New need advice

Got this from a friend

TASCO
40-114675
D-114MM
F=900MM

Lenses SR4MM
H20MM
H12.5MM

Barlow Lense 3X


Can see excellent pictures of moon but if you put barlow lense on
doesnt seem to focus , what sort of detail of planets could we
expect to see with this setup?

Thanks

"nguk" wrote in message
...
Got this from a friend

TASCO
40-114675
D-114MM
F=900MM

Lenses SR4MM
H20MM
H12.5MM

Barlow Lense 3X


Can see excellent pictures of moon but if you put barlow lense on
doesnt seem to focus , what sort of detail of planets could we
expect to see with this setup?

Thanks

If you divide the focal length of the scope (F=900) by the focal length of
the eyepiece (4, 20 or 12.5) you'll come to the magnification that you're
observing at. As a good general guideline you can't use more than 50x
magnification per inch of aperture (D=114mm (114/25 = about 41/2 inches)).
So with your maximum being about 225x you're stretching the scope's optics
using the 4mm eyepiece (900/4 = 225)

In reality you'll probably be happy using around 100x magnification. A 9mm
eyepiece or thereabouts.

At about 100x you'll be able to see Saturn's rings and cloud bands on
Jupiter (also its moons). I've not made out the red spot with my own 41/2
inch reflector but have heard of other people that have seen it with 4 1/2"
scopes. You'll be able to see the phases on Venus too. I always found mars
to be a bit of a disappointment with a small scope.

Deep sky stuff isn't off the list either. M81 and M82 Galaxies (and others)
are achieveable, as are several nebula such as M42 (the Orion Nebula) and
even M57 (Ring Nebula). A few globular clusters should be interesting
through your scope, Try M13, M15 and M92.

For a book showing realistically what you can achieve with your scope in the
deep sky, try "Turn Right at Orion". It's got hand drawn objects that aren't
likely to disappoint when comparing what you can actually see, versus the
hubble shots that are used to advertise some scopes.

Also try getting another decent eyepiece or two and things should clear up a
little.

Hope this helps

Regards


Chris

Chris Taylor wrote:
For a book showing realistically what you can achieve with your scope
in the deep sky, try "Turn Right at Orion".

"Turn Left at Orion" is even better! :-)

Best,
Stephen

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What is partly missing from Chris Taylor's admirable description of
magnification etc is that better eyepieces than those supplied with the
telescope will offer clear advantages.

Even cheap Plossls will offer a larger field of view than you have now.
A larger field of view means things are easier to find in the
telescope. Lower powers are also more useful. Offering even larger
fields of view. (In other words you can see a much bigger area of sky
though the telescope)

Plus the advantage that instead of a big fuzzy blob bouncing about in
the field of view you will have a small razor sharp image that you can
study carefully. With a big fuzzy blob pretending to be a bouncing
planet you have nothing to study except the amount of fuzziness and how
much it can shake about. Touching the telescope will give it the shakes
and so will a wind or stiff breeze. The higher the magnification the
more it will shake.

With magnifications below about 120x you can see everything that there
is in the telescope image. But you need to study it carefully to see
the detail. Which takes a bit of practice.

If you magnify too much you lose everything. Lack of clarity, small
field of view and unsteadiness all spoil what you hoped to see by
making everything bigger. So forget 3 x Barlows. You will see far more
with two or three good, but inexpensive eyepieces (like Plossls) at
lower powers. 120x, 90x and 35x is a good spread of magnifications.
Using something like 7.5mm, 10mm and 25 or 26mm. I'd start with a 10mm
Plossl to get an immediate improvement over the Huygenians you have
now.

Chris.B

If you magnify too much you lose everything. Lack of clarity, small
field of view and unsteadiness all spoil what you hoped to see by
making everything bigger. So forget 3 x Barlows. You will see far more
with two or three good, but inexpensive eyepieces (like Plossls) at
lower powers. 120x, 90x and 35x is a good spread of magnifications.
Using something like 7.5mm, 10mm and 25 or 26mm. I'd start with a 10mm
Plossl to get an immediate improvement over the Huygenians you have
now.

Chris.B


Thanks for the help everyone ill see what i can do

Even cheap Plossls will offer a larger field of view than you have now.

Sorry to butt in, but where's the best place to purchase budget Plossls?
I've seen Celestron Plossls advertised on some web sites but do they offer
real value for money?

Thanks,

Rich

"Stephen Tonkin" wrote in message
...
Chris Taylor wrote:
For a book showing realistically what you can achieve with your scope in
the deep sky, try "Turn Right at Orion".

"Turn Left at Orion" is even better! :-)

LOL - My memory's fading again....