Meant to be Seen

I would vouch Ultraoptix due to fact that its Scratch Resistant and do not introduce fish eye distortion

http://www.ebay.com/itm/UltraOptix-Powe ... 0671586531

As low as 8$ a piece for 1.1/2" glass good enough big....50mm focal length.

Do post your results once you complete your project..if possible with display through image.
best of luck.

¡Thanks for your good wishes, and thank you for responding so quickly!. That's what I read. But DK1 screen is 7 inches and ideally a 5.6 inches screen as Palmer says, and my phones are 4.8 and 4 inches. For this reason I think Ultraoptix not give me a good FOV. I need someone who has tried ultraoptix 7x lenses give me your opinion on phones with small screens.

PD: ultraoptix 7x has 50 mm focal length? I thought it was less!

PD 2: Chinese lenses (like OpenLoop Lenses 30x21mm) hurt my eyes? damage my sight?

Off topic: lenses cost $ 8 each one and the shipping is $ 5, if I buy 2 lenses, I pay one shipping or pay 2 shipments? I mean, I pay $ 16 + $ 5 or $ 16 + $ 10.?

JoseM2S wrote:Off topic: lenses cost $ 8 each one and the shipping is $ 5, if I buy 2 lenses, I pay one shipping or pay 2 shipments? I mean, I pay $ 16 + $ 5 or $ 16 + $ 10.?

In my place if you buy two items from ebay's same shipper the shipping applies only of one item provided that shipper is in same country as you.
contact seller i hope he will help in favor.

JoseM2S wrote:PD 2: Chinese lenses (like OpenLoop Lenses 30x21mm) hurt my eyes? damage my sight?

Depend on time duration you are using it with. i would suggest 5 mins break after 20/30/40 mins (depending on your own preference) constant viewing with any lenses what so ever.

they generally have 40mm to 50mm focal length but i don't think lesser then that.

including aspherical lenses? I thought there was no harm to the vision according to OculusVR here: https://support.oculusvr.com/hc/en-us/a ... ended-use-

you're referring to the eye strain? because in that case it's normal when the computer is also used. In that case you would have to do as you say, use 20/30/40 minutes rest 5 minutes, and I would add use drops against dryness.

Not a bad idea,one must give some rest to eyes too

7x lenses have approximately : 250 mm / 7 = 35.7 mm focal length.
250 mm is the closest distance people can focus on an object (=punctum proximum)
Magnification = 250 mm / FL (in mm)
The smaller the display, the higher the magnification (i.e. the shorter the FL).
However, a limiting factor is the IPD. If the screen is too small, it will be difficult for each eye to observe one half of the screen.
That's why the ideal screen has a diagonal of 5.6, 5.7". In this case, the distance between the middle of each half is about 6.3 cm: that correspond to the average IPD.

@josem2s : you could try a 2 steps magnification:
1) magnify the whole screen with a Fresnel lens (plastic sheet). So that, you get a bigger screen, and the IPD is large enough.

2) magnify this image with convex lenses (one for each half).

Menas wrote:@josem2s : you could try a 2 steps magnification:
1) magnify the whole screen with a Fresnel lens (plastic sheet). So that, you get a bigger screen, and the IPD is large enough.

2) magnify this image with convex lenses (one for each half).

¡thanks for your answer Menas! I now understand the focal lenght but I understood your second post (and I'm sorry, my English is not very good). What magnification should be used for each phone? I remind you that I have an iPhone 5 (4 inches) and a Galaxy S3 (4.8 inches)

Could you specify the lenses should be used for each step? you help me with the names of the lenses or the link to buy.

Menas wrote:Magnification = 250 mm / FL (in mm)

It depends which formula the lens manufacturer is using though, they often use M = (25cm / FL) + 1 instead.

I think that's the case for the lenses in the DK1, they're advertised at 7X and have been measured at ~24 diopters by an optometrist.

That would give :
- 5X = 16D = 6.25cm
- 6X = 20D = 5cm
- 7X = 24D = 4.16cm
- 8X = 28D = 3.57cm
- 9X = 32D = 3.125cm
- 10X = 36D = 2.77cm

How does the eye's own focal length fit in the equation? I imagine the lens system should permit the eye to focus as though the image were some distance away. Perhaps that distance is the same as infinity. Does that equate to using a lens that has a focal length of the distance between the lens and the screen? What is the proper distance between the eye and the lens?

-Joe