Eye Pieces

[Afatnuglybloke]

Seeking opinions and hopefully a consensus on the best two eyepieces (size & brand) for the following: 16" SW Dob & SW ED100 Apo.

[dannat]

do you want planetary DSO, i presume the ed100 is 900mm f/l & the dob is 1800mm f/l?

[Afatnuglybloke]

The ED100 is F9 and will be used for visual and astrophotography and the dob is F4.4. visual.

[Wavytone]

Very different scopes. No one-size-fits-all answer, and a lot depends on what you use these for.

Personal experience suggests for the refractor, a big fat low power 2" eyepiece e.g. the Vixen LVW42mm or an ES equivalent.

For the 16" dob, a medium eyepiece around 10-13mm, possibly Nagler, Panoptic or LVW. Higher power may be pointless in average being conditions.

[Afatnuglybloke]

Thanks waves...But what I meant was 2xeyepieces for each scope

[Wavytone]

In that case that suggests you'll buy 4 eyepieces.

For the refractor, two at 40mm and 20mm, for the dob two at 12 and 8 mm. You could also use the 20mm in the dob, and all four will be good in the refractor.

As for the series to choose, pretty much anything will suit an f/9 refractor so no need to overboard $-wise for that.

To get the full benefit from a 40mm you'll need an ultra wide in a 2" barrel, examples include the Vixen LVW42, Panoptic 35 or 41, or the ES 40mm/68-degree, or the ES30mm/82-degree.

For the 20mm, too many to choose from Televue, ES, even a humble Plossl would be quite an OK choice. Personally I use the Vixen LXW22.

For the dob, the choice is probably between Televue Delos (12 and 8 are available) or Naglers (12 and either 7 or 9, there is no 8mm), or Vixen LVW 13 and 8mm.

[Afatnuglybloke]

Thanks heaps Waves....I really appreciate you taking the time to help. I am an absolute beginner who bought the only 2 scopes I will ever own. I love being thrown in the deep end. Is it ok to contact you every now and then along the journey? Thanks again mate.

[MattT]

Here is my cheaper version, and what I have for both f12 frac and OOUK 10" f4.8, which I'm now keeping ;)
ES 82º 30 18 11 and 6.7. Add a coma corrector and use all 4 in both scopes.

If you use glasses go with Wavy's selection. The ES's are all tightish on the ER front.

[bobbyf]

I noticed you're from Virginia. Are you a member of ASSA yet?
There's a members viewing night at Stockport tonight and conditions are expected to be really good, so there should be a few there.
It'll be a great chance to see for yourself, as there'll be big dobs and refractors there I'm sure, with lots of different eyepieces. I'm taking my (was MattT's :)) ED100 up there.
Cheers

Bob

[Wavytone]

Tony, four other things for you to consider.

1. Weight. eyepieces of radically different weight many force you to rebalance your scope. Rebalancing can be avoided if they're all roughly similar weight - even if this means the smaller ones are mostly lumps of metal.

2. Eye relief. One particular aspect that annoys me is eyepieces with short eye relief. 20mm is very comfortable and IMHO about perfect, but ultrawides tend to have much shorter eye relief as a consequence of the ultra wide view.

Many of the older designs like orthoscopic, Plossls and RKE's have lots of eye relief for the longer eyepieces (20m and up) but none at the short end. For example, at 8mm you will have to screw your eyeball into contact with the eyelens to get the full field of view.

This is one aspect that Vixen, Televue and Explore Scientific have all covered quite well and you can find the specs for their eyepieces online.

3. Parfocal. When changing eyepieces its a big help if they all have the focal plane at the same spot to minimise refocussing (this is what par focal means). Eyepieces from different manfacturers won't be parfocal.

4. 2" vs 1.25" barrels. I hate swapping adapters to switche between 2"/1.25 barrels.

One reason I chose the Vixen LVW set is that they were one of the few series, if not the only series, that are all about the same weight from 3.5 to 42mm focal length, and have dual barrels (1.25/2") or 2" only (the 42mm) so no adapter required, and all have 20mm eye relief or more.

OTOH there are many who assemble a "bast*rd set" mix of various types if that suits them.

[Renato1]

For hunting down the thousands of faint galaxies at a dark site with your dob, you want an eyepiece which is ultrawide angle and with a 2mm exit pupil. In your telescope, that equates to an 8.8mm eyepiece. Meade sell an 8.8mm UWA, though I'd imagine another manufacturer's 9mm UWA eyepiece would be close enough.

Regards,
Renato

[Afatnuglybloke]

Buggah...Just read your post Bob...I am a member.

[Afatnuglybloke]

Thanks so much everyone...much appreciated.