Telescope Reviews: Widest field of view eyepiece for Maxbright

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Equipment Discussions >> Binoviewers

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mgwhittle
scholastic sledgehammer

Reged: 08/24/11

Loc: Chattanooga, TN

Widest field of view eyepiece for Maxbright new

#5291773 - 06/27/12 03:43 PM

Am I correct in thinking that a 20mm 68 degree eyepiece will give the widest true field of view of available eyepieces without edge dimming in a Maxbright binoviewer? Is there another eyepiece that gives a wider tfov but still retains full illumination?

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Astrojensen
Post Laureate

Reged: 10/05/08

Loc: Bornholm, Denmark

Re: Widest field of view eyepiece for Maxbright new

[Re: mgwhittle]
#5291837 - 06/27/12 04:33 PM

Quote:

Am I correct in thinking that a 20mm 68 degree eyepiece will give the widest true field of view of available eyepieces without edge dimming in a Maxbright binoviewer?

Basically, yes. IF you want the widest true field with a 68° AFOV... If you only need a 50° AFOV, you'll be able to go up to 25mm focal length. If you can accept a 40° AFOV, you can use a 32mm, a 40mm for 30°. etc. Similarly, a 15mm can have an 80+° AFOV and still have no vignetting, a 13mm can have 100° and so on.

To get the widest TFOV, match the eyepiece field stop to the exit field stop in the Maxbright, which is ~21mm.

BTW, a slight dimming of the outer 1 - 2mm is hardly noticeable in a wide field eyepiece of moderate focal length. It is much more easily noticeable in a long focal length narrow field eyepiece. Also since the magnification is lower in the long focal length eyepiece, so that the background sky is brighter, any darkening of the outer field is much more noticeable.

Clear skies!
Thomas, Denmark

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mgwhittle
scholastic sledgehammer

Reged: 08/24/11

Loc: Chattanooga, TN

Re: Widest field of view eyepiece for Maxbright new

[Re: Astrojensen]
#5291886 - 06/27/12 05:09 PM

Thomas,

Yes, that was what I was thinking but didn't say about sky darkening and magnifications. Thanks for pointing that out. I just ordered a Maxbright and I'm trying to figure out what my options are for eyepieces with best field performance.

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Eddgie
Postmaster

Reged: 02/01/06

Re: Widest field of view eyepiece for Maxbright new

[Re: mgwhittle]
#5291902 - 06/27/12 05:15 PM

Even using one of the new 68 degree AFOV 20mm Explore Scientifics, my Maxbrights displayed a bit of uneven illumination in one eyepiece barrel. I think that the prism edges themselves may be responsible. At about 5 o'clock in one barrel the view looked very slightly vignetted.

I do not know if they will all do this or only my sample.

I use a pair of Orion Flat Field 19mm eyepeices with a 65 degree AFOV (as I recall this is right) and they work great.

They also costs less for both than for a single ES 20mm. Not perfect off axis performers, but I am happy enough with them, and I tend to be picky about off axis performance. For the price, I was very pleased.

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mgwhittle
scholastic sledgehammer

Reged: 08/24/11

Loc: Chattanooga, TN

Re: Widest field of view eyepiece for Maxbright new

[Re: Eddgie]
#5291917 - 06/27/12 05:21 PM

Thanks Eddgie, I'm sensitive to dimming, much less so to off axis performance. I'll check out the Orion's.

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Astrojensen
Post Laureate

Reged: 10/05/08

Loc: Bornholm, Denmark

Re: Widest field of view eyepiece for Maxbright new

[Re: Eddgie]
#5291971 - 06/27/12 05:45 PM

Quote:

using one of the new 68 degree AFOV 20mm Explore Scientifics, my Maxbrights displayed a bit of uneven illumination in one eyepiece barrel. I think that the prism edges themselves may be responsible. At about 5 o'clock in one barrel the view looked very slightly vignetted.

I do not know if they will all do this or only my sample.

My own Maxbright doesn't show anything like this with my 20mm/70° GSOs, nor with the 25mm/52° Zeiss eyepieces. The 40mm/42° TS Superviews are heavily vignetted, but the vignetting is round and even in both sides.

Clear skies!
Thomas, Denmark

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johnnyha
Postmaster

Reged: 11/12/06

Loc: Sherman Oaks, CA

Re: Widest field of view eyepiece for Maxbright new

[Re: Astrojensen]
#5292074 - 06/27/12 07:00 PM

I've seen some great prices on used 19mm Pans lately too, there was a mint pair for $325 this weekend on the other site - that's a steal. Excellent binoviewer eyepieces. If you can swing the price difference I think it's worth it, otherwise I'm very impressed with the ES 68 degree line and just ordered a 16mm pair myself.

Edited by johnnyha (06/27/12 07:02 PM)

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mgwhittle
scholastic sledgehammer

Reged: 08/24/11

Loc: Chattanooga, TN

Re: Widest field of view eyepiece for Maxbright [Re: johnnyha]
#5292147 - 06/27/12 08:11 PM

Quote:

I've seen some great prices on used 19mm Pans lately too, there was a mint pair for $325 this weekend on the other site - that's a steal. Excellent binoviewer eyepieces. If you can swing the price difference I think it's worth it, otherwise I'm very impressed with the ES 68 degree line and just ordered a 16mm pair myself.

Yes, I saw them, missed them, same seller had some Denk II's pretty cheap, missed getting them also.

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