7mm Nagler or 13mm & barlow?

[DaveM]

Hi,
I'm looking to get a Nagler in the 7mm range for a 16" Lightbridge(I already have a 9mm Nagler and a 5mm Stratus) and was wondering if it might be better to Barlow a 13mm Nagler, which gives me 2 useful focal lengths? I have read that the 2.5x Televue Powermate is the best choice for barlowing, but that would give me a 5.5mm focal length from the 13mm, which is not what I am after. In this case, a 17mm Nagler and 2.5x Powermate might be useful.

What experiences do people have with Barlowing or Powermating these eyepieces? I suspect that I should just go for the simple 7mm Nagler, but I'd be interested to hear what other people are doing.

Thanks,
David

[wavelandscott]

Dave,

Not to confuse your question...but, I would highly recommend that you consider the Pentax XW in that area of magnification...I have the 7 mm XW and highly recommend it. I also have a 10 mm XW which in the end I kept over an 11 mm T6 Nagler (it was a hard choice but I was able to swap the 11 mm T6 for a 13 mm T6...it fits a bit better in my eyepiece line up and with the 10 already in hand I felt it was a good trade).

I do own a 2.5x Powermate but find I rarely use it...I have found I prefer to use my eyepieces without it...As I currently have undriven dobs I tend to not push the magnification too high anyway.

The 13 T6 Nagler is a fine eyepiece and I suspect that it would work a treat in your new scope! I have not tried to use it in the Powermate yet...

With a scope like that what are you using on the lower magnification end?

The T5 series Naglers seem to work real well!

[DaveM]

Thanks for the reply. I hadn't thought of the Pentax. From a quick search on the internet, the 7mm seems to offer slightly better on-axis views, with a smaller field of view of course. Another plus I suppose would be the lack of kidney beaning in a 70 degree EP. Given that this will probably be mostly used as a planetary eyepiece, the Pentax might be a better option.

My lower power EPs are a 13mm and 17mm Orion Stratus and 35mm and 27mm Panoptics, however the 35mm will only be able to be used with my Paracorr, which would reduce the exit pupil size to something just under 7mm.

Cheers,
David

[matt]

Hi David.

Don't know if this is of much help, but I have both the 13mm T6 Nagler and 10mm Pentax XW, and you're welcome to look through both in your scope.

I also have a 2.5x Powermate and 2x Ultima Barlow.

I also live in Canberra, so it shouldn't be too difficult to hook up:)

If you could borrow a 7mm of whatever brand from someone else, you'd be able to compare.

[DaveM]

Hi Matt,
Thanks for the offer. Are you a member of CAS? I might see if I can find someone with a 7mm Nagler or Pentax to do some comparisons (when the rain and moon are gone).

Cheers,
David

[matt]

No. Not a member of CAS.

But very active member of IIS:)

[DaveM]

Hi Matt,
I'll PM you when I can track down a 7mm EP. I'm not sure how long that would take, but if I can't find one, I might just have a look at the EPs you have if that's OK.

Thanks,
David

[wavelandscott]

The Pentax eyepieces are well worth considering...

The 7 and 10 XW are very good (the Naglers are very good too)...the look through them is "colder" (my poor description) to my eyes...the Naglers tend to add a "warmer" tone to the view...

If you are looking for a 7 mm, you will be hard pressed to find anything better than the Pentax XW...

[matt]

Not a problem.

Just call out when you're ready:)

[MortonH]

TeleVue also make a 2x Powermate, although it's expensive cos it's a 2" fitting, not 1.25".

Morton

[DaveM]

Thanks for the advice. I'm now on the lookout for a 7mm Pentax XW, though it is probably worth having a look at the Nagler.

David

[DJVege]

I've got a 7mm Nagler on the way. Just ordered it from Bintel, and they sent it yesterday. I've got nothing to compare it with, though.