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# 130 starsense newtonian question

6 replies to this topic

### #1 WIZARD1325

WIZARD1325

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Posted 04 August 2020 - 03:10 AM

where can i buy mount rings for the starsense.

Which ones would fit.

Thanks

### #2 macdonjh

macdonjh

Fly Me to the Moon

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Posted 04 August 2020 - 11:38 AM

If you have a cloth measuring tape (a dress maker's tape) wrap it around your telescope tube to find the circumference.  Divide that number by pi (3.1415) giving you the diameter.  If your tape measures in inches, multiply that result by 25.4 to get millimeters.  Rings are sold by the diameter measured in mm.

Orion and Agena Astro both sell inexpensive OTA rings.

### #3 WIZARD1325

WIZARD1325

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Posted 04 August 2020 - 02:25 PM

MATH nooooooo!!!!!!!!!!!!

### #4 WIZARD1325

WIZARD1325

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Posted 04 August 2020 - 02:31 PM

ok im confuse so if i do inches i get 20 *25.4 = 508mm

but when i due millimeters i get 160.7512

Edited by WIZARD1325, 04 August 2020 - 03:11 PM.

### #5 fgraus

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Posted 05 August 2020 - 02:39 PM

ok im confuse so if i do inches i get 20 *25.4 = 508mm

but when i due millimeters i get 160.7512

Is your 20 inches the distance wrapped around the scope? If so, you need to divide by 3.1416 (Pi). This will give you the diameter in inches. You then multiply by 25.4 to convert the inches into mm.   20 inches / 3.1416 = 6.366 inches  x  25.4 = 161.7 mm diameter.

I don't know where you are measuring the 160.7512 mm.

Actually I can't think of a way the Starsense could measure anywhere near 20 inches in circumference. Mind measures 2.115 inches in diameter.  That converts to 53.721 mm.

Edited by fgraus, 05 August 2020 - 02:50 PM.

### #6 WIZARD1325

WIZARD1325

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Posted 05 August 2020 - 03:11 PM

See 20 inches

### #7 gnowellsct

gnowellsct

Hubble

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Posted 06 August 2020 - 02:23 PM

If you have a cloth measuring tape (a dress maker's tape) wrap it around your telescope tube to find the circumference.  Divide that number by pi (3.1415) giving you the diameter.  If your tape measures in inches, multiply that result by 25.4 to get millimeters.  Rings are sold by the diameter measured in mm.

Orion and Agena Astro both sell inexpensive OTA rings.

Actually it is more traditional these days to take a piece of printer paper and wrap it around, making a mark where the edge meets the rest of the paper.

The reason being that the paper does not stretch.

You can then do a linear measurement with the paper outstretched.

Greg N

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