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  #41  
Old 01-09-2019, 07:09 PM
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Slawomir (Suavi)
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Great to hear that Greg - looking forward to seeing the results of the first light

I hope you don't mind - in another thread Nick has shared an interesting graph of 128 scopes from a Russian lab showing PV and RMS vs Strehl with some approaching Strehl of 1.

I approximately positioned the values from your certificate on the graph - blue line for PV and red for RMS - both are better than 128 scopes in this sample Clearly, none of these scopes, with some approaching Strehl of 1, are better than PV 1/8 wavelength - maybe Russians got it wrong too
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  #42  
Old 01-09-2019, 08:13 PM
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Try the updated graph - a least squares quadratic fit is more appropriate as it’s a a square law relationship in theory. Hence the problem with the intercept with a linear fit.
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  #43  
Old 02-09-2019, 03:54 PM
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Originally Posted by Slawomir View Post
Great to hear that Greg - looking forward to seeing the results of the first light

I hope you don't mind - in another thread Nick has shared an interesting graph of 128 scopes from a Russian lab showing PV and RMS vs Strehl with some approaching Strehl of 1.

I approximately positioned the values from your certificate on the graph - blue line for PV and red for RMS - both are better than 128 scopes in this sample Clearly, none of these scopes, with some approaching Strehl of 1, are better than PV 1/8 wavelength - maybe Russians got it wrong too
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Originally Posted by Wavytone View Post
Try the updated graph - a least squares quadratic fit is more appropriate as it’s a a square law relationship in theory. Hence the problem with the intercept with a linear fit.
Thanks for the graphs. Impressive indeed.

Any statistical measure will be useless if it does not take enough samples. That is basic statistics. So it would not surprise me, as some have mentioned, that the formula used by most companies would be the one that gives the best marketing spin not the most accurate.

Greg.
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  #44  
Old 03-09-2019, 08:13 AM
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I mounted the CFF 105 on top of the AP Honders last night. Luckily the counterweights just make it in balancing it with a bit left over. I was able to image with round stars with the Honders and Proline last night.

The CFF has a lovely slightly sparkly pearl finish. Its not a solid white. The rotating Feathertouch focuser is simply superb. Fabulous fine control.

I used the scope visually last night. My eyepiece collection is not that extensive but it gave pleasant views. A bit dim as 4 inch scope don't collect a lot of light. But the planets looked good. I have a collection of Meade Plossls so I'll look again tonight if its clear and use the shortest focal length I can. I have a TV barlow as well so I'll get that out.

I plan to mount the Microline 16 on it which should give a wider field than the Honders and perhaps it can be collecting colour when the Honders is collecting luminance if I can get them to see much the same spot. Its close now and I haven't really tried.

Visually though an SCT or a larger refractor are hard to beat.

I plan to spend a night or two with the Honders visually. It just means removing the imaging train and refitting the focuser which isn't a big deal but enough of a job to put it off! I think I'll do the same with the CDK again. It really needs good seeing otherwise its horrible visually.

Greg.Attachment 248813
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  #45  
Old 03-09-2019, 11:48 AM
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Great news with the visual test Greg.

The setup looks very impressive - so I was correct stating that I take images with a guidescope!
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  #46  
Old 03-09-2019, 12:47 PM
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Great news with the visual test Greg.

The setup looks very impressive - so I was correct stating that I take images with a guidescope!
Hehehe
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