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

Telescope Mirror Aluminising
Telescope Mirrors


Telescopes & Astronomy Telescope Mirrors, Blanks, Tools, Aluminising, Testing, and Materials for Mirror Making.

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Telescope Mirror Blanks



Mirror Aluminising Telescope Mirror Making Telescope Mirrors



UPDATED 7th June 2014


BBC Sky at Night
How to Make a Mirror


Mirror 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


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


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)


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 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


booksAdvanced Telescope Making Techniques
Volume 1 & Volume 2 $60AUD

booksAmateur Telescope Making
Volume 1, 2 & 3

booksBuild Your Own Telescope
Complete plans for 5 high quality telescopes

booksThe Dobsonian Telescope
A practical manual for building large aperture telecopes

booksHow To Make a Telescope
2nd Edition


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