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EP selection for 8" F/10

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#1 Guest_**DONOTDELETE**_*

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Posted 24 June 2004 - 12:00 AM

This is a cross-posting from the Newbie Forum. http://www.cloudynig...5/o/all/fpart/1

Can anyone tell me if I am overlooking something that would have motivated the previous owner of my LX200 to end his EP series with a 26mm as the longest focal length? I suppose the GOTO technology could lend itself to that (due to little or no manual scanning being required).

#2 matt

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Posted 24 June 2004 - 05:35 AM

26mm on an F/10 scope is a little too much magnification; even with perfect goto you will want wider views at times. But very long FL eyepieces make people seasick, as the 40-45mm plossls (because of a too long eye relief) and they have a narrow field. Unless you can locate a 50°+ eyepiece in the 40mm range (or can afford a 41mm panoptic!) I would recommend the Celestron Ultima 35mm. Pretty sharp, 50° view, and it would bring about a 1° field.

#3 Guest_**DONOTDELETE**_*

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Posted 24 June 2004 - 08:39 AM

What is the difference between these two metrics: "50° view and 1° field"?

#4 Greg K.

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Posted 24 June 2004 - 09:18 AM

50° refers to the apparant field of view (AFOV), which is to say how big the image in the EP appears to you. 1° field refers to the true field of view (TFOV), which is the amount of the sky you can actually see. A 50° AFOV EP will show 1° TFOV at 50x magnification, which is pretty close to what your 2000mm FL scope will give you with a 35mm EP ( 2000mm/35mm = 57x).

See the first part of this article for a better explanation:

The FOVs of the SCT and Dob

#5 Guest_**DONOTDELETE**_*

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Posted 25 June 2004 - 03:27 PM

Without elaboration, the article "Eyepiece Review Pitfalls" urges caution when considering a 2" eyepiece with a SCT. Can someone explain this warning?

#6 LivingNDixie

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Posted 25 June 2004 - 03:39 PM

Best eyepiece for a 8in F/10 SCT is the 19mm Panoptic. I went whole nights using just that eyepiece. The FOV is wide enough for all GOTOs and its arround 100X, which is poerfect for many of the DSOs out there

#7 jrcrilly

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Posted 25 June 2004 - 04:00 PM

Hi, Preston.

That's a good one, and perhaps the best bang for the buck. I'd suggest that the best EP for that power range, however, is either the 20mm Nagler T2 or the 22mm Nagler T4.

#8 Mike28

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Posted 25 June 2004 - 04:17 PM

26mm on an F/10 scope is a little too much magnification; even with perfect goto you will want wider views at times. But very long FL eyepieces make people seasick, as the 40-45mm plossls (because of a too long eye relief) and they have a narrow field. Unless you can locate a 50°+ eyepiece in the 40mm range (or can afford a 41mm panoptic!) I would recommend the Celestron Ultima 35mm. Pretty sharp, 50° view, and it would bring about a 1° field.


Matt: I have gone as far as 12mm (Nagler) on my NS11GPS (F10) with no problem. My 17mm Nagler is about perfect for all viewing. I even went to 6mm Radian during Mars Op last summer and that was really pushing it! The 82' FOV is great for wide viewing. But I am a Nagler fan. I know others will differ on this. there are Ultima fans out there too!

#9 Guest_**DONOTDELETE**_*

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Posted 28 June 2004 - 01:58 PM

26mm on an F/10 scope is a little too much magnification; even with perfect goto you will want wider views at times.


Let the record show I haven't attempted to use the GOTO yet and am not real eager.

But I am a Nagler fan. I know others will differ on this.

I seem to recall Naglers and other "modern" eyepieces are designed for fast scopes and are not recommended for slow scopes.
Can anyone comment on Kellners in this equipment?

#10 LivingNDixie

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Posted 28 June 2004 - 04:30 PM

Hi, Preston.

That's a good one, and perhaps the best bang for the buck. I'd suggest that the best EP for that power range, however, is either the 20mm Nagler T2 or the 22mm Nagler T4.


Oh I agree those are awesome too. Back when I used the 19mm pan combo the 20mm t5s didn't exist :( Also good is the 22mm Panoptic, has a little bit better eye relief :)

#11 Mike28

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Posted 03 July 2004 - 01:01 PM

[I seem to recall Naglers and other "modern" eyepieces are designed for fast scopes and are not recommended for slow scopes.
Can anyone comment on Kellners in this equipment? [/quote]

Fast scopes? Slow scopes? No no It's Optics the EPs are good with. 'Go To' has nothing to do with EP's. It' comes down to the optics of your scope. SCT's, refractors, Newts,etc, They are all available with 'Go To' or none 'Go To' mounts. It's their optics that count. 4,6,8,10,12,14" scopes and the right EP for the right size scope! Except for Dobs. I dont recall a 'Go To' for dobs :thinking:

#12 jrcrilly

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Posted 03 July 2004 - 01:07 PM

I seem to recall Naglers and other "modern" eyepieces are designed for fast scopes and are not recommended for slow scopes.


That's not quite what is meant. Faster optics are much more demanding of eyepieces. Naglers and other premium widefield EP's are designed to work well EVEN IN faster optics. They will, of course, also work well in less demanding, slower systems.


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