Plossl ??

Thanks for your help with my question about my new scope.

So I have played with my 10" hardin now for a few nights.
I have a few obserations.
1. The X2 barlow may work on the moon but make mars look blury.
2. It looks like there is a light coating or haze on the primary mirror 10"
and none on my old 4.5 does the 10" need cleaning?
3. Rotaion bearing way to easy-- i will need to put felt down to stop this.
4. Does a 2" plossl do more for viewing then a 1.25. Is it worth the upgrade
for a backyard duffus like me.

PS this is the kit the scope came with -- Celestron #94304. It is OK or
junk?

Mark F.
--
Fly Lexx!

On Mon, 28 Apr 2008 03:57:53 GMT, "Mark F." wrote:
1. The X2 barlow may work on the moon but make mars look blury.
2. It looks like there is a light coating or haze on the primary mirror 10"
and none on my old 4.5 does the 10" need cleaning?
3. Rotaion bearing way to easy-- i will need to put felt down to stop this.
4. Does a 2" plossl do more for viewing then a 1.25. Is it worth the upgrade
for a backyard duffus like me.

PS this is the kit the scope came with -- Celestron #94304. It is OK or
junk?

Mark F.

Pardon if I'm butting in...
1) It's typical that with more magnification, you magnify whatever
inherent blur exists. If you're lucky, it's just a night of bad
seeing. Less lucky, you're in an area that has a lot of local thermal
disturbance (like if you're observing from a large paved area), or
your optics may need cleaning or collimation. If you're very unlucky,
it's a poorly manufactured barlow or worst of all, something poorly
made in an optical component of the scope.
2) Sounds like your primary could use a good cleaning. Maybe the
secondary, too.
3) OK
4) It depends on the actual light path. If the smallest opening it
clears is 2" (so you'd be using a 2" to 1¼" adapter for your
eyepieces), then yes, a 2" eyepiece would help. If your light path
goes through a 1¼" constriction and you're thinking of geting a 1¼" to
2" adapter, then I'd be less inclined to think it would help much. It
would a bit, because the 2" lenses are (rule of thumb) higher quality
anyway. But you probably wouldn't gain much if anything by way of more
light. Please note, there are eyepieces that have both 1¼" and 2"
barrels (Televue 12mm Type II Nagler, e.g.), and in these cases a 2"
mount would not help.

Dunno for the Celestron #94304.

Good luck!

Mark F. wrote:
Thanks for your help with my question about my new scope.

So I have played with my 10" hardin now for a few nights.
I have a few obserations.
1. The X2 barlow may work on the moon but make mars look blury.

Moon is very high contrast and plenty of light.

2. It looks like there is a light coating or haze on the primary mirror 10"
and none on my old 4.5 does the 10" need cleaning?

Unlikely. It is amazing how dirty a mirror can be and still give prefect
images. Cleaning it can risk surface damage and additional wear if done
improperly.

3. Rotaion bearing way to easy-- i will need to put felt down to stop this.
4. Does a 2" plossl do more for viewing then a 1.25. Is it worth the upgrade
for a backyard duffus like me.

It gets you a wider field of view for the same focal length eyepiece
assuming that the 2" exploits the larger diameter to full effect.

You are probably better off with a couple of decent 1.25" eyepieces to
start with unless you already know you want widest possible field for
deep sky and are prepared to pay the price.

PS this is the kit the scope came with -- Celestron #94304. It is OK or
junk?

Probably a reasonable mid range eyepiece of around 1" focal length.
If you have a 2x Barlow it is worth avoiding eyepieces exactly 2x
ratio apart. A 17mm focal length eyepiece is often a good choice.

These days the better zoom eyepieces are worth considering too.

Regards,
Martin Brown
** Posted from http://www.teranews.com **

On or about Mon, 28 Apr 2008 03:57:53 GMT did "Mark F."
dribble thusly:

Thanks for your help with my question about my new scope.

So I have played with my 10" hardin now for a few nights.
I have a few obserations.
1. The X2 barlow may work on the moon but make mars look blury.

If anything looks blurry, you're overmagnifying. The ceiling magnification
for a 10" scope is about 600x, but it's quite unlikely viewing conditions will
ever be good enough to support that. More reasonably, you're better off
staying at 300x or less. Assuming 1250mm as the focal length, that means you
shouldn't use less than a 4mm EP, or an 8mm EP with a 2x barlow.

It may look OK with the moon simply because it's a lot bigger, and there's
plenty of large-scale detail. Mars, however, is tiny.

2. It looks like there is a light coating or haze on the primary mirror 10"
and none on my old 4.5 does the 10" need cleaning?

Unlikely. I'm assuming it's not something as obvious as dew. In general,
don't clean the mirror. As someone else pointed out, they can get quite
apparently filthy before you notice any impact on performance.

4. Does a 2" plossl do more for viewing then a 1.25. Is it worth the upgrade
for a backyard duffus like me.

In general, a 2" EP barrel simply allows a larger focal length without
reducing the apparent FOV. For a Plossl, that means if it's about 40mm or
higher, you'll want a 2" barrel, so the AFOV can stay around 50-60 degrees.

PS this is the kit the scope came with -- Celestron #94304. It is OK or
junk?

Probably OK or better. Very doubtful that it's junk.

If that 12.5mm EP is what you're trying with the barlow, that should give you
about 200x magnification. If that's blurry, the most likely culprit is bad
seeing.

On Apr 28, 2:40*am, SkySea wrote:
On Mon, 28 Apr 2008 03:57:53 GMT, "Mark F." wrote:
1. The X2 barlow may work on the moon but make mars look blury.
2. It looks like there is a light coating or haze on the primary mirror 10"
and none on my old 4.5 does the 10" need cleaning?
3. Rotaion bearing way to easy-- i will need to put felt down to stop this.
4. Does a 2" plossl do more for viewing then a 1.25. Is it worth the upgrade
for a backyard duffus like me.

PS this is the kit the *scope came with -- Celestron #94304. It is OK or
junk?

Mark F.

Pardon if I'm butting in...
1) It's typical that with more magnification, you magnify whatever
inherent blur exists. If you're lucky, it's just a night of bad
seeing. Less lucky, you're in an area that has a lot of local thermal
disturbance (like if you're observing from a large paved area), or
your optics may need cleaning or collimation. If you're very unlucky,
it's a poorly manufactured barlow or worst of all, something poorly
made in an optical component of the scope.
2) Sounds like your primary could use a good cleaning. Maybe the
secondary, too.

Do not attempt to clean the primary mirror -- you will -- without fail
-- screw it up.

Leave it alone.



3) OK
4) It depends on the actual light path. If the smallest opening it
clears is 2" (so you'd be using a 2" to 1¼" adapter for your
eyepieces), then yes, a 2" eyepiece would help. If your light path
goes through a 1¼" constriction and you're thinking of geting a 1¼" to
2" adapter, then I'd be less inclined to think it would help much. It
would a bit, because the 2" lenses are (rule of thumb) higher quality
anyway. But you probably wouldn't gain much if anything by way of more
light. Please note, there are eyepieces that have both 1¼" and 2"
barrels (Televue 12mm Type II Nagler, e.g.), and in these cases a 2"
mount would not help.

Dunno for the Celestron #94304.

Good luck!

Thank for your wise help and wisdom.
And getting me off the hook about cleaning the mirror. (grin)
Mark



"Mark F." wrote in message
news:5XbRj.6156$E77.3509@trnddc05...
Thanks for your help with my question about my new scope.

So I have played with my 10" hardin now for a few nights.
I have a few obserations.
1. The X2 barlow may work on the moon but make mars look blury.
2. It looks like there is a light coating or haze on the primary mirror
10" and none on my old 4.5 does the 10" need cleaning?
3. Rotaion bearing way to easy-- i will need to put felt down to stop
this.
4. Does a 2" plossl do more for viewing then a 1.25. Is it worth the
upgrade for a backyard duffus like me.

PS this is the kit the scope came with -- Celestron #94304. It is OK or
junk?

Mark F.
--
Fly Lexx!

Mark F. wrote:
Thank for your wise help and wisdom.
And getting me off the hook about cleaning the mirror. (grin)
Mark

There are ways to clean the surface if needed, but it's best
to do so as little as possible. Frequent cleaning can eventually
degrade or wear away the mirror coating (some types are more
durable than others), and a bit of scattered dust doesn't really
cause too much trouble.

-dave w

On 2008-04-29, Kickin' Ass and Takin' Names wrote:

Do not attempt to clean the primary mirror -- you will -- without fail
-- screw it up.

Leave it alone.

That seems a bit of an overgeneralisation. There are many people
who perfectly successfully clean their primaries and regard it as
nothing more than routine (if irregular) telescope maintenance.
I've done it myself. Sure you have to obey a few simple rules when
doing it but it is hardly a difficult operation.

--
Andrew Smallshaw

Andrew Smallshaw wrote:
On 2008-04-29, Kickin' Ass and Takin' Names wrote:
Do not attempt to clean the primary mirror -- you will -- without fail
-- screw it up.

Leave it alone.

That seems a bit of an overgeneralisation. There are many people
who perfectly successfully clean their primaries and regard it as
nothing more than routine (if irregular) telescope maintenance.

Although it is easy enough to do. The amount of random specs of dust
muck and rubbish that the mirror can tolerate is surprisingly large
whereas any systematic scratches caused by over zealous cleaning can
cause considerable damage to the image contrast.

I've done it myself. Sure you have to obey a few simple rules when
doing it but it is hardly a difficult operation.

Beginners in particular are prone to excessive cleaning. And there are a
limited number of times you can clean the mirror.

The only time I would make an exception and clean ASAP is when the
mirror surface has been contaminated with a well aimed bird lime deposit
or bat droppings which may be corrosive if left in place.

Regards,
Martin Brown
** Posted from http://www.teranews.com **

On Mon, 28 Apr 2008 17:38:34 -0700 (PDT), "Kickin' Ass and Takin' Names"
wrote:

Do not attempt to clean the primary mirror -- you will -- without fail
-- screw it up.

Hardly. Cleaning a mirror is no big deal. These days, nearly all have a
hard coating over the aluminum, and with a modicum of care (and use of
the correct cleaning materials) cleaning will not result in any damage.

This whole business about leaving the mirror alone and rarely if ever
cleaning it is nonsense. It is left over from days when mirrors were
more delicate, and is a message promulgated by telescope manufacturers
who don't want to deal with the results if their customers don't do it
right.

Mirrors have been damaged by contaminants left on them too long, and
critical observers can see the difference in a few percent loss of
light- something a thin layer of dust can result in.

There's no need to be fanatical about cleaning, but it's not a bad idea
to keep the primary relatively clean. Most Newts can use a cleaning
every year or two.
_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com