Eyepieces seem fiddly to look through properly?

[pipnina]

I don't know if it's just me, but I've noticed that even the medium-to-high quality EPs I have seem to be rather challenging to observe through.

For instance, my vixen SLV 10mm and stellalyra uwa 6mm both seem very hard to get a proper look through. I find as I get closer to the eyepiece, the field of view widens, but by the time I get close enough for it to widen to above say 40 degrees afov, the edges blacken as if I am now too close?

For my maxvision 24mm/82deg EP, I find it's quite hard to see the edge of the afov too, but I can definitely see much more of the afov in that EP despite not having as much eye relief as the 10mm and 6mm, it also lets me move my eye around much more than the other two, which seem very fussy about my eyes pointing straight forward all the time.

Could it just be that the small exit pupil makes them more challenging, the EPs genuinely aren't as good as I thought they were (mismatched expectations) or maybe the clouds have gotten me too far out of practice haha. 

 

Am I alone here with this struggle? I'm not a newbie by any means but I do seem to be struggling.

[doublevodka]

Not just you, I'm not a fan of the tighter eye relief on shorter focal length eyepieces, I mostly prefer to barlow where possible, so instead of a 10 I'll use a 20mm and a 2x barlow, just find it suits me better.

I bought an 8mm BST because they are highly rated on here, but prefer a barlow and a basic 20mm plossl, although the seeing has been rubbish for months where I am so jury is still out a little as it's slightly more magnification

[pipnina]

10 minutes ago, doublevodka said:

Not just you, I'm not a fan of the tighter eye relief on shorter focal length eyepieces, I mostly prefer to barlow where possible, so instead of a 10 I'll use a 20mm and a 2x barlow, just find it suits me better.

I bought an 8mm BST because they are highly rated on here, but prefer a barlow and a basic 20mm plossl, although the seeing has been rubbish for months where I am so jury is still out a little as it's slightly more magnification

Thing is, my 24mm I think has LESS relief than my shorter EPs! Both the Vixen SLV and Stellalyra UWA have 20mm whereas I think the maxvision is around 17 or 18. Yet the shorter lengths feel harder to use somehow.

[vlaiv]

28 minutes ago, pipnina said:

For instance, my vixen SLV 10mm and stellalyra uwa 6mm both seem very hard to get a proper look through. I find as I get closer to the eyepiece, the field of view widens, but by the time I get close enough for it to widen to above say 40 degrees afov, the edges blacken as if I am now too close?

This is quite interesting.

If you are far away - you will only see center of the field of view - and this is normal because "pencils of light" diverge after they form an exit pupil:

In above diagram - if you place your eye too far away - red and blue "pencils" will miss your iris and you won't see that part of the FOV. You will only see green.

There is one place where all pencils intersect - this is where you should place your eye and you will see whole FOV without any blackening. Be careful not to mistake field stop which is the edge of the field with blackening of the edge of the field.

If you push your eye too much while having long eye relief - you will start to see similar thing - edges of the field will again blacken. This is again because in above diagram blue and red pencils can't enter your eye.

Slowly moving your eye towards the eye lens will let you hit the sweet spot - where you can see entire AFOV without any blackening. Long eye relief eyepieces often have eye guard that you can adjust for height. This is very handy so you can move it to represent correct eye placement height.

If you never hit the sweet spot - that is very strange, but in principle can happen with eyepieces that have SEAP and very big exit pupil while your iris is very contracted.

[vlaiv]

Maybe best way to practice looking thru the eyepiece is actually during daytime with eyepiece only.

Take your eyepiece and hold it against white wall or sky or some bright uniform surface. Whole FOV will simply be uniform white (or that other color like pale blue or whatever). You easily adjust distance by moving eyepiece in your hand rather than your head - which can stay put for this.

This will give you sense of best placement - one that presents whole FOV and there is no blackening of any sorts. Each EP will behave differently so you can sort of practice this way and get muscle memory to how should each eyepiece feel.

Most telescopes will keep exit pupil roughly in the same place - but some scopes will move it. I have some issues with my Mak102 and 32mm plossl - eye relief is just too long in this combination. That 32mm Plossl is otherwise extremely forgiving and comfortable EP to use in other scopes.

[doublevodka]

16 minutes ago, pipnina said:

Thing is, my 24mm I think has LESS relief than my shorter EPs! Both the Vixen SLV and Stellalyra UWA have 20mm whereas I think the maxvision is around 17 or 18. Yet the shorter lengths feel harder to use somehow.

Hard to say as I've not used those eyepieces but I think @vlaiv has made some good points there in regards to the sweet spot, certainly worth a go.

My personal favourite in my small collection is an eyepiece salvaged from a broken pair of 10x50 binos, it's the least fussy and has worked fine in all of my scopes, took the idea from here - https://www.facebook.com/groups/1484777181687589/

 

[Franklin]

On 06/01/2023 at 12:08, pipnina said:

my vixen SLV 10mm and stellalyra uwa 6mm both seem very hard to get a proper look through.

The Vixen SLV range, as you say, have 20mm of ER and are considered very easy on the eye. Have you tried extending the screw-up eye cup? Compared to more traditional eyepiece designs like Plossls and Orthoscopics, the SLV range should be much easier to look through. They were for me and I had the whole set, even the very short 2.5mm was very usable.

[bosun21]

I appear to be quite lucky in this respect, as regardless of the eye relief I simply move my eye in or out to obtain the full FOV. Using your scope during the day fixed on a distant target let’s you achieve the optimum distance for your eye to hit the sweet spot easier. After repetition with your eyepiece collection it becomes second nature. HTH

Edited January 8, 2023 by bosun21
Typo

[Mr Spock]

With SLVs I have the eye cup all the way up and put my eye into it. That way I can see the whole fov and the field stop is sharp.

[markse68]

On 06/01/2023 at 12:47, vlaiv said:

Maybe best way to practice looking thru the eyepiece is actually during daytime with eyepiece only.

I was most disappointed when i first got my Nagler 16mm doing this. Could it be because pupils smaller in daylight? But I really struggled with it to get the whole view whilst holding it up to a bright light- blackouts galore! What a relief when i tried it for proper in my scope- it’s a lovely comfortable ep to use with no issue at all.

Mark

[vlaiv]

27 minutes ago, markse68 said:

I was most disappointed when i first got my Nagler 16mm doing this. Could it be because pupils smaller in daylight? But I really struggled with it to get the whole view whilst holding it up to a bright light- blackouts galore! What a relief when i tried it for proper in my scope- it’s a lovely comfortable ep to use with no issue at all.

Mark

That is quite interesting.

Never encountered something like that. Maybe it is indeed down to size of pupil. It will certainly be smaller during the day and SEAP does depend on size of pupil.