Pimax 8kx: no clarity and sharpness in the far distance

Hey,
at first i was really dissapointed with the picture quality of my Pimax 8kx, but after playing around with the IPD adjustments for hours i found a setting which suits me mostly well.
I normally have an IPD of 65mm, but i get the most clarity with 60mm (!!!) and IPD offset adjustments similar as seen in the video of MRTV Pimax IPD Tutorial - So stellt ihr das IPD bei der Pimax 8KX richtig ein! - YouTube with focus on one Base Station 3m away, so that the virtual base station matches the real base station.
I have tried this setting now for hours, without headache or eyestrain yet.

I do just seated simracing with my pimax… the image is really sharp in the near (wheel, inside the car) and still good at cars directly in front of me, i would say about 20-30m. BUT when looking in the distance (30m +) the clarity and sharpness is very bad.

Does anybody know a way do adjust more clarity and sharpness in the distance? Or is it just “normal” for a Pimax 8kx this way?
Thank you very much!

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It’s possible that it’s an IPD issue, but it sounds like you’ve got it just about as good as it could get. Is it perhaps a resolution or rendering issue? I don’t play any racing sims, but I know they can be fairly demanding and make it difficult to reach an ideal level of supersampling.

I’m not really sure how to accomplish this, but a good test to see if it’s resolution or if it’s really a focal depth issue would be to render some text on the screen in a way that lets you move it further away from your face while increasing its size so that it stays the same number of pixels on the screen. It should stay the same sharpness unless there’s an issue with your lens adjustment. You can sort of do this with the menus in SteamVR, and I think BigScreen as well, by changing the menu distance, but I don’t know if those would get far enough away to demonstrate the issue.

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The focus plane is constant whether or not virtual objects are near or far. This is a limitation of current VR technology in general. It’s not really possible for distant virtual objects to be out of focus while near objects are in focus.

Objects which are farther away are smaller and made up of fewer pixels. So the limitations of resolution become more apparent than they are when the object is up close and large, and I suspect that’s what you’re experiencing.

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Resolution should not be the problem i think. It is set to 1.25 in pitool and 110% in steamvr.
The idea with the text is good :+1:t2:

And if i look at something (near or far) and slightly move my head - while still focus on the same object - the sharpness/clarity also changes. So the best clarity is not really exactly in the center. But for now no idea how to set it right, IPD 58mm would be better i think, but not possible :sweat_smile:

There are many possibilites, as intimated, What happens if you keep one eye closed?

(…which will A: Let you move HMD around to find the sweet spot for that one eye, alone, and B: Let the open eye focus without interferrence from your vergence-accomodation reflex.)

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The sweet spot on the 8KX is three dimensional. The shape of it is very roughly spherical, so if your eyes are closer or farther away than the ideal distance, the two dimensional (up/down, left/right) sweet spot becomes much smaller because it’s like a slice through a smaller and smaller portion of that sphere the farther you get away from its center. You get the effect you’re describing where you can have either one eye or the other in focus when looking at a virtual object in front of you, but not both.

The 8KX does not place the centers of the lenses (and thus sweet spots) directly in front of you. They are offset toward the peripheries in order to have more of the wide FOV in focus. And the idea is for the sweet spot to be large enough that looking straight ahead is still within the sweetspot for both eyes anyway.

But if the size of the sweetspot is diminished for you, it won’t be large enough to do this.

People set smaller than their real IPD in order to bring the lens centers closer inline with their eyes when looking forward. This sacrifices peripheral sharpness to try to get more forward sharpness.

What really needs to be adjusted, however, is the distance of your eyes from the lenses. And the only way to do this is to vary the thickness of the facial gasket padding.

You can try taking the facial gasket off entirely and just holding the headset in front of your eyes with your hands and see if you can find a distance where the sweet spot becomes much larger. You’ll generally find at this distance that peripheral distortions go away, too.

The challenge after that is to figure out how to adjust the thickness of the padding to get your eyes at the right distance when you’re wearing the headset normally. For me, the right distance is in between their 11mm and 15mm padding. So what I ended up doing is using the 11mm and then adding double sided velcro to make it effectively thicker up to what I need. You can also use this to make the shape of the gasket match the contours of your face better, too, while you’re at it.

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Have you changed “MaximumRecommendedResolution” in stettings, that is crazy software resolution limit in SteamVR?
If your game is SteamVR, then this is a must.

@BrziJoe i didn’t know about this yet… i found “MaximumRecommendedResolution” in this post How To Make Your Pimax Image/Picture/Screen Clear/Crisp (Increase Clarity) … is changing this setting still actual?

i’m only playing iracing (openxr) via steamvr … so is it then affected by the MaximumRecommendedResolution?

MaximumRecommendedResolution can also be adjustet in the Pimax Experience under Settings "Advanced"am i right? … is this the same setting?

I forgot where is it exactly, you have to search forum. It is hard to find right file. After that you need to restart steamvr.

The difference is obvious with bigger resolutions. You may try with Pimax Experience setting, I do not use it, so I do not know.
It is really mean from SteamVR developers to make that limit, it is ok for medium HMDs, but sure not for Pimaxes in big fov and top hardware.

yes, everything with steamvr

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Great, thank you… i will try this today and will report :wink:

@BrziJoe i changed the MaximumRecommendedResolution to 16384 (befor 8192) + gpuspeed to 5000 (before 2000) via the Pimax Experience (very easy to do under Advanced Settings).

And i have to say THANK YOU VERY MUCH, it’s a totally game changer for me, the clarity and sharpness especially in the distsance is much much better and the sweetspot is much much bigger. I’m running now on 1.0 in Pitool and 120% in steamVR, so a little bit lower than before + have to set AA samples to 4x from 8x ingame (iracing).

Maybe a little bit of fine tuning to do, but for now it’s a great image quality, i would say no real difference to my Reverb G2 + bigger sweetspot now.

I don’t unterstand why this is such a “hidden” feature!? Everybody just speaks about IPD adjustments (of course very very important too!) when you talk about clarity!?

But what i don’t really unterstand is the technical background of this… the resolution in steamVR - as i see it - stays the same as before, but the image quality is better !?

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Steamvr probbably force this limit to avoid rage of people which just put resolution to high.
Technitians make things “optimised” for valve index and not more.

I kicked many times steamvr limit, when trying games with fholgers openvrfsr, or his new version perfkit.
I usually upscale games with that tool, at least to 1.3 scale, and add high sharpening. You need to try that too :slight_smile:

On pimax, especially large fov, I was kicking that limit almost on all games. People mostly do not know that, and believe that steamvr shows correct value, but resolution is lower. I saw it in openvrfsr log.

And you are right, pimax should have that as second most important guide, just after installing pitool and dialing ipd in.