous to have both the 9 X 50 and a Telrad mounted on my scope?


If your telescope can stay in balance, I recommend having both a Telrad and an optical finder. The Telrad will get you close, and the optical finder will give you a telescopic image, making the view at the eyepiece much easier to identify the object you are looking for.

#15 panhard

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Posted 21 January 2013 - 10:14 PM

Terry: Then a Telrad is a valuable tool, get one!
I have to drive for 30+ minutes to get to an orange zone.

#16 Tony Flanders

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Posted 22 January 2013 - 06:02 AM

I have an 8" Newtonion on a DOB mount with a 9 X 50 right angle finder scope and I am having more trouble than I thought finding things ... Do you think the Telrad would help in that regard?


Yes, hugely.

Also do you guys think it would be advantagous to have both the 9 X 50 and a Telrad mounted on my scope?


Yes, yes, yes!

Frankly, I find a right-angle finderscope very nearly unusable unless it's supplemented with some kind of unit-power finder. I'm somewhat shocked that vendors sell telescopes equipped that way; it seems like a recipe for disappointment.

The only way I would be able to use such a scope would be to sight along the tube for my initial star fix. Which works but requires some gymnastic maneuvers.

#17 kenrenard

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Posted 22 January 2013 - 06:21 AM

One easy way to mount the telrad base is with zip ties on your optical tube. If your dob gets out of balance add some large magnets to the bottom of the tube. I used cheap hook magnets from harbor freight. Four magnets has my dob balanced perfectly.

As the others have already said the Telrad and a Finder scope work well in tandem.

#18 Jon Isaacs

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Posted 22 January 2013 - 10:02 AM

Thanks in advance for your thoughts and advice.



Terry:

The combination of a Telrad and a magnifying finder is my first choice. If the skies are dark enough, most often, the Telrad is all that is required to put an object in a low power eyepiece.

If there is substantial light pollution, then the Telrad is not as useful but it can still serve to get me into the right area. A simple red dot is also worth considering, it's lighter and more compact so it may be a better fit for an 8 inch Dob.

A couple of thoughts:

- The Right Angle Correct Image finders have become very popular in the last 10 years but they do have one serious drawback when compared to a straight through finder. When using a straight-through finder, you are looking in the direction the scope is pointing, this is much more intuitive, I liken it it to aiming a rifle. I cannot imagine trying to aim a rifle with a right angle finder...

With a straight through finder, a Telrad is not as necessary because when moving towards your first guide star, you can keep both your eyes open and you see the finder cross hairs displayed across the naked eye field of view, very much like a Red Dot finder or Telrad. Once it pops into the finder, you close the other eye. I have several Newtonians, all have straight through finders, some have Telrads as well.

Most straight through finders are not correct image, some are though.

- Finder eyepiece: Do you have a low power, 2 inch widefield eyepiece, maybe a 35mm with a 70 degree AFoV? If not and assuming your scope has a 2 inch focuser, a Finder eyepiece like this makes hunting down faint fuzzies much easier because you have a much wider field of view. A 25mm Plossl provides a 1 degree field of view, a long focal length 2 inch can provide more the 2 degrees, it's like cheating...

Jon

#19 tedbnh

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Posted 22 January 2013 - 11:32 AM

Telrad: absolutely (although the Rigel Quickfinder is smaller, lighter, and works about the same.)

Green laser: I like having this too! However mounting 3 things on your dob can make it start to look like Medusa. Get yourself a green laser (Radio Shack has them for about $50) and try just shining it through the eyepiece end of your existing right-angle finder. A green beem should be visible shining out the front end of the finder scope. Just move your scope around until the beam is in the direction of the object you want to start looking for and then put the laser back in your pocket (to keep it warm) and look in the finderscope normally.

#20 ensign

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Posted 22 January 2013 - 11:34 AM

do you guys think it would be advantagous to have both the 9 X 50 and a Telrad mounted on my scope?


If your telescope can stay in balance, I recommend having both a Telrad and an optical finder. The Telrad will get you close, and the optical finder will give you a telescopic image, making the view at the eyepiece much easier to identify the object you are looking for.

If you need to choose one or the other due to balance or other issues, the Telrad is the one to keep. You can use the Telrad, as others have said, to get the scope pointed in the vicinity of your quarry and then use a low power "finder eyepiece" to further home in on the object. This approach takes advantage of the full aperture (light gathering power) of your main scope while in the process of finding objects.

After centering the object, it's then a simple matter to swap in different eyepieces to increase magnification.

#21 MawkHawk

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Posted 22 January 2013 - 11:47 AM

I do have a Telrad and a RA finder but I prefer a straight thru finder. Keep both eyes open with 1 eye at the finder and the other eye to "guide" you. A Telrad helps me only somewhat, mostly because I have not taken time to learn how to use it properly. A right angle finder alone on a scope is a crime against humanity, IMO. I would either replace it with a straight thru finder or add a Telrad.

#22 Tony Flanders

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Posted 22 January 2013 - 12:24 PM

When using a straight-through finder, you are looking in the direction the scope is pointing, this is much more intuitive.


Not for me. If anything, I find the RA finder more intuitive because I look down into it at the same angle that I look down into the main eyepiece -- and down at my charts, too.

Mind you, I have no trouble at all using straight-through finders as far as matching them up with my charts is concerned. And they certainly have the virtue of eliminating the need for a unit-power finder to get the initial fix on the sky.

However, any way you slice it, looking upward through a telescope requires a certain degree of contortion, especially when the scope is pointed high in the sky. There's a reason that almost everyone in the U.S. who owns a refractor or SCT uses a star diagonal!

I don't mind the contortion for getting a quick fix, as when looking through a Telrad, or sighting on a planet with a straight-through finderscope. But when working out a complex multi-minute starhop to a target that's not directly visible in the finderscope, I find the (literal) pain in the neck entailed in using a straight-through finderscope to be a major obstacle to mental concentration.

That's why my favorite combination, assuming no other constraints, is a Telrad plus a right-angle correct-image finderscope.

#23 panhard

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Posted 22 January 2013 - 12:28 PM

I am with you on that one Tony.

#24 SteveG

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Posted 22 January 2013 - 12:34 PM

I use a green laser exclusively, but I've kept my Telrad for star parties. My smaller scopes have RDF's but I use the laser on all of them (fits a standard finder shoe). From there it's straight to a low-power eyepiece. I've given up completely on optical finder scopes.

#25 csrlice12

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Posted 22 January 2013 - 12:46 PM

Who's gonna come out with a finderscope where the "eyepiece" can flip up to become either right angle or straight thru?????

I love the Telrad, especially in dark skies. It will get you "very close", at the very least, the object will be in your finderscopes FOV. That being said, in heavy light pollution, you won't use it. But with even some darkness, it is useable and I would not want to be without one at the dark site. Oddly enough, I moved my straight thru finder from my refractor as I've found I prefer the RACI on the refracor--and actually finding out I like the straight thru on the dob--I seem to find it easier to use. However, if something is high in the sky, the RACI would still be best as I'm getting too old to play Twister anymore.






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