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wider field eyepiece recommendations


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Indeed so, Steve. Since I probably have a bit more time to wibble... :wink:

With a 1.25" diagonal on a MAK127, you are primarily limited (by that) to about one Deg TRUE field of view (TFoV) on the sky. With your "default" 25mm (plossl, keller, whatever), you are probably getting only about 0.8 Deg. With your setup, you could e.g. get that potential ONE deg with a 32mm (super) Plossl type (Apparent field of view 50 degrees) OR a ~24mm 70 Deg AFoV eyepiece. With an F12 scope, which is quite accommodating of eyepieces, you could explore various typical "Super Plossl" (or more upmarket Plossl) series. As a (slightly quirky!) possibility, the Antares W70 24mm (esp. at reduced price). IMO, it is NOT worth considering the various 40mm eyepieces. These are inherently vignetted to the same TFoV, as the 32mm ones (of same field) anyway!

Or, if you are feeling adventurous, various Baader offerings. You can even "swing" a 21mm Hyperion on the back end, of your setup, if you are CAREFUL. But heavier eyepieces do benefit from an upgrade (screw fit, 2" etc.) "back end" (diagonal) to avoid "fallout" (onto Concrete!). Many possibilities, for a GREAT scope... :D

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Are you looking for around the same magnification but with a wider field?

good question. at moment 25mm supplied is by my reckoning 60x magnification. hyperion 21mm would give me 70x but i am wondering if i can get any wider field of view or whether i should save my money and do the "second scope" thing in a while and get an equinox or something.

i am, or should i say when clouds not immediately over my house, concentrating at moment on finding way around night sky by constellation, lunar and planetary. but understand that this is not the best year, 2007-2008 for planetary?

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Can you use 2" EP's? If so why not get one of the Rigel widefield ones from Ian King Imaging? They come in 26mm, 32mm and 38mm and for only £50.

Probably the 26 or 32 would be ideal for you?

Or the William Optics SWAN ones are nice too, Ian King does them as well.

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Assuming f/12 for that mak, the true FOV in a 25mm plossl would be .72 degrees at 72x, in any scope with the same f.l. I have an f/9.5 refractor, and I don't find myself limited by anything but the field stop. I don't see vignetting even with my 1.25" 82 degree AFOV eps. Is the Mak truly not capable of covering a larger FOV than any but the longest eps allow?

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The MAK 127's TFoV (true field of view) is limited, in default configuration, by the 1.25" diagonal. The max. True Field of View (~1.0 deg on the sky) corresponds to ANY eyepiece that can achieve the greatest available field stop size (typically ~27mm) in 1.25" format. (Basically the "exit hole" of a 1.25" eyepiece!) In ascending Apparent Field of view (given in brackets) these would be a: 32mm (50 Deg), 24mm (68/72 Deg), 20mm (~82 Deg). But I don't think Mr.Nagler makes the latter - and certainly not for <£100. :wink:

With a little "jiggery pokery" (adding true/pseudo 2" "back ends" / diagonals etc., you can pursuade THIS Mak to yield greater true fields of view. 1.5 Deg (certainly), more - perhaps! But that is about the physical limit! I do LIKE the idea of pairing a MAK with e.g. a short tube "fast" (F5 etc.) refractor of approximately the same aperture. Such would EASILY give MUCH bigger true fields of view and share (with judicious choices) the same eyepieces and mount etc. On a budget, e.g.the various Skywatchers: 80mm, 102mm, 120mm Startravel achromats are one (or three) possibilities. If you can afford something grander, Apochromat etc. so much the better...

If you want to be "hip" to geek talk, it's a bit like having a "virtual telescope" (Of two real telescopes!) covering all powers from 16x (4.5 Deg!) to 200x. But, by then, you'll probably be saving for a big Dob(sonian) "light bucket" like me... :lol:

Aside: (If you/others haven't) It's probably good to get used to the "back of envelope" calculations of ALL the "fields of view" thingies, then you can "wax eloquent" on forums (LOL), but also develop some sort of "money saving" strategy re. purchase of eyepieces etc. The 3:1 focal length ratio of my MAK127 (1500) and ST102 (500) means even I can master the mental arithmatic to KNOW the powers of my eyepieces, in EITHER scope! :D

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Mac.....were you leaning on a mantlepiece above a roaring fire, smoking a pipe when you posted the that explanation.....I love your posts, they are just like Physics lessons back in Uni! :wink:

Only I wish I paid more attention as you obviously did!

JV (with his tongue firmly embeded in his cheek)

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Mac.....were you leaning on a mantlepiece above a roaring fire, smoking a pipe when you posted the that explanation.....I love your posts, they are just like Physics lessons back in Uni! :wink:

Only I wish I paid more attention as you obviously did!

JV (with his tongue firmly embeded in his cheek)

Sadly not, Jon(?). (Nice allusion - IF you count storage heaters and a G&T!) But just an old PEDANT, who suffered under the lash of the "service level agreement" (to be "RIGHT"!) in scientific support. Well meaning generally, but I know... I know... :D

:violent1:

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  • 2 years later...
The MAK 127's TFoV (true field of view) is limited, in default configuration, by the 1.25" diagonal. The max. True Field of View (~1.0 deg on the sky) corresponds to ANY eyepiece that can achieve the greatest available field stop size (typically ~27mm) in 1.25" format. (Basically the "exit hole" of a 1.25" eyepiece!) In ascending Apparent Field of view (given in brackets) these would be a: 32mm (50 Deg), 24mm (68/72 Deg), 20mm (~82 Deg). But I don't think Mr.Nagler makes the latter - and certainly not for <£100. :o

With a little "jiggery pokery" (adding true/pseudo 2" "back ends" / diagonals etc., you can pursuade THIS Mak to yield greater true fields of view. 1.5 Deg (certainly), more - perhaps! But that is about the physical limit! I do LIKE the idea of pairing a MAK with e.g. a short tube "fast" (F5 etc.) refractor of approximately the same aperture. Such would EASILY give MUCH bigger true fields of view and share (with judicious choices) the same eyepieces and mount etc. On a budget, e.g.the various Skywatchers: 80mm, 102mm, 120mm Startravel achromats are one (or three) possibilities. If you can afford something grander, Apochromat etc. so much the better...

If you want to be "hip" to geek talk, it's a bit like having a "virtual telescope" (Of two real telescopes!) covering all powers from 16x (4.5 Deg!) to 200x. But, by then, you'll probably be saving for a big Dob(sonian) "light bucket" like me... :D

Aside: (If you/others haven't) It's probably good to get used to the "back of envelope" calculations of ALL the "fields of view" thingies, then you can "wax eloquent" on forums (LOL), but also develop some sort of "money saving" strategy re. purchase of eyepieces etc. The 3:1 focal length ratio of my MAK127 (1500) and ST102 (500) means even I can master the mental arithmatic to KNOW the powers of my eyepieces, in EITHER scope! :)

Dear MAC can you help me- i have a skywatcher pro 150 mak 1800mm f12 6 inch ap and wonder if i too can add a baader |T2 diagonal to the back of it and use a baader aspheric eyepiece......like you did can you advise me ...urgent!!! thanks p

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I think the issue here is that Mak's are just not scopes that lend themselves to wide fields of view - their focal length is long and, the smaller ones at least, have small rear apertures which will cause some vignetting, even if you cannot see it.

The 25mm wide angle eyepiece on sale here (not by me !):

http://stargazerslounge.com/sale/86949-pair-eyepieces.html

Would work very well in a Mak IMHO and would give you the maxmum amount of sky visable in the 1.25" format.

If you want to go wider then you might want to consider a 2nd scope - something with that takes 2" eyepieces and that is of shorter focal ratio such as F/5 - F/7.

John

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hi

the skywatcher nirvana ep seems to be good, i have 2 coming soon myself.

alfi

They are great :o

Very nearly as good as Naglers. Maksutov scopes though are long focal length designs so not as "fussy" sbout eyepieces as the shorter FL ones so you can get decent wide field performance without spending big bucks.

John

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