11 replies to this topic

[T-rav82]

I am soon travelling to a dark site for a week and leaving my dob behind. My refractor will come instead, an 80ed f/6.25 (fl 500mm).

I am trying to decide what eyepieces to take as ideally I would prefer to keep it to a minimum.

I do not plan on viewing anything at high power, that is not what this scope is for.

I am thinking of magnification and exit pupil and what I have used already with this scope and have settled on the following although I think one or two are possibly redundant:

 

17.5mm or 18.2mm

12.5mm

10mm or 9mm

7mm

5mm

 

I could go higher than the 5mm with a 3x focal extender on other eps but on this scope I prefer to keep thing light.

I would like to mainly view dso and clusters and could only think that going higher than x 100 would be beneficial on globulars. I could also go lower but do not think  that would be necessary as I have never felt the need for less than x 27.

 

I am very well aware I could be wrong and your thoughts and opinions would be much appreciated.

Edited by T-rav82, 29 April 2025 - 11:46 PM.

[triplemon]

All those eyepieces would make plenty sense for the purpose stated. Unless you have space limitations, bring them all.

 

And I would not discount bringing a wider view 2" eyepice. Emphasis is on field stop size, i.e. absolute wide FOV. There are a few things in the summer sky that can take as wide of a view as you can get - like the north America Nebula and the Veil. In particular if you have a UHC filter to boot.

[eblanken]

Hi (aka T-rav82),

 

I would take the 18.2mm, 13mm, 9mm, 7mm & 5mm. In my case, these would be TeleVue DeLites . . .

 

So, for a 500mm Focal Length:  27.5x, 38.5x,  55.5x,    71.0x  &   100x

 

And 80mm Aperture gives EP of 3.0mm, 2.1mm, 1.4mm, 1.1mm & 0.8mm

 

Best,

 

Ed

Edited by eblanken, 29 April 2025 - 11:25 AM.

[Spikey131]

When traveling with a small refractor, I always include a 32 Plossl or 24 Panoptic so that I can maximize the 1.25” FOV.  This is especially helpful in dark places where sweeping the Milky Way is so much fun.  It also serves as a finder eyepiece.

 

I also bring the Nagler Zoom which covers the entire short end in a tiny package.  But your 5mm/barlow combo will serve the same purpose.

[eblanken]

Hi Again, 

 

Hi (aka T-rav82),

 

I would take the 32mm, 18.2mm, 13mm, 9mm, 7mm & 5mm. In my case, these would be TeleVue DeLites . . .

 

So, for a 500mm Focal Length:  15.6x, 27.5x, 38.5x,  55.5x,    71.0x  &   100x

 

And 80mm Aperture gives EP of 5.1mm, 3.0mm, 2.1mm, 1.4mm, 1.1mm & 0.8mm

 

Best,

 

Ed

 

 

When traveling with a small refractor, I always include a 32 Plossl or 24 Panoptic so that I can maximize the 1.25” FOV.  This is especially helpful in dark places where sweeping the Milky Way is so much fun.  It also serves as a finder eyepiece.

 

I also bring the Nagler Zoom which covers the entire short end in a tiny package.  But your 5mm/barlow combo will serve the same purpose.

Edited by eblanken, 29 April 2025 - 11:50 AM.

[Jay_Reynolds_Freeman]

You don't say whether your 80 mm can handle two-inch-barrel eyepieces or not. In either case, I recommend one low magnification eyepiece which takes advantage of the field of view that your focuser provides: If you have a 1.25-inch focuser a 24 mm Panoptic might be a good choice; if you have a 2-inch focuser then perhaps a wide-field eyepiece in the range 27 to 32 mm focal length, depending on how wide the pupils of your dark-adapted eyes will dilate.

 

For many deep-sky objects, an exit pupil around 1.5 mm is useful. How about a 10 mm eyepiece, or maybe a 12 mm if your low-magnification eyepiece is a 32 mm? If you have a zoom eyepiece which allows these focal lengths, and if it will work with your telescope, that might do as well.

 

Add a 5 mm for the low end of high magnification, and you are all set.

 

Incidentally, minor confusion in your posting: 80 mm aperture at 500 mm focal length is f/6.25, not f/5.9; at least one of those numbers must be wrong.

 

 

Clear sky ...

[rgk901]

take your 17/9/5

[Procyon]

Take the 3 Pentax, 3 Morpheii and 1 delite and compare them all : ) Find out what they're all about.

[T-rav82]

You don't say whether your 80 mm can handle two-inch-barrel eyepieces or not. In either case, I recommend one low magnification eyepiece which takes advantage of the field of view that your focuser provides: If you have a 1.25-inch focuser a 24 mm Panoptic might be a good choice; if you have a 2-inch focuser then perhaps a wide-field eyepiece in the range 27 to 32 mm focal length, depending on how wide the pupils of your dark-adapted eyes will dilate.

 

For many deep-sky objects, an exit pupil around 1.5 mm is useful. How about a 10 mm eyepiece, or maybe a 12 mm if your low-magnification eyepiece is a 32 mm? If you have a zoom eyepiece which allows these focal lengths, and if it will work with your telescope, that might do as well.

 

Add a 5 mm for the low end of high magnification, and you are all set.

 

Incidentally, minor confusion in your posting: 80 mm aperture at 500 mm focal length is f/6.25, not f/5.9; at least one of those numbers must be wrong.

 

 

Clear sky ...

Thanks for correcting, it is f/6.25. Focuser is 2” and I have an es 24 and a 30mm uff which I prefer

[Jay_Reynolds_Freeman]

Thanks for correcting, it is f/6.25. Focuser is 2” and I have an es 24 and a 30mm uff which I prefer

Then I would recommend taking the 30 mm for low magnification and wide field, the 5 mm for high magnification, and fill in with either just the 12 mm or perhaps the 18 mm and the 10 mm.

 

Clear sky ...
 

[T-rav82]

I am thinking 24, 12.5, 7 and 5 as I have a 1.25" uhc filter. If I choose 3, then I think the above makes sense.

Thanks for replying everyone

[C. Evangelista]

The entire Nikon NAV SW line (5, 7, 10, 14, 17.5), because they are not so big and have BEST optical performance.

Additionally, a Panoptic 24 ???

However, this set will be expensive....

Edited by C. Evangelista, 01 May 2025 - 09:49 PM.