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Celestron 100 FED

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Expand view Topic review: Celestron 100 FED

Re: Celestron 100 FED

Post by Kjohn on Mon Jul 16, 2012 1:48 am

Hello I have a similar question about the regal 100 except I looking for a eyepiece to use for higher magnifIcation ( more than the stock 67x zoom) I know most scopes stop at 60x due to atmosphere limit but I would like to go a little higher on those nice clear days.
Do you have any ideas on a good eyepiece that can get a useable image above 70x. I'm not sure how far I can go on this scope on a good day, would a high quality 5mm like a televue or Pentax be too much power? Can you suggest any high mag eyepieces for this scope? Thank you.

Re: Celestron 100 FED

Post by Jne_K on Fri Dec 16, 2011 9:23 am

Hi

Good questions, absolutely, so feel free to ask away :)

Televue is the premium name in telescope eyepieces. You can do as good with some other select models in various brands, but no better. Most serious astronomers own one or two Televue eyepieces.

Haven't used the Televue Plossls in that particular scope, but not to worry, they will do fine.

Re: Celestron 100 FED

Post by In Va on Thu Dec 15, 2011 6:39 pm

Thanks for all the info Jne...

I'm sure I exposed lack of knowlege by my questions but that's how we learn :)



I looked up the Televue eyepieces and they are affordable - how is the quality? Have you used these on the 80mm you reviewed?


Other Optics -

I purchased Nikon monarch 8x36's and Nikon SHE 10x36's and couldn't be happier. I try to purchase at the point of diminishing returns. If I were a professional photographer or something I might go for a Ziess but I just can't justify the expense.

Thanks again...

Re: Celestron 100 FED

Post by Jne_K on Thu Dec 15, 2011 9:54 am

Hi

Good choice. You'll love the Regal 100F -ED.

First, a primer on image brightness. You can exit pupil asa guide, here. Exit pupil is the width of the beam of light in mm that leaves an eyepiece. It can easily be calculated by dividing objective size, in this case 100mm, by magnification. So, for your 10x magnification, you get an exit pupil of 10mm (100mm divided by 10x). Sounds good, but it's on paper, only, since most folks have eyes that only open wide enough to use an exit pupil width of between 5 to 7mm. In other words, your 10mm exit pupil is giving you more image brightness than you can use. If you are young, say under 40, you can probably use an exit pupil of 7mm. That will be achieved at about 14x. As we age, though, our eyes are less and less able to open, so if you're over, say, 40, you may be able to use an exit pupil of only 5mm. This would be achieved in the Regal at 20x.

As for eyepieces, yes, short focal length telescopes - and this is a short focal length telescope - are fussy about eyepieces. I'd recommend going with Televue eyepieces or Pentax eyepieces, since both of these folks make short focal length telescopes/spotting scopes and eye pies to match.Magnification? These are telescope eyepieces, so they are not sold by magnification; they're sold by focal length. To determine magnification when used in any particular scope, divide the focal length of the scope (the Celestron Regal 100F -ED is 540mm) by the focal length of the eyepiece.

In the Televue, the Plossls are a good match and, as Televues go, are affordable. The 32mm Plossl will get you the widest practical field of view in a 1.25" Plossl (don't get the 40mm Plossl - actually has a narrower field of view) and a magnification of about 17x which is about as bright as you'll get. (You won't see a difference between a 14x and a 17x).

Remember, your scope can only use 1.25" diameter eyepieces, so make sure to check barrel size in the specs. A lot of long focal length, wide-angle eyepieces are 2" barrel eyepieces and won't fit in the Regal.

Celestron 100 FED

Post by In Va on Wed Dec 14, 2011 9:10 pm

About me - I know enough about scopes to make me dangerous.

I'm interested in the Cel 100FED for all the reasons people/reviewers talked about and I'm not put off by size or wieght. My question is the about aftermarket wide angle lenses. I read on here that some may work - or not work.I'm confused on this point.

Another question I have is - if I do get an aftermarket eyepiece to fit/work, what is the LOWEST power wide angle available? I'd like to go as low as 10x if possible.

Low power + huge good quality objective = excellent low light performance. No?

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