Beginners Questions

I am now the proud owner of a new Skywatcher 250 10" dob and I am very
pleased with it, but I would appreciate some advise on the following
questions.

1 - How important is it to let your telescope cool down?. I was looking at
Jupiter and 4 of her moons last night and they all had a slight haze around
them. The telescope had been outside for about 10 - 15 minutes, is this long
enough?

2 - I don't mind lugging the telescope and stand in and out of the back
garden, but I am frightened of dropping it or squeezing the tube too much
and damaging it. Is there any kind of handle or harness available to carry
it correctly?

3 - What extra eyepieces would anyone recommend getting next?

Thanks in advance

Steve

WOW a 10" dob - very nice... No wonder it's never stopped raining this week!

It's very important to let the scope cool down or the image quality degrades
with all the 'heat haze' or currents in the tube. I usually leave my 6"
reflector out for an hour before I go near it. I put my hand just inside the
top of the tube and if I can still feel warm air rising I know its not
cooled down enough - doesn't stop me observing though ;-)

Not sure if there is a handle or the like for the tube, I'm someone else
will have an opinion on this.

As for eyepieces I'm guessing that the scope came with a 25mm and 10mm
kelner? If so I would go for a low power eyepiece such as a 32mm or 40mm (I
love my 32mm eyepiece) and you may want to consider a 4 or 5mm eyepiece.
Then add in a quality 2X barlow and you'll double your eyepiece
collection...

Regards

Alistair
http://www.geocities.com/the_150mm_reflector



"Steve" wrote in message
...
I am now the proud owner of a new Skywatcher 250 10" dob and I am very
pleased with it, but I would appreciate some advise on the following
questions.

1 - How important is it to let your telescope cool down?. I was looking at
Jupiter and 4 of her moons last night and they all had a slight haze
around
them. The telescope had been outside for about 10 - 15 minutes, is this
long
enough?

2 - I don't mind lugging the telescope and stand in and out of the back
garden, but I am frightened of dropping it or squeezing the tube too much
and damaging it. Is there any kind of handle or harness available to carry
it correctly?

3 - What extra eyepieces would anyone recommend getting next?

Thanks in advance

Steve

Is it the lower the mm, the higher the power?
Some eyepieces say x100 or x175 etc...

Hello Steve, I got the 200mm version a couple of weeks ago. From my limited
experience with it (weather induced!) I'd say that the haze is more likely
to be condensation / dew on the eyepiece? Warm mirrors tend to cause tube
currents that induce shimmering unstable images rather than haze, as far as
I know.

Does yours have handles sticking out of the side (where the altitude
bearings are)? I use these to carry mine in and out, though I must admit the
8-inch is heavy enough for me ....... do you carry yours in one piece? If
not, you could always re-insert the handles after takine the tube off the
base .........

I chose the one with the pyrex mirror because I had read about cooling etc,
and can observe almost instantly with it .....it is kept in the garage
however so the temperature difference is not as high as if it were kept in
the house.

I am also thinking about new eyepieces ......... wondering about taking
advantage of the 2 inch focusser with a nice wide-angle and maybe getting
something in the region of 8mm for higher power; I've not found the barlow
that useful so far.

Cheers

Alan

"Steve" wrote in message
...
I am now the proud owner of a new Skywatcher 250 10" dob and I am very
pleased with it, but I would appreciate some advise on the following
questions.

1 - How important is it to let your telescope cool down?. I was looking at
Jupiter and 4 of her moons last night and they all had a slight haze
around
them. The telescope had been outside for about 10 - 15 minutes, is this
long
enough?

2 - I don't mind lugging the telescope and stand in and out of the back
garden, but I am frightened of dropping it or squeezing the tube too much
and damaging it. Is there any kind of handle or harness available to carry
it correctly?

3 - What extra eyepieces would anyone recommend getting next?

Thanks in advance

Steve

Steve wrote:
Is it the lower the mm, the higher the power?
Some eyepieces say x100 or x175 etc...

Hi Steve,

you're right there. According to

http://astunit.com/tutorials/telescope.htm

the magnification of a telescope is pretty close to
(focal length of objective)/(focal length of eyepiece)

So, the lower the focal length (mm) of your eyepiece, the higher the
magnification. E.g. my telescope has 1000mm focal length, so if I use my
10mm eyepiece that would yield 1000mm / 10mm = 100x magnification.
(AFAIK you can't tell the magnification of an eyepiece without knowing what
telescope it's used with, so the magnifications those eyepieces state are
for telescopes with one focal length only)

HTH,

Joerg

--
Joerg Glissmann
remove pants to reply.. :-)

Thanks your advice everyone.

I was going to use the handles to carry the scope but then would be unable
to drop it into the stand without having to place it on the floor, remove
the handles, then pick it up and drop it into the stand. The scope is more
akward than heavy!!

Good point :-). How about storing the scope outside in a weatherproof
enclosure (upside down water-but if you can get one tall enough) - or at
least closer to the door (in a cupboard?) and just carrying the mount in and
out?


"Steve" wrote in message
...
Thanks your advice everyone.

I was going to use the handles to carry the scope but then would be unable
to drop it into the stand without having to place it on the floor, remove
the handles, then pick it up and drop it into the stand. The scope is more
akward than heavy!!

In article , Steve wrote:

2 - I don't mind lugging the telescope and stand in and out of the back
garden, but I am frightened of dropping it or squeezing the tube too much
and damaging it. Is there any kind of handle or harness available to carry
it correctly?

I have the 8" and yes, the tube is rather thin walled. I keep mine in
the hall and carry it out in stages.
1/ Lift OTA off Dobsonian base and stand it in the corner (mirror end
down).
2/ Carry base out into garden and position it.
3/ Carry OTA outside and place it on the base.
I carry the OTA by resting the tube on my left arm and over my left
shoulder, with my right hand firmly gripping the mirror end of the tube.
I worry about slamming it into a door frame or some other obstruction,
but have been OK so far. I expect the 10" is a lot more cumbersome.
--
Jim Easterbrook http://astro.jim-easterbrook.me.uk/
N51.36 E0.25

On Thu, 5 Feb 2004 08:41:18 -0000, "Steve"
wrote:

I am now the proud owner of a new Skywatcher 250 10" dob and I am very
pleased with it, but I would appreciate some advise on the following
questions.

1 - How important is it to let your telescope cool down?. I was looking at
Jupiter and 4 of her moons last night and they all had a slight haze around
them. The telescope had been outside for about 10 - 15 minutes, is this long
enough?

2 - I don't mind lugging the telescope and stand in and out of the back
garden, but I am frightened of dropping it or squeezing the tube too much
and damaging it. Is there any kind of handle or harness available to carry
it correctly?

3 - What extra eyepieces would anyone recommend getting next?

Thanks in advance

Steve


How has your 250 10" worked out? What sorts of objects have you been
able to see?

Paul D, Worcestershire, UK