Telescope Mirrors, Blanks, Tools,
Aluminising, Testing & Materials

TELESCOPE MIRROR ALUMINISINGMirror Size (ins)	Aluminium + Quartz R>91%	Aluminium Enhanced R>95%	Silver Enhanced + Protected R>98%
6" 				$210AUD 					$245AUD 					$275AUD
8" 				$270AUD 					$305AUD 					$342AUD
10" 				$330AUD 					$365AUD 					$409AUD
11" 				$360AUD 					$395AUD 					$443AUD
12.5" 			$405AUD 					$440AUD 					$493AUD
14.5" 			$465AUD 					$500AUD 					$560AUD
16" 				$510AUD 					$545AUD 					$611AUD
17.5" 			$555AUD 					$605AUD 					$678AUD
18" 				$569AUD 					$619AUD 					$695AUD
20" 				$630AUD 					$680AUD 					$762AUD
22" 				$690AUD 					$740AUD 					$830AUD
24" 				$750AUD 					$808AUD 					$906AUD
28" 				$870AUD					$928AUD 					$1,040AUD
30" 				$930AUD 					$988AUD 					$1,107AUD

NOTES:
- Prices current as at May 2014
- Prices may be subject to change without notice
- Prices include removal of existing coating if applicable
- Prices are not inclusive of shipping charges

COMPLETED TELESCOPE MIRRORS
Mirrors completed with the aluminised or silver coating are available from 1" (25mm)
 to 40" (1016mm) diameter and varying Focal Ratios.  There are many different qualities to 
suit your budget.

The following Mirrors have an overcoating of Al+SiO2.
Strehl Ratio of better than 0.88
Wave Front Error Rating of 1/8 or better.

T&A		Lens Cloth								$1AUD
114mm (4.5") Glass f/8 Parabolic Mirror				$60AUD
153mm (6") Soda Lime f/5 Parabolic Mirror			$215AUD
153mm (6") Soda Lime f/7.8 Parabolic Mirror			$215AUD
200mm (8") Soda Lime f/4 Parabolic Mirror			$340AUD
200mm (8") BK7 f/4 Parabolic Mirror					$360AUD
200mm (8") Pyrex f/4 Parabolic Mirror				$375AUD
200mm (8") Soda Lime f/6 Parabolic Mirror			$340AUD
200mm (8") BK7 f/6 Parabolic Mirror					$360AUD
200mm (8") Pyrex f/6 Parabolic Mirror				$375AUD
250mm (10") BK7 f/5 Parabolic Mirror				$470AUD
250mm (10") Pyrex f/5 Parabolic Mirror				$510AUD
SPECIAL!
300mm (12") BK7 f/5 Parabolic Mirror				$550AUD
300mm (12") Pyrex f/5 Parabolic Mirror				$700AUD
SPECIAL!
400mm (16")BK7 F/4.5 Parabolic Mirror				$800AUD

The following mirrors have been hand finished and corrected for optimal performance by highly experienced mirror makers.
The Aluminium and additional Coatings are also the highest quality.
Strehl is a minimum 96%.
All the Mirrors in this range come with Ronchi, Foucault and Testing Data.

300mm (12") Glass F/5 Parabolic Mirror			$1480AUD
300mm (12") Glass F/6 Parabolic Mirror			$1400AUD
350mm (13.7") Glass F/5 Parabolic Mirror			$1800AUD
350mm (13.7") Glass F/6 Parabolic Mirror			$1700AUD
400mm (15.8") Glass F/5 Parabolic Mirror			$1980AUD
450mm (17.7") Glass F/5 Parabolic Mirror			$2270AUD

Larger sizes are available.

The following mirrors have been hand finished and corrected for optimal performance by highly experienced mirror makers.
In particular these Mirrors have been "Fluked", "Blessed", or by a "Stroke of Luck" achieved a very high Strehl. The 
Aluminium and additional Coatings are also the highest quality. All the Mirrors in this range come with Ronchi, Foucault 
and Testing Data using the Texereau method. Software testing is also used indicating Strehl, Wave Front, RMS and deviation 
from the true shape, and its location.

Two ways of measuring a telescope's accuracy is by Wave Front Error and Strehl. Both ways can be related to each other. Wave front Error 
measures how flat the surface of the mirror is from trough to peak (hill to valley). This is measured in light waves. One wave is equal to 
5.588 x 104 mm (0.000022"). Whenever a Wave Front Error is given in a magazine or website advertising, it can generally be halved to give a 
true indication of the error. This figure has been proven to be overstated by many manufacturers. A 1/8 Wave front Error is more like 1/4. 
Also, a wave front test is only testing one part of the Mirror, so it is an average.

A better way of showing how accurate a telescope mirror is by Strehl. The strehl percentage indicates the amount of light which is returned 
by the mirror, within the central peak of the Airy Disk. One of the most expensive mirror makers around is R. F. Royce. R. F. Royce does 
not let his mirrors out unless they have a strehl of at least 96%. During mirror making, a very high strehl measurement can be case of luck. 
Testing and correcting the mirror until the sweet spot is achieved.

Glass 200mm x 25mm F/6
Average Maximum Wave Front Error 1/23.6
Average Strehl Ratio 0.983
$650AUD

MIRROR BLANKS AND TOOLS

Plate Glass: Plate Glass is the least expensive material to build a mirror from.  The thicker the 
glass, the less is will bend out of shape if the mirror is to be large.  Thinner 
glass is perfectly well to work with, as long as the glass is supported properly in the finished
 telescope.  Thinner glass is less expensive and reduces the overall weight of the telescope.
To reduce the cost further, the Tool Glass doesn't have to be as thick as the Mirror Glass.
Sizes available: 1" (100mm) to 25" (635mm) diameter.

Pyrex: Please Note - Dow Corning no longer produce Pyrex.  The next best thing to Pyrex in price and Expansion Rate is Borosilicate
 - see below.

Pyrex has a lower expansion rate than glass.  When there is a change of temperature, 
either by the conditions where the telescope is being used or by the heat generated by the 
hands while grinding or polishing, pyrex will be less effected.  Since Pyrex is harder than 
glass the grinding and polishing time is longer.  Pyrex blank thickness is a ratio of 6:1 
which is the theoretical thickness best suited for mirror making.
Sizes available: 1" (25mm) to 40" (1016mm)

Borosilicate:
Next best thing to Pyrex for price and Expansion Rate.
See Wiki Entry;

Borosilicate Glass

Contact us with your specifications for a quote.

Fused Silica: Larger diameter mirrors tend to bend under their own weight.  
Fused silica between thin blanks supports the mirror and also keeps the weight to 
a minimum.  These blanks have the lowest expansion rate and are also the most 
expensive.  Flat surfaces or pregenerted blanks are available.

Light Weight: Thin Pyres blanks are available which are less than 
the recommended theoretical 6:1 ratio thickness.

Pyrex Schmidt-Cassegrain:  It doesn't take much more to make a 
Schmidt-Cassegrain mirror.  Blanks are supplied with a started hole in the 
middle eliminating having to drill.  The primary mirror is a full parabola and the 
secondary is a hyperbola.

Custom Blanks: Different shapes and sizes are available.  Let us know your specifications.

PLATE GLASS BLANKS
148mm diameter x 8.4mm thick 					$25AUD
150mm (6") diameter x 25mm (1") thick 			$50AUD
150mm (6") diameter x 19mm (3/4") thick 			$45AUD
200mm (8") diameter x 25mm (1") thick 			$75AUD
200mm (8") diameter x 19mm (3/4") thick 			$68AUD
254mm (10") diameter x 25mm (1") thick 			$118AUD
254mm (10") diameter x 19mm (3/4") thick 		$105AUD
305mm (12") diameter x 25mm (1") thick 			$162AUD
305mm (12") diameter x 19mm (3/4") thick 		$145AUD
330mm (13") diameter x 25mm (1") thick 			$170AUD
330mm (13") diameter x 19mm (3/4") thick 		$155AUD
457mm (18") diameter x 25mm (1") thick 			$365AUD
457mm (18") diameter x 19mm (3/4") thick 		$335AUD
457mm (18") diameter x 16mm (5/8") thick 		$315AUD
500mm (19.6") diameter x 25mm (1") thick 		$425AUD
600mm (23.6") diameter x 25mm (1") thick 		$480AUD

SUPRAX GLASS BLANKS (LOWER EXPANSION THAN PYREX - REALLY GOOD SHINE)
100mm diameter x 23-26mm thick 			$58AUD
148mm diameter x 24mm thick 				$65AUD
175mm diameter x 28-31mm thick 			$125AUD
198mm diameter x 30mm thick 				$145AUD
250mm diameter x 30mm thick 				$220AUD

PYREX GLASS (PYREX IS NO LONGER MADE AND REPLACED WITH BOROSILICATE)
254mm (10") diameter x 28mm (1.1") thick 		$190AUD - last pieces available

QUARTZ BLANKS
Quartz Blanks need to be ordered in.  Please inquire for pricing and availability.

BOROSILICATE BLANKS
Larger Borosilicate Blanks need to be ordered in.  Please inquire for pricing and availability.

Other Materials, Diameters and Thicknesses available, please enquire.

Pre-generated Curves:  These blanks have the focal ratio curve already made so minimal grinding 
needs to be done.  It also aids in obtaining the correct curve which can be difficult for the 
beginner mirror maker.  The tool supplied is a matching curve. Pre-Generated Curves saves the cost of the 80 
Grade Grinding Material
Sizes available: 1" (25mm) to 40" (1016mm)

GRINDING AND POLISHING MATERIALS
Aluminium oxide grinding powder per kilo			$40AUD
Tin oxide grinding powder per kilo				$30AUD
Pumice grinding powder per kilo					$30AUD

80 Grade grinding powder per 8" mirror				$2AUD
120		"		"						$2AUD
220		"		"						$3AUD
320		"		"						$4AUD
500		"		"						$6AUD
1000		"		"						$8AUD
1600		"		"						$8AUD
Cerium Oxide		"						$8AUD
Lap resin kit		"						$15AUD


SECONDARY/DIAGONAL MIRRORSSecondary Mirrors available in all sizes from 15mm to 215mm.  All measurements are taken across 
the narrow diameter (minor axis) of the mirror.

CHOOSING THE CORRECT SECONDARY/DIAGONAL SIZE
The size of the diagonal is measured by its width across the mirror (minor axis).
To work out what size Secondary Mirror is needed for the telescope, things need to be worked 
out in order. Knowing the diameter of your Main Mirror. Firstly, find the focal length of the 
completed mirror.  Secondly, work out the height of your focusing unit.  The focuser needs to 
be wound out about 25mm (1") (roughly where you expect the focus or eyepiece to be) then take 
the height measurement.  Thirdly, the outside diameter of the telescope tube (where the focuser 
will go) needs to be measured and halved.  Having these measurements, the Secondary Mirror size 
can now be worked out.  Add the height of the focuser to the halved outside diameter of the 
telescope tube. This gives the distance from the Secondary Mirror to the eyepiece.

The formula now used is:

Main Mirror diameter divided by Focal length times the distance from the diagonal to the eyepiece.

eg. Main Mirror Diameter 200mm (8")
    Focal Length = 1000mm
    Height of Focuser = 70mm
    Outside Diameter of Tube = 230mm divided by 2 (half) = 115mm
    Total distance from Secondary to Eyepiece = 70mm + 115mm = 185mm

Using Formula:

eg. 200mm divided by 1000mm times 185mm = 37mm diameter Secondary Mirror.

Take note that the diameter of the diagonal across the Minor Axis is about 1mm less 
due to the glass being beveled

Highest Quality Pyrex 1/10 Wave Secondary Mirrors with Enhanced Coatings
Commonly kept sizes:
25.4mm (1") dia					$55AUD
28mm (1.1") (dia				$60AUD
31mm (1.25") dia				$65AUD
32mm (1.33") dia				$68AUD
33mm (1.29") dia				$70AUD
35mm (1.37") dia				$75AUD
40mm (1.57") dia				$80AUD
42mm (1.65") dia				$85AUD
46.5mm (1.83") dia				$95AUD
50mm (1.97")") dia				$105AUD
50.8mm (2") dia					$109AUD
62mm (2.44") dia				$160AUD
63mm (2.48") dia				$165AUD
65mm (2.56) dia				$180AUD
70mm (2.76) dia				$220AUD

Standard Quality BK7 1/6 Wave Secondary Mirrors with Coating
Commonly kept sizes:
23mm (0.91") dia				$15AUD
28mm (1.11") dia				$35AUD
31mm (1.22") dia				$40AUD
41mm (1.62") dia				$45AUD
50mm (1.97") dia				$50AUD
63mm (2.33") dia				$60AUD
70mm (2.29") dia				$70AUD

TELESCOPE MIRROR MAKING BOOKSAdvanced Telescope Making Techniques
Volume 1 & Volume 2 $60AUD




Amateur Telescope Making
Volume 1, 2 & 3
$70AUD



Build Your Own Telescope
Complete plans for 5 high quality telescopes
$70AUD



The Dobsonian Telescope
A practical manual for building large aperture telecopes
$82AUD



How To Make a Telescope
2nd Edition
$70AUD