(Prices reviewed:- 01 November 2007)
Newtonian Mirror Sets
(Primary Mirror Plus Elliptical Flat)
|
Mirror Diameter inches mm |
Focal Ratio |
Focal Length (mm) |
Flat Minor Axis (mm) |
Field Of View (mm) #1 |
Obstruction Ratio % #1 |
Mirror Thickness (mm) |
Price, Plate Glass 1/4 λ |
Price, Low Expansion Glass 1/4 λ |
Price, Low Expansion Glass 1/10 λ |
| 6.25 158 | 7.7 | 1220 | 36 | 18 | 23 | 19 | Ask#3 |
Ask#3 |
Ask#3 |
| " | 5.7 | 914 | 36 | 14 | 24 | " | Ask | Ask | Ask |
| " | 4.8 | 762 | 44 | 14 | 27 | " | Ask | Ask | Ask#3 |
| 8.75 222 | 7.3 | 1625 | 44 | 15 | 17 | 25 | Ask | Ask | £430 |
| " | 5.8 | 1295 | 50 | 14 | 20 | " | Ask | Ask | £400 |
| " | 4.5 | 1000 | 56 | 17 | 25 | " | Ask | Ask | £450 |
| 10.0 254 | 6.4 | 1625 | 50 | 14 | 17 | " | Ask | Ask | £550 |
| " | 5.8 | 1473 | 50 | 17 | 19 | " | Ask | Ask | £560 |
| " | 5.1 | 1295 | 56 | 18 | 22 | " | Ask#3 | Ask#3 | £580 |
|
12.0 304 |
6.0 | 1829 | 63 | 19 | 16 | " | £500 | £620 | £790 |
| " | 5.3 | 1625 | 63 | 14 | 18 | " | £580 | £710 | £800 |
| " | 4.3 | 1295 | 68 | 17 | 22 | " | £650 | £760 | £820 |
| 14.0 355 | 5.0 | 1778 | 75 | 14 | 18 | 30 |
 |
£900 | £1,138 |
| " | 4.1 | 1473 | 83 | 27 | 23 | " | £1,000 | £1,338 | |
| 16.0 406 | 5.0 | 2032 | 83 | 14 | 17 | 30 | £1,350 | £1,500 | |
| " | 4.4 | 1776 | 89 | 30 | 22 | " | £1374 | £1,700 | |
| 18.0 457 | 4.4 | 2032 | 89 | 17 | 18 | " | £1,760 | £2,100 | |
| " | 3.9 | 1776 | 96 | 22 | 21 | " | £1,900 | £2,320 | |
| 20.0 495 | 4.1 | 2032 | 96 | 14 | 18 | 35 #2 | £2,088 | £2,800 | |
| " | 3.6 | 1776 | 102 | 15 | 21 | " | £2,900 | £3,600 | |
| 22.0 560 | 3.6 | 2032 | 115 | 21 | 21 | 35- 45 #2 | £4,000 | £4,600 | |
| 24.0 610 | 3.3 | 2032 | 130 | 36 | 21 | " | £5,500 | £6,500 | |
| 30.0 762 | 4.5 | 3430 | 130 | 35 | 17 | " | Ask | Ask |
#1 Figures assume FP = 75mm outside Telescope Tube. See Design Page for more explanation.
We are happy to supply alternate sizes of elliptical flats.
#2 For Mirror sizes of 20" or above, Thickness of glass may vary depending on our source of supply,
If you require a particular thickness, please advise with order.
#3 We expect most orders for smaller mirrors will be for first time buyers for their first telescopes?
We suggest there is more need for this group to talk about your requirements
so have not filled in all the prices in the 6-10" range.
Cassegrain Mirror Sets:- In Low Expansion Glass.
(Primary plus Secondary Mirror)
(Prices reviewed:- 25th February 2008)
|
Primary Diameter (mm) |
System Focal Ratio |
System Focal Length (mm) |
Field Of View (mm) | Obstruction Ratio % | Mirror Spacing |
Primary Focal Length (mm) |
Primary Focal Ratio |
Secondary Diameter (mm) |
Vertex Back Focal length (mm) | Price |
| 200 #3 | 10.0 | 2000 | 30 | 35 | 495 | 750 | 3.75 | 80 | 200 | £1,700 |
| 250 #3 | 8.5 | 2142 | 30 | 42 | 490 | 750 | 3.3 | 105 | 250 | £1,900 |
| 300 #3 | 8.0 | 2400 | 40 | 36 | 573 | 870 | 2.9 | 110 | 250 | £2,400 |
| 350 #3 | 12.0 | 4200 | 50 | 33 | 720 | 1000 | 2.8 | 115 | 250 | £4.500 |
| 400 #3 | 10.0 | 4000 | 60 | 33 | 865 | 1200 | 3.0 | 134 | 250 | £6,500 |
| 500#3 | 12.5 | 6200 | 60 | 27 | 1080 | 1400 | 2.8 | 134 | 300 | £10,000 |
| 500#3 | 10.0 | 5000 | 80 | 30 | 955 | 1400 | 2.8 | 150 | 300 | £11,000 |
| 600#3 | 10.0 | 6000 | 100 | 30 | 1300 | 1800 | 3.0 | 200 | 300 | £18,000 |
#3 Coma Free System (Ritchey-Chretien)
Using the same basic primary mirror, we can customise the secondary mirrors
to offer a range of Focal ratios, Vertex Back Focal Lengths and Obstruction ratios.
Please contact us for more details.
| "Standard" Specifications | |
| Peak/Valley: | <1/4 λ on the Wave Front, measured at 625nM. |
| (Equivalent to <1/8 λ on the Mirror Surface) | |
| R.M.S: | <1/15 λ |
| Strehl: | >0.82 (Typically ~ 0.9) |
|
Available in Plate or Low Expansion Glass |
|
|
Listed In Price table as 1/4 λ |
|
| "Diffraction Limited" Specifications: | |
| Peak/Valley: | <1/10 λ on the Wave Front, measured at 625nM. |
| (Equivalent to <1/20 λ on the Mirror Surface) | |
| R.M.S: | <1/30 λ |
| Strehl: | >0.96 (Typically ~ 0.97) |
|
Available in Low Expansion Glass Only |
|
|
Listed In Price table as 1/10 λ |
|
Other Notes
Sets above can be supplied with different sized elliptical flats.
Other Mirror Sizes Available To Order.
All Items Can Be Sold Separately.
Certificate of Conformity Free with Mirrors of 20" or Over,
Available for Smaller mirrors at Additional cost of £40.
Please Discuss Any Special Requirements.
All Prices Include VAT and Carriage in Mainland UK.
Payment in Sterling, or Euros at Current Exchange Rate.
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