High power - large AFOV?

[gooseholla]

Hello,

I currently own a 8mm TMB designed 58 degree eyepiece. I want to upgrade it in the future to a better eyepiece. Fine for planets and tonight viewing the Dumbbell nebula it was nice to see just that. But it got me thinking, say for example an 8.8 ES 82 degree eyepiece. Now that would be more useful on say the Andromeda galaxy, but what do people think? Should high power eyepieces have less field of view to avoid distraction, or is it nice to have a larger field? Not looking for any particular advice on the eyepiece mentioned just in general, do people use larger or smaller AFOVs with their high power observations and do you think one is better than the other.
 

Thanks
John

 

[Charic]

Hi there gooseholla

I once owned the 6mm TMB and found it too tight with only  a 58° afov, but mainly  the eyepiece just did not feel right to me, having dropped from my normal 60° afov, and how can only 2° make such a difference, it does ? same as focal length in an eyepiece, amazingly 1mm makes a difference. My 5mm BST has 60° afov which is more comfortable for my needs, but does not give me the 200x power requirement for my present scope, then finding  a William Optics SPL 6mm for  a great  price,  it has become,  for now my 200X provider, for my  f/6 scope, but still with only 55° afov and about 20mm eye-relief, less than the TMB, and  this EP snaps into focus just nicely, and  feels right, but  I would change it if the right EP came along,  I'm still waiting for a 6mm Starguider?

Viewing M31 from a darker site, I find my Panaview 2" fitting 32mm with its 70° afov fits the bill better for my needs. The Moon looks pretty small in my Panaview, floating in a Sea of space,  but stunningly quick when looking into its craters at 6mm or less.

Having wide views is ok, but only enough to frame the subject is my suggestion ( Al Nagler's quote )  and I have often looked at the Delos designed EP's giving me  72° afov to play with, using just three of the Delos EP's, but that idea has been dropped for now, as it was to coincide with the purchase of a newer 12" scope this Month?. 

[Stu]

Hello,

I currently own a 8mm TMB designed 58 degree eyepiece. I want to upgrade it in the future to a better eyepiece. Fine for planets and tonight viewing the Dumbbell nebula it was nice to see just that. But it got me thinking, say for example an 8.8 ES 82 degree eyepiece. Now that would be more useful on say the Andromeda galaxy, but what do people think? Should high power eyepieces have less field of view to avoid distraction, or is it nice to have a larger field? Not looking for any particular advice on the eyepiece mentioned just in general, do people use larger or smaller AFOVs with their high power observations and do you think one is better than the other.

Thanks

John

In your scope John I think it would be rude not to use Ethos eyepieces

The 21mm is fantastic for many targets, but the 8mm is pretty popular with quite a few of the Dob mob, high power with a relatively large field of view is hard to beat!

With these scopes, Andromeda and the Veil are never going to fit in the fov, so it is a matter of viewing sections at a time. Whilst orthos are very nice in shorter focal length refractors, I do believe that they would give too narrow an fov on a big Dob.

[Mak the Night]

I tend to prefer my 16mm TeleVue Nagler T5 combined with the 2.5x Powermate for high magnifications (particularly lunar and planetary viewing) with an 82° AFOV. I also have a 10mm Celestron Luminos. I like the larger FOV as I rarely use a motor drive to compensate for RA.  That may change when I get a GOTO though. The T5 only has 10mm eye relief, although I don't really mind that. I think field stop size is almost as important as AFOV. 

The eyepiece on the left (above) is a 15mm relatively inexpensive Celestron Kellner. I found a 15mm focal length a nice compromise between magnification and FOV on my Newtonian and my small Mak, especially as I could easily double or triple the magnification with Barlows. The EP on the right is a 15mm Celestron Omni Plossl I purchased as an upgrade later than the Kellner (which was originally part of a kit). The odd thing was that I kept returning to that Kellner, so much so that I ended up buying specific wide angle EP's.

[John]

I certainly use wide angles of view at high power but you want a good sharp field right across otherwise you can't make the most of the wide field. With your F/4 scope and, I believe, no coma correction, I think that might be a challenge to achieve.

The Andromeda galaxy is not a great example for this discussion though because of it's size, unless you want to start searching for it's globular clusters of course !

I've used orthos and plossls with my dob but wides, ultra-wides and hyper wides make life a lot easier

I agree with Stu - provided that you don't wear glasses when observing, 100 degree eyepieces and big dobs are made for each other, however is has to be said that:

     Sharp, wide field, fast newtonian optics = not a cheap taste to develop !

[rwilkey]

Hi John, yes, I certainly use wide angles at higher power, slower transit times and other benefits, I use the ES82's 8.8; 6.7 and 4.7.  They are very effective and comfortable to use.  For M31 Andromeda you need the low power 30mm or the Nag 31mm.

[alan potts]

With the scope you have which is almost the same as mine I cannot over egg the value of Ethos, though they are very expensive and with that I feel you would need a Paracorr.

However I have also used the Meade 8.8mm S5000 and I stress the old one not the one on the market now and it is a fine eyepiece, I feel the ExSc will be exactly the same and for me 82 degrees works very well indeed on a Dob.

I like to frame planets in a high power field ( Plossl and orthos) though i find on a Dob this is more difficult than knitting fog and again resort to poor old Ethos, these do make the job so much easier. I do use the narrower FOV eyepieces on my driven scopes though, but since the Nichol/Sumerian came alone the other scopes seem to be collecting dust, I think someone told me they would but I didn't believe them.

Alan

[gooseholla]

Some interesting responses. Thanks guys. On the one hand, I like my planets very much on their own at high power. I think it makes studying them easier, if not a bit frustrating having to move ever 30 seconds or so. But there is just something about DSOs that I think need sky and stars around them to really make them memorable. Perhaps the solution is something like an 82 degree or 100 degree for those and keep a smaller AFOV for planetary work. Who knows though, maybe I'd end up liking planets in a bit of a wider field of view.

I think the thing to do is start viewing objects in my 20mm and 15mm 82 AFOV eyepieces with a barlow to see what kind of images they produce then decide from there.

A lot to think about.

John

[estwing]

listen up brother of the truss...get the 8mm ethos, trust me its money well spent and is my second fave ethos... this ep just blows your mind in an 18" and when coupled with a powermate on Globs....forget messing around trying other ep's this is where you should be looking to expand your ep collection to.

[gooseholla]

listen up brother of the truss...get the 8mm ethos, trust me its money well spent and is my second fave ethos... this ep just blows your mind in an 18" and when coupled with a powermate on Globs....forget messing around trying other ep's this is where you should be looking to expand your ep collection to.

Maybe I'll have to look through some of these expensive eyepieces at SGL in March!

John

[faulksy]

realy do second what calv says, the great thing about the ethos is you dont have to keep nudging the dob, if you have good go to then yes a pentax xw would be my number one choice, but for a undriven scope the ethos is amazing close to ortho performance and a massive fov with good eye relief, wind up the power to 3-400x on a glob or pn and this is where things come to life rather thana grey blob. also you can reduce your ep collection and still cover all bases, its also easyer to view all night as you only need 3 or 4 ethosesss

[faulksy]

Maybe I'll have to look through some of these expensive eyepieces at SGL in March!

John

if its clear you wont

[estwing]

mate you know you're gonna be rockin up to us all weekend...might as well borrow what we've got so you know what to buy next....I mean, faulksy has still got my zoom from sgl

[gooseholla]

Yes... borrow...  

[Mike73]

Ethos has a big following on SGL, don't join the flock and be a sheep goose!!   I'II tell ya why.....

The human eye cant see 100˚ so you don't see the whole object in one go, you have to kinda look around. The problem with this is that as you look towards one edge you lose sight of the opposite edge, quite a lot of people who don't enjoy 100˚ say they have to move their head around just to see the field stops!! Imagine doing that all night!! 

Some people struggle with nudging a dob around, last night you were watching the Dumbbell at x230 with your little 8mm TMB, I can honestly say that you don't struggle with dob nudgers syndrome. 

Ethos are very good eyepieces, maybe not as good as Delos, XW, Nikon HW and Leica but they are nearly up there amongst them, just wait until you've had a chance to try before you buy. 

In the meantime the 12mm and 17mm Nagler T4's are still very good as are the ES 82˚ range, if you want to see the whole object in one look then both Delos and Pentax XW's are amazing!

Lots of choices....but John.....dont be a sheep!   

[Mak the Night]

Oh, I so want an 8mm Ethos! 

[John]

....The human eye cant see 100˚ so you don't see the whole object in one go, you have to kinda look around. The problem with this is that as you look towards one edge you lose sight of the opposite edge, quite a lot of people who don't enjoy 100˚ say they have to move their head around just to see the field stops!! Imagine doing that all night!! 

I must be odd then Mike - I can see the whole field of view of my Ethos eyepieces without any trouble at all. I just put my eye to the eyecup and there it is, field stop edge to field stop edge.

I can't say the same for other 100 degree eyepieces that I've tried and the 110 degree Myriads definitely needed some eye / head turning. Not the Ethos though. I'd have got rid of them PDQ if they were uncomfortable to use as I'm not rolling in cash but I really love using them and can put in a 3-4 hour session with them no problem at all 

I'd have got rid of them if their optical quality was not top notch as well - they are basically 100 degree Pentax XW's as far as I'm concerned (I've got a couple of those too).

But otherwise I agree - they are dreadful eyepieces

Baaa, Baaa !!!

NB: I'm just one person / sheep though. Definitely worth trying eyepieces if you can before committing - personal preferences in them can vary perhaps more than any other astro accessory !

[Piero]

I don't have ethoi, but I have 3 naglers plus powermate and all these options are medium-high power eyepieces.

I much prefer observing DSO with wide afov eyepieces because they let me see the target and its context. Swapping between eyepieces of very different afov is something I don't like because it makes me think about the eyepiece rather than the target. This is for me at least.

For very bright objects (surely the sun, but also the moon), I found I prefer simpler schemes and a 50 deg is all what I need. In these cases, I see less scatter light, more neutral colour and higher contrast.

Whether these simple high transmission eyepieces are better for faint galaxies as suggested in the site http://www.faintfuzzies.com/AboutUs2.htmlI don't know, as my telescope is too little for those targets.

As said above i think you should try these eyepieces, particularly ethoi, before buying them. They are expensive, but only you can tell whether they are worth for yourself.

Cheers,

Piero

[alan potts]

listen up brother of the truss...get the 8mm ethos, trust me its money well spent and is my second fave ethos... this ep just blows your mind in an 18" and when coupled with a powermate on Globs....forget messing around trying other ep's this is where you should be looking to expand your ep collection to.

I agree with Calvin, last time out i was going to uproot trees armed with a to do list. However I locked on the M13 and spent 2 hours looking at it with the 8mm, words fail me as to what it was like but Calvin and Steve (swampthing) have been telling me these things for as long as i have had the scope. I think it was Steve that told me the other scopes will collect dust.

[gooseholla]

Whether these simple high transmission eyepieces are better for faint galaxies as suggested in the site http://www.faintfuzzies.com/AboutUs2.htmlI don't know, as my telescope is too little for those targets.

That site makes interesting reading concerning eyepieces and DSOs. Thanks for bringing it to my attention.

Ethos has a big following on SGL, don't join the flock and be a sheep goose!!   I'II tell ya why.....

Baaahonk?!

listen up brother of the truss

Does this mean I am going to be initiated at SGL 11 by being forced to walk between two rows of people in a dob shroud being paddled by star atlases?!

[Davey-T]

Be bringing these with me John, you can try them all if you haven't splashed the cash before then, haven't got an 8mm but the 6mm is quite nice.

Dave

[Charic]

Nice line up.

[estwing]

I get near the 6E by power mating the 13E... But it looks a cracker

[gooseholla]

Well I tried using a 2x barlow on my Nagler 20mm and 15mm 80 degree eyepiece. It was actually quite nice to have a larger AFOV and made it easier to view. Whether it will be the same on a planet will remain to be seen.

Can't wait to look through some of these nice looking eyepieces in March!

John

[callisto]

Be bringing these with me John, you can try them all if you haven't splashed the cash before then, haven't got an 8mm but the 6mm is quite nice.

Dave

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