Oldham Optical: Price List

(Prices previously reviewed:- 01 November 2007)

(Prices reviewed:- 01 July 2010)

 

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

14.0   355 5.0 1778 75 14 18 30 Ask £1,229
" 4.1 1473 83 27 23 " Ask £1,445
16.0    406 5.0 2032 83 14 17 30 Ask £1,620
" 4.4 1776 89 30 22 " Ask £1,836
18.0    457 4.4 2032 89 17 18 " Ask £2,268
" 3.9 1776 96 22 21 " Ask £2,505
20.0    495 4.1 2032 96 14 18 35 #2 Ask £3,024
" 3.6 1776 102 15 21 " Ask £3,888
22.0    560 3.6 2032 115 21 21 35- 45 #2 Ask £4,968
24.0    600 3.3 2032 130 36 21 " Ask £7,020
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 6-14" 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 
250 #4 8.5 2142 30 42 490 750 3.3 105 250 £2,160
300 #4 8.0 2400 40 36 573 870 2.9 110 250 £3,240
350 #4 12.0 4200 50 33 720 1000 2.8 115 250 £5,400
400 #4 10.0 4000 60 33 865 1200 3.0 134 250 £8,100
500#4 12.5 6200 60 27 1080 1400 2.8 134 300 £12,690
500#4 10.0 5000 80 30 955 1400 2.8 150 300 £13,959
600#4 10.0 6000 100 30 1300 1800 3.0 200 300 £22,842

 

#4 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.

 

 

 

1/4λ 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)

Figures measured on the optical surface outside any expected central obstruction

Available in Plate or Low Expansion Glass

Listed In Price table as 1/4 λ

 

 

1/10λ Specifications:
Peak/Valley: <1/10 λ on the Wave Front, measured at 625nM on the area outside the expected central obstruction.
  (Equivalent to <1/20 λ on the Mirror Surface)
R.M.S: <1/30 λ
Strehl: >0.96      (Typically ~ 0.97)

Figures measured on the optical surface outside any expected central obstruction

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 & Carriage in Mainland UK.

Payment in Sterling.

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