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PostPosted: Thu Jun 14, 2018 12:51 pm 
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Joined: Thu Jun 07, 2018 11:50 am
Posts: 23
Hi @ the SPA forum

I'm not entirely new to astronomy, but I'm more of a returning novice :( - so much to see & so little time!

I have treated myself to a second-hand spotting scope to supplement my little tabletop Dobo & my larger reflecting 'scope (still storage - sob, sob :cry: . It's a Helios Fieldmaster II with an Opticron eyepiece. Now I've sussed out telescope eyepiece specs/numbers, but there are lots of number on the Opticron EP that I can't really figure out, so any help would be very gratefully received. So, here goes:

30xW HR 60/66 41xW HR 80
27xW IM 65 34xW IM 80
22x IF-2 60MT 27xW IF-2 75 MT

Many thanks in advance :)

BTW, if anyone has a manual for the Helios Fieldmaster II & would share a scan of it I’d be really grateful as I can’t fine one online.

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"Where the telescope ends, the microscope begins. Which of the two has the grander view?" Victor Hugo


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PostPosted: Thu Jun 14, 2018 7:07 pm 
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Joined: Fri Dec 03, 2004 9:58 pm
Posts: 3628
Location: Wellingborough
Hi Sue and Welcome! :D

A number of members here use spotting scopes for observing, so I'm sure someone will be along with a definitive answer. However I'll guess that the numbers on that eyepiece are giving you the magnifications you get when it's used with certain 'scopes (magnification times then 'scope model number)
i.e.
30xW HR 60/66 41xW HR 80 (30x used with model HR60 and HR66, 41x used with model HR80, where 60/66/80 are the diameters of the 'scopes objective lens)
and so on
27xW IM 65 34xW IM 80
22x IF-2 60MT 27xW IF-2 75 MT

Hope this helps,

regards,

_________________
Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
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PostPosted: Thu Jun 14, 2018 7:25 pm 
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Joined: Thu Jun 02, 2016 11:32 am
Posts: 504
Location: New Farnley, Leeds lat 53.8N long 1.6W
Yes Brian, the numbers are the magnifications you get with various types of Opticron spotting scopes. That doesn't tell you what it will give with the Helios Fieldmaster II. I am guessing (but it's merely a guess) that the HR eyepiece is around 22mm focal length. I don't know what the Helios focal length is. Mike and David are probably the ones with more knowledge and experience in this area. Kind Thoughts, Bob


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PostPosted: Thu Jun 14, 2018 9:24 pm 
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Joined: Mon Jan 18, 2010 9:25 am
Posts: 5333
Hi Sue.
Opticron have a useful website that gives some details of present and historic eyepieces.
I may have some of these eyepieces.
Some eyepieces need adapters, some not, depending on which telescope, eyepiece combination.

Opticron eyepieces usually have a model number written on them.
This will give more certainty as to which particular eyepieces you have.
Please let us know the eyepiece model numbers.

The reason for the different magnification is that different scopes have different focal length objectives.
The magnifications are probably accurate to the nearest whole number, with lower magnifications at least.

Action optics, Southampton, website also has some information on some eyepieces used with different makers telescopes.
It may have something on Helios scopes.

Optical Vision Ltd may have the focal length of their individual scopes.
They may also have instruction books.

Regards,
David


Last edited by David Frydman on Fri Jun 15, 2018 3:36 pm, edited 1 time in total.

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PostPosted: Fri Jun 15, 2018 10:12 am 
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Joined: Thu Jun 07, 2018 11:50 am
Posts: 23
Hi Brain, David & Bob

Thank you so much for you replies - you've been a great help :D
Bearing in mind the info you've supplied I'll be able to do a bit more research & pop along to the Opticron website.

Thanks also for the very friendly welcome - I'm looking forward to learning lots & hopefully contributing once I'm a bit more experienced :wink:

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"Where the telescope ends, the microscope begins. Which of the two has the grander view?" Victor Hugo


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