To BV Nag Zooms (or to just GPC)?

[vineyard]

Hello,

A q for more experienced SGLers pls.  I currently have, & v much enjoy (separately) a BV and a Nag 3-6 Zoom.  So much so that I did start wondering whether 2 zooms in a BV would be amazing on the moon...but on reflection I'm wondering whether it would be worthwhile:

My main visual scopes are an old Telementor 2 (840mm f/l), an old Vixen 102 (1000mm f/l) for when I want more resolution & an old TV76 (480mm f/l) for widefield & Ha solar.

For the BV I have a 1.25x GPC & a T2 prism diagonal.  This allows me to find focus w both the TM2 & the TV76 (but not the Vixen). W the TV76 though, that is only for nighttime, b/c there is only about 10mm of inward travel left once infinity focus is found - so if I use TV76+BV for solar visual, the blocking filter unit adds about 35mm to the path, and the BV can no longer find focus.

Given that only 35mm is added, I think if I used a 1.7x GPC instead of 1.25x, that would allow me to find focus for daytime solar too?  So I will probably be doing that b/c I do want to be able to BV solar (I'm told its much nicer, just as with the moon?).

This though makes me pause on the idea of a second zoom.  My shortest BV EPs are 9mm & 18.2mm.  So if I had a 1.7x GPC, that would make them equiv to 5.3mm & 10.7mm.

I do find myself using the Nag Zoom for mono-vision at 3-4mm a fair bit b/c both the TM2 & Vixen can support that, so an effective 5.3mm f/l would leave a bit wanting.  But a 2.6x GPC would make those BV EPs equivalent to 3.5mm and 7mm.

Given that, would it actually be better to just get a 2.6x GPC instead of another zoom.  That would give more or less the range of a zoom.  Yes it would mean swapping EPs but FOV would be higher (62deg)?  And it would be a fraction of the cost.  (In fact even getting both a 1.7x and 2.6x GPC would be <50% of a Zoom - I could probably get both GPCs & another prism & still come in below a 2nd hand zoom!).

I'm v glad to have a zoom for mono-lunar, but am I missing s/thing in the above or would it actually be better to just get another GPC for close up lunar?

Thank you!

Vin

(PS - the other angle that makes me hesitate on BV'ing Nag Zooms is that w a 1.25x GPC, the effective f/l would be 2.4-4.8mm...I don't think the seeing would support 2.4mm that often w a little TM2 or the V102)

 

[mikeDnight]

The Nag zoom is a great eyepiece in many ways, but you'll have a much better observing experience if you use longer focal length eyepieces and a GPC or a barlow lens. With a barlow attached to the nose of your binoviewer you'll get fabulous lunar and planetary views without having to go below 15mm. And you really do not need expensive eyepieces. Simple orthoscopic's or plossl's will be every bit as sharp as a supermonocentric. Much more comfortable too!

[Highburymark]

Definitely the 2.6x GPC is a better solution. Many people find it difficult to merge images from two high power eyepieces. It’s easier using lower f/l eps and adding magnification through a GPC and/or barlow. Also the small eye lens of the Nagler zooms might be detrimental to viewing comfort. My highest power pair is two 11mm Delites which I use up to 225x on the Moon and - when possible in good seeing - 135x for solar Ha. But most solar sessions are around 60-70x. Binoviewing the Sun is wonderful - brings a whole different dimension to the experience. 
Worth being aware that the 1.7x GPC is actually only 1.5x, so doesn’t offer quite as much help if you’re struggling to reach focus.

[Louis D]

Agree with @Highburymark about merging high power eyepieces in a BV.  The problem is that they expose even the slightest miscollimation of the BV.

I just use a pair of Celestron Regal 8-24mm zoom eyepieces with a 2x Barlow nose piece that yields 3x in the BV.  That way, I'm operating the zooms at 2.7mm to 8mm.  Absolutely no problems merging the images at any focal length, although I rarely go much higher than about 12mm natively (4mm Barlowed) on the zooms in this mode due to viewing conditions and exit pupil issues.

I also have no problems matching zoom focal lengths.  I zoom both roughly to where I want to be power-wise, tweak focus using my dominant eye if needed, and then fine tune the focal length of the zoom for my non-dominant eye until the images exactly merge.  It's actually easier to figure out best merge than best focus in my experience.

[vineyard]

Thank you @mikeDnight @Highburymark @Louis D that's really helpful & exactly the kind of rich feedback I was hoping for.  Much appreciated!  2.6x GPC it is  

[vineyard]

So I have to apologise to everyone for the clouds.  Got a 2.6x GPC via FLO & yes it arrived today.  Luckily managed to set it up and get a quick stint w 18.2mm Delites.

And. Oh. Wow!  @mikeDnight@Highburymark@Louis Dare bang on.

I know Sol is particularly active these last few days but oh my goodness it was breathtaking.  It really seems to come alive - and the sheer power really comes through.  One prom (around 7 clock on the disc) changed shape within a period of c 20 mins?  When you pause & think about the amount of energy involved in what you're watching in real-time, its staggering.

I remember being wow'ed when BV'ing the moon.  This is the same but different.  BV'ing the moon is like seeing something that is graceful, demure & serene, whereas BV'ing the Sun in Ha is like watching raw unbridled power that would demolish anything in its way!

It was so good I didn't even want to set up the camera, just sit there & watch.

Edited April 21, 2021 by vineyard
wrong EP focal length originally

[Highburymark]

On 20/04/2021 at 17:58, vineyard said:

So I have to apologise to everyone for the clouds.  Got a 2.6x GPC via FLO & yes it arrived today.  Luckily managed to set it up and get a quick stint w 18.2mm Delites.

And. Oh. Wow!  @mikeDnight@Highburymark@Louis Dare bang on.

I know Sol is particularly active these last few days but oh my goodness it was breathtaking.  It really seems to come alive - and the sheer power really comes through.  One prom (around 7 clock on the disc) changed shape within a period of c 20 mins?  When you pause & think about the amount of energy involved in what you're watching in real-time, its staggering.

I remember being wow'ed when BV'ing the moon.  This is the same but different.  BV'ing the moon is like seeing something that is graceful, demure & serene, whereas BV'ing the Sun in Ha is like watching raw unbridled power that would demolish anything in its way!

It was so good I didn't even want to set up the camera, just sit there & watch.

Fantastic! Glad it worked out well.