Red dot finders

[crabbiT Scot]

Hi all,

A couple quick question.s Given my difficuly finding objects in my finderscope (I don't know what I see in teh finderscope!!!), would a red dot finder be beneficial? How do these work? If I bought one, and upgraded my scope at a later date, could I use the finder on any scope?

Could anyone recommend a decent, fairly cheap red dot finder?

Cheers

Scott

[Astrodread]

Hi Scott

Ive been using RDF for about 2 years and yes they are great. they fix on to where your normal finder fits. You align it with your scope like you would with a normal finder. I use a bright object like the moon or a street lamp for this. Then look through the finder keeping your head about a foot away from the finder it self. so you see the red dot in the center of the finder. move the scope to what you want to look at and the object should be in your field of view. If your slightly out just spiral the telescope out from that point and you should find the object your looking for. Ive got the Baader skysurfer 3 from Rother valley Optic. Really good price. and the finder is a nice wide 30mm optic. and comes with lots of different brackets so you've no doubt it will fit.

Hope that helps Friend.

Pete (Astrodread)

[John]

A low cost, but decent RDF is the Baader Sky Surfer III:

Finders - Baader 30mm Sky Surfer III

It comes with a number of base options (including the Skywatcher dovetail type) and it's lens is larger than some designs and well hooded so you have less issues with dewing.

[Astrodread]

it is a great finder better than the standard ones you get with normal scopes. your right John

[Nexus 6]

For another £20 you could have this one, much better quality in my opinion.

http://www.harrisontelescopes.co.uk/acatalog/Revelation_Advanced_Red_Dot_Finder.html

Alan

[sixela]

If you want the Rolls-Royce of the red dot finders, take a look at the TelRad (with the extra dew shield if you have some money or with some insulation foam to hack your own if you haven't). Bulky and ugly, but otherwise unparallelled because of its 0.5°, 2° and 4° circles and collimation bolts at the back.

[johnnychaos]

thanks for the link John. I've been thinking of getting one for a couple of weeks.

[sixela]

Links for "better than just a red dot" thinggummies:

1) if you don't like the bulk of the TelRad, there's the Rigel Quickfinder

2) if you don't mind the clunky appearance of the TelRad, it's here and here with a dew shield, and can be found at lots of other places as well, like here, here, here.

Last time I saw an article comparing finders, the Telrad was a (justifiable) group winner in a Sky at Night article despite its looks. A bit of a pity that FLO don't seem to be carrying it, really.

Some plain RDF finders are actually just as expensive as a Rigel Quickfinder or Telrad, and that's a bit beyond me, really.

[crabbiT Scot]

Cool, cheers for the replies. Will this make it much easier to find objects rather than the finder scope I got with the 150P?

I think my poroblem, is when I have stars in my finderscope view, I struggle to tell if they are the ones I need to be viewing, if that makes sense. I feel a little dumb just now.

[Porl]

I must admit we've been having a little trouble aiming the telescope at what we want to view with the red dot finder thats come on our 130EQ. We've even had problems finding the moon which we thought we wouldnt have any problem with.

The main problem I find is where you put your head to see through the RDF because if your eyes arent in a dead straight line with your finder your going to be off target right?

The only work around we've found is my girlfriend peers through the eyepeice and I stick my head at the back of the scope, look up through the RDF and move the telescope around in the general direction of the moon until she see's it haha.

Does anyone have any better techniques for using the finders? surely there is an easier way, especially if your observing on your own

Thanks

Porl''

[sixela]

Cool, cheers for the replies. Will this make it much easier to find objects rather than the finder scope I got with the 150P?

Yes and no. You'll be sure you're in the right neighbourhood, but a good optical finderscope will show more stars so allows more precise positioning if you know the star field well. A Telrad is somewhere in the middle in regions where there are a couple of Mag 4-5 stars within 2°, because you can then use the extra circles to position yourself much more precisely than with a red dot finder.

Ideally, you have both, or a setup that allows the same functionality. What I tend to do is use a green laser pointer finder as a unit finder and then use binoculars in the other hand looking at the beam as an optical finder, but I have a Telrad as backup for precise positioning when GLPs are not allowed.

I think my problem, is when I have stars in my finderscope view, I struggle to tell if they are the ones I need to be viewing, if that makes sense. I feel a little dumb just now.

That's exactly what these unit finders are for.

[sixela]

The main problem I find is where you put your head to see through the RDF because if your eyes arent in a dead straight line with your finder your going to be off target right?

Wrong. That's why it uses a LED projecting a dot from back to front and a glass to reflect the LED source. As long as you see the red dot, you're fine. Unless somehow you managed to put it frontside back.

Of course, you do have to align the red dot finder or unit finder once, but I've never had a scope in which I couldn't at least start with an object on the horizon in daylight first.

"Easier" is a green laser pointer finder, but you also have to align these first (and they can be fickle beasts in cold weather, especially with plain alkaline batteries instead of true lithium batteries). But these are easier to check for alignment: you switch on the beam and if a GLP pointer is aligned well you should directly see it in the eyepiece.

[John]

There is a technique to using an RDF. Firstly make sure that the RDF is as precisely aligned with where the main scope is pointing as possible. This is easiest done in daylight using a distant object such as a telegraph pole / tree top / church spire etc as a target. When using one at night I find you should actually be focussing on the stars, not the RDF. I find my eye needs to be back 6 inches or more from the RDF and I sort of look at the stars past it, as it were. The red dot or red rings (depending on the finder) should then appear as if projected against the night sky.

Once you have the technique they are very useful in making sure the scope is pointing at the right bit of the sky (as determined by a good star atlas). The object you are looking for should be somewhere in the field of view of a low powered eyepiece then (unless it's too faint for your scope / observing conditions of course !).

It's worth persevering with RDF's (though some are better than others) as they are very effective devices when mastered.

[star_chaser]

I must admit we've been having a little trouble aiming the telescope at what we want to view with the red dot finder thats come on our 130EQ. We've even had problems finding the moon which we thought we wouldnt have any problem with.

The main problem I find is where you put your head to see through the RDF because if your eyes arent in a dead straight line with your finder your going to be off target right?

The only work around we've found is my girlfriend peers through the eyepeice and I stick my head at the back of the scope, look up through the RDF and move the telescope around in the general direction of the moon until she see's it haha.

Does anyone have any better techniques for using the finders? surely there is an easier way, especially if your observing on your own

Thanks

Porl''

i have the same scope r/d finder and seem to be having the same trouble but i put it down to me not being very good .i look from the end of the scope like you do when your gf looks through the eyepiece.have you zeroed (?) it in on an object during the day i had a bit better results after doing this .but still not that great maybe a new r/d finder is in order.this astronomy is one cam of worms

[star_chaser]

I must admit we've been having a little trouble aiming the telescope at what we want to view with the red dot finder thats come on our 130EQ. We've even had problems finding the moon which we thought we wouldnt have any problem with.

The main problem I find is where you put your head to see through the RDF because if your eyes arent in a dead straight line with your finder your going to be off target right?

The only work around we've found is my girlfriend peers through the eyepeice and I stick my head at the back of the scope, look up through the RDF and move the telescope around in the general direction of the moon until she see's it haha.

Does anyone have any better techniques for using the finders? surely there is an easier way, especially if your observing on your own

Thanks

Porl''

i have the same scope r/d finder and seem to be having the same trouble but i put it down to me not being very good .i look from the end of the scope like you do when your gf looks through the eyepiece.have you zeroed (?) it in on an object during the day i had a bit better results after doing this .but still not that great maybe a new r/d finder is in order.this astronomy is one cam of worms

{edit} just read the above post jah explians it much better than i

[star_chaser]

I must admit we've been having a little trouble aiming the telescope at what we want to view with the red dot finder thats come on our 130EQ. We've even had problems finding the moon which we thought we wouldnt have any problem with.

The main problem I find is where you put your head to see through the RDF because if your eyes arent in a dead straight line with your finder your going to be off target right?

The only work around we've found is my girlfriend peers through the eyepeice and I stick my head at the back of the scope, look up through the RDF and move the telescope around in the general direction of the moon until she see's it haha.

Does anyone have any better techniques for using the finders? surely there is an easier way, especially if your observing on your own

Thanks

Porl''

i have the same scope r/d finder and seem to be having the same trouble but i put it down to me not being very good .i look from the end of the scope like you do when your gf looks through the eyepiece.have you zeroed (?) it in on an object during the day i had a bit better results after doing this .but still not that great maybe a new r/d finder is in order.this astronomy is one cam of worms

{edit} just read the above post jah explians it much better than i

sry i seem to have made a double post

[Nexus 6]

Note the post given by John above, it should enable you to use an RDF effectively. I have used mine as a way to help me understand exactly what part of the sky I am viewing as well as finding a particular object, I check I have the object right in the finder and then in the centre of the fov, I then check again with the RDF and switch it on and off a few times to get an idea were the scope is pointing even if I am using GOTO it is still a helpfull way to gain more knowledge of the skies. I have also found that because I have been using this method for 3 years now I can now locate objects with Binoculars.

Alan

[Porl]

Ah ha nope we haven't tried setting it up in the daytime, we just kinda jumped in with both feet and thought it would work straight off and that I just wasnt putting me head/eyes in the right place

I'll give lining it up with a tree/telegraph pole and then seeing how it works out. I guess figuring it out in the daytime when you can actually see whats going on is better than bodging through in the dark hey.

Thanks guys

Porl''

[the milster]

I bought a Telrad which I think is awesome, don't know if it's actually classed as red dot finder. I know one thing though, once lined up everything I pointed it at was in the middle of the scope . I got it from Rother Valley Optics. Good service.