Refractor For Purely Visual Astronomy?

[johninderby]

Or this one.

Steel Circle Template Adjustable Measurement Ruler for Drawing Circles 12.5cm 4.9in

https://www.amazon.co.uk/Template-Measurement-Aluminum-Alloy-Stainless-Adjustable/dp/B08MXS2MCQ/ref=sr_1_9?keywords=iris+circle+drawing+tool&qid=1637694082&qsid=262-0528779-5571604&sr=8-9&sres=B08QZKCBSS%2CB08837FBZ4%2CB08P21D3CX%2CB08FCFQKY5%2CB08MXS2MCQ%2CB08QMFL8V7%2CB08RP3LJZ5%2CB08CDH5VZ9%2CB0842JDXX5%2CB083J4Q6LP%2CB08N4MXNK6%2CB091T8GDB2%2CB07NZMHWVQ%2CB08N62CB5N%2CB081F67KJB%2CB07CJ4GHY4%2CB095HX24BW%2CB07GCLGDFN%2CB086QKXLZ9%2CB08K8FMJBQ

[vlaiv]

3 minutes ago, johninderby said:

Or this one.

Steel Circle Template Adjustable Measurement Ruler for Drawing Circles 12.5cm 4.9in

I think it is the same one (except for color) - full diameter is around 125mm but inner opening is still around 70mm

[Muc]

I've made a very rough cardboard mask of about 90mm for my 120mm f/8.3 achromat. But it's all damp and annoying to use. Would be willing to hand over cash to someone who could 3d print one or two simple masks based on the dust cover. I honestly thought they would be something widely available

[Stu]

3 hours ago, johninderby said:

You should ask Stu as he has both versions on test for FLO.

This was what I managed in terms of comparison so far. I’ll revisit at some point when I get a chance.

Summary is that there is not a huge difference between the two. Most obviously the first diffraction ring is a little brighter in the f12.5 which is either a strength or weakness in terms of observing doubles depending on where the secondary falls in relation to the diffraction ring. Lunar detail seemed to be much of a muchness under the conditions I observed. It’s possible that more would come out under the best seeing, but how often does that happen? Comes down to cost, mount and whether f15 is just really what you want .

[Ian McCallum]

By getting this second hand SW Evostar 120, I hope to have cured my refractor itch! 🤞🤐😄

[johninderby]

1 minute ago, Ian McCallum said:

By getting this second hand SW Evostar 120, I hope to have cured my refractor itch! 🤞🤐😄

Unfortunately the “cure” has a habit of wearing off. 😁

[John]

14 minutes ago, Ian McCallum said:

By getting this second hand SW Evostar 120, I hope to have cured my refractor itch! 🤞🤐😄

That will help a lot with your achromatic refractor itch. Hope you don't develop an ED doublet / Fluorite itch

 

Edited December 3, 2021 by John

[Louis D]

48 minutes ago, Ian McCallum said:

By getting this second hand SW Evostar 120, I hope to have cured my refractor itch! 🤞🤐😄

I hate to tell you, but you'll need a "booster refractor" sooner than you realize as this "cure" wanes in effectiveness over time. 😉

[Ian McCallum]

37 minutes ago, John said:

That will help a lot with your achromatic refractor itch. Hope you don't develop an ED doublet / Fluorite itch

 

Who says I'm suffering from that malady? 🤔😂