Need to know what certain parts are on a telescope are

On 24/08/2012 4:08 AM, Martin Brown wrote:
Notch filter technology pricing has improved enormously with modern
vacuum coating deposition techniques. Not much good visually but helpful
for CCD imaging since it cuts down skyglow a lot.

A solar H-alpha is a much more expensive and exotic affair but its
passband of 0.7A or so is 10x smaller than the deepsky. They also have
to be used with a red glass energy filter on the input to the scope.

Okay, so that's a nada on the h-alpha, but can somebody suggest a good,
cheap filter for viewing the Sun?

Second, what's a good eyepiece for taking pictures with a digital camera?

Yousuf Khan

On 23/08/2012 8:45 PM, Quadibloc wrote:
On Aug 23, 5:51 pm, Yousuf wrote:

Yes it does look like that, though not quite as nice, more plasticky.
And yes, there are actual eyepieces included with it, separately, but I
knew what those are for, I wasn't aware of what this thing was for.

Oh! So that thing isn't an eyepiece either, it's an erecting lens. So,
like the Barlow lens, you put it between the lens and your eyepiece to
gain additional magnification (thus you have basically a larger
selection of eyepieces this way).

If you have also more than one real eyepiece, of course you will
notice that the ones with shorter focal lengths also have a smaller
area for your eye to look into. So using an eyepiece with a longer
focal length with a Barlow lens provides greater eye relief - greater
comfort in looking through a bigger eyepiece - for the same
magnification.

It came with 3 eyepieces: an SR4mm, an H12.5mm, and an H20mm. What
situations are these used for?

Yousuf Khan

On Aug 24, 6:01*pm, Yousuf Khan wrote:
On 23/08/2012 8:45 PM, Quadibloc wrote:









On Aug 23, 5:51 pm, Yousuf *wrote:

Yes it does look like that, though not quite as nice, more plasticky.
And yes, there are actual eyepieces included with it, separately, but I
knew what those are for, I wasn't aware of what this thing was for.

Oh! So that thing isn't an eyepiece either, it's an erecting lens. So,
like the Barlow lens, you put it between the lens and your eyepiece to
gain additional magnification (thus you have basically a larger
selection of eyepieces this way).

If you have also more than one real eyepiece, of course you will
notice that the ones with shorter focal lengths also have a smaller
area for your eye to look into. So using an eyepiece with a longer
focal length with a Barlow lens provides greater eye relief - greater
comfort in looking through a bigger eyepiece - for the same
magnification.

It came with 3 eyepieces: an SR4mm, an H12.5mm, and an H20mm. What
situations are these used for?

The 20 is for low power, the 4 for high power. I would avoid using
the 4mm at first (or maybe entirely) and stick to the 20 and maybe the
12.5mm.

If you buy this:

http://www.telescope.com/Clearance-C...81/p/79843.uts

you will get a couple of decent eyepieces with it. However, you
haven't told us what size focuser your scope has; either the standard
1.25-inch or the sub-standard 0.965-inch. Can you describe your
scope some more?

On Fri, 24 Aug 2012 17:56:21 -0400, Yousuf Khan
wrote:

Okay, so that's a nada on the h-alpha, but can somebody suggest a good,
cheap filter for viewing the Sun?

Cheapest, and amongst the best, will be a full aperture filter made
with Baader film. The plastic is cheap, making a filter cell is easy.
Google "full aperture solar filter" and you'll find a raft of
possibilities. Just remember that full aperture filters are the only
practical safe solar filters for amateur setups.

Second, what's a good eyepiece for taking pictures with a digital camera?

If you have a DLSR, no eyepiece at all is best, you just do prime
focus imaging. If your camera doesn't have a removable lens, you can
do afocal imaging through almost any eyepiece, you just need some sort
of adapter to mount your camera to the telescope body or eyepiece
holder.

Yousuf Khan wrote in news:5037f887$1
@news.bnb-lp.com:

On 24/08/2012 4:08 AM, Martin Brown wrote:
Notch filter technology pricing has improved enormously with modern
vacuum coating deposition techniques. Not much good visually but
helpful
for CCD imaging since it cuts down skyglow a lot.

A solar H-alpha is a much more expensive and exotic affair but its
passband of 0.7A or so is 10x smaller than the deepsky. They also have
to be used with a red glass energy filter on the input to the scope.

Okay, so that's a nada on the h-alpha, but can somebody suggest a good,
cheap filter for viewing the Sun?

Second, what's a good eyepiece for taking pictures with a digital
camera?

Yousuf Khan


I think, good and cheap kind of dont go together.
My neutral density solar filter is a three layer 10 inch
glass based filter, recalculated to todays currency,
about 800 Euro, and works quite nicely.

On 25 Aug 2012 02:22:30 GMT, Sjouke Burry s@b wrote:

I think, good and cheap kind of dont go together.
My neutral density solar filter is a three layer 10 inch
glass based filter, recalculated to todays currency,
about 800 Euro, and works quite nicely.

Yet a 10 Euro piece of Baader film will probably outperform your glass
filter. Every now and then, good and cheap actually do go together.

On 24/08/2012 23:01, Yousuf Khan wrote:
On 23/08/2012 8:45 PM, Quadibloc wrote:
On Aug 23, 5:51 pm, Yousuf wrote:

Yes it does look like that, though not quite as nice, more plasticky.
And yes, there are actual eyepieces included with it, separately, but I
knew what those are for, I wasn't aware of what this thing was for.

Oh! So that thing isn't an eyepiece either, it's an erecting lens. So,
like the Barlow lens, you put it between the lens and your eyepiece to
gain additional magnification (thus you have basically a larger
selection of eyepieces this way).

If you have also more than one real eyepiece, of course you will
notice that the ones with shorter focal lengths also have a smaller
area for your eye to look into. So using an eyepiece with a longer
focal length with a Barlow lens provides greater eye relief - greater
comfort in looking through a bigger eyepiece - for the same
magnification.

It came with 3 eyepieces: an SR4mm, an H12.5mm, and an H20mm. What
situations are these used for?

Almost never, higher magnification, medium magnification.

And with the 3x Barlow lens: Never, Never and highest magnification.

The 3x Barlow and 4mm eyepiece are intendeed to allow manufacturers to
claim up to 500x magnification or some such absurdity. It is rare to use
much over 20x per inch of aperture (maybe twice that on double stars).
try them out and see for yourself.

At some point in the future you probably want to buy a 32mm Plossl for
widest apparent field of view lowest magnification from your scope.

And after that a light pollution filter if you don't have dark skies.

Regards,
Martin Brown

On Aug 25, 4:12*am, Martin Brown
wrote:
On 24/08/2012 23:01, Yousuf Khan wrote:









On 23/08/2012 8:45 PM, Quadibloc wrote:
On Aug 23, 5:51 pm, Yousuf *wrote:

Yes it does look like that, though not quite as nice, more plasticky.
And yes, there are actual eyepieces included with it, separately, but I
knew what those are for, I wasn't aware of what this thing was for.

Oh! So that thing isn't an eyepiece either, it's an erecting lens. So,
like the Barlow lens, you put it between the lens and your eyepiece to
gain additional magnification (thus you have basically a larger
selection of eyepieces this way).

If you have also more than one real eyepiece, of course you will
notice that the ones with shorter focal lengths also have a smaller
area for your eye to look into. So using an eyepiece with a longer
focal length with a Barlow lens provides greater eye relief - greater
comfort in looking through a bigger eyepiece - for the same
magnification.

It came with 3 eyepieces: an SR4mm, an H12.5mm, and an H20mm. What
situations are these used for?

Almost never, higher magnification, medium magnification.

And with the 3x Barlow lens: Never, Never and highest magnification.

The 3x Barlow and 4mm eyepiece are intendeed to allow manufacturers to
claim up to 500x magnification or some such absurdity. It is rare to use
much over 20x per inch of aperture (maybe twice that on double stars).
try them out and see for yourself.

The more reputable vendors generally do not even include a Barlow,
supplying instead a reasonable quality eyepiece or two. However, the
OP's telescope might perform quite well with a high-quality Barlow
purchased later, assuming that iit is not used to obtain mags over 50x
per inch. BTW, most scopes can handle much more than 20x per inch.
(Your scope might be different.)

On Aug 24, 10:22*pm, Sjouke Burry s@b wrote:
Yousuf Khan wrote in news:5037f887$1
@news.bnb-lp.com:











On 24/08/2012 4:08 AM, Martin Brown wrote:
Notch filter technology pricing has improved enormously with modern
vacuum coating deposition techniques. Not much good visually but
helpful
for CCD imaging since it cuts down skyglow a lot.

A solar H-alpha is a much more expensive and exotic affair but its
passband of 0.7A or so is 10x smaller than the deepsky. They also have
to be used with a red glass energy filter on the input to the scope.

Okay, so that's a nada on the h-alpha, but can somebody suggest a good,
cheap filter for viewing the Sun?

Second, what's a good eyepiece for taking pictures with a digital
camera?

* * *Yousuf Khan

I think, good and cheap kind of dont go together.
My neutral density solar filter is a three layer 10 inch
glass based filter, recalculated to todays currency,
about 800 Euro, and works quite nicely.

Just for laughs you should compare it to the inexpensive filters now
available.

On 25/08/2012 12:59, wrote:
On Aug 25, 4:12 am, Martin Brown
wrote:
On 24/08/2012 23:01, Yousuf Khan wrote:

It came with 3 eyepieces: an SR4mm, an H12.5mm, and an H20mm. What
situations are these used for?

Almost never, higher magnification, medium magnification.

And with the 3x Barlow lens: Never, Never and highest magnification.

The 3x Barlow and 4mm eyepiece are intendeed to allow manufacturers to
claim up to 500x magnification or some such absurdity. It is rare to use
much over 20x per inch of aperture (maybe twice that on double stars).
try them out and see for yourself.

The more reputable vendors generally do not even include a Barlow,
supplying instead a reasonable quality eyepiece or two. However, the
OP's telescope might perform quite well with a high-quality Barlow
purchased later, assuming that iit is not used to obtain mags over 50x

Not with those eyepieces. I don't understand why makers don't provide
beginner sets in the golden ratio and with a 2x Barlow - it makes so
much more sense and gives a wide range of useful magnifications.

eg 26, 16, 10 and with Barlow 13, 8, 5 all of which are useful.

His best buy before anything else would be a 32mm plossl without a
doubt. Or an A4 sheet of Baader visual solar screen.

per inch. BTW, most scopes can handle much more than 20x per inch.
(Your scope might be different.)

Smaller scopes can be if you don't mind empty magnification but larger
ones tend to be seeing limited to about 1" arc fwhm most of the time at
least in the UK under the jetstream. Unless the seeing is exceptionally
good I don't have much use for anything above 25x per inch.

I also suspect that the sort of scope that comes with 3x Barlow, Huygens
and 4mm Ramsden eyepieces is not going to be truly diffraction limited
or particularly free from false colour.


--
Regards,
Martin Brown