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Finderscope or red dot finder?


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47 minutes ago, Geoff Lister said:

Standard RDF converted to right-angle with 2-off 10mm dia 1mm thick rare-earth magnets, a wood offcut, 30mm/40mm acrylic mirror tile, and some glue.

RDF123.thumb.jpg.cd0250d947ebbe6a7aa22983f3431e63.jpg

Ingenious! Are those just different mirror size/shape options?

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Different sizes (30mmx30mm, 30mm dia. and 40mmx40mm), and also slightly different slope angles. By careful selection of slope angle, it is possible to direct the RDF image towards the eyepiece, and thus minimise eye & neck movement. The 40mm mirror tile gives a decent bit of sky surrounding the RDF's forward sight tube. This is the one that I use with my Heritage 130p, with a 30 degree slope, as it moves the viewing point close to the 130's EP. The magnets hold the assembly like a limpet, (the little wooden side-pieces are not necessary), and by careful positioning, the assembly snaps into place on the back of the RDF body. I have 4 OTAs with the same type of RDF, so I swap the mirrors around as required.

The acrylic mirrors were bought on eBay, from a firm specialising in mirror tiles for bathrooms. If using a contact adhesive, don't use too much on the rear of the mirror, as the solvent can pass through the mirror's backing layer and cause spotting on the mirror surface.

Geoff

Edited by Geoff Lister
add 130p info
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Recently put a telrad on my revelation 8 inch dob, its transformed my observing. Much easier to find stuff and you can find the telrad messier chart online to make it even easier.  Have made a home made dew shield though as it dews up easily.  Amazing piece of kit I'd recommend it. One for sale on astrobuysell for £30, definitely worth it.

Steve 

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I second the recommendation for a Telrad. It works especially well with apps like SkySafari that can superimpose the Telrad reticule on the star chart. Just point the scope until the star pattern through the Telrad matches the SkySafari view and you’re bang on target!

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I could also recommend the Telrad but with the provisio that it does not magnify the image, simply aids finding by displaying a set of reticules at infinity, and for this reason alone, I sold both units.
I  found that I needed to wear glasses in order to see the reticles with pin sharp clarity.
I don't normally wear glasses  whilst  using binoculars or at the telescope, so my choice was to not use the Telrad in favour of the supplied 9x50.
When using the 9x50 I view the target with both eyes open! my left eye on the target, my right eye looking through the finder, and when the two images coincide, I move to the eyepiece.

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9 hours ago, Charic said:

I don't normally wear glasses  whilst  using binoculars or at the telescope, so my choice was to not use the Telrad in favour of the supplied 9x50.
When using the 9x50 I view the target with both eyes open! my left eye on the target, my right eye looking through the finder, and when the two images coincide, I move to the eyepiece.

By "my left eye on the target", do you mean on the sky?  If so, wouldn't it be all blurry just like when using a Telrad?

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6 hours ago, Louis D said:

......wouldn't it be all blurry just like when using a Telrad?

NO.
My right eye is dominant, but these days, its the weakest of the two and needs correction, normally the finder/eyepiece  provides this, yet looking through the Telrad, my issue was with the reticules which appear to be blurred without visual correction?

Conditions now, with 'left eye on the sky and right eye magnified though the 9x50, its just a matter of aligning the two Stars? which to me is instinctive, takes seconds!

As with most things, you wont know how well an item will work unless you try it for yourself, be that a different finder or an eyepiece?
Prior to buying my first Telrad, I don't recall anyone  telling me about their issues with regards to having to wear glasses to achieve focus on the reticules.

I can't be the only one who has to wear glasses to see the reticles correctly focused! and for me, it just became a distraction, otherwise, yes, the Telrad is fine if I wear my prescriptions, and should be fine for someone who does not need glasses. 

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14 minutes ago, Charic said:

NO.
My right eye is dominant, but these days, its the weakest of the two and needs correction, normally the finder/eyepiece  provides this, yet looking through the Telrad, my issue was with the reticules which appear to be blurred without visual correction?

Conditions now, with 'left eye on the sky and right eye magnified though the 9x50, its just a matter of aligning the two Stars? which to me is instinctive, takes seconds!

As with most things, you wont know how well an item will work unless you try it for yourself, be that a different finder or an eyepiece?
Prior to buying my first Telrad, I don't recall anyone  telling me about their issues with regards to having to wear glasses to achieve focus on the reticules.

I can't be the only one who has to wear glasses to see the reticles correctly focused! and for me, it just became a distraction, otherwise, yes, the Telrad is fine if I wear my prescriptions, and should be fine for someone who does not need glasses. 

I'm seriously myopic and without eyeglasses can't see anything but the moon and the sun in the sky.  Perhaps you have good distance vision and can see the sky without glasses.  The Telrad reticle is supposed to be projected onto the sky at infinity focus so both it and the stars are at the same focus point to reduce eye strain.

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On ‎25‎/‎10‎/‎2017 at 15:01, leo82 said:

Hi all,

When my scope fell off the shelf in the shed, the red dot finder took the brunt of the damage and now I can’t adjust it accurately enough to keep using it. I have a skywatcher heritage 130, this scope only has 1 mounting so I can have either a red dot finder or finderscope. I was thinking of getting anew red dot finder and a lower power eyepiece to use as the finder? What power should I be looking to get? What red dot finder are the best? Will they all fit my scope? The cheap red dot finders ain’t that much cheaper than a telrad or star pointer, sorry for all the questions I’m just a bit confused as to what to do next.

Any advice will be much appreciated.

 

Alternate option, which I use all the time with my 10" dob

Just lay a laser along edge of the dovetail mount, and aim laser at what you want to observe

Fine tune then through eyepiece as scope is manual

Cheers

John

 

 

Edited by cletrac1922
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Unfortunately, due to a few idiots pointing laser-pointers at the cockpits of passing aircraft, they have got a bad reputation in the UK. If you live in an area of dense air traffic, a laser pointer may not be a good idea. If you do use a laser pointer, please use it sparingly, and make sure it is off if you see or hear a passing aircraft.

Geoff

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Just when I thought I had it worked out, red dot finder and revelation 32mm eyepiece (thanks @happy-kat), I now think about a telrad and/or finderscopes on dual mounts, it’s never easy is it. I’d never aim a lazer in the sky, it’s just too risky.

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4 hours ago, Geoff Lister said:

Unfortunately, due to a few idiots pointing laser-pointers at the cockpits of passing aircraft, they have got a bad reputation in the UK. If you live in an area of dense air traffic, a laser pointer may not be a good idea. If you do use a laser pointer, please use it sparingly, and make sure it is off if you see or hear a passing aircraft.

Geoff

It was such idiots in Australia that led to the most Draconian laser pointer laws in the world there.  Somehow, astronomers were able to get themselves written into the law as an exception under certain conditions.

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On 06/11/2017 at 02:56, Louis D said:

Telrad reticle is supposed to be projected onto the sky at infinity

Correct.

Our eyes are different! I can see the Stars, but their sharper with correction, but 9 Telrad reticles fractionally offset is distracting?
Its by choice I don't use the Telrad, due to the reticules, and with glasses on, their pin sharp, hopefully this answers your question?

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  • 2 weeks later...

JOC got you beat, have same that you have and also one that mounts 3, got off amazon......love both of them.....makes life simpler again, lol. one question JOC, is the orange used as a counterweight?, lol

 

Edited by Redbird48oo
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