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Double Star Magnification

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#1 ATM57

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Posted 07 January 2013 - 01:41 PM

I don't know if info like this has been posted before but here is a quick reference chart that shows the magnification needed for splitting double stars of equal magnitudes. The minimal magnification is for the eagle eyed amoung us that own telescopes with excellent optics. Hopefully this is some use.

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#2 azure1961p

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Posted 07 January 2013 - 07:29 PM

The minimum isn't really too too minimal infact quite a few folks will halve the minimum 4' value of 240x on a 1" double, tho for me the 240x value is ideal and I'd venture 400x for 0.5" sep, that it 500x.

Low power 5" doubles to me look exquisite at 70x.

Pete

#3 Ed D

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Posted 07 January 2013 - 10:26 PM

I agree with Pete about the chart being on the conservative side when using scopes with good optics. However, I remember when I had the factory Chino mirrors in my Dob and the chart's figures would have been reasonable. So yes, I think it is useful for a lot observers as a general guide. Thanks for posting it.

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#4 Kon Dealer

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Posted 08 January 2013 - 06:28 PM

The "Double-Double" is about 2".
I can do this easily at 61x (and very occasionally at 51x) with my 4" 'frac.

#5 ATM57

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Posted 09 January 2013 - 12:53 AM

Good refractors and good eyesight with good seeing will easily exceed the minimum requirement but everyone is not so blessed. Average optics, tube currents, standard seeing, collimation, etc. can make the minimal a challenge. This is just a guide. Here is an experiment for you, go to the Dawes limit of your scope and see if the "minimum" is so easy.

#6 azure1961p

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Posted 09 January 2013 - 08:50 AM

The "Double-Double" is about 2".
I can do this easily at 61x (and very occasionally at 51x) with my 4" 'frac.


Fine for the lesser light of a 4" refractor but in an 8" reflector the glare is so overwhelming you want to do at least double that value.
I'd imagine big dobs would need similar or more magnification just so as to tone it down a bit.

Pete
P

#7 Kon Dealer

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Posted 09 January 2013 - 10:58 AM

The "Double-Double" is about 2".
I can do this easily at 61x (and very occasionally at 51x) with my 4" 'frac.


Fine for the lesser light of a 4" refractor but in an 8" reflector the glare is so overwhelming you want to do at least double that value.
I'd imagine big dobs would need similar or more magnification just so as to tone it down a bit.

Pete
P

That's what the table suggests :grin:

#8 GlennLeDrew

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Posted 10 January 2013 - 03:45 PM

This table is really nothing more than a converter of angle based on magnification. To be a more complete reference, it should include a column for 2', and perhaps even 1'.

#9 azure1961p

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Posted 10 January 2013 - 08:47 PM

The "Double-Double" is about 2".
I can do this easily at 61x (and very occasionally at 51x) with my 4" 'frac.


Fine for the lesser light of a 4" refractor but in an 8" reflector the glare is so overwhelming you want to do at least double that value.
I'd imagine big dobs would need similar or more magnification just so as to tone it down a bit.

Pete
P

That's what the table suggests :grin:


Heh, look at that.

Pete

#10 ATM57

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Posted 11 January 2013 - 12:05 AM

I didn't want to push the envelope. I've been observing multiple stars for over 30 years and with this chart I could have easily pushed the observing limits but this would have alienated some who don't have premium optics or superior eyesight. Some of us mortals would have a difficult time with a 1' apparent separation.

Your suggestion is noted. Care to do up a chart based on your parameters?






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