Cross eyed after use


#41

Hi,

I’ve never really found much difference between versions. I always use pimax IPD 55-57, my real IPD is 68. I find that IPD 55 in pimax gives me even better results than 57 but I also find this gives me much more eye strain, that’s why i use 57, it’s the first acceptable IPD. I don’t wear glasses and my eyes are perfectly normal.

I think the problem arises when people have high real IPD, higher than 62. My theory is that because the Pimax has a hardware IPD of about 62 (the distances between the 2 lense cores), that people with higher IPD’s need to have their eyes look inward. The point where the lines of their eyes then meets the screen is even further inward (‘cross eyed’). So the higher real IPD one has (above 62) the lower the Pimax IPD will be. At least, that’s my theory and I think it’s about right because when I use my Homido lenses and use hardware IPD of about 68, then also my Pimax IPD goes to about 68.

So in short, I think this problem is caused by the fact that the Pimax does not have hardware IPD. I really hope the pimax 8k has hardware IPD, it would be a HUGE bummer if it hasnt …


#42

I’m certainly no expert but that makes a lot of sense. But I wonder if Pimax chose the fixed lenses because they thought they could work this problem out in software or that they completely underestimated how they had to make a working lens system for all possible customers. It sounds like they just didn’t think this through. I can only think of a software solution that properly warps the image to accompany a different view angle through the lenses. Which would not be easy but might solve the issue?


#43

Its a fairly common practised of late with soft ipd.

GearVR, E3, PSVR & more.

The idea there using is a sweet spot around average ipd. The trouble of course comes to individuals drasticly outside the comfort zone. Too wide cross eyed effect; to narrow & you get bug eyes.

From what i’ve read soft ipd is better when coupled with some physical adjustment.


#44

I don’t think I will buy a headset again with soft IPD. Even my simple Homido cardboard viewer has hardware IPD. Reallly hoping Pimax will enable hardware IPD for their Pimax 8k.


#45

Your homido like most Cardboard headsets have the hardware ipd & focus adjustment due to i would imagine to accommodate different phone sizes & such.

But yeah its another miss on many hmd manufacturers like the Camera in headset.

All headsets should have physical ipd adjustment with soft ipd as a way to fine tune it.


#46

Sorry, I am a laser based diagnostics professor and get long-winded.

TLDR; If your actual IPD is significantly different than the Pimax 4K mechanical IPD, then the software IPD must be set excessively high or low. This will make you feel like you have lazy eye or crossed eyes when you take the set off. Also, it will cause the image to be blurry in some areas and sharp in others.

Having just purchased a Pimax 4K I can verify the cross-eyed effect after wearing for a while, as well as an off actual IPD value needed to get a semi focussed image. The problem is that there is a geometric increase in the offset needed in the soft IPD versus the physical center-to-center of the lenses. Ideally the mechanical c2c would be equal or just slightly less than the human IPD and the image centers on the halves of the LCD would be in line with the ray determined by the two.
In the VR set the problem with the fixed mechanical c2c is that our eye needs to look through the lens focal center to get a focussed image. If IPD is close to the c2c then everything works fine and the image is in focus over the entire field of view. If the IPD is bigger than the c2c, then the sharp image is only attainable when the soft IPD is set smaller than the c2c, so that you focus through the focal center of the lens. The image will not be sharp elsewhere.
Our eyes become crossed as we focus nearer to our face, and the brain will work hard to ensure alignment and focus. In effect, we are holding an image too close to our face and need to cross our eyes so that the retinal image contains enough overlapping information to construct an image. If we stay that way for a while, the brain image processing sets that as normal and when we look out the window we get double images until the brain recalibrates the eye muscles and image processing. Pretty cool, but terrible for your eyesight.


#47

Makes sense. Thank you.

Personally i think that there must be additionally another reason for my eye-demanding pimax 4k-experience because

  1. with other headsets like dk2, which has also no hardware-ipd i have clear, relaxed vision. Even with only software-ipd setting.
  2. only some of the pimax customers experience this problem.

So my guess would be: angled lenses because of shitty assembling?

And to be precise you have to take into account that all lenses do bend the individual colors differently which results in blue/yellow “banding” problem (like on the old rgb projector tv which had problems with the color alignment) the more you look at the edges of the lens. So, yes, you maybe see clear, but the image colors are off. Pretty obvious when trying to read white text off the center of the lens.


#48

No it’s really the IPD. I’ve modded my headset and now have perfect relaxed vision. See: Hardware IPD mod


#49

@mr.uu
Do you know what the center-to-center distance on the DK2 was? It would be interesting to see if it was closer to your physical IPD.
Angled lenses could well cause problems and eye fatigue as your brain flips repeatedly between eyes to focus.
@sjefdeklerk
Damnit, my girlfriend just gave me these for my birthday and already I am thinking of ripping into them thanks to you. If I lose a cool girlfriend because of you, I will never buy you a beer. But. . . it might be worth it to not feel like I have been flicked in the eye for half an hour.


#50

Haha. Keep in mind though that it’s not perfect, because if you move the lenses outside, you’ll move them beyond the display edges, so you’ll see vertical black parts at the edges. However I feel it’s a good price to pay for having much more relaxed vision.


#51

As far as i remember 64mm. But next time i measure it.
My measured ipd is 69.5.

Anyone with a wmr headset with only soft-ipd setting possible and higher ipd? Your experience?


#52

Sjef, you cool. Haha. I don’t have the time to persue any of my ideas but then again, I don’t have to because you already did it AND documented it 3 months earlier


#53

I would recommend to test cheap reading glasses with +1 or +1.5 correction. Those and software IPD set to your real one could help the situation.


#54

How are those supposed to help? I don’t think reading glasses force the line of sight to be more cross-eyed? Maybe if you bend the glasses though so that they force the line of sight to be cross eyed, someone did this I remember and he said it fixed the situation too.


#55

Sj if ypu recall that fellow used metal reading glasses & bend them inward (i believe) which would. The lens being angled redirects your eyes inward without “crossing eyes”.


#56

Yes that’s exactly my point. He said it worked and it makes a lot of sense. But just reading glasses without bending them, I don’t see how that would work.


#57

True enough unless his ipd isn’t that far out? Maybe the reading glasses helps this out to a small degree?


#58

Well … I could ask that why I do not need reading glasses and can set correct IPD with Windows MR headset, which also have fixed lenses. So far I have not noticed any complaints about those causing cross eye issues :wink:

Since I am not professional on this area it is better that I do not offer theories - rather just rely on own experience. I’ll be testing this setup with Project cars 2 and Elite and so far it is looking promising. I have not taken long session yet (>1hour), so outcome may still change.

Anyways I do not think it is a huge investment to test this workaround - I used glasses that cost 10eur.


#59

Too bad you don’t have Dollar like stores. :beers::sunglasses::+1::sparkles: