Favourite Combinations

[Littleguy80]

I've noticed recently that when I find a target  the first eyepiece I reach for is my 12mm BST Starguider with the Astronomik UHC filter. Assuming a filter is required of course. The 12mm gives 75x magnification with my scope. I'm not sure if it's down to the eyepiece being the standout or simply that it gives the most useful magnification. Possibly it's the right balance of magnification and exit pupil to get the best out the filter. M8, the Lagoon, was the first target that I really noticed how well this combination worked. 

Does anyone else have a favourite combination and is it around the same magnification?

[Knighty2112]

With my C8 SCT I tend to use my 18mm X-Cel EP mostly, along with my Baader Semi-Apo filter to give a darker sky contrast. This works well for most DSO's etc. For planetary or lunar observing I would normal use my 10mm Tele Vue Delos EP for more detailed observations of those objects. 

[ronin]

Not that surprised, on one poll of the most used magnification the result was around the 80x area, which matches up with your 75x. Considering that you likely do not ahve an eyepiece for 80x specifically.

Always makes it amusing when people talk of magnifications beyond belief. I suppose that a patch of sky around the 0.75 to 1.0 degrees size is the reason, enough in there to give context to the object.

My combination is the 8mm or 12mm on a 600mm scope so much the same. On an ED however (similar focal lenght) I go for the 8mm or 6mm as it can extract more detail.

[Stu]

Interestingly, both those combinations give around 1.8mm exit pupil, despite the very different scopes. Around 2mm is supposed to give best contrast on many smaller DSOs.

I am somewhat limited with eyepiece choice currently so normally my 24mm Panoptic is my first choice in the Tak, 3.2mm Exit Pupil and x30 butvthats mainly as a Finder. The 12.5mm BGO goes in for observing quite often which is 1.7mm and x59 mag.

[John]

I've a number of different eyepiece sets, rather embarrasingly

Of the hyper-wides, the 21mm Ethos to the 8mm Ethos is a favourite and frequently used pairing, especially with my 12" dob.

Of the wides, the 24mm Panoptic and the 10mm Pentax XW make nice steps, sometimes followed by the 5mm XW for smaller targets.

Of the "normal" fields, the Baader Classic  ortho 18mm followed by either the 10mm of 6mm Baader Classic ortho although with the smaller fields I tend to press more eyepieces into use during a session so the Vixen NPL 30 plus the Nagler 2-4mm zoom get lots of use.

When my Leica ASPH zoom is back from it's service it's likely to stir the above up a bit I reckon

 

[Littleguy80]

21 hours ago, Stu said:

Interestingly, both those combinations give around 1.8mm exit pupil, despite the very different scopes. Around 2mm is supposed to give best contrast on many smaller DSOs.

I am somewhat limited with eyepiece choice currently so normally my 24mm Panoptic is my first choice in the Tak, 3.2mm Exit Pupil and x30 butvthats mainly as a Finder. The 12.5mm BGO goes in for observing quite often which is 1.7mm and x59 mag.

That is interesting. There may be something to the idea of picking your eyepieces based on exit pupil then!

[Littleguy80]

20 hours ago, John said:

I've a number of different eyepiece sets, rather embarrasingly

Of the hyper-wides, the 21mm Ethos to the 8mm Ethos is a favourite and frequently used pairing, especially with my 12" dob.

Of the wides, the 24mm Panoptic and the 10mm Pentax XW make nice steps, sometimes followed by the 5mm XW for smaller targets.

Of the "normal" fields, the Baader Classic  ortho 18mm followed by either the 10mm of 6mm Baader Classic ortho although with the smaller fields I tend to press more eyepieces into use during a session so the Vixen NPL 30 plus the Nagler 2-4mm zoom get lots of use.

When my Leica ASPH zoom is back from it's service it's likely to stir the above up a bit I reckon

 

Hehe you have almost as many favourites as I have eyepieces, John  Interesting that both you and Stu enjoy Orthos in some of the longer focal lengths. I have just have the 5 and 6mm BGOs as I mainly think of Orthos as being good on targets requiring high magnifications. I bought the BGOs for planetary mainly. Having said that, I used them both on M2 and M15 over the weekend. The 6mm BGO is great for globs  

[John]

Orthos are excellent deep sky eyepieces too. Folks in the USA deserts who use massive dobsonians to observe very faint objects rate premium orthoscopics as the best for going as deep as possible.

I was using the Baader Classic Orthos in 18mm and 10mm last night with my 12" dob and they were excellent at picking up faint galaxies and planetary nebulae.

[Littleguy80]

23 minutes ago, John said:

Orthos are excellent deep sky eyepieces too. Folks in the USA deserts who use massive dobsonians to observe very faint objects rate premium orthoscopics as the best for going as deep as possible.

I was using the Baader Classic Orthos in 18mm and 10mm last night with my 12" dob and they were excellent at picking up faint galaxies and planetary nebulae.

It's surprising they're not more popular given their reputation seems to be so good. I guess people are put off by the small FOV? 

[Louis D]

6 hours ago, Littleguy80 said:

It's surprising they're not more popular given their reputation seems to be so good. I guess people are put off by the small FOV? 

And limited eye relief for astigmatism sufferers like me.  I'd like to try a 25mm ortho sometime just because it would have enough eye relief for using eyeglasses.  I have some cheap Kellners (9mm and 12.5mm) that mimic the field of view and eye relief of orthos.  They are no fun to use with eyeglasses.  They are pretty sharp on axis, though.

[John]

7 hours ago, Littleguy80 said:

It's surprising they're not more popular given their reputation seems to be so good. I guess people are put off by the small FOV? 

As Louis says, orthos and plossls and kellners are not really suitable for those who wear glasses because the eye relief of those designs (of whatever brand, not just the Baader Classics) is around 80% of the focal length.

I'm usually a wide field junkie (hence the Ethos and others) but lately I've been appreciating again the light weight, compact size and optical quality of the simpler designs such as the Baader Classic Orthos. Also the whole set plus the Vixen 30mm LVW and Baader Q-Turret barlow (also optically excellent) cost about 30% of the cost of a single Ethos eyepiece. So I can afford to have a set for when I fancy those as an alternative to the hyper-wides and wides.

 

 

 

 

[Littleguy80]

Yes, I'd forgotten about the eye relief. It's pretty tight on the 5mm BGO. I've never tried a hyper wide eyepiece. I like the idea that you can't see the edge of the FOV so it's totally immersive. Must really add something to the experience.

[Stu]

11 hours ago, Littleguy80 said:

That is interesting. There may be something to the idea of picking your eyepieces based on exit pupil then!

That's absolutely possible and not a bad approach.

You could choose the following for instance:

6mm as a low power/widest field for objects like M31 or the Veil. Probably only useable at very dark sites.

4mm still lowish power but better with less than pristine skies as you have a darker sky background.

2mm is reputed to be the optimum for contrast on DSOs particularly the smaller galaxies and nebulae.

1.5mm high-ish power for globs and planetary nebulae for instance

1.0mm good as a high power for planetary/lunar on larger (250 or 300mm) aperture scopes

0.5mm useful on apo fracs as a high power again for planetary/lunar

Obviously the aperture of the scope makes a big difference, particularly at the high end. A 20" dob (500mm let's say) would give x250 with a 2mm exit pupil which might be all the atmosphere could take for planetary observing. To get the same on a 100mm apo frac you are down at 0.4mm which is quite achievable but can be challenging if you are prone to floaters.

I often think in terms of the field of view of eyepieces at the lower end and mag/exit pupil at the higher end. I think that's because I largely use fracs or SCTs which not that fast, so it's not often that you are at too large an exit pupil. If you have a fast dob then working out your lowest power by exit pupil is key as it is easy to go too big. Stick a 40mm eyepiece in an f3.7 dob and you are at 10.8mm! In an f10 SCT you are quite safe at 4mm.

[Littleguy80]

That's an excellent guide, Stu. Through reading countless threads, I think kind of ended up with that type of set up. Orthos at the high end and ES68 for max FOV at the low end. I certainly didn't have any kind of grasp on the ideas of exit pupil when picking those eyepieces but would, without doubt, factor it into future eyepiece purchases. 

[25585]

32mm Erfle and Plossl for centering. Plossl also used with X2 Barlow.

20mm Erfle if latter unsatisfactory. Using push-to mounts I need to whisk eps out and in of my focusser for upping magnification.

31.7mm diameters usually have filter use, while 2 inch wide field like 27mm Panoptic is more for scanning and exploring as well as immersive use.

 

[Louis D]

On 9/2/2017 at 07:36, 25585 said:

while 2 inch wide field like 27mm Panoptic is more for scanning and exploring as well as immersive use.

I find I like my 27mm Panoptic in my 15" dob as a primary eyepiece due to its 2000mm focal length.  I operates similarly to a 14mm eyepiece in a 1000mm focal length telescope.  It all depends on the focal length of your scope how you'll use a particular eyepiece.

[Moonshane]

It depends greatly on which scope I am using and what I am doing :

102mm F7 ED - Mainly a travel scope so I like looking at wide fields at darker sites therefore 24mm Panoptic (29x and 3.4mm exit pupil (EP)) unless doing white light solar with it in which case 20mm TV plossls with a binoviewer (BV) and 2.6x GPC (91x and 1mm EP). Lunar same set up but also use high mag pairs.

100mm PST mod - Ha solar only - 20mm pair in BV 1.7x GPC (85x and 1.2mm EP)

120ED - general use probably 24mm Panoptic (38x and 3.2mm EP) and 11mm Delite (81x and 1.5mm EP) or white light solar  20mm plossl pair in BV plus 2.6x GPC (117x and 1mm exit pupil) Lunar same set up but with more magnification too.

6" f11 Newtonian - doubles, lunar and planets - 15mm plossl air in BVs with 1.7x GPC (181x and 0.8mm exit pupil) but sometimes more on doubles and moon

12" f4 dobsonian with paracorr - 27mm Panoptic (50x and 6mm EP) and 11mm Delite (121x and 2.4mm EP) - I am saving for a 9mm Delite to achieve 149x and 2mm exit pupil but for now also use a 7mm Delite (191x and 1.5mm EP)

16" f4 dobsonian with paracorr - 27mm Panoptic (68x and 6mm EP) and 11mm Delite (167x and 2.4mm EP) - same applies as above for 7mm Delite and requirement for 9mm.

I do have a number of other eyepieces which I use regularly and the most used being 25mm TV plossl pair where seeing dictates less mag, and a 6-3mm Nagler zoom where seeing allows more mag. Possibly me least used eyepiece is my 19mm Panoptic but it's such a gem and frames some objects so nicely I am loathe to even think about selling it.

Roughly looking at the figures above I also subscribe to the same sort of magnification and exit pupils discussed above albeit I am forced to use a larger exit pupil with my big dobs to gain the field - this is sometimes useful when using e.g. Oiii filters on large objects.

[Littleguy80]

I've noticed that the 24mm panoptic, 5mm Pentax XW and Nagler 3-6mm zoom seem to regularly come out as favourites on this and other threads

[Louis D]

5 hours ago, Littleguy80 said:

I've noticed that the 24mm panoptic, 5mm Pentax XW and Nagler 3-6mm zoom seem to regularly come out as favourites on this and other threads

Don't overlook a good deal on a used 5.2mm Pentax XL.  I've been using one for nearly 20 years, and it has just a slightly lighter background than the XW, possibly due to coatings improving over the years.  It is super sharp edge to edge at f/6 with no ghosting or flaring.  I use it regularly to resolve globular clusters in my 8" dob.