telerad,minor miracle or ?

[hes not well again]

I must admit to being a bit confused about the whole telerad thing. Within these pages are people who claim that they are the best thing since sliced houmus. Since its unlikely that they are doing so at the point of a gun by some unknown third party I must conclude that they are telling the truth. The trouble that I am having in my happy ignorance is as follows:-

1 As the telerad works as I understand it by projecting a circle of light on to a screen, does this not wash out what you are trying to see.

2 Because it does not magnify does this not make homing in on dso's difficult because you can't see them, especially in poor seeing.

As you can see, no man could easily beat me in ignorance of telerads and I write this in the hope that I will become a wiser, and thus happier person. No longer will people rush up to me in the street with urgent enquiries about telerads only for me to hang my head in shame and confess the dreadfull truth.

[Stephen]

1) The Telrad has a variable brightness control - you can set it dim enough to see what's beyond

2) You use it in a star hopping methodology, just because you can't see it - doesn't mean you can't point the telrad circle at the place in the sky where it's supposed to be

EG I know that DSO XYZ is 1/2 a telrad circle above bright star 123 (From Stellarium or any Telrad chart.) : So if I put the telrad circle where the chart says, I must (reasonably) be pointing at the target

[hes not well again]

So the method would be to point at the sky where the object is supposed to be and then start with a low power ep to find the object

[Stephen]

So the method would be to point at the sky where the object is supposed to be and then start with a low power ep to find the object

Bingo

[John]

All these red dot finders work by projecting a dot, circles, a cross or similar of light onto a screen. In the dark you look through and past the screen and actually focus on the sky beyond it. The dot / circles / etc appear to be project on the sky. By making sure beforehand that the above marker is pointed exactly where your scope points you can be sure at night that the dot / circles / etc mark exactly where the scope is pointed.

Having done your homework and using star charts to determine where an object is, once you have aligned the scope quite precisely on that area the object in question should be in or close to, the field of view of a low power eyepiece.

The Telrads and the Rigel Quikfinders project circles of defined diameter against the sky, ie: .5, 2 and 4 degrees (just 2 with the Rigel). This helps with star hopping as your star chart can show you how far an object is from a certain star and in which direction it lies.

There are some circumstances when using an optical finder is also useful to zero in on something like a fainter planet or binary star.

As with all equipment, Telrads and other red dot type finders don't suit everyone but their popularity shows that for many they really do make life easier.

No magic involved though !

Edit: I see that Kh3ldar has provided a more concise explanation while I have been typing !. As he says they can be adjusted to be very faint - just visible against the black sky so not drowning out anything.

[hes not well again]

Thank you all for your concise and patient replies. I feel happier already.

[Stephen]

Edit: I see that Kh3ldar has provided a more concise explanation while I have been typing !. As he says they can be adjusted to be very faint - just visible against the black sky so not drowning out anything.

Yours was much more informative though

[Moonshane]

best bet is to try one and I reckon you'll never look back. the only exception for me is a short refractor in which case a Rigel would be better. I am almost lost without mine. I use the telrad for initial positioning and then home in with the 9x50 finder (usually it's then in the eyepiece - even a higher power one).

[hes not well again]

I must admit I don't have a finder of any description on my 8" newt. My method is to point it in the general direction and swear at it until it works. In my experience no piece of technology can withstand a really sustained burst of profanity. However a telerad seems much better.

[Moonshane]

seriously, a Telrad will transform your ability to point the scope to the right area of sky and make your observing more enjoyable.

[hes not well again]

They seem a lot cheaper than a good finder scope, could you manage without your 9x50 finder or do you need both?

[Moonshane]

if I had to make the choice I'd have the telrad first. for me, ideally both is better but get the Telrad first and you may never need another finder. your advantage (based on your location) is that your skies must be a lot darker than mine which makes a Telrad even easier to use accurately.

I found at a dark site that I could pick out things like the Dumbbell in the 9x50 finder after initial placement with the telrad. even at home I can see M31 and M13 etc in the 9x50.

[rubberman]

seriously, a Telrad will transform your ability to point the scope to the right area of sky and make your observing more enjoyable.

Yup since I fitted one to the dob, makes finding objects of interest a doddle even in my light polluted sky. A Telrad combined with Stellarium & a ever improving knowledge of the night sky is a winner.

[hes not well again]

I suppose with an optical finder at the best you only get about 5 degrees of sky. Where I am the sky is dark enough to see the orion nebula with naked eye quite clearly.

[twotter]

Dew prone, ugly, boxy monstrosities!

Vote RDF

Pretend you're in a SWAT team with a single red dot

This has been a public information message from the Red Dot Liberation Front :D

[David Smith]

Have to admit I am lost without my RDF, the discovery of a flat battery leaves me bewildered and concerned that I will have to "do it the hard way". The 8 x 50 finder I have is reserved for special occasions these days!

Quite like the idea of simply swearing at the scope until it points itself!

David

[hes not well again]

Rdf? New vistas of not having a clue have opened up. Does the red dot bounce of the atmosphere or what? Your not actually projecting a dot on to a dso are you?

[Astro Imp]

All the above is good advice but one thing that hasn't been mentioned is to use both eyes open when using a Telrad (as you would with a straight through finder.)

[Moonshane]

the dot/target is projected onto a little glass screen and this what you see from behind. it's like it is projected but is not.

[Moonshane]

quite right Alan - I keep forgetting to mention this myself!

[hes not well again]

What about paralax error, does it have a back sight to enable you to line your eye up properly? The rdf seems to have one in the photo

[Alma]

Dew prone, ugly, boxy monstrosities!

Vote RDF

Completely agree, Telrads have been around for over 30 years and it shows.

The best RDF i.m.o.h. is the current Baader 40mm Sky Surfer V .... metal construction, has its own built in dew shields, big 40mm projection screen so it's easy to see the projected dot, and not that much more expensive than a Telrad.

[John]

What about paralax error, does it have a back sight to enable you to line your eye up properly? The rdf seems to have one in the photo

No it doesn't have that - a few RDF's do but you can't see them at night, just the red dot. I believe these things are closely related to gun sights which is why some have that feature.

If these devices had significant flaws they would have fallen by the wayside years ago - the astronomy community is very quick to find the weak points in something and vote with it's feet

The Telrad has existed in the design we see today since 1982. There are many other red dot / reticule designs around nowadays but the Telrad maintains a very strong following particularly with Newtonain users.

[Chris H]

The RDF and Telrad work the same way keep both eyes open when using and there is no parallax.

I had a RDF on my Skywatcher Heritage but the Telrad is better, IMO. Dew however is a problem but you just have to make a DIY dew shield.

When I got a Telrad I removed my 8x50 finderscope and have never looked back. My skies are pretty dark and with the Telrad I can easily point the scope at DSO's, over time you just learn where they are and with more stars visible to the naked eye it makes locating them even easier. Don't know how you manage without a finder of any sort must take ages to line the scope up.

[hes not well again]

The RDF and Telrad work the same way keep both eyes open when using and there is no parallax.

I had a RDF on my Skywatcher Heritage but the Telrad is better, IMO. Dew however is a problem but you just have to make a DIY dew shield.

When I got a Telrad I removed my 8x50 finderscope and have never looked back. My skies are pretty dark and with the Telrad I can easily point the scope at DSO's, over time you just learn where they are and with more stars visible to the naked eye it makes locating them even easier. Don't know how you manage without a finder of any sort must take ages to line the scope up.

The alt has a car jack for fine control so i point in the general direction and screw up ten degrees or so and give a nudge approx to the fov and then screw down and keep doing that until you find whatever your looking for. You have to swear at the same time or it does'nt work. You get a feel for it after a while.