which is a better eyepiece for my 120mm refractor telescope 6mm witha x2 barlow lense or 3mm?

Question

which is a better eyepiece for my 120mm refractor telescope a 6mm with x2 barlow or a 3mm

Answer 1

Which do you like?

Answer 2

I know from your later post that this is a 120mm f/5 refractor manufactured by Synta (even though it has another brand name on it). I tested two of these refractors and found that they both suffered from extreme chromatic and spherical aberration, so that the weren't usable above about 100x. So a 6mm eyepiece without Barlow or a 12mm eyepiece with 2x Barlow would be the upper limit for your scope.

The popular belief that refractors are good for planetary observation is only true for achromatic refractors of classic design (f/15 focal ratio) and apochromatic refractors; this does not apply to the current crop of short focal ratio Chinese achromats, which are f/5 to f/9. A 6" f/8 reflector will easily outperform these on the planets.

Despite what some answers say, a good quality Barlow has very little detrimental effect, and using a Barlow with a longer focal length eyepiece will generally give you more eye relief and a more comfortable view.

Answer 3

In general, a barlow will detract slightly from image quality, though with a high-quality barlow the actual impact is negligible. I got rid of my barlow in favor of a 2-4mm Nagler zoom mainly for convenience.

Barlows are particularly useful if with simple eyepieces like Plossls and othoscopics, because they give you higher magnification while preserving the eye relief. I suspect this isn't an issue with the 3mm eyepiece you're considering. If you do a lot of observing at 3mm, or if you want to use it for critical planetary observation, the dedicated eyepiece might be more useful. Otherwise, the barlowed 6mm will be fine for occasional use.

Answer 4

While a 6mm with a 2X Barlow will give you the same magnification as the 3mm eyepiece; you will get a more clear picture with the 3mm eyepiece. The reason is that each additional piece of glass an image has to pass through takes away from the quality of the image.

Answer 5

I think 3mm plus Barlow is too much magnification. If it has a focal length of 600mm, the 6mm alone will give 100 power and the 3mm alone will give 200 power. The 3mm plus Barlow will give you 400 power, which is WAY too much for a 120 mm telescope.

Answer 6

I really do not have an answer to this with using the barlow and i am wanting to know the same thing,, I have a x3 barlow and have been unable to use it because it makes it to hard to view anything,,
Interesting question,,

Answer 7

More information please. Focal length of the scope? What are you trying to see? 120mm is a pretty serious refractor. What make and model is it?

Answer 8

Hi, Try using 9mm 12mm or even 18mm, on there own especially for planets,