Below are some of the telescopes I have used for observing and astro-imaging.

For astro-imaging the most important considerations in picking a telescope are:

Focal Ratio: F/4 is fast, F/10 is slow.

for me this is the most important factor.

With an F/4 scope I can image the Andromeda Galaxy unguided with 1 minute exposures.

With F/10 you require additional equipment for guiding and more time to capture the images.

Focal Ratio is calculated by dividing the Focal Length by the Aperture,

E.g. a 200mm (8") Telescope of 1000mm Focal Length has a focal ration of F/5.

Aperture: 6" and larger is required for most Deep Sky Objects.

With a smaller scope, you can obtain excellent wide field images of clusters and larger objects

such as The Orion Nebula.

Focal Length: 600mm is very short, 2,000mm is quite long

The longer the focal length, the larger the image will appear on your camera.

But the longer the focal length, the more accurate your tracking and guiding will have to be.

To summarise, if you want to begin astro-imaging by the easiest route, use a

small telescope with fast focal ratio.  A 150mm (6") Newtonian at F/4 or F/5 would be inexpensive,

easy to handle and would not require a large expensive mount.

Likewise a 100mm (4") refractor at F/4 or F/6 would also work well.

Larger, longer focal length scopes are required for Deep Sky Objects (DSO) such as galaxies.

These scopes require larger more expensives mounts which track accurately.

Guiding is usually employed in longer exposures of fainter DSO.

Celestron Schmidt Cassegrain 8"

with Canon 300D attached.

The C8 is surprisingly light

at just 12 lbs

C8 on CG5 Advanced GT Mount

Celestron C8 on CG5 Advanced

GT Mount

Orange rail on the C8 fits

the vixen style dovetail mount

The Corrector Plate on The C8

I use a Televue 2" visual back

then an Orion 2" zero profile

adapter attached to the

Canon's T-ring

Straight Through viewing

using the Televue 2" visual back

and a 2" Celestron Ultima LX


3am in the backyard waiting

for LCROSS to hit

The Moon

Celestron Omni 150 XLT

a 6" Newtonian on CG4 mount

The Celestron CG4 is identical

to The Orion Astroview Mount

An RA drive can easily be

attached for photography

Planetary imaging setup with

The Omni 150 XLT

using eyepiece projection

and a pocket digital camera

Antares 200mm Newtonian

F/5 - 1000mm Focal Length

HEQ5 Mount

Jack Newton's Observatory B&B

Osoyoos B.C.

Jack is looking through his

7" Apo' Refractor with

a binocular viewer

EMC on the tube means

'Enhanced Multi Coatings'

Meade LXD75 AR5

5" Refractor on Goto Mount

Polar Scope on LXD75

the scope is illuminated

Astro-Tech AT8IN on

Celestron CG5 Advanced

GT Mount

Multiple light baffles in the Optical

Tube of The Astro-Tech AT8IN

Also note the focuser is placed several inches down the

optical tube to protect the

secondary mirror from light

and dew formation.

The AT8IN OTA weighs 18 lbs

without the 8x50 finder.

two 11 lb counter weights

are required.

The CG5 has a 30 lb (plus)

payload capability so the AT8IN is quite stable on this mount.

The two speed precision Crayford

style focuser on the

Astro-Tech AT8IN

Focusing scale on the AT8IN

The 35mm extension tube is not

long enough to bring most

eyepieces to focus.  But if you

slightly extract it - tightening the wider part of the barrel in

the focuser, it works.  A 50mm

extension is available.

Celestron Omni XLT 150

Newtonian Reflector and

Orion 100mm Astroview Refractor

both excellent small scopes

My first shoot out with these two


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