Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

General Astronomy >> Beginners Forum

Pages: 1 | 2 | 3 | 4 | (show all)
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
RACI finder scope
      #5832987 - 04/30/13 06:51 PM

Looking for some opinions on this finder scope. I'm looking to replace my straight through scope on my 8" dob. I'm tired of crinking my neck just to look through it.

I'm assuming there isn't too much to worry about since it's just a finder scope? Or, are there things to worry about, things to avoid? Looking for some wisdom on finder scopes. Thanks all!!


Post Extras: Print Post   Remind Me!   Notify Moderator  
StrangeDejavu
Carpal Tunnel
*****

Reged: 03/20/13

Loc: Florida
Re: RACI finder scope new [Re: Haas]
      #5833014 - 04/30/13 07:01 PM

I knew that feeling all too well, especially on a refractor. Wanted to see something at zenith? Sure, no problem, lay on your back like you're changing your oil. I recommend the Orion 9x50 RACI:

http://www.telescope.com/Accessories/Telescope-Finder-Scopes/Black-9x50-Right...

I absolutely love mine, if something were to happen to it, I would immediately buy another. They also make an illuminated reticle version, but it costs a little bit more.

Edited by StrangeDejavu (04/30/13 07:04 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gary Riley
sage


Reged: 12/01/11

Loc: White Bluff, TN
Re: RACI finder scope new [Re: StrangeDejavu]
      #5833037 - 04/30/13 07:18 PM

+1 for the 9x50 RACI!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: StrangeDejavu]
      #5833039 - 04/30/13 07:19 PM

Quote:

I knew that feeling all too well, especially on a refractor. Wanted to see something at zenith? Sure, no problem, lay on your back like you're changing your oil. I recommend the Orion 9x50 RACI:

http://www.telescope.com/Accessories/Telescope-Finder-Scopes/Black-9x50-Right...

I absolutely love mine, if something were to happen to it, I would immediately buy another. They also make an illuminated reticle version, but it costs a little bit more.




Ok, now that one looks a lot like the one I linked to, but the price is a little different. Any reason why one might be better than another? I assume one might offer a little more magnification, but is that really that important on a finder scope?


Post Extras: Print Post   Remind Me!   Notify Moderator  
StrangeDejavu
Carpal Tunnel
*****

Reged: 03/20/13

Loc: Florida
Re: RACI finder scope new [Re: Haas]
      #5833045 - 04/30/13 07:22 PM

Quote:

Ok, now that one looks a lot like the one I linked to, but the price is a little different. Any reason why one might be better than another? I assume one might offer a little more magnification, but is that really that important on a finder scope?




I think the link was left out of the original post, mind linking it again?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: StrangeDejavu]
      #5833050 - 04/30/13 07:24 PM

Quote:

Quote:

Ok, now that one looks a lot like the one I linked to, but the price is a little different. Any reason why one might be better than another? I assume one might offer a little more magnification, but is that really that important on a finder scope?





LOL!!! What a dork I am. Forgot to link it.
Here it is:

http://www.telescope.com/Accessories/Telescope-Finder-Scopes/Black-6x30-Right...

I think the link was left out of the original post, mind linking it again?




Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: Haas]
      #5833053 - 04/30/13 07:25 PM

Wow, then I screwed that up too. I'm just a mess today.

Post Extras: Print Post   Remind Me!   Notify Moderator  
newtoskies
Pooh-Bah


Reged: 07/15/12

Loc: SE Ma.
Re: RACI finder scope new [Re: Haas]
      #5833059 - 04/30/13 07:30 PM

Or this GSO RACI from Agina GSO 8x50 RACI I'll most likely be getting this one for my Dob and XLT102.

Post Extras: Print Post   Remind Me!   Notify Moderator  
tag1260
scholastic sledgehammer
*****

Reged: 10/07/12

Loc: Ohio, USA
Re: RACI finder scope new [Re: Haas]
      #5833062 - 04/30/13 07:32 PM

You want the 9*50. The 6*30 just would be enough field of view. Plus the magnification of the 9*50 makes it easier to see what your looking for. Of course people also love zero magnification of the telrads and such.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: tag1260]
      #5833077 - 04/30/13 07:38 PM

So, the 9X50 will offer a wider field of view, and that's the only difference? Is there any way to tell what the field of view is on my current finder?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Geo.
Carpal Tunnel
*****

Reged: 10/01/08

Loc: Upstate NY
Re: RACI finder scope new [Re: tag1260]
      #5833078 - 04/30/13 07:39 PM

I haven't seen a 6 by 30 offered anywhere and $45-50 will get you a good used 8/9 by 50. Antares and GSO are all good names. The tall Synta braket is good with the dovetail shoe making it easy to remove for transport.

Post Extras: Print Post   Remind Me!   Notify Moderator  
tag1260
scholastic sledgehammer
*****

Reged: 10/07/12

Loc: Ohio, USA
Re: RACI finder scope new [Re: Geo.]
      #5833084 - 04/30/13 07:42 PM

The 9*50 has a 9 magnification while the 6*30 has a 6 time magnification.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: tag1260]
      #5833086 - 04/30/13 07:46 PM

Quote:

The 9*50 has a 9 magnification while the 6*30 has a 6 time magnification.




So, is that second number a measurement for field of view?


Post Extras: Print Post   Remind Me!   Notify Moderator  
tag1260
scholastic sledgehammer
*****

Reged: 10/07/12

Loc: Ohio, USA
Re: RACI finder scope new [Re: Haas]
      #5833087 - 04/30/13 07:47 PM

Yes.

Post Extras: Print Post   Remind Me!   Notify Moderator  
tag1260
scholastic sledgehammer
*****

Reged: 10/07/12

Loc: Ohio, USA
Re: RACI finder scope new [Re: Geo.]
      #5833096 - 04/30/13 07:52 PM

There actually happens to be a GSO in the classifieds right now.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: tag1260]
      #5833104 - 04/30/13 07:55 PM

Quote:

There actually happens to be a GSO in the classifieds right now.




Yeah, I saw that, but it has no mounting shoe. Didn't know if that's an issue or not. Is it?


Post Extras: Print Post   Remind Me!   Notify Moderator  
MikeBOKC
Post Laureate
*****

Reged: 05/10/10

Loc: Oklahoma City, OK
Re: RACI finder scope new [Re: Haas]
      #5833145 - 04/30/13 08:20 PM

The mounting shoe on your scope may or may not accept a specific finder. If not it's easy to order the Orion finder shoe (be sure to specify the non-SCT model) with the RACI and swap it out with the existing screws. Might just call Orion and tell them what you have and they can advise whether you need the substitute shoe. I use my 9x50 RACI on both of my large scopes, with a shoe mounted on each. It's better than Tylenol for that straight through finder pain in the neck.

Edited by MikeBOKC (04/30/13 08:21 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: RACI finder scope new [Re: Haas]
      #5833191 - 04/30/13 08:48 PM

Quote:

Looking for some opinions on this finder scope. I'm looking to replace my straight through scope on my 8" dob. I'm tired of crinking my neck just to look through it.

I'm assuming there isn't too much to worry about since it's just a finder scope? Or, are there things to worry about, things to avoid? Looking for some wisdom on finder scopes. Thanks all!!




Something to consider:

I know that many like RACI finders on their Dobsonians, I prefer a straight through finder. With an RACI finder, you are looking in a different direction than the scope is pointing so pointing the scope to the first guide star requires using either another finder or sighting down the tube. With a straight through finder, I am looking in the direction the scope is pointing, I can keep both eyes open so the finder itself functions as a unit power finder.

I think the most important factor in successfully using a straight through finder is a dedicated observing chair that allows easy adjustment of the seat height. If you are trying to stand or are using a fixed height chair, a straight through finder can be awkward. But with a chair, I find it's quite easy.

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
pjensen
super member


Reged: 04/08/12

Loc: Highland Village, Tx
Re: RACI finder scope new [Re: Haas]
      #5833219 - 04/30/13 09:09 PM

Quote:

Looking for some opinions on this finder scope. I'm looking to replace my straight through scope on my 8" dob. I'm tired of crinking my neck just to look through it.




Telrad.

Once you get one, you will never want anything else. If it is placed at the top the scope, it is easy to look up at the sky (along the tube) and see exactly what you are pointed at - no guessing. Moving the scope in the correct direction is easy. The time it takes (to do this) is so short that you won't get that neck crink.

Paul


Post Extras: Print Post   Remind Me!   Notify Moderator  
TexasRed
scholastic sledgehammer


Reged: 05/17/11

Loc: East Texas
Re: RACI finder scope new [Re: pjensen]
      #5833267 - 04/30/13 09:40 PM

When comparing a 6x30 finder with a 9x50, please be aware that the second number is the diameter of the objective lens in millimeters. Most people consider a 30mm objective lens to be not quite large enough for astronomical use. A 50mm objective will produce a larger exit pupil at the same magnification and show stars over a full magnitude fainter, as well as forming a much sharper image.

If you don't like craning your neck to look through your finder or point your scope in the right general direction, just try shining a green laser pointer into the eyepiece of the finder.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: RACI finder scope new [Re: pjensen]
      #5833279 - 04/30/13 09:46 PM

Quote:

Quote:

Looking for some opinions on this finder scope. I'm looking to replace my straight through scope on my 8" dob. I'm tired of crinking my neck just to look through it.




Telrad.

Once you get one, you will never want anything else. If it is placed at the top the scope, it is easy to look up at the sky (along the tube) and see exactly what you are pointed at - no guessing. Moving the scope in the correct direction is easy. The time it takes (to do this) is so short that you won't get that neck crink.

Paul




In my experience, Telrad's are great when the skies are dark and clear. When I am out in the mountains, I find most objects with a Telrad. From a light polluted backyard, there are large regions of the sky without sufficient stars to use a Telrad so a magnifying finder that will show the fainter stars is required.

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: Jon Isaacs]
      #5833364 - 04/30/13 10:38 PM

Quote:

Quote:

Looking for some opinions on this finder scope. I'm looking to replace my straight through scope on my 8" dob. I'm tired of crinking my neck just to look through it.

I'm assuming there isn't too much to worry about since it's just a finder scope? Or, are there things to worry about, things to avoid? Looking for some wisdom on finder scopes. Thanks all!!




Something to consider:

I know that many like RACI finders on their Dobsonians, I prefer a straight through finder. With an RACI finder, you are looking in a different direction than the scope is pointing so pointing the scope to the first guide star requires using either another finder or sighting down the tube. With a straight through finder, I am looking in the direction the scope is pointing, I can keep both eyes open so the finder itself functions as a unit power finder.

I think the most important factor in successfully using a straight through finder is a dedicated observing chair that allows easy adjustment of the seat height. If you are trying to stand or are using a fixed height chair, a straight through finder can be awkward. But with a chair, I find it's quite easy.

Jon




That is a good point. I'll keep that in mind. If I get a Raci, I'll still keep the straight through just in case I don't like it.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: Haas]
      #5833377 - 04/30/13 10:45 PM

The telrad has my curiosity, but there is a lot of light pollution around here, that has me concerned. I wish there was a way to try a few different ones out before I buy something. I know, a star party, but the only one I know of around here, still has a web site, but apparently no one gets together any more.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Classic8
professor emeritus


Reged: 04/12/06

Loc: Naperville, IL, USA
Re: RACI finder scope new [Re: TexasRed]
      #5833396 - 04/30/13 10:51 PM

Also, with a 50mm finderscope some of the Messier objects can be seen directly in the finder (if light pollution isn't terrible), so they're much nicer in that respect than the smaller 6X30 finders. I love my right angle finders for starhopping.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: Classic8]
      #5833401 - 04/30/13 10:53 PM

Quote:

Also, with a 50mm finderscope some of the Messier objects can be seen directly in the finder (if light pollution isn't terrible), so they're much nicer in that respect than the smaller 6X30 finders. I love my right angle finders for starhopping.




I think I'm really leaning towards this.


Post Extras: Print Post   Remind Me!   Notify Moderator  
panhard
It's All Good
*****

Reged: 01/20/08

Loc: Markham Ontario Canada
Re: RACI finder scope new [Re: Haas]
      #5833434 - 04/30/13 11:14 PM

Hass the more light pollution there is the less useful a telrad is. Believe me I own both.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: panhard]
      #5833455 - 04/30/13 11:32 PM

Thanks panhard. I think the 90 degree RACI is the ticket for me.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Kunama
professor emeritus


Reged: 10/22/12

Re: RACI finder scope new [Re: Haas]
      #5833488 - 04/30/13 11:55 PM

For the Rolls Royce of affordable RACI get the Stellarvue F50W2 which has excellent optics, illuminated reticle and interchangeable eyepieces, I often use mine with a 13mm Vixen LVW, makes for a beautiful mini-refractor.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Tony Flanders
Postmaster
*****

Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: RACI finder scope new [Re: Haas]
      #5833696 - 05/01/13 05:59 AM

Quote:

Quote:

The 9*50 has a 9 magnification while the 6*30 has a 6 time magnification.




So, is that second number a measurement for field of view?




No, the second number is the diameter of the main lens. It determines how much light the finderscope gathers.

Most decent finderscopes have apparent fields of view around 50 degrees. That means that the true field of view is 50 divided by the magnification. So a 6x30 finderscope typically has a true field of view around 50/6 = 8+ degrees, while a 9x50 finderscope has a (considerably smaller) true field of view around 50/9 = 5+ degrees.

I find both 6x30 and 8x50 finderscopes to be useful. The former has a bigger field of view, but is less likely to show the object that you're aiming for, due to its much smaller aperture. So in practice, you're more likely to use it to get to the right point in the star field than to sight directly on the object.

6x30 finderscopes are also much smaller and lighter than 50-mm finderscopes.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Tony Flanders
Postmaster
*****

Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: RACI finder scope new [Re: Haas]
      #5833700 - 05/01/13 06:04 AM

Quote:

Looking for some opinions on this finder scope. I'm looking to replace my straight through scope on my 8" dob. I'm tired of crinking my neck just to look through it.




I love the right-angle finderscope on my 12.5-inch Dob. But you should be aware that a right-angle finderscope does not eliminate the need to crink your neck.

Why? Because you still need to supplement it with something else to get the right-angle finderscope pointed in the right direction. That's unlikely to happen just by feel or guesswork. It could be something as simple as sighting along the tube, though a red-dot or red-circle finder works better. But you still end up crinking your neck to look directly at your target.

The only ways around that are using a green-laser pointer or some kind of electronic or mechanical finding aid, such as a Go To drive, a push-to controller, or old-fashioned setting circles


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jeff2011
Pooh-Bah
*****

Reged: 01/01/13

Loc: Sugar Land, TX
Re: RACI finder scope new [Re: Tony Flanders]
      #5833956 - 05/01/13 09:48 AM

Quote:

or old-fashioned setting circles




+1

I added an azimuth setting circle to my Dob and bought an inexpensive Wixie digital angle gauge. I used it a few nights ago to locate M81 from my light polluted backyard. It worked great. I found it on my first try. It would have been difficult to acheive that using my Telrad since there was not a bright enough star close to it.

I don't have a RACI finder, but I was at an outreach a month ago and one of the guys had one on his Dob. He was using it in combination with a Telrad. I was impressed with how well it worked.


Post Extras: Print Post   Remind Me!   Notify Moderator  
panhard
It's All Good
*****

Reged: 01/20/08

Loc: Markham Ontario Canada
Re: RACI finder scope new [Re: Jeff2011]
      #5833975 - 05/01/13 10:01 AM

Quote:

9x50 finderscope has a (considerably smaller) true field of view around 50/9 = 5+ degrees.


The 5° field of view means with a little adaptation you can use that finder scope with the Telrad finder charts.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Thomas Karpf
Carpal Tunnel


Reged: 02/09/09

Loc: Newington, CT
Re: RACI finder scope new [Re: panhard]
      #5833984 - 05/01/13 10:05 AM

I really like Stellarvue's. It's pricey, and you need to make sure you get the right rings for you scope, but you can use whatever 1.25" eyepiece you want with it, and you can add the illuminator for the reticle later if you want.

Highly recommended.

http://www.stellarvue.com/f50.html


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: Kunama]
      #5833990 - 05/01/13 10:08 AM

Quote:

For the Rolls Royce of affordable RACI get the Stellarvue F50W2 which has excellent optics, illuminated reticle and interchangeable eyepieces, I often use mine with a 13mm Vixen LVW, makes for a beautiful mini-refractor.




Wow, currently unavailable. At least at the first place that google brought up.


Post Extras: Print Post   Remind Me!   Notify Moderator  
kdill2160
journeyman
*****

Reged: 04/02/13

Loc: McHenry County IL
Re: RACI finder scope new [Re: Haas]
      #5834223 - 05/01/13 12:10 PM

Do take a look at the Stellarvue finders, they are very well made, helical focuser, RACI or straight through, uses standard 1.25" eyepieces and comes with a nice 23mm reticle eyepiece, the illuminator is an option... their customer support is the very best, the products I've purchased are all very well made with quality fit and finish...

JMO... Ken


Post Extras: Print Post   Remind Me!   Notify Moderator  
kdill2160
journeyman
*****

Reged: 04/02/13

Loc: McHenry County IL
Re: RACI finder scope new [Re: Tony Flanders]
      #5834247 - 05/01/13 12:18 PM

Quote:

Quote:

Quote:

The 9*50 has a 9 magnification while the 6*30 has a 6 time magnification.




So, is that second number a measurement for field of view?




No, the second number is the diameter of the main lens. It determines how much light the finderscope gathers.

Most decent finderscopes have apparent fields of view around 50 degrees. That means that the true field of view is 50 divided by the magnification. So a 6x30 finderscope typically has a true field of view around 50/6 = 8+ degrees, while a 9x50 finderscope has a (considerably smaller) true field of view around 50/9 = 5+ degrees.

I find both 6x30 and 8x50 finderscopes to be useful. The former has a bigger field of view, but is less likely to show the object that you're aiming for, due to its much smaller aperture. So in practice, you're more likely to use it to get to the right point in the star field than to sight directly on the object.

6x30 finderscopes are also much smaller and lighter than 50-mm finderscopes.





+1 on the Stellarvue, I own the F50M2 and love it, bases on two of my scopes to accept it... JMO... Ken


Post Extras: Print Post   Remind Me!   Notify Moderator  
pjensen
super member


Reged: 04/08/12

Loc: Highland Village, Tx
Re: RACI finder scope new [Re: Jon Isaacs]
      #5834296 - 05/01/13 12:39 PM

Quote:



In my experience, Telrad's are great when the skies are dark and clear. When I am out in the mountains, I find most objects with a Telrad. From a light polluted backyard, there are large regions of the sky without sufficient stars to use a Telrad so a magnifying finder that will show the fainter stars is required.




Or another option is to get a tracking telescope.

With a goto/tracker, the only time you would need to sight through a finder (or telrad) is on the setup (6 stars). This takes me 15 minutes. Then the rest of the night the GoTo puts the objects right in the eyepiece (even at 200x, 0.30* True Field Of View). I don't even need to use the hand control at all (to center it). I don't even need to swap eyepieces (to find the object). It is possible to see dozens of nebula, double stars, clusters all within an hour or two. I can return repeatedly to prior objects that were not visible before - and see them.

As a person who has used (hand push) telescopes all my life, this stuff is simply amazing.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: RACI finder scope new [Re: kdill2160]
      #5834323 - 05/01/13 12:50 PM

Straight through finders are more sensible on alt-az mounted scopes because of the consistent location. On equatorially mounted scopes there can be positions hard to get to.

In any event, I've long preferred RA finders (and binos) simply because they're more neck- and back-friendly. With practice it becomes easier to get close initial pointing when using RA finders. I do it all the time with my RA bino and its higher power, 4.7 degree field. The aforementioned green laser through the finder eyepiece idea is a good one. You could try it through the scope's eyepiece, too, although at higher powers the beam is expanded (by a ratio equalling the magnification) considerably and hence 'diluted', and you must dodge the secondary shadow in relevant scopes.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: RACI finder scope new [Re: GlennLeDrew]
      #5834425 - 05/01/13 01:35 PM

Quote:

Straight through finders are more sensible on alt-az mounted scopes because of the consistent location. On equatorially mounted scopes there can be positions hard to get to.




In my experience, RA finders can be a bigger problem with equatorially mounted scopes unless the scope can be rotated in the rings relatively easily. Consider an SCT on a fork mount. The straight through finder may be awkward but at least it will be sticking out the rear of the scope where one can get to it. With an RA finder, it may not only difficult to reach but the eyepiece maybe pointed in some direction so it is unreachable.

Jon
Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: GlennLeDrew]
      #5834435 - 05/01/13 01:39 PM

Quote:

Straight through finders are more sensible on alt-az mounted scopes because of the consistent location. On equatorially mounted scopes there can be positions hard to get to.

In any event, I've long preferred RA finders (and binos) simply because they're more neck- and back-friendly. With practice it becomes easier to get close initial pointing when using RA finders. I do it all the time with my RA bino and its higher power, 4.7 degree field. The aforementioned green laser through the finder eyepiece idea is a good one. You could try it through the scope's eyepiece, too, although at higher powers the beam is expanded (by a ratio equalling the magnification) considerably and hence 'diluted', and you must dodge the secondary shadow in relevant scopes.




Holding a laser through my finder scope seems impractical to me. How could you ever tell that you're holding that laser parallel to the finder scope? Seems like your hand wouldn't really be steady enough for that to work at all.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Classic8
professor emeritus


Reged: 04/12/06

Loc: Naperville, IL, USA
Re: RACI finder scope new [Re: Haas]
      #5834465 - 05/01/13 01:52 PM

Has anyone tried using a GLP attached with velcro? That way you wouldn't have to hold it - not sure if I can get it lined up well enough but it just has to be close. Then the finder would just be needed to confirm I'm on the right star, and for starhopping from there. Plus the laser could be removed quickly.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Tony Flanders
Postmaster
*****

Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: RACI finder scope new [Re: Haas]
      #5834485 - 05/01/13 02:00 PM

Quote:

Holding a laser through my finder scope seems impractical to me. How could you ever tell that you're holding that laser parallel to the finder scope?




When you shine something backward through a telescope, magnification works in reverse. So any error in alignment of the laser is divided by 9 in a 9x50 finderscope. Certainly good enough to get your initial fix on the sky.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: Tony Flanders]
      #5834495 - 05/01/13 02:05 PM

Quote:

Quote:

Holding a laser through my finder scope seems impractical to me. How could you ever tell that you're holding that laser parallel to the finder scope?




When you shine something backward through a telescope, magnification works in reverse. So any error in alignment of the laser is divided by 9 in a 9x50 finderscope. Certainly good enough to get your initial fix on the sky.




I guess I'm not understanding. Why would you be shining the laser backwards through the scope? It wouldn't shine to the sky, it would shine in your eye, no?


Post Extras: Print Post   Remind Me!   Notify Moderator  
TexasRed
scholastic sledgehammer


Reged: 05/17/11

Loc: East Texas
Re: RACI finder scope new [Re: Haas]
      #5834572 - 05/01/13 02:46 PM

Quote:

Quote:

Holding a laser through my finder scope seems impractical to me. How could you ever tell that you're holding that laser parallel to the finder scope?




I guess I'm not understanding. Why would you be shining the laser backwards through the scope? It wouldn't shine to the sky, it would shine in your eye, no?




Remember that most finderscopes are just small refractors. When you shine the laser into the eyepiece at that back, the light will come our of the objective lens at the front and into the sky, showing you where the finderscope is pointed. You won't need to center the laser or hold it rock steady or perfectly parallel to the finderscope. You just need to point it into the eyepiece of the finderscope to get a green line going into the sky in the same direction as the finderscope.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: TexasRed]
      #5834581 - 05/01/13 02:53 PM

Quote:

Quote:

Quote:

Holding a laser through my finder scope seems impractical to me. How could you ever tell that you're holding that laser parallel to the finder scope?




I guess I'm not understanding. Why would you be shining the laser backwards through the scope? It wouldn't shine to the sky, it would shine in your eye, no?




Remember that most finderscopes are just small refractors. When you shine the laser into the eyepiece at that back, the light will come our of the objective lens at the front and into the sky, showing you where the finderscope is pointed. You won't need to center the laser or hold it rock steady or perfectly parallel to the finderscope. You just need to point it into the eyepiece of the finderscope to get a green line going into the sky in the same direction as the finderscope.




So, if I have the laser tipped at a slight angle through the finder scope, it will still come through the scope the same as if I were not tipped?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Thomas Karpf
Carpal Tunnel


Reged: 02/09/09

Loc: Newington, CT
Re: RACI finder scope new [Re: TexasRed]
      #5834700 - 05/01/13 03:57 PM

Quote:


If you don't like craning your neck to look through your finder or point your scope in the right general direction, just try shining a green laser pointer into the eyepiece of the finder.




It'd be a lot more precise if you just shined the laser pointer through the eyepiece of the scope, right?


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: RACI finder scope new [Re: Thomas Karpf]
      #5834760 - 05/01/13 04:42 PM

If one were to aim the laser even so badly as to just skim the field edge (25 degrees off axis fir a 50 degree apparent field) the beam would still point in the sky to a point at the edge of the true field. As long as light gets out the front, you're still hitting somewhere in the finder's FOV. It's not hard to obtain pointing into the eyepiece to within 5 degrees, and 10's a doddle. at 9X, that's to better than a degree on the sky. If one were to get really ICD over it, an adapter could be made up which slips over or abuts the eyepiece so as to obtain very near axial alignment.

Thomas,
As I mentioned in my previous post, with a scope the magnification expands the beam to the point of diluting its photon flux, making it more difficult to see. At 100X, for example, a 1mm beam (which is just about as small as you get) expands to 100mm.

But then the pointing accuracy is much better, if one is uncertain of using the finder for this purpose.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: GlennLeDrew]
      #5834766 - 05/01/13 04:45 PM

Quote:

If one were to aim the laser even so badly as to just skim the field edge (25 degrees off axis fir a 50 degree apparent field) the beam would still point in the sky to a point at the edge of the true field. As long as light gets out the front, you're still hitting somewhere in the finder's FOV. It's not hard to obtain pointing into the eyepiece to within 5 degrees, and 10's a doddle. at 9X, that's to better than a degree on the sky. If one were to get really ICD over it, an adapter could be made up which slips over or abuts the eyepiece so as to obtain very near axial alignment.

Thomas,
As I mentioned in my previous post, with a scope the magnification expands the beam to the point of diluting its photon flux, making it more difficult to see. At 100X, for example, a 1mm beam (which is just about as small as you get) expands to 100mm.

But then the pointing accuracy is much better, if one is uncertain of using the finder for this purpose.





Now I understand. So, it's not perfect, but still gets you withing the range of just a nudge or two.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: RACI finder scope new [Re: Haas]
      #5834809 - 05/01/13 05:03 PM

Just to clarify. The idea is to use the laser to know where the finder is *roughly* aimed. Then when putting eye to finder, you already know you're in the ballpark and can rely on getting your bearings immediately.

It's not necessarily to be expected that this will get you to within the main scope's field right off the bat. But you can, with due care.


Post Extras: Print Post   Remind Me!   Notify Moderator  
newtoskies
Pooh-Bah


Reged: 07/15/12

Loc: SE Ma.
Re: RACI finder scope new [Re: Haas]
      #5834946 - 05/01/13 06:17 PM

oh great, now I am thinking for buying a laser to point through the finder scope. Very cool info fellas, thanks.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: newtoskies]
      #5835002 - 05/01/13 06:50 PM

LOL, I know. I had my mind set on a RACI, now I'm thinking about laser also.

Post Extras: Print Post   Remind Me!   Notify Moderator  
newtoskies
Pooh-Bah


Reged: 07/15/12

Loc: SE Ma.
Re: RACI finder scope new [Re: Haas]
      #5835025 - 05/01/13 07:04 PM

Me too Haas. Been looking at RACI's and trying to find the green laser pointer. I had seen them before, but now that I am interested in it, I can't find them..lol

Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: newtoskies]
      #5835029 - 05/01/13 07:07 PM

Quote:

Me too Haas. Been looking at RACI's and trying to find the green laser pointer. I had seen them before, but now that I am interested in it, I can't find them..lol




I'm looking at one here, but don't know if I should be looking at others or not. This is the only one I've found so far.

http://www.telescope.com/Accessories/Telescope-Finder-Scopes/pc/3/49.uts


Post Extras: Print Post   Remind Me!   Notify Moderator  
Grandpa Jim
old fogey
*****

Reged: 08/04/12

Loc: GREAT AMERICAN DESERT
Re: RACI finder scope new [Re: newtoskies]
      #5835267 - 05/01/13 09:27 PM

Quote:

Me too Haas. Been looking at RACI's and trying to find the green laser pointer. I had seen them before, but now that I am interested in it, I can't find them..lol




http://www.scopestuff.com/ss_lasre.htm

http://www.scopestuff.com/ss_sfind.htm


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: Grandpa Jim]
      #5835277 - 05/01/13 09:36 PM

I have to admit something here, maybe irrational, but here goes. One thing that scares me with the laser pointers is, what if I'm pointing out at a star, or moon, or anything else, and that just happens to be an area where an airplane comes into the same line as the laser? I don't want to be in trouble for being accused of deliberately pointing a laser at an airplane. Silly fear, or legit? Of course it wouldn't be on purpose, but accidents do happen.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Kunama
professor emeritus


Reged: 10/22/12

Re: RACI finder scope new [Re: Haas]
      #5835627 - 05/02/13 03:24 AM

in response to a few comments of the RACI being hard to get to on an Eq mounted Newt, the Stellarvue has a rotateable diagonal to allow a better angle if the scope rotation causes the focuser to be difficult to access.

It also fits beautifully into the Takahashi finder bracket and probably many other brackets, by simply removing the diagonal then installing the finder tube and lastly refit the diagonal. See pic below on my TSA120 in the Tak bracket.



I did have to paint the Stellarvue to better match the Tak TSA, but the benefits of not bending my arthritic old neck to odd angles are well worth it:



Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: RACI finder scope new [Re: Kunama]
      #5835631 - 05/02/13 03:33 AM

For the brief time a laser is used, statistically speaking an aircraft will be intercepted in its beam at almost vanishingly small probabilities.

I mean, think of it. A plane might subtend an angle of 2 arcminutes. That amounts to an area of 0.0000085% of the 180 degrees of the celestial hemisphere. What do you think are that chances of accidentally illuminating a cockpit?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: GlennLeDrew]
      #5835863 - 05/02/13 09:30 AM

Quote:

For the brief time a laser is used, statistically speaking an aircraft will be intercepted in its beam at almost vanishingly small probabilities.

I mean, think of it. A plane might subtend an angle of 2 arcminutes. That amounts to an area of 0.0000085% of the 180 degrees of the celestial hemisphere. What do you think are that chances of accidentally illuminating a cockpit?




I dunno, I'm a little leary going strictly by chance, even when the odds are in my favor. Ever hear the joke, "when it's a 50/50 chance, there's a 95% chance I'll pick the wrong one"? That's me!
I'm fairly close to the Milwaukee airport too. I think I'll try the RACI, and if I still have issues, then I'll give the laser a whirl.


Post Extras: Print Post   Remind Me!   Notify Moderator  
newtoskies
Pooh-Bah


Reged: 07/15/12

Loc: SE Ma.
Re: RACI finder scope new [Re: Haas]
      #5835921 - 05/02/13 10:01 AM

Haas I was looking at the Orion one too, after my comment above. I hadn't realized they were that expensive. I'll just get a RACI first, then wait for when the budget allows for another toy.
I have the RIGEL finder but only used it once. LP here so the Rigel didn't help me much....yet.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Haas
sage


Reged: 11/22/12

Loc: Wis., USA
Re: RACI finder scope new [Re: newtoskies]
      #5835954 - 05/02/13 10:19 AM

Quote:

Haas I was looking at the Orion one too, after my comment above. I hadn't realized they were that expensive. I'll just get a RACI first, then wait for when the budget allows for another toy.
I have the RIGEL finder but only used it once. LP here so the Rigel didn't help me much....yet.





LP= ?

Nevermind, just dawned on me "light pollution".

Edited by Haas (05/02/13 10:20 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
SteveG
Post Laureate
*****

Reged: 09/27/06

Loc: Seattle, WA
Re: RACI finder scope new [Re: GlennLeDrew]
      #5836329 - 05/02/13 01:34 PM Attachment (3 downloads)

Quote:

For the brief time a laser is used, statistically speaking an aircraft will be intercepted in its beam at almost vanishingly small probabilities.

I mean, think of it. A plane might subtend an angle of 2 arcminutes. That amounts to an area of 0.0000085% of the 180 degrees of the celestial hemisphere. What do you think are that chances of accidentally illuminating a cockpit?




I use a laser every night out. It draws a precision line to the point in the sky the scope is looking at. You would have to purposely try to shine the beam into the cockpit of an airplane. If it were to happen by chance, it would likely only hit the bottom of the plane - for a brief second, and no one would ever know. Claims that 5mW or less lasers are somehow unsafe for astronomy are unfounded, in my opinion.


Post Extras: Print Post   Remind Me!   Notify Moderator  
pjensen
super member


Reged: 04/08/12

Loc: Highland Village, Tx
Re: RACI finder scope new [Re: SteveG]
      #5836344 - 05/02/13 01:43 PM

Quote:

Quote:

For the brief time a laser is used, statistically speaking an aircraft will be intercepted in its beam at almost vanishingly small probabilities.

I mean, think of it. A plane might subtend an angle of 2 arcminutes. That amounts to an area of 0.0000085% of the 180 degrees of the celestial hemisphere. What do you think are that chances of accidentally illuminating a cockpit?




I use a laser every night out. It draws a precision line to the point in the sky the scope is looking at. You would have to purposely try to shine the beam into the cockpit of an airplane. If it were to happen by chance, it would likely only hit the bottom of the plane - for a brief second, and no one would ever know.




I live in the dallas/fort worth area and on a busy night, there can be a plane coming in to land every minute. Typically they are 3000' to 5000' above (where I live). Every month or so, we hear of someone being arrested for shining lasers - it makes the evening news. Apparently it is a serious crime (Homeland Security). If a pilot sees a laser (nearby), they will report it.

So it might depend where you are using those laser pointers. Just something to consider.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Thomas Karpf
Carpal Tunnel


Reged: 02/09/09

Loc: Newington, CT
Re: RACI finder scope new [Re: SteveG]
      #5836383 - 05/02/13 01:57 PM

Quote:

Claims that 5mW or less lasers are somehow unsafe for astronomy are unfounded, in my opinion.




I agree. However, it seems to me I've read recently (at NEAF, I think) that those 'power is under ###mW' claims are ofter not particularly accurate.


Post Extras: Print Post   Remind Me!   Notify Moderator  
newtoskies
Pooh-Bah


Reged: 07/15/12

Loc: SE Ma.
Re: RACI finder scope new [Re: Thomas Karpf]
      #5836451 - 05/02/13 02:25 PM

I have planes overhead, almost. They fly from SW to N-NE, from Prov. to Boston. Luckily I can't view in those directions due to trees, house and LP. I view mainly NE-SE and they don't fly in that area. Will have to consider a laser.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | (show all)


Extra information
12 registered and 35 anonymous users are browsing this forum.

Moderator:  zjc26138, WOBentley, kkokkolis 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1139

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics