Quote:Mark, yes the report claims the mirror is 1/20 wave PV. Your RNS is listed as 1/167 wave. if this is true, this is an overkill which is an excuse to charge more money. Unless your primary can match the secondary it's a waste of money, imo.You say the mirror is trimmed? Interesting. I wonder why. I detect a small curvature on the middle fringe at the left edge. The surface seems smooth, but they should test mirrors uncoated. It gives better contrast.The only way you can know how good it is is to have it tested independently. Why? Read my tagline. Mladen
7x50 tasco binoculars, 60 mm tasco refractor, 10" f/6 dob, (4" f/14 newtonian)
Hypotheses non fingo
Quote: have read that it is desirable to have a secondary that is twice as good as the primary.
Quote:Do I believe it's a good secondary? Yeah, it performs well in the field.
Do I believe it's that good?
No. I don't believe in the Tooth Fairy, either.
AS of NSW
AS of Hunter Valley
Fact: I like reflectors and big ones. All the refractors I own are either finderscopes, binoculars, or riflescopes.
18"/F4.5 Obsession #1333 fully optioned (OMI Optics)
14"/F4.5 SDM #33 fully optioned (Zambuto Optics)
10"/F5.3 SDM #50 fully optioned (Suchting Optics)
Pentax XW's, T4 & T5 Naglers , UO HD orthos, 6mm Delos, 8mm Radian, 8.5mm Pentax XF, 13mm Ethos. 12mm Celestron Illum Astrometric eyepiece. Rainbow Optics Spectroscopic Eyepiece Set. Orion Optics UK 250 lpi Ronchi grating eyepiece. 2" Astronomiks UHC, OIII & H-Beta filters, 2" DGM Optics NPB filter. 2" Variable Polariser. 2" Hoya colour filters.
Leupold 10x42 & Pentax 16x60 binos.
Quote: --how many points were sampled? It would have to be a lot for any level of confidence those figures were anything other than fictitious.--what reference machine allowed measurements of that level?1/250 wave RMS? Really? Come on.
Quote:--how many points were sampled?
Quote:Your right, "Our new 12 inch phase measuring interferometer is 1/30 wave PV over the entire 12 inch aperture. If you measure a small 2.00" diameter on its reference flat, it measures better than 1/50 - 1/100 wave PV. More than adequate to measure a 1/20 or 1/30 wave PV on a little secondary mirror" I just seen the 1/100 wave part and that stuck in my head.
-DannyMy warehouseMy Channel
Quote: Typical interferometer tests sample a limited number of points. Otherwise the calculations get too intense.