1.25" v's 2" accessories

As a astro-newb and soon-to-be owner of an 8" Dob (which for those not
familiar, can accommodate either 1.25 or 2" eyepieces & accessories), I
am clueless as to the advantages and disadvantages between the two, and
hence, also clueless into which size future investments should be made.

I guess one could say I have put the cart before the horse in that I
have already made purchases for 1.25" accessories, e.g. filters and
barlow... I did this because it seemed money well spent; 5 filters and
barlow w/ shipping for $90. In my mind, I was maximizing my abilities
with what accessories where coming stock with the Dob.

However, if 2" is "noticeably superior", then I am "destined" to resort
to 2" (and all necessary, associated, accessories), ergo making all
current 1.25" purchases - wasteful. Of course I could send back the
1.25" accessories and exchange them for 2", but then I'd have to
purchase 2" eye pieces as well; spending more money. Is it worth it?

Please make up my mind for me.....

Errol NOLA

Starboard wrote:
As a astro-newb and soon-to-be owner of an 8" Dob (which for those not
familiar, can accommodate either 1.25 or 2" eyepieces & accessories), I
am clueless as to the advantages and disadvantages between the two, and
hence, also clueless into which size future investments should be made.


A very good question.

You might want to look around Cloudy Nights a bit:

Here is an article on how to set up a Dob (scope is similar to Orion XT-8).

Don't know if they have any 1.25 vs. 2" articles or reviews, but worth
looks.

FWIW, at this point in time, all my EPs, diagonals, etc. are 1.25" ..
though at least two of my scopes will support 2" accessories.

Phil

Phil Wheeler wrote:
Starboard wrote:

As a astro-newb and soon-to-be owner of an 8" Dob (which for those not
familiar, can accommodate either 1.25 or 2" eyepieces & accessories), I
am clueless as to the advantages and disadvantages between the two, and
hence, also clueless into which size future investments should be made.


A very good question.

You might want to look around Cloudy Nights a bit:

Here is an article on how to set up a Dob (scope is similar to Orion XT-8).


Oops! He


http://www.cloudynights.com/item.php...d=1058&pr=3x74

For starts I will not make your mind up.

Fact #1 all eyepeices are not best used in all scopes.

Fact #2 is that what eyepiece you used depends on what you want to
look at and what scope you are using at that time.

Some basic generalities:

1) 1.25 inch eypieces are generally limited to about 55 degree field
of view max. 2 inch eyepieces can achieve higher fields of view.
Upwards to 80 degrees.

2) Generally speaking 2 inch eyepieces are heavier and cost more due
to larger diameter and thickness of the glass used in 2 inch
eyepieces.

3) Longer focal lengths are better off in 2 inch eyepieces. Generally
greater than 30 mm focal length eyepieces.

Also limiting your choice to just eyepiece diameter is limiting visual
performance. A good selection of eyepieces will have both for
different viewing conditions and objects.

The only recommendation that I can make it that you have a selection
that comprises of both. Most of you 2 inch eyepieces will be used for
low pwer and wide field of views. Most of your 1.25 inch eyepieces
will be short focal length for high magnification and specific
viewing. Even some of your eyepieces can be narrow field of view for
double stars and planetary work.

james



On 31 Dec 2005 12:16:01 -0800, "Starboard"
wrote:

+As a astro-newb and soon-to-be owner of an 8" Dob (which for those not
+familiar, can accommodate either 1.25 or 2" eyepieces & accessories), I
+am clueless as to the advantages and disadvantages between the two, and
+hence, also clueless into which size future investments should be made.
+
+I guess one could say I have put the cart before the horse in that I
+have already made purchases for 1.25" accessories, e.g. filters and
+barlow... I did this because it seemed money well spent; 5 filters and
+barlow w/ shipping for $90. In my mind, I was maximizing my abilities
+with what accessories where coming stock with the Dob.
+
+However, if 2" is "noticeably superior", then I am "destined" to resort
+to 2" (and all necessary, associated, accessories), ergo making all
+current 1.25" purchases - wasteful. Of course I could send back the
+1.25" accessories and exchange them for 2", but then I'd have to
+purchase 2" eye pieces as well; spending more money. Is it worth it?
+
+Please make up my mind for me.....
+
+Errol NOLA

"Starboard" wrote in message
oups.com...
As a astro-newb and soon-to-be owner of an 8" Dob (which for those not
familiar, can accommodate either 1.25 or 2" eyepieces & accessories), I
am clueless as to the advantages and disadvantages between the two, and
hence, also clueless into which size future investments should be made.

I guess one could say I have put the cart before the horse in that I
have already made purchases for 1.25" accessories, e.g. filters and
barlow... I did this because it seemed money well spent; 5 filters and
barlow w/ shipping for $90. In my mind, I was maximizing my abilities
with what accessories where coming stock with the Dob.

However, if 2" is "noticeably superior", then I am "destined" to resort
to 2" (and all necessary, associated, accessories), ergo making all
current 1.25" purchases - wasteful. Of course I could send back the
1.25" accessories and exchange them for 2", but then I'd have to
purchase 2" eye pieces as well; spending more money. Is it worth it?

Please make up my mind for me.....

Errol NOLA


It depends entirely on what your likes and objectives are, whether 2"
eyepieces make good sense for you...

I have an 8" f/6 equatorial reflector with exceptional optics, and it has
a 1.25" focuser. It delivers a 1.2 degree field WITH a Paracorr, and a
bit more without.

I have completely refurbished this scope over the years, adding top
quality mirror cells, exquisite mirrors (primary by Mike Spooner,
certified secondary by Antares), new focuser, etc, but it still has a
1.25" focuser, even though I could easily have installed a 2" BOTH times I
replaced the focuser. I just never felt the need.

But if you want to go somewhere beyond about 1.2 or 1.3 degrees of actual
field, you WILL have to go to a 2" focuser... I am a DSO type person, so
I DO like larger objects, but I have found over the years that, while 1.2
degrees doesn't encompass EVERYTHING I like to observe, it does get MOST
of it. So I have stuck with a 1.25" focuser, and have never been unhappy
with that decision...

I did upgrade my 13" Dob's focuser to 2", but that was to try to maintain
*about* the same maximum field I have in the 8"...

Everyone's tastes are different, so what works for me may suck for you...

But what I would suggest would be to get your new scope, use it for awhile
with what you HAVE. And while you get used to the scope and it's
capabilities, and how you can best use them, you will also begin to
understand what kinds of things you most like to observe. And as you do
THAT, you will sort of fall into an understanding of what kinds of
eyepieces will be required to deliver the types of objects you most like
to view... NEVER, EVER, let the rest of us tell you what YOU should
like... That is a VERY personal thing, and only YOU know the answer, and
can't really know the answer until you have some eyepiece time.

Good luck, and keep us posted on how things go... I'm sure you will have
more questions after your scope arrives, and you start to use it. But for
now, don't WORRY too much about things like what size eyepieces do you
need... Once you have received your scope, and you have used it awhile,
that will become apparent to YOU, and you can move accordingly...

Oh. I forgot to mention that I have a LOT of 2" eyepieces, but that STILL
has not convinced me that I need them on my 8" f/6...

--
Jan Owen

To reach me directly, remove the Z, if one appears in my e-mail address...
Latitude: 33.6
Longitude: -112.3

Please make up my mind for me.....

For starts I will not make your mind up.

James,

I suppose the choice phrase was, at risk of sounding somewhat gay,
"cutesy." (no offence to any gay astro's, or "gastro's" per' se.......
oh there I go again). No, you're right, my mind will be made up through
the composite of all the ideas expressed through this group; and the
great google search engine.

I do thank you for your time and being so generous with your knowledge.
Please keep it coming..

Errol
NOLA

Seems that site was designed for me. Thankx!

Errol
NOLA

Starboard wrote:
As a astro-newb and soon-to-be owner of an 8" Dob (which for those not
familiar, can accommodate either 1.25 or 2" eyepieces & accessories), I
am clueless as to the advantages and disadvantages between the two, and
hence, also clueless into which size future investments should be made.

I guess one could say I have put the cart before the horse in that I
have already made purchases for 1.25" accessories, e.g. filters and
barlow... I did this because it seemed money well spent; 5 filters and
barlow w/ shipping for $90. In my mind, I was maximizing my abilities
with what accessories where coming stock with the Dob.

However, if 2" is "noticeably superior", then I am "destined" to resort
to 2" (and all necessary, associated, accessories), ergo making all
current 1.25" purchases - wasteful. Of course I could send back the
1.25" accessories and exchange them for 2", but then I'd have to
purchase 2" eye pieces as well; spending more money. Is it worth it?

Please make up my mind for me.....

Errol NOLA


o Most 1.25" accessories will work on any telescope you are
likely to own.

o Most 2" eyepieces are only available in longer focal length.

o Most 2" eyepieces are more expensive.

o For very long focal length eyepieces and mounting 35mm cameras
at prime focus, 2" is preferred, if not necessary.

Jan,

Thanks for the detailed explanation. Didn't realize that eye piece
diameter could be subjective. I was expecting someone to say (based on
prior warnings I've read to avoid .96" eye pieces) that bigger is
better for physical reasons. I chalk it up as a lesson learned.

Your avid reader
Errol
NOLA

Errol NOLA posted:

As a astro-newb and soon-to-be owner of an 8" Dob (which for those not
familiar, can accommodate either 1.25 or 2" eyepieces & accessories), I
am clueless as to the advantages and disadvantages between the two, and
hence, also clueless into which size future investments should be made.

I guess one could say I have put the cart before the horse in that I
have already made purchases for 1.25" accessories, e.g. filters and
barlow... I did this because it seemed money well spent; 5 filters and
barlow w/ shipping for $90. In my mind, I was maximizing my abilities
with what accessories where coming stock with the Dob.

However, if 2" is "noticeably superior", then I am "destined" to resort
to 2" (and all necessary, associated, accessories), ergo making all
current 1.25" purchases - wasteful. Of course I could send back the
1.25" accessories and exchange them for 2", but then I'd have to
purchase 2" eye pieces as well; spending more money. Is it worth it?

Please make up my mind for me.....


2" barrel eyepieces are not necessarly "noticably superior" to any
others. Basically, all 2" barrels will allow you to do is access the
*potential" of wider true fields of view on the sky than you might be
able to get with 1.25" eyepieces. If you don't need a huge field, then
you won't need a 2" eyepiece or the hardware that goes with them.
With an 8 inch Newtonian, you may be also limited on the maximum field
size by the size of your secondary mirror, which if not big enough won't
fully illuminate the outer portions of wider fields of view. Thus,
going to 2" eyepieces might not gain you all that much. You should be
able to get at least a full degree of true field on the sky with some of
the longer focal length 1.25" eyepieces in an 8 inch f/6 telescope,
which is generally plenty except for maybe a few of the really large
Deep-sky objects. *SOME* 2" eyepieces are superior, but there are also
some that are just downright dogs with horrid performance, so the barrel
size doesn't tell the whole story. For an example of a "noticably
superior" 1.25" eyepiece, the Tele Vue 24mm Panoptic is probably one
which fits that description. You may want to eventually go 2", but for
right now, 1.25" should serve you fairly well. Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

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