Do I need a planetary ep when I can barlow my 9mm?

[Lerxst]

My Explore Scientific 14mm and 9mm 100° ep's are waiting for me at the post office.

(naturally luck would have it that it's almost raining vertically today, after about a whole week of clear skies)

I have a 12" dob, and I'm simply wondering: would I need a 3-6mm planetary ep when I can barlow the 9mm instead? Or are there certain drawback to barlowing high(er) res ep's on planets?

[John]

Difficult to tell because I don't know how well the ES 100 degrees EP's barlow. If they are anything like the Ethoi's then you should be OK - I use an Antares 1.6x 2" barlow with my 8mm and 6mm Ethoi's to get 5mm and 3.7mm and the results are excellent IMHO - the barlow really "gets out of the way" with that setup. Obviously you want a really good barlow or a Powermate / TeleXtender and be prepared to have to counterbalance !.

That said, there are many who would prefer dedicated planetary eyepieces for highpower work (eg: Baader Genuine Orthos). I've tried them and like them but I felt the barlowed Ethoi's produce results that are 95% or more as good while retaining the mammoth FoV (my scopes are alt-azimuth and undriven) and reasonable eye relief so I'm happy with that.

[Lerxst]

The reviews for the ES ep's are in the mixed bag as follows:

People think they either

1) Are better than the Etho's

2) Are good, but they prefer the Etho's anyway

3) Can't tell the difference

Well, I'll guess I'll have to wait (it's pouring down at the moment) and find out.

[John]

I guess not many people have the chance to try both types of eyepiece "back to back", over a prolonged period, with different scope types, on different objects, under a variety of sky conditions. IMHO thats whats needed to be able to really compare two pretty similar products.