Which gap to fill.

[Ally8446]

Currently I have the following EPs. 

ES 14 82°, ES 24 68°, BCO 10mm. 2x Barlow. 

I've just placed an order for an F6.3 10" dob. Unfortunately the Lukehurst had to go due to weight. 

I'm reckoning I should be looking at a 82° or 100° ES (or similar) around the 30mm FL. Should I sell any of my current EPs ? What would you marvelous folks suggest ? Budget around £500.

Al

[John]

20 / 21mm is the longest FL 100 degree eyepiece you can get in the 2 inch fitting. Unless you are planning to go to a 3 inch focusser

The ES 30mm might be the answer, unless you want to shell out on the mighty "Terminagler" 31mm ?

Otherwise I would say your eyepiece run is quite good when you take the barlow into account:

24mm, 14mm, 12mm, 10mm, 7mm, 5mm

If I'm going to "pack" the focal lengths it's at the shorter ones so I'd probably squeeze a 6mm in there.

[Louis D]

I'll parrot my usual recommendation of the 30mm APM UFF at that focal length.  I prefer it to my 30mm ES-82 due to its better edge to edge correction.

Since it's an f/6.3 Dob what will likely be f/7 or so with a coma corrector, you could even opt for a 40mm Maxvision to achieve maximum true field of view while staying under a 6mm exit pupil.  It can be easily deloaked to reduce the weight.

I find 70 to 72 degree AFOV eyepieces more enjoyable than 80+ degree ones because I don't have to scan around the field as much to see everything.  That said, they are fun to get lost in the view once in a while.  My 12mm and 17mm ES-92s give me a lot of the Wow factor.

[John]

Are you going to use a coma corrector in an F/6.3 dob ?. I don't find that I need one with my F/5.3.

[Ally8446]

14 minutes ago, John said:

Are you going to use a coma corrector in an F/6.3 dob ?. I don't find that I need one with my F/5.3.

No John, no corrector. That's precisely the reason I went for F/6.3 + I'm over 6' tall. 

[John]

Just now, Ally8446 said:

No John, no corrector. That's precisely the reason I went for F/6.3 + I'm over 6' tall. 

I had my 12 inch F/5.3 mounting designed for observing while standing - I'm 6' tall.

 

[Ally8446]

2 hours ago, Louis D said:

I'll parrot my usual recommendation of the 30mm APM UFF at that focal length.  I prefer it to my 30mm ES-82 due to its better edge to edge correction.

Since it's an f/6.3 Dob what will likely be f/7 or so with a coma corrector, you could even opt for a 40mm Maxvision to achieve maximum true field of view while staying under a 6mm exit pupil.  It can be easily deloaked to reduce the weight.

I find 70 to 72 degree AFOV eyepieces more enjoyable than 80+ degree ones because I don't have to scan around the field as much to see everything.  That said, they are fun to get lost in the view once in a while.  My 12mm and 17mm ES-92s give me a lot of the Wow factor.

Is it this one you're referring to... 

http://apm-telescopes-englisch.shopgate.com/item/333631373637

[Louis D]

2 hours ago, Ally8446 said:

Is it this one you're referring to... 

http://apm-telescopes-englisch.shopgate.com/item/333631373637

Yes.  I replaced my venerable 27mm Panoptic with it because it has better eye relief, less field curvature, and better edge correction.  The field is also wider, both apparent field and obviously true field due to the 10% lower power.  The Panoptic might be a tiny bit sharper on axis, but I don't do much planetary viewing with it, so it's not an issue to me.

[PlanetGazer]

On 20/08/2019 at 19:07, John said:

Are you going to use a coma corrector in an F/6.3 dob ?. I don't find that I need one with my F/5.3.

At which focal ratio do you usually start needing a coma corrector?

 

Sorry for going off topic😅

[Louis D]

3 hours ago, PlanetGazer said:

At which focal ratio do you usually start needing a coma corrector?

It's more of a question of how discerning has your observing eye become.  I didn't use a coma corrector in my f/5 and f/6 Dobs for years.  One day, I picked up a used GSO CC just to see if it would help.  After I got the distance set about right, I couldn't believe what I had been living with at the edges.  The field was flatter, coma was practically gone from the edge, and the only thing left was eyepiece field curvature and astigmatism.  I only remove it for high power work when some sort of residual spherical aberration shows up or when using a 2" 2x Barlow because I can't reach focus otherwise.  I really didn't think CCs mattered at f-ratios above f/5, but I found out otherwise.

[Paz]

I'd vote for a 30 or 31mm first, then consider the small focal length end of the spectrum once I'd got a feel for how much the scope/conditions will take.

I don't know if you need a paracorr at your focal ratio, I have one with a f4.6 dob and it is a helps with both  field curvature and coma at that focal ratio.

[Ally8446]

25 minutes ago, Paz said:

I'd vote for a 30 or 31mm first, then consider the small focal length end of the spectrum once I'd got a feel for how much the scope/conditions will take.

I don't know if you need a paracorr at your focal ratio, I have one with a f4.6 dob and it is a helps with both  field curvature and coma at that focal ratio.

No paracorr required Paz, it's F6.4. I've got a wanted ad on here and ABS for either APM 30mm or ES 82°

Al

[Mike_S]

For that budget you could get an ES 82 degrees 30mm (I love mine) and a Televue Delos 6mm (haven’t tried but but heard only great stuff and plan on one myself to bridge a gap). Sorted. 

Edited August 25, 2019 by Mike_S