What are my 30-40mm eyepiece options?

[parallaxerr]

I'm looking for one or potentially two new eyepieces to round out my set in the 30-40mm range, purely for increased exit pupil to hunt down fainter stuff with the help of UHC/OIII filters, thus FoV is not a consideration. Oh and they need to be 1.25" fitting!

Candidates I've considered so far:

1. Televue 32 & 40mm plossls. Reportedly, eye relief on the 32 can be an issue requiring the eyeguard extender. Most expensive option.

2. Celestron Omni 32 & 40mm plossls. Had the 32mm previously and sold it on, regrettably. £39ea.

3. SW 32mm & 40mm plossls. Are they the same as the Celestrons? They are apparently heavier due to construction, which I prefer and half the cost @ £20ea.

4. Baader 35mm Eudiascopic? Can't find much info on this - eye relief being of specific interest - any comments?

 

Has anyone any comments or EP suggestions that may suit? FYI, my longest FL is currently an ES 68° 24mm. Should I skip the 30mm and go striaght for 35mm+? What would be the maximum useful exit pupil, with or without above mentioned filters, from typical suburban location with moderate LP?

Cheers all,

Jon

[25585]

I have TV 40mm Plossls, and Baader Eudiascopic 35mm eps.  Both have greater effective eye relief than my TV 32mm Plossl. TV 40 has most definitely. I need the eyecups even with my glasses.

Eudiascopics are limited in how many are left out there, while TV Plossls will be around forever. For largest eye relief, the 40s have most in the FL range you want. They are great performers edge to edge.

 

 

 

[John]

I've tended not to go beyond 24mm / 68 degrees in the 1.25" format - the additional mag seems to work better on DSO's under my skies at Portishead (which may be similar to yours).

I get along fine with UHC and O-III filters with this focal length with exit pupils ranging from 4.5mm in my 12" dob to 2.6mm in my 130 refractor (my slowest scope).

I have owned quite a few 30-something 1.25" eyepieces over the years including the ones you list. In the 1.25" format I don't usually bother with 40mm eyepieces.

[johnturley]

I recommend the Baader Hyperion Aspheric 36 or 31mm eyepieces, they provide a generous 72 degree apparent field of view, but are relatively lightweight and compact, more compact I belive than the 35mm Eudiascopic, and considerably cheaper than the 80 degree plus eyepieces from Explore Scientific and Tele View which are massive and weigh over 1kg, note these are all  2in eyepices.

If you are wanting a 1.25 in eyepiece you will not get a wider field than in a 32mm plossl, there is no point in getting a 40mm plossl in 1.25in as the field of view will be no wider than the 32mm.

John

[parallaxerr]

2 hours ago, John said:

I've tended not to go beyond 24mm / 68 degrees in the 1.25" format - the additional mag seems to work better on DSO's under my skies at Portishead (which may be similar to yours).

I get along fine with UHC and O-III filters with this focal length with exit pupils ranging from 4.5mm in my 12" dob to 2.6mm in my 130 refractor (my slowest scope).

I have owned quite a few 30-something 1.25" eyepieces over the years including the ones you list. In the 1.25" format I don't usually bother with 40mm eyepieces.

Thanks John, interesting. If the 24/68 is up to the job (it yields a 3.2mm exit pupil in my scope), then I may well have all the EP's I need now.

I do actually have a 30mm NPL, but I'm not overly enamoured with it, I preferred the Celestron Omni so may just sell the NPL on and get another Omni - cheap enough.

What are your thoughts on exit pupil when using the UHC from your location? By which I mean have you identified a sweet spot?

[Louis D]

2 hours ago, johnturley said:

If you are wanting a 1.25 in eyepiece you will not get a wider field than in a 32mm plossl, there is no point in getting a 40mm plossl in 1.25in as the field of view will be no wider than the 32mm.

There is if you have not yet maxed out your exit pupil and want a brighter, smaller, more concentrated nebula image to then filter with a UHC or OIII filter.  I do this with 32mm plossls in my Arcturus binoviewer despite vignetting compared to 23mm Vite aspherics.  It noticeably brightens up nebula making faint tendrils a bit easier to see.

[parallaxerr]

34 minutes ago, Louis D said:

There is if you have not yet maxed out your exit pupil and want a brighter, smaller, more concentrated nebula image to then filter with a UHC or OIII filter.  I do this with 32mm plossls in my Arcturus binoviewer despite vignetting compared to 23mm Vite aspherics.  It noticeably brightens up nebula making faint tendrils a bit easier to see.

Exactly what I was thinking Louis

[John]

2 hours ago, parallaxerr said:

What are your thoughts on exit pupil when using the UHC from your location? By which I mean have you identified a sweet spot?

I find that I prefer using an O-III over a UHC (I have both though). I'm not very systematic / scientific / analytical in the way that I use them though - when I feel I want one I bung it in and have a look

I found this short piece understandable (to me) and it tends to match my experiences:

https://www.astronomics.com/eyepiece-exit-pupils_t.aspx

 

 

[parallaxerr]

Just now, John said:

I find that I prefer using an O-III over a UHC (I have both though). I'm not very systematic / scientific / analytical in the way that I use them though - when I feel I want one I bung it in and have a look

I found this short piece understandable (to me) and it tends to match my experiences:

https://www.astronomics.com/eyepiece-exit-pupils_t.aspx

 

 

Yes, I regulary reference that article John and it's where I got the idea that I may benefit from a larger exit pupil for certain targets. I must admit thouth, that I often find what is deemed to be the best mag/exit pupil on paper, is rarely the case in reality. It is of course, a personal thing.

I am debating between the OMEGA/DGM NPB (on your recomendation in another thread) or an OIII filter to get started. Many articles place the UHC slightly ahead of OIII for general all-round usability, but then I read so many comments stating that OIII teases out more fine detail?

I think I'll get a filter first, try it in the 24/68 and 30mm NPL and go from there. Of course, in time, I aim to pick up a few filters to cover all bases.

[John]

When I had just one deep sky filter it was an O-III - the Astronomik. As I use an O-III quite a bit more than a UHC I could be content with just that one again I think.

 

[25585]

True. The 40mm Plossl is king of 1.25 fit eye relief, also slightly brighter but smaller images. I find as the TFOV in these 1.25 eps is average, background light is not the big issue that wider FOV eps have.

Older TV Plossls were Japanese made, not sure if modern ones still are, or from Taiwan n9w. The newer have a groove in their stem, while the older have smooth stems.

 

[25585]

On 07/06/2018 at 16:08, John said:

When I had just one deep sky filter it was an O-III - the Astronomik. As I use an O-III quite a bit more than a UHC I could be content with just that one again I think.

 

Same with me, its the OIII, my precious early Lumicon that gets used, its 1.25. I have an Astronomik 2 inch OIII which is like a cross between the former type and an UHC. Beautiful results with my 2 big Panoptics using it, but nebulae glow a bit more with the Lumicon.

Recently I bought a 1.25 Tak 28mm Erfle from FLO. This has better usable eye relief than a TV 32mm Plossl, comparable with a 35mm Eudiascopic. It is a but fuzzier at the edge but is comfier to use for eye placement than the TV 32.

None of the above are quite as sharp as my Tak 32mm Abbe Ortho, which has similar usable eye relief to the TV 32.

[Littleguy80]

I bought a 32mm Celestron Omni Plossl for the exact same reason to use in my old 130mm reflector. I mostly tested using an OIII on the Veil. Overall, I concluded that the image was brighter in appearance but I preferred the view in my ES68 24mm. I didn’t enjoy the long eye relief on the Plossl. I found eye placement was trickier compared to the ES. The side affect of increasing the exit pupil is decreasing the magnification. Changing the magnification also affects how well your eye can detect the object. Depending on the size of the object you’re trying to observe, you make actually it harder to see. Probably stating the obvious but it’s worth keeping in my mind. 

All in all, I got much better results by going to darker skies to observe than I did from increasing the exit pupil.  

[25585]

If you just want to go out in the garden though, using the right ep and filters makes a difference.

My first ep to have an OIII was a 20mm Erfle. Second was a 13mm Nagler. Both gave good results, for larger nebulae, but the Nagler was awesome for going deep into them and picking out fainter stars. I miss that experience, but not its small eye relief or kidney beans.

[Mr Spock]

I'm using a Meade 32mm 4000 Plössl. Not that expensive but super sharp and a nice dark background.

[parallaxerr]

Well having decided to pick up another Celestron Omni 32mm plossl, that I've previously owned and rated well, @DRT posted one up for sale in new condition for near half price, so I went ahead and bought it 

As the OIII vs UHC debate is never ending, I've ordered one of each. A DGM NPB and an Astronomik OIII......Plus a new diagonal, filter wheel and 2 planetary filters!

 

[25585]

12 hours ago, parallaxerr said:

Well having decided to pick up another Celestron Omni 32mm plossl, that I've previously owned and rated well, @DRT posted one up for sale in new condition for near half price, so I went ahead and bought it 

As the OIII vs UHC debate is never ending, I've ordered one of each. A DGM NPB and an Astronomik OIII......Plus a new diagonal, filter wheel and 2 planetary filters!

 

Glad you found one you wanted for the right price.