OVL Nirvana 16mm EP - kidney beaning

[Pixies]

Hi everyone.

Following on from a post by @Pitch Black Skies, who appears to suffer from the same issue, I thought I'd mention this to you all and see whether it's a known problem or something to do with the way we are using them. Normally, these EPs get great reviews.

With 82 deg FOV, this is the widest 1.25" eyepiece I have. However, in order to see the field stop, I need to get my eye pretty close in, and as I move my eye around to view the wide field, I suffer from blackouts/kidney beaning. If I want to look from one edge to the opposite side, I can't just move my eyeball, I need to lift my head away slightly as my centre of vision approaches the midpoint. Does that make sense? It's like the eye relief is a curved plane.

Is this just my limited experience with wide FOV EPs or a lack of technique on my part? I was looking forward to the "porthole in space" experience, but the above means that I can't easily take in the whole field. I feel like I might as well just use a lower powered 70deg EP. 

I was listening to the recent Actual Astronomy podcast, where they mention that these blackouts can be related to the scope too. I.e., the aperture/speed of the scope has an effect and that an EP can suffer really badly in one type of scope but be fine in another. @Pitch Black Skiesis using an 8" F6 dob too. Perhaps I should test it out in my little ST80. However, I do notice it too when just holding the EP up to my eye in daylight.

[Louis D]

You can't pivot your eyeball to take in the edges without rotating your head as well or you'll lose the exit pupil.  Think about it.  Does your eyeball pivot about an axis through your cornea?  No, it pivots about an axis roughly through the middle of your entire eyeball.  Thus, your entrance pupil swings from side to side necessitating that you move your whole head to keep it centered above the eyepiece.

Kidney-beaning or SAEP makes it impossible to see the entire field at once regardless of eye position unless you have an enormous entrance pupil (dilated iris).

See the below post by @Ruud which does a good job explaining the different types of blackout:

 

[Pitch Black Skies]

52 minutes ago, Louis D said:

You can't pivot your eyeball to take in the edges without rotating your head as well or you'll lose the exit pupil.  Think about it.  Does your eyeball pivot about an axis through your cornea?  No, it pivots about an axis roughly through the middle of your entire eyeball.  Thus, your entrance pupil swings from side to side necessitating that you move your whole head to keep it centered above the eyepiece.

Kidney-beaning or SAEP makes it impossible to see the entire field at once regardless of eye position unless you have an enormous entrance pupil (dilated iris).

See the below post by @Ruud which does a good job explaining the different types of blackout:

 

Thanks to Pixies for the mention.

So basically Louis, you cannot ever see the whole field of view with UWA eyepieces, that's what gives them the immersive effect. You have to move your head about in order to take in the areas not directly in sight. Is that correct?

I was practicing this to be fair but still found it quite difficult with that big black kidney bean flopping all over the place. Not the most pleasurable experience.

I'm sure it's probably going to take practice on my part. It probably doesn't help that I was testing in on the moon too 😳😆. My pupils were surely not dilated enough. I think I'll give it another chance before asking to return it. It's probably a cracking eyepiece and I'm just using it wrong.

[Pixies]

1 hour ago, Louis D said:

You can't pivot your eyeball to take in the edges without rotating your head as well or you'll lose the exit pupil.  Think about it.  Does your eyeball pivot about an axis through your cornea?  No, it pivots about an axis roughly through the middle of your entire eyeball.  Thus, your entrance pupil swings from side to side necessitating that you move your whole head to keep it centered above the eyepiece.

Kidney-beaning or SAEP makes it impossible to see the entire field at once regardless of eye position unless you have an enormous entrance pupil (dilated iris).

See the below post by @Ruud which does a good job explaining the different types of blackout:

 

Many thanks, your post and that link explains it very well. 

I think that perhaps my expectation was higher than was is possible, then.  I was hoping for a more 'immersive' view. This 'porthole' onto space analogy is true, I guess - just that it's a small porthole that you've got your face pressed up against!

Just tried again in daylight with the little ST80 - and I can see what you mean. Moving my head lets me see the whole field, just not all at once. I was busy burying my head into the eyecup so that the field-stop was visible in all directions.

I'll try and live with it a bit more and see whether my experience improves. I'm sure there are more expensive EPs that are easier to use.

 

Thanks again, @Louis D

[Louis D]

36 minutes ago, Pitch Black Skies said:

So basically Louis, you cannot ever see the whole field of view with UWA eyepieces, that's what gives them the immersive effect.

You can, but you have to expand your area of concentration from your central vision to include your peripheral vision.  Think of it like when you're driving.  You can only read signs if you look straight at them, but you can see cars entering the road from the right or left, just not at high resolution without moving your gaze.

[ScouseSpaceCadet]

Tbh I've not noticed kidney beaning with my 16mm Nirvana. It's been used with the now sold 150p plus the current Skymax 102 and 102ED. In fact it's one of my favourite & most used eyepieces, as is the 7mm. I did have quite intrusive vignetting issues with the 4mm Nirvana and 150p though.

Edited April 29, 2021 by ScouseSpaceCadet

[Pitch Black Skies]

Just a quick update.

I tested it again last night and have to say it was much better. The moon was down this time.

I know magnification probably plays a part but the contrast in the Nirvana compared to the 25mm MA was stark. The sky was almost pitch black through the Nirvana, the Leo Trio, M81 & M82 as well as M51 looked nice.

Edited April 30, 2021 by Pitch Black Skies
Typo

[Pixies]

On 29/04/2021 at 21:33, Pitch Black Skies said:

Just a quick update.

I tested it again last night and have to say it much. The moon was down this time.

I know magnification probably plays a part but the contrast in the Nirvana compared to the 25mm MA was stark. The sky was almost pitch black through the Nirvana, the Leo Trio, M81 & M82 as well as M51 looked nice.

The subject of 'contrast'/visibility and eyepiece magnification (or primarily the exit-pupil) is covered in this interesting thread from near the end of page 2: 

 

[Stardaze]

Only just stumbled across this thread. Interesting link above but my own experiences of ultra wide follow similar. I have found some EP's take me a while to acclimatise to and funnily enough the least widest I own, XW 5, is the most difficult for eye placement where I do get black outs depending. The eye cup seems to affect where I want to be (noting that the Pentax eye relief is a much more solid type than all of my others) and I find myself hovering, or lightly resting, with that EP instead of nestling it into the socket as per my 100 degree EP's, even though the cup is as far raised as possible. I seem to have acclimatised best to my two APM 100 degree EP's but you do have to roll your head around to take them all in. I use the 13 and 20 for so much of my viewing that when I use something else, it can take a little time to readjust, but that's just my own time served that I think that's due to. 

[Pitch Black Skies]

So I've just compared the 16mm Nirvana to a 15mm Starguider that I have just received and can confirm that the latter is much more pleasant, at least on my eyes anyway. 🙂

Edited May 5, 2021 by Pitch Black Skies
Typo

[Pixies]

20 minutes ago, Pitch Black Skies said:

So I've just compared the 16mm Nirvana to a 15mm Starguider that I have just received and can confirm that the latter is much more pleasant, at least on my eyes anyway. 🙂

The Starguiders are only 60deg FOV though, aren't they?

I admit that I find them very comfortable to use compared to the wider 80deg Nirvana. That's probably down to my lack of experience with such wide field EPs. My only other wide-field is the more modestly angled 68deg 2" Aero EDs. Which again is just a case of stick your eye in and look around.

Anyone reading this familiar with both the Nirvanas and the ES 82 deg EPs? How do they compare?

[Stardaze]

40 minutes ago, Pixies said:

The Starguiders are only 60deg FOV though, aren't they?

I admit that I find them very comfortable to use compared to the wider 80deg Nirvana. That's probably down to my lack of experience with such wide field EPs. My only other wide-field is the more modestly angled 68deg 2" Aero EDs. Which again is just a case of stick your eye in and look around.

Anyone reading this familiar with both the Nirvanas and the ES 82 deg EPs? How do they compare?

Interestingly I had an ES 24, and still do have an ES 6.7 82 deg but, the bit I'm not so keen on is the eye cup. For me, it's a bit too flimsy as I like to lean into them, it just folds up under a little pressure and isn't very long anyway. As far as eye placement is concerned, haven't personally noted anything detrimental. Maybe someone with more experience is better placed to comment. 

[ScouseSpaceCadet]

3 hours ago, Pitch Black Skies said:

So I've just compared the 16mm Nirvana to a 15mm Starguider that I have just received and can confirm that the latter is much more pleasant, at least on my eyes anyway. 🙂

Individuals vary so much. I got rid of my BST 15mm and kept the 16mm Nirvana... 🙄

[Stardaze]

3 hours ago, ScouseSpaceCadet said:

Individuals vary so much. I got rid of my BST 15mm and kept the 16mm Nirvana... 🙄

And do you think that there's something in the eye relief design, where preference is concerned? The likes of ES and TV are a softer cup; Pentax and BST are a very solid design with no flex; OVL/Morpheus/APM all have a similar 'middle of the road' in terms of stiffness than the other two? Length aside, I wonder whether it affects eye placement in general? All that said, acknowledging Louis’ post on kidney beaning, it looks like many models are affected to a degree regardless of brand/cost, some of those pictures posted looked very slight, which some people may detect more than others? I definitely had issues with blackouts the first couple of times using the XW 5, took a while to get used to that EP.

Edited May 5, 2021 by Stardaze

[ScouseSpaceCadet]

Stardaze I really don't know. I like BST eps. For the money all the focal lengths I've owned have presented me with a decent image and they're comfortable to use. I just felt the Nirvana 16mm had better contrast, was a bit tighter to the edge and obviously a wider fov so saw no reason to keep the 15mm BST.

Regarding eye cups, the only eyepiece I've not liked purely based on comfort/eye positioning, was the 2" 30mm Vixen NVLW. A stonking ep absolutely great with 120mm f5 refractor, but the eye cup was horrible.

[Pitch Black Skies]

4 hours ago, Pixies said:

The Starguiders are only 60deg FOV though, aren't they?

I admit that I find them very comfortable to use compared to the wider 80deg Nirvana. That's probably down to my lack of experience with such wide field EPs. My only other wide-field is the more modestly angled 68deg 2" Aero EDs. Which again is just a case of stick your eye in and look around.

Anyone reading this familiar with both the Nirvanas and the ES 82 deg EPs? How do they compare?

That's right 60° FOV, much more pleasing to my eyes.

[John]

Ultra-wide (80+ degrees) and Hyper-wide (90+ degrees) eyepieces do take a bit of getting used to I've found. If you wear glasses when observing the 60 - 76 degree ranges are likely to be more comfortable because their eye relief is usually longer than the wider eyepieces.

I used to have a Nirvana 16mm which I quite liked but mine had a different eye cup design to the current version:

With the above design the eye cup twists up and down. Maybe the newer design with the folding rubber eyecup (I assume it folds ?) combined with 12mm of eye relief (not all of which is usable) does not help eye positioning ease ?

 

 

[Pitch Black Skies]

28 minutes ago, Stardaze said:

And do you think that there's something in the eye relief design, where preference is concerned? The likes of ES and TV are a softer cup; Pentax and BST are a very solid design with no flex; OVL/Morpheus/APM all have a similar 'middle of the road' in terms of stiffness than the other two? Length aside, I wonder whether it effects eye placement in general? All that said, acknowledging Jerry's post on kidney beaning, it looks like many models are affected to a degree regardless of brand/cost, some of those pictures posted looked very slight, which some people may detect more than others? I definitely had issues with blackouts the first couple of times using the XW 5, took a while to get used to that EP.

It's funny you mention that because on the 16mm Nirvana I wasn't able to rest my eye socket on the fully raised eye cup at all without having problems. It had to hover a millimetre or two over it to be usable and even then, that was excessively restricting the FOV.

In regards to the solid eye cup design with the BST, I can find the right eye relief distance, twist the cup up to it, and then just rest my face on it with as much pressure as I want and it doesn't budge.

On the other hand, I do have a 32mm Panaview 70° which has the soft cup and it's nice to use.

[Pitch Black Skies]

5 minutes ago, Pitch Black Skies said:

It's funny you mention that because on the 16mm Nirvana I wasn't able to rest my eye socket on the fully raised eye cup at all without having the kidney beaning problems. It had to hover a millimetre or two over it to be usable and even then, that was excessively restricting the FOV.

In regards to the solid eye cup design with the BST, I can find the right eye relief distance, twist the cup up to it, and then just rest my face on it with as much pressure as I want and it doesn't budge.

On the other hand, I do have a 32mm Panaview 70° which has the soft cup and it's nice to use.

 

Edited May 5, 2021 by Pitch Black Skies
I'm not sure what happened there.. I tried to edit the previous post and instead it duplicated with the edit.

[Don Pensack]

8 hours ago, Stardaze said:

Only just stumbled across this thread. Interesting link above but my own experiences of ultra wide follow similar. I have found some EP's take me a while to acclimatise to and funnily enough the least widest I own, XW 5, is the most difficult for eye placement where I do get black outs depending. The eye cup seems to affect where I want to be (noting that the Pentax eye relief is a much more solid type than all of my others) and I find myself hovering, or lightly resting, with that EP instead of nestling it into the socket as per my 100 degree EP's, even though the cup is as far raised as possible. I seem to have acclimatised best to my two APM 100 degree EP's but you do have to roll your head around to take them all in. I use the 13 and 20 for so much of my viewing that when I use something else, it can take a little time to readjust, but that's just my own time served that I think that's due to. 

Just a note: to adjust to a new experience, or, in this case, eyepiece, one acclimates to the eyepiece, with the spoken accent on the first syllable.

When one ascends a mountain and has to get used to the altitude, or one steps out of an air-conditioned house to a hot outdoors, one acclimatizes (or acclimatises in British English) to the new conditions, with the accent on the second syllable.

I only mention this because you used it incorrectly twice in your post.

Not that this is an egregious error, of course.

[Stardaze]

16 minutes ago, Don Pensack said:

Just a note: to adjust to a new experience, or, in this case, eyepiece, one acclimates to the eyepiece, with the spoken accent on the first syllable.

When one ascends a mountain and has to get used to the altitude, or one steps out of an air-conditioned house to a hot outdoors, one acclimatizes (or acclimatises in British English) to the new conditions, with the accent on the second syllable.

I only mention this because you used it incorrectly twice in your post.

Not that this is an egregious error, of course.

Noted sir 😉

[Louis D]

27 minutes ago, John said:

Ultra-wide (80+ degrees) and Hyper-wide (90+ degrees) eyepieces do take a bit of getting used to I've found.

The ES-92s were pretty easy for me to get used to.  I never got on with the 17mm or 12mm Nagler T4s very well.  It turns out the latter two have strong SAEP.  The 22mm NT4 is pretty decent to use.

I'm wondering if the 16mm Nirvana has undiagnosed SAEP.  It makes the field of view all but impossible to hold once the field stop pops into view.

[John]

4 minutes ago, Louis D said:

The ES-92s were pretty easy for me to get used to.  I never got on with the 17mm or 12mm Nagler T4s very well.  It turns out the latter two have strong SAEP.  The 22mm NT4 is pretty decent to use.

I'm wondering if the 16mm Nirvana has undiagnosed SAEP.  It makes the field of view all but impossible to hold once the field stop pops into view.

I'm still learning how to make the best of the 17mm ES 92. The 12mm I just could not get on with so I let that one go. I had the 22mm T4 Nagler many years back and liked that one.

As we so often say on here (including earlier in this very thread) eyepiece preferences are a very personal thing. What works wonderfully for one person may well be just not suit another at all.

 

[Stardaze]

2 hours ago, Pitch Black Skies said:

It's funny you mention that because on the 16mm Nirvana I wasn't able to rest my eye socket on the fully raised eye cup at all without having problems. It had to hover a millimetre or two over it to be usable and even then, that was excessively restricting the FOV.

In regards to the solid eye cup design with the BST, I can find the right eye relief distance, twist the cup up to it, and then just rest my face on it with as much pressure as I want and it doesn't budge.

On the other hand, I do have a 32mm Panaview 70° which has the soft cup and it's nice to use.

I actually didn’t like the solid cup of the BST and wonder whether there’s a correlation there for me with the XW, maybe I prefer a cup with a medium stiffness? I do find the ES cup too soft. It doesn’t bother me so much with the 6.7 as you tend to be very tight to the lens with longer focal lengths and don’t nestle into the eye socket. There’s definitely some preference for different folks.

Edited May 5, 2021 by Stardaze

[Stardaze]

2 hours ago, John said:

I'm still learning how to make the best of the 17mm ES 92. The 12mm I just could not get on with so I let that one go. I had the 22mm T4 Nagler many years back and liked that one.

As we so often say on here (including earlier in this very thread) eyepiece preferences are a very personal thing. What works wonderfully for one person may well be just not suit another at all.

 

The 22T4 Nagler is held in very high regard I understand John, yet noted that @Louis Dfound there to be some kidney beaning evident in that model too. Was it something you noticed yourself?

Apologies to the OP for slightly veering away from the EP under debate, but it’s interesting that even some high-end EP’s seem prone to this too.