Eye strains when reading on my Kobo

[Katsunami]

What I haven't seen in this thread (but I didn't read ALL the replies to be honest) is that the e-reader itself could be the problem.

Is it at all possible for an e-reader to have a screen that is not sharp, somehow?

In photography, the focusing system of a lens could be off by a (fraction of) a millimeter, which would cause your pictures to be unsharp; and you can't fix that in any way except having the lens adjusted.

[bastringue777]

Originally Posted by DNSB

The last time I was browsing through a battery manufacturer's website, their published test results showed their lithium-ion batteries were good for ~650 full charge cycles before the battery capacity dropped to 70% of the original capacity (there are dependencies on environmental conditions such as temperature and very bad ideas such as overcharging). One of the chart showed the life cycle for various depths of discharge which basically showed that shallower discharges allowed more discharge/charge cycles (a 50% charge cycle giving about 2400 cycles). So if you read enough each day to result in 50% battery use and plug your ereader into a charger when you go to bed you should get around 6 years before the battery reaches EOL.

Wow those are nice stats! Do you have a link to suggest so I can read more about that? Is it the same for all lithium-ion batteries? Very nice. So if I get it right, I could charge it every night and would still have 50% battery after 6 and a half year (2400/365)? Seems really good.

[bastringue777]

I've read at some places that usually a lithium-ion battery can last between 300-500 cycles for 2-3 years... Some sources, like this one: https://www.newark.com/pdfs/techarti...onix/LIBMG.pdf

Not bad, but I'd hate to replace my Kobo after 2-3 years.

[HLS]

It's not the reader it's your eyes probably. You may need reading glasses. Sometimes you do not realize you need it till you try it. I would try getting a cheap pair at Walmart. I can't read without mine. I have the same device and have no strain when using my reading glasses

[leftright]

Reading at greater than arms length my vision is perfect, unfortunately my body hasn't learnt to lengthen my arms to suit my eyesight so I have to use +1 glasses, with glasses I've discovered that my eyesight various considerably.

In low ambient light my near vision is blurry irrespective of object brightness.
If I'm lying in bed face up with glasses text appears smaller. (dark room). If I read on my side with glasses text appears larger.
In bright sunlight my near vision is perfect. (no glasses).
My near vision is good with a hangover. no glasses required.

[DNSB]

Originally Posted by bastringue777

Wow those are nice stats! Do you have a link to suggest so I can read more about that? Is it the same for all lithium-ion batteries? Very nice. So if I get it right, I could charge it every night and would still have 50% battery after 6 and a half year (2400/365)? Seems really good.

I'm not sure which site I was looking at when I jotted those numbers down during a project looking at replacement battery information. If you look at the BatteryUniversity site, they have fairly similar numbers. Check BU-808: How to Prolong Lithium-based Batteries for some information.

And no, the lifespan won't be that good since Li-Ion batteries will gradually deteriorate even if stored at 50% charge/20°C but with moderate care, you should be well over the 3 year mark before the battery deterioration becomes an issue.

Oddly quite a bit of the improvement in Li-Ion batteries has been driven by EVs. For some strange reason, being told that you will need to replace your battery in a few years for $5000-$7000 doesn't go over well with the purchasers. Who woulda thought! BTW, that price is for a Tesla 3 which does come with a 8 year battery warranty.

BTW, if you drive an EV in West Virginia—West Virginia State Energy Profile—you are responsible for more CO2 being added to the atmosphere than a new gasoline vehicle. Not to mention the radioactivity—check a Scientific American article from 2007 ( Coal Ash Is More Radioactive Than Nuclear Waste ).
TriviaЯUs

[4691mls]

Originally Posted by Katsunami

What I haven't seen in this thread (but I didn't read ALL the replies to be honest) is that the e-reader itself could be the problem.

Is it at all possible for an e-reader to have a screen that is not sharp, somehow?

In photography, the focusing system of a lens could be off by a (fraction of) a millimeter, which would cause your pictures to be unsharp; and you can't fix that in any way except having the lens adjusted.

A couple of us questioned whether the possibility that the reader could be defective but this idea didn't seem to gain traction. Maybe it's unlikely? I'm certainly not a tech expert.

I suppose the OP could try borrowing a different e-ink reader from a friend and see if he experiences the same problems on a different device.

[DNSB]

Originally Posted by 4691mls

A couple of us questioned whether the possibility that the reader could be defective but this idea didn't seem to gain traction. Maybe it's unlikely? I'm certainly not a tech expert.

I suppose the OP could try borrowing a different e-ink reader from a friend and see if he experiences the same problems on a different device.

There is no focusing system in a eInk panel. It's possible there are issues with the various overlays over the capsules (manufacturing defect, overly high temperatures, etc.) but that is fairly unlikely. I'd expect to see blotches on the screen as a more likely result of such defect or damage.

[pdurrant]

Originally Posted by HLS

It's not the reader it's your eyes probably.

I must agree with HLS. You mentioned that you were 40. That's when many people start to notice it, although most don't need reading glasses until they're 45 or so.

However, if you have an undiagnosed small amount of long sightedness, that'll cause you to need reading glasses earlier.

Get a pair of cheap generic brand +2.00 reading glasses. If you find they make reading easier for you, it will be worth getting your eyes tested and getting a custom pair for your exact prescription. And possibly even a distance pair as well. (Well, once you can visit an optician again.)

Presbyopia only continues to worsen with age. By the age of 50, everyone needs reading glasses. Except those of us who are short sighted and have worn glasses most of our lives. We get to just take off our glasses to read.

[meeera]

Originally Posted by leftright

In low ambient light my near vision is blurry irrespective of object brightness.
If I'm lying in bed face up with glasses text appears smaller. (dark room). If I read on my side with glasses text appears larger.
In bright sunlight my near vision is perfect. (no glasses).
My near vision is good with a hangover. no glasses required.

Have you had a recent diabetes test? A primary feature of a hangover is hypoglycaemia. Swings in blood sugar can cause the lens to swell and shrink, even in the short term. I'd get a full eye checkup and a full general medical.

[pdurrant]

Originally Posted by meeera

Have you had a recent diabetes test? A primary feature of a hangover is hypoglycaemia. Swings in blood sugar can cause the lens to swell and shrink, even in the short term. I'd get a full eye checkup and a full general medical.

It sounds to me more like changes in pupil diameter. In bright light the pupil is small, and the depth of field is greater (and so close vision improves). In low light, the opposite is true.

[meeera]

Originally Posted by pdurrant

It sounds to me more like changes in pupil diameter. In bright light the pupil is small, and the depth of field is greater (and so close vision improves). In low light, the opposite is true.

Does that change depending on a hangover?

[pdurrant]

Originally Posted by meeera

Does that change depending on a hangover?

No idea. I have't had a hangover since I was young enough not to have to worry about how good my close vision was.