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Should I Get Rid of the Telrad?

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#1 Sarkikos

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Posted 28 January 2013 - 09:26 AM

I use a Telrad on my 10" Dob. But I haven't drunken the Telrad Kool-Aid. I also have eight Brandons, though I don't consider myself a Brandonista.

I don't think Telrads are perfect. They are bigger and bulkier than they need to be. The length could easily be cut in half. Some users have actually done this - cut their in Telrad in half to save space on the OTA. Sounds like a good project to me.

One negative consequence of reducing the length of the Telrad, is that it would no longer fit on a riser. Which brings up another fault of this finder: it is too low to the OTA. Without a riser, it can be uncomfortable to get close enough to the OTA to sight through the Telrad, and you risk bumping the scope.

Also, Telrads dew too easily. The Telrad is the first thing to dew over on my scopes. There is no good solution to the Telrad's dew problem - I've tried them all, I believe - except to stick a special dew buster prong under the view screen and make sure the battery is strong and fully charged.

Some Telrad owners use the three concentric circles to help them star hop to objects. This always seemed more trouble than it's worth. You need to find out the distance between a star or asterism and the object, and then figure out the number of star hops of which circle to get there. This can involve star hopping across many degrees of empty space - so to speak - with no easily visible stars to delimit the hops. For some objects, you might need to do this several times.

Do I really want to put this much effort into planning and executing a star hop? No, not really. So I don't. I like to "plan" my star hops on-the-fly. I find the naked-eye star nearest to the object, sight on that star with the Telrad, and then star hop with my 15x70 optical finder, referencing a good printed atlas or StarSafari on my tablet. IME, this is much easier than trying to star hop with a naked-eye, 1x finder.

On the other hand, I do use the Telrad for simple geometrical triangulations. For instance, M101 is at one apex of an equilateral triangle with Alkaid and Mizar toward Draco. Put the bull's eye of the Telrad in that position, and it will be close to M101. But I could do this with a QuickFinder or Red-Dot. A Telrad with its fancy triple-circle bullseye isn't necessary.

I'm experimenting with replacing the Telrad with a straight-through true erect-image optical finder. I've never liked the fact that the Telrad can only show me naked-eye stars. For a long time I've thought that a straight-through erect-image non-reversing finder with a little magnification would be the ideal replacement for a Telrad. Such a finder might even do the job of both a Telrad and an optical finder for star hopping.

Recently I bought an ES 8x50 Erect Image Illuminated Finder. It is straight-through and does not reverse the image. I'm hoping this will be the ideal replacement for my Telrad.

Mike

#2 Doug Culbertson

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Posted 28 January 2013 - 10:52 AM

I use a Telrad on both of my dobs, and a Rigel Quickfinder on my refractor. In all honesty, I have always felt that the Telrad is just about the most useless tool for starhopping ever created, for the reasons that you already laid out.

Nowadays I only use the Telrad to align my DSCs, as it's pretty convenient for quickly aligning my alignment stars with the telescope. Once that's done I turn off the Telrad until I decide to look at Jupiter or Saturn.

FWIW, of late I have found that on my ASGT mounted refractor I prefer a RACI finder over the Rigel for doing my alignments and calibration for gotos because it is more convenient than the Rigel.

If I still starhopped, I would have abandoned the Telrad long ago.

#3 Tom Polakis

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Posted 28 January 2013 - 11:21 AM

I don't think Telrads are perfect... The length could easily be cut in half.

Which brings up another fault of this finder: it is too low to the OTA. Without a riser, it can be uncomfortable to get close enough to the OTA to sight through the Telrad, and you risk bumping the scope...

Some Telrad owners use the three concentric circles to help them star hop to objects. This always seemed more trouble than it's worth.

Do I really want to put this much effort into planning and executing a star hop? No, not really. So I don't. I like to "plan" my star hops on-the-fly. I find the naked-eye star nearest to the object, sight on that star with the Telrad, and then star hop with my 15x70 optical finder, referencing a good printed atlas or StarSafari on my tablet. IME, this is much easier than trying to star hop with a naked-eye, 1x finder.



Sorry for chopping up your post. Agreed that Telrads are anything but perfect. As you point out, they are too long and too low. If you don't care for the three rings, the high-profile Rigel Quickfinder seems like it would be the preferred option. Oh, and thanks for referring to it as a "1x finder rather than the dreaded "zero power," which would shrink the universe to a singularity.

I don't plan star hops, either, but I would defend the bullseye circles as being much more useful than a single circle. If the bullseye rings had an arbitrary size, they would have limited usefulness, but the 1/2, 2, and 4 degree diameters are great for comparing to a chart with a grid. I have a pretty good feel for angles on the sky by now, and those diameters are just about perfectly designed.

I agree that a combination of a 1x and a low-power finder is the way to go. It will be interesting to learn how you fare using a finderscope with very low magnification. Something with a 15-degree field (4x or so?) that goes to magnitude 8 or 9 under a dark sky might be enough to really improve matters.

Tom

#4 RAKing

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Posted 28 January 2013 - 11:24 AM

Mike,

I use both a Telrad and a RACI finder for star-hopping. The Telrad is faster to get me to the 'hood, then the RACI takes over. I use an 11mm Nagler T6 in my RACI because it gives me the same FOV in the SV50 as the outer ring of the Telrad.

If you are good enough working with plastic to shorten your Telrad, shortening the riser should not be an issue. I haven't shortened my Telrad, but I have disassembled my risers and rebuilt them to better suit my needs. They are plastic and glue or epoxy works fine. :)

Cheers,

Ron

#5 beatlejuice

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Posted 28 January 2013 - 11:24 AM

Mike,

They are bigger and bulkier than they need to be.



Whether it needs to be or not, I'm not sure, but this is compensated for by its light weight.



The length could easily be cut in half. Some users have actually done this - cut their in Telrad in half to save space on the OTA. Sounds like a good project to me.



There is plenty of room on a 10" or larger dob. It may look odd, but do you really need more room?

Without a riser, it can be uncomfortable to get close enough to the OTA to sight through the Telrad, and you risk bumping the scope.



This is certainly true, but the fact is that risers are available, inexpensive and they work.
Also, I don't see how a straight through finder will get you much higher off the tube then the telrad without a riser.

Also, Telrads dew too easily. The Telrad is the first thing to dew over on my scopes. There is no good solution to the Telrad's dew problem - I've tried them all, I believe



Yes they do dew easily. I just wipe it off with a small cloth that I keep handy. Starman1(Don) says he wipes it off with his fingers! The telrad dew shield helps a bit between uses but wiping it off works for me.

Methods of use probably depend more on how dark your skies are more than anything else. I just like it as a pointer to get me to a starting point for using my finder ( at times a difficult process under light polluted skies). Under darker skies it really comes into its own allowing you to often go directly from telrad to your low power eyepiece.

I am curious about a straight through right side up finder. I did't know you could get one.

Trying to re-invent the Telrad has been going on for many years and as far as I am concerned, I like it the way it is.

Eric

#6 Sarkikos

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Posted 28 January 2013 - 11:24 AM

Doug,

I use a Telrad on both of my dobs, and a Rigel Quickfinder on my refractor. In all honesty, I have always felt that the Telrad is just about the most useless tool for starhopping ever created, for the reasons that you already laid out.


Thank you. My sentiments exactly. I was concerned that I might only receive posts that claim the Telrad is the greatest advancement in astronomy since the sextant. Sometimes I think the Telradistas are greater fanboys than the Brandonistas. I can say that since I have a Telrad and eight Brandons. :grin:

There is an inherent contradiction in using a Telrad to star hop. If you're at a fairly light-polluted site, how are you supposed to star hop with a Telrad from a bright star to your intended object with no naked-eye stars in the intervening space? How do you know when you've moved the telescope the distance of a Telrad circle? There are no visible stars to delimit each move. Not intuitively obvious and impractical in actual use.

On the other hand, if you are at a dark site with plenty of naked-eye stars, why do you need to star hop with the Telrad? Just point it at the visible star or asterism closest to the object and then star hop with a magnifying optical finder. It just makes more sense.

As I've said, the only exception to this protocol is when there is an easy and obvious geometrical triangulation with the Telrad available for the object. And that is often not the case. Even when the geometry is there, a short star hop with the optical finder is usually necessary.

Mike

#7 Jim Rosenstock

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Posted 28 January 2013 - 12:02 PM

The Telrad is a classic--big and clunky, indeed, but a good match for the big, clunky home-made Dobs they first went on... :bow:

Two of the biggest "Aha!" moments in my years of observing were the first time I used a Dob, and the first time I used a Telrad. I had found my comfort zone! :bow:

I use Rigel finders now, but must acknowledge Telrad as the original classic! :bow:

Jim

#8 droid

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Posted 28 January 2013 - 12:06 PM

Mike; being only being a middle of the road star hopper, I just love the telrad, of course it isnt perfect, not much of my equipment is, but with all my charts and at least one of my books being based on the telrad I would be lost honestly.
I also use a 50mm finder, and plan to use an 80mm finder, on the scope with the telrad, use the telrad to get close, finder to fine tune and then the main scope.All my scopes have mounting plates from which my two telrads are shared.
All that said, thats me, and may not be for everyone.

To each his own, live and let live, and all that. :tonofbricks:

#9 nevy

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Posted 28 January 2013 - 12:50 PM

There is a way to keep the telrad dew free all night even in the worst dewy conditions, it requires no batteries and is very light and it can be put on and took off in about 2 seconds , when I get time I'll post a picture of it.

#10 Don Trinko

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Posted 28 January 2013 - 12:58 PM

For my dob I prefer the telrad. Yes there are some negatives but it is the one I use the most.
I do like GLP's but when its anywhere near cold or light they do not work. All IMO; Don t.

#11 rmollise

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Posted 28 January 2013 - 01:07 PM

The Telrad isn't perfect--just better than anything else. :lol:

#12 t.r.

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Posted 28 January 2013 - 01:07 PM

I hate the Telrad! I have turned down the purchase of used scopes because it was mounted to them. In my mind it devalues them. I think for dobs they may be the right choice, but when I see these slapped on top other scope types...I cringe!!! :tonofbricks: Just me and my own hang-up!

#13 Sarkikos

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Posted 28 January 2013 - 01:21 PM

Tom,

Sorry for chopping up your post.


No need to apologize. What I don't like is when someone quotes an entire lengthy post, especially when they only comment on one or two points. Are they afraid of being accused of taking something out of context? Just quote what you need to and don't worry about it. That's what I do. ;)

Agreed that Telrads are anything but perfect. As you point out, they are too long and too low. If you don't care for the three rings, the high-profile Rigel Quickfinder seems like it would be the preferred option.


Yes, especially if you're going to mount it on a smaller scope. I wouldn't be surprised if someone hasn't mounted a Telrad on an ST80 or binoculars!

But I have mounted the Quickfinder on my ST80, my 90mm Mak and even my 150mm Mak. It can get to the point, though, where you're mounting a finder on a finder. For example, at one time I had the Quickfinder on my 25x100 binos. Finally, I took it off. I realized that I could find objects just as easily by just looking through the binoculars. :shrug:

I don't plan star hops, either, but I would defend the bullseye circles as being much more useful than a single circle. If the bullseye rings had an arbitrary size, they would have limited usefulness, but the 1/2, 2, and 4 degree diameters are great for comparing to a chart with a grid. I have a pretty good feel for angles on the sky by now, and those diameters are just about perfectly designed.


The rings haven't been so useful for me. I have a good idea of the relative field size of my optical finder versus the layout on printed charts, or on SkySafari for Android. Then I just look for simple asterisms on-the-fly, star hopping from one to the next until I reach the desired object. I don't spend much time at all looking through the Telrad.

I agree that a combination of a 1x and a low-power finder is the way to go. It will be interesting to learn how you fare using a finderscope with very low magnification. Something with a 15-degree field (4x or so?) that goes to magnitude 8 or 9 under a dark sky might be enough to really improve matters.


The ES finder is an 8x50. The total FOV is 6 degrees. Like a Telrad, the illuminated reticle has an open center so it won't mask the object. The reticle has markings for for 1.5, 3, and 4.5 degrees. For my purposes, about a 4x or 5x finder might have been better, but I'll see how this one works for me.

Up to now I've had the Telrad and a 15x70 optical finder on my 10" Dob when I go to a dark site. I plan on using the ES 8x50 straight-through as a direct replacement for the Telrad. I'll use the ES 8x50 in tandem with the 15x70. The 15x70 is a RACI, and is a nice RFT as well as star hopper. Also, since it is a RACI, it's much more comfortable to use for longer star hops and for a low-power wide-view look at an object than is a straight-through finder.

I'm also thinking about mounting the ES 8x50 by itself on my C6. It is my medium size grab-n-go for at home. The ES 8x50 would take the place of an optical finder for double stars and brighter DSO. And it would serve the purpose of a QuickFinder/Red-Dot for centering the C6 on the Moon and bright planets. It's nice to have more than 1x when refinding a planet with a mount that doesn't track.

Mike

#14 Sarkikos

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Posted 28 January 2013 - 01:30 PM

Ron,

I use both a Telrad and a RACI finder for star-hopping. The Telrad is faster to get me to the 'hood, then the RACI takes over.


Yes, a straight-through - whether red-ring/dot or optical - is much easier than a RACI for initially sighting a star for the beginning of a star hop or for centering the scope on a planet or the Moon. But after that, the optical RACI is better and more comfortable for extended star hopping or low-power observation, of course.

If you are good enough working with plastic to shorten your Telrad, shortening the riser should not be an issue. I haven't shortened my Telrad, but I have disassembled my risers and rebuilt them to better suit my needs. They are plastic and glue or epoxy works fine.


Plastic, foam core and such are easy materials to work with. It's the metal and wood that are not so good for me without a workshop or extensive tools. :grin:

I've already cut the middle section out of the base of my Telrad riser. A little hand saw made that easy enough. I did that so I could attach a shoe for the ES 8x50 between the two ends of the Telrad base. That would give me the option of using either the Telrad or the ES finder, until I determined which I liked better.

Mike

#15 Sarkikos

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Posted 28 January 2013 - 01:34 PM

Jim,

I use Rigel finders now, but must acknowledge Telrad as the original classic! :bow:


Yes, it is a classic. :ubetcha: Even if the ES finder replaces the Telrad for me, I might not sell the Telrad. I might still find a use for it on one of my scopes, especially if I cut it down to size. Besides, they are inexpensive new and don't sell for much used. Hardly worth the effort to sell it.

Mike

#16 Sarkikos

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Posted 28 January 2013 - 01:35 PM

Rod,

The Telrad isn't perfect--just better than anything else. :lol:


Give me time ... I'm working on that.

:grin:
Mike

#17 Tom Polakis

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Posted 28 January 2013 - 01:42 PM

I hate the Telrad! I have turned down the purchase of used scopes because it was mounted to them. In my mind it devalues them. I think for dobs they may be the right choice, but when I see these slapped on top other scope types...I cringe!!!


Man, you'll really cringe when you learn that there's a Telrad on the 48" UK Schmidt at Siding Spring Observatory, and on the 60" at Mount Wilson, shown below. I have seen Telrads on other observatory scopes, and they are only installed for the case when the pointing is not established or working correctly.

Tom

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#18 Sarkikos

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Posted 28 January 2013 - 01:46 PM

Don,

For my dob I prefer the telrad. Yes there are some negatives but it is the one I use the most.
I do like GLP's but when its anywhere near cold or light they do not work. All IMO; Don t.


Yep, I went through a period when I was captivated by the idea of mounting GLPs on my scopes and just having that beautiful green beam point to the object. Neat. You don't even have to bend over to look through any viewer or eyepiece to do it. But I quickly discovered that at least 3/4 of the year it gets too cold here at night for the GLPs to work. Went through several GLPs, GLP mounts and related gizmos before I gave up on the idea. But I still have GLPs mounted on my 4.5" Ball Scope and my 3" FirstScope reflector. I take out those scopes for hand-held, walk-about viewing in the summer.

Now I mostly use GLPs to show my daughter, wife and other newbies the location of constellations and objects in the sky. And, of course, that's only during the warm summer nights when the *** things will work.

:grin:
Mike

#19 Sarkikos

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Posted 28 January 2013 - 01:48 PM

Tom,

Man, you'll really cringe when you learn that there's a Telrad on the 48" UK Schmidt at Siding Spring Observatory, and on the 60" at Mount Wilson, shown below. I have seen Telrads on other observatory scopes, and they are only installed for the case when the pointing is not established or working correctly.


Did someone stick a Telrad on that big telescope as a joke? If any scope needs goto, well ....

:grin:
Mike

#20 Sarkikos

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Posted 28 January 2013 - 01:52 PM

t.r.,

I hate the Telrad! I have turned down the purchase of used scopes because it was mounted to them. In my mind it devalues them. I think for dobs they may be the right choice, but when I see these slapped on top other scope types...I cringe!!! :tonofbricks: Just me and my own hang-up!


I don't think I'd pass up a good scope at a good price because the owner stuck on a Telrad. But I'd be ready with the dental floss and Goop Gone as soon as I got my hands on it.

My 150mm Rumak came with a Telrad base. :foreheadslap:

Mike

#21 rmollise

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Posted 28 January 2013 - 02:32 PM

Rod,

The Telrad isn't perfect--just better than anything else. :lol:


Give me time ... I'm working on that.

:grin:
Mike


Go got it! :cool:

#22 beatlejuice

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Posted 28 January 2013 - 02:39 PM

I wouldn't be surprised if someone hasn't mounted a Telrad on an ST80 or binoculars!



Guilty, I am a 'Telradista'

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#23 t.r.

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Posted 28 January 2013 - 02:40 PM

Man, you'll really cringe when you learn that there's a Telrad on the 48" UK Schmidt at Siding Spring Observatory, and on the 60" at Mount Wilson


http://www.youtube.c...h?v=g6GuEswXOXo

#24 demiles

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Posted 28 January 2013 - 02:52 PM

As you may know Mike I use the Telrad exclusively on my Dob,no optical finder for me. Having to add two more dew heaters and more battery power for the optical is the only reason I don't use one. FYI I have no issues finding objects/star hopping, red dots are all I ever used. I do use the Rigel finder on small refractor.

#25 Jon Isaacs

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Posted 28 January 2013 - 03:52 PM

If you don't care for the three rings, the high-profile Rigel Quickfinder seems like it would be the preferred option.



The Rigel appears to be taller than the Telrad but if you measure the height of the reticule, they are within 1/8" of each other.

I have 4 scopes with Telrads, they all have magnifying finders as well. When the skies are dark and clear, I use the Telrad most of the time. It's particularly handy for identifying unknown objects.

I suspect the ES finder won't be a replacement for the Telrad. The TFoV of the Telrad is huge.

Jon






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