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Eyepieces and Barlows


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Another Eye Piece question I'm afraid.

Even using the scope just once, plus a few terrestrial viewings, I think it's pretty obvious that the sky watcher 10mm is a bit of a letdown. the 25mm isn't too bad at all, but my newly acquired 32mm Celestron Omni Possl is my favourite.:)

I also think the 10mm with the Barlow (180x) is pushing the Evostar 90 a bit far in general conditions.

I've ordered a bargain price 12mm Celestron Omni Plossl, (I've been impressed with the 32mm version), which will give a 150x Barlowed magnification.

However, is it better to just have a 6mm EP to achieve the same mag, or is it better to use a longer eye piece and Barlow it.

I'm considering one of the 6mm TMB Planetary EP's, is this a good move?

Finally, is the Skywatcher deluxe Barlow ok, or would a Barlow upgrade be money better spent?

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I'm hoping the 12mm Plossl isn't too bad for eye relief, but the 10mm that came with the telescope is a little tricky to use.

I'll stick with the 6mm for now, but I did actually think the 9mm would be a nice addition.

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If you can afford, buy the eyepieces you need to obtain the desired magnification.

It's better to use less glass. No matter how good the quality and coatings of a Barlow lens, it will always take it's share of light.

Years ago, before long-eye relief EP's came around, a barlow was very useful to allow you to use a longer focal lenght eyepiece, with it's natural longer eye relief, and getting a higher magnification.

Nowadays, you can easily get short f.l. EP's that will give you a pleasant long eye relief.

OTOH, one single Barlow lens can be used with several of yours already existing EP's, providing different magnifications and thus avoiding the need to purchase other EP's. report.gif

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I am in a similar position, I have a skywatcher heritage 130p with the standard 10mm and 25mm lens. I have been considering whether to get a barlow to increase the magnification of the lens i have or to purchase a new planetary lens.

I am hesitant to spend lots on the baader hyperion EP's as i have only recently bought my first scope.

Would people recommend buying individual EP's or an EP set such as

http://firstlightoptics.com/products.php?cat=81

Edited by junior
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If you can afford, buy the eyepieces you need to obtain the desired magnification.

It's better to use less glass. No matter how good the quality and coatings of a Barlow lens, it will always take it's [sic] share of light.

Years ago, before long-eye relief EP's came around, a barlow was very useful to allow you to use a longer focal lenght eyepiece, with it's natural longer eye relief, and getting a higher magnification.

Nowadays, you can easily get short f.l. EP's that will give you a pleasant long eye relief.

And they're usually implemented with an extra negative doublet in front of the rest (i.e. something very like a barlow, but matches to the rest of the design), i.e. more glass, invalidating your original point.

There's nothing bad about a good barlow, especially when coupled with simple eyepiece types. The advantages are that one barlow doubles the eyepiece collection. The disadvantages are that a good barlow actually costs more than a single long eye relief eyepiece (with a negative doublet built into the design) like the TMB Planetary and that handling barlows in the dark is cumbersome.

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The 6mm TMB is a very nice EP. You will not believe how comfortable it is compared to a 10mm plossl. It will give you 150X mag in your scope which requires reasonably good seeing conditions to get the best out of it. The 9mm would give 100X mag and would probably get more use.

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