Kobo Clara HD and Libra 2 Comparisons and Questions

Benjamelon · 12-26-2021, 09:58 PM

Hello all! I've been lurking around around a week taking a look over the threads, and I've settled mostly between these two. I've read the spec sheets and used the table in the wikipedia article to settle on one of these two; however, I'm more curious about aspects not covered by the spec sheet.

How is display quality with and without the front light turned on?
Does one display have better uniformity or contrast ratio?
How "hackable" is the software (namely custom firmware) and/or hardware (namely storage upgrade, battery upgrade) for each device?
How responsive are the touchscreens?
Is the Libra 2 noticeably slower due to the higher resolution?
Is the Libra 2's battery life noticeably worse for the same reason?
Does the Libra 2's "darkmode" work with fixed page formats (PDF, CBZ, CBT, etc.) or only with reflowable e-book formats (EPUB, MOBI, TXT, etc.)?
Does the aforementioned "darkmode" also work with KOReader?

As far as use cases and previous e-reader experience goes, I plan on mostly reading sideloaded manga/epubs converted with calibre, and I have my trusty old Kindle Keyboard that I've been using for almost a decade now. I'm also open to other device suggestions if you know of any that would better fit my needs.

Thank you for your time,

Benjamelon

Sirtel · 12-26-2021, 11:14 PM

I don't have a Clara HD, so can only answer some of your questions.

- the Libra 2 screen is excellent. The text is very sharp and dark, the light is even. I think it has better contrast than the Clara, as the Libra 2 uses a newer Carta 1200 screen. But as I said, I don't own a Clara, so don't take this as a fact.

- the software is the same on both and it's pretty hackable. You can patch and install alternative readers (Plato, KOReader), custom screensavers, custom fonts, custom dictionaries etc. Also manage your metadata and collections automatically via Calibre.

- the hardware of the Libra 2 is not really hackable, from what I've gathered. But I may be wrong. No idea about the Clara.

- the resolution is the same on both (300 ppi), so I don't see any reason for the Libra 2 to be slower.

Sorry, I don't use the dark mode, KOReader or any other formats besides epub/kepub, so can't answer that.

John F · 12-27-2021, 05:43 AM

Quote:

Originally Posted by Sirtel

...

- the resolution is the same on both (300 ppi), so I don't see any reason for the Libra 2 to be slower.

...

The resolution are different (same DPI, different resolutions, the Libra 2 having a higher resolution), so it may take longer to render pages? While reading, each page is larger, so more "work" must be done to render a page. In theory.

LDB · 12-27-2021, 09:02 AM

My thought would be even if the Libra is slowed down the net result would be the same as the Libra is 17% larger so fewer page turns mean the same net time elapsed. That's if it is slower which it may not be.

I am from the bigger is better camp and now lean toward my Kobo Aura One with its 7.8 inch screen. It is gradually supplanting my Oasis with only a 7 inch screen. I am considering the Forma to get buttons and won't complain about the 8 inch screen which while only marginally larger should give several extra words per page and reduce page turns that much more.

Good luck with your decisions.

Benjamelon · 12-27-2021, 10:11 AM

Thanks for the replies so far! I thought of another question as well. Is the front light controlled using voltage (consistent if you wave your hand in front of it) or pwm (flickery if you wave your hand in front of it)? A good reference for voltage control is to wave your hand in front of a traditional incandescent light bulb.

Quoth · 12-28-2021, 01:06 PM

PWM done at a high enough frequency can't be detected like that and can't be distinguished from a static drive.

A single chip colour wheel based DLP will show up because it's sequential RGB L frames.

I can't see flicker on any LCD panel or eink front light (PW3, PW4, Kobo H2O original or Libra Original) doing that.

In practice I hardly ever use a front light. My Libra (original) is fine in every respect as an ereader. I have or had maybe 11 models/makes of eink over the years. I still have 3 models of Kindle, 2 Kobos, Sony PRS350 and a Mars.

I'd imagine the Libra 2 is as good as my Libra which is the best for epubs (I don't use kepubs) and I read all my Amazon ebooks on it. I do a huge amount of annotation/proof reading and Calibre Kobo Utilities to copy/paste in to text files. A window then beside source wordprocessor to edit.

DNSB · 12-28-2021, 02:32 PM

I just tried that waving hand suggestion on my Kobo Forma which does have a PWM front light. The Forma uses 1KHz PWM and even in a dark room waving a pencil in front of the display, I do not see any flickering/strobing. I then tried using a photodetector good up to 130KHz to detect any variation. I could notice a very minor effect on the oscilloscope display but given even moderate persistence in the phosphors used to convert the LED light to white, that was pretty much as expected.

Benjamelon · 12-28-2021, 04:55 PM

Glad to hear they've implemented it well! That settles my decision then, I'm going with the Libra 2. I appreciate all help!

Quoth · 12-28-2021, 07:33 PM

Yes, white LEDs don't exist. All are Blue, violet or UV with at least a yellow emitting phosphor mix. Most phosphors, except some blues used in instrument CRTS and flying spot scanner CRTs for mono film have lag. It's easy to give them more lag than the R G B on a colour CRT. OLEDs are actually using phosphors and dye filters as they are really diode-like electroluminescent dots and not true LEDs.

There isn't usually any phosphor on red, yellow or orange LEds used to tint front lights, but 1kHz is high enough that it would be unlikely to visibly flicker with normal movement.

12-26-2021, 09:58 PM	#1
Benjamelon Junior Member Posts: 7 Karma: 10 Join Date: Dec 2021 Device: none	Kobo Clara HD and Libra 2 Comparisons and Questions Hello all! I've been lurking around around a week taking a look over the threads, and I've settled mostly between these two. I've read the spec sheets and used the table in the wikipedia article to settle on one of these two; however, I'm more curious about aspects not covered by the spec sheet. How is display quality with and without the front light turned on? Does one display have better uniformity or contrast ratio? How "hackable" is the software (namely custom firmware) and/or hardware (namely storage upgrade, battery upgrade) for each device? How responsive are the touchscreens? Is the Libra 2 noticeably slower due to the higher resolution? Is the Libra 2's battery life noticeably worse for the same reason? Does the Libra 2's "darkmode" work with fixed page formats (PDF, CBZ, CBT, etc.) or only with reflowable e-book formats (EPUB, MOBI, TXT, etc.)? Does the aforementioned "darkmode" also work with KOReader? As far as use cases and previous e-reader experience goes, I plan on mostly reading sideloaded manga/epubs converted with calibre, and I have my trusty old Kindle Keyboard that I've been using for almost a decade now. I'm also open to other device suggestions if you know of any that would better fit my needs. Thank you for your time, Benjamelon

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12-26-2021, 11:14 PM	#2
Sirtel Grand Sorcerer Posts: 10,129 Karma: 224760044 Join Date: Jan 2014 Location: Estonia Device: Kobo Sage & Libra 2	I don't have a Clara HD, so can only answer some of your questions. - the Libra 2 screen is excellent. The text is very sharp and dark, the light is even. I think it has better contrast than the Clara, as the Libra 2 uses a newer Carta 1200 screen. But as I said, I don't own a Clara, so don't take this as a fact. - the software is the same on both and it's pretty hackable. You can patch and install alternative readers (Plato, KOReader), custom screensavers, custom fonts, custom dictionaries etc. Also manage your metadata and collections automatically via Calibre. - the hardware of the Libra 2 is not really hackable, from what I've gathered. But I may be wrong. No idea about the Clara. - the resolution is the same on both (300 ppi), so I don't see any reason for the Libra 2 to be slower. Sorry, I don't use the dark mode, KOReader or any other formats besides epub/kepub, so can't answer that.

12-27-2021, 09:02 AM	#4
LDB Baker Street Irregular Posts: 439 Karma: 9920853 Join Date: Aug 2008 Location: Houston suburb Device: Oasis 3, PaperWhite 5, Aura One, Glowlight Plus, Scribe, Sage	My thought would be even if the Libra is slowed down the net result would be the same as the Libra is 17% larger so fewer page turns mean the same net time elapsed. That's if it is slower which it may not be. I am from the bigger is better camp and now lean toward my Kobo Aura One with its 7.8 inch screen. It is gradually supplanting my Oasis with only a 7 inch screen. I am considering the Forma to get buttons and won't complain about the 8 inch screen which while only marginally larger should give several extra words per page and reduce page turns that much more. Good luck with your decisions.

12-27-2021, 10:11 AM	#5
Benjamelon Junior Member Posts: 7 Karma: 10 Join Date: Dec 2021 Device: none	Thanks for the replies so far! I thought of another question as well. Is the front light controlled using voltage (consistent if you wave your hand in front of it) or pwm (flickery if you wave your hand in front of it)? A good reference for voltage control is to wave your hand in front of a traditional incandescent light bulb.

12-28-2021, 01:06 PM	#6
Quoth the rook, bossing Never. Posts: 11,156 Karma: 85874891 Join Date: Jun 2017 Location: Ireland Device: All 4 Kinds: epub eink, Kindle, android eink, NxtPaper11	PWM done at a high enough frequency can't be detected like that and can't be distinguished from a static drive. A single chip colour wheel based DLP will show up because it's sequential RGB L frames. I can't see flicker on any LCD panel or eink front light (PW3, PW4, Kobo H2O original or Libra Original) doing that. In practice I hardly ever use a front light. My Libra (original) is fine in every respect as an ereader. I have or had maybe 11 models/makes of eink over the years. I still have 3 models of Kindle, 2 Kobos, Sony PRS350 and a Mars. I'd imagine the Libra 2 is as good as my Libra which is the best for epubs (I don't use kepubs) and I read all my Amazon ebooks on it. I do a huge amount of annotation/proof reading and Calibre Kobo Utilities to copy/paste in to text files. A window then beside source wordprocessor to edit.

12-28-2021, 02:32 PM	#7
DNSB Bibliophagist Posts: 35,393 Karma: 145435140 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Forma, Clara HD, Lenovo M8 FHD, Paperwhite 4, Tolino epos	I just tried that waving hand suggestion on my Kobo Forma which does have a PWM front light. The Forma uses 1KHz PWM and even in a dark room waving a pencil in front of the display, I do not see any flickering/strobing. I then tried using a photodetector good up to 130KHz to detect any variation. I could notice a very minor effect on the oscilloscope display but given even moderate persistence in the phosphors used to convert the LED light to white, that was pretty much as expected.

12-28-2021, 04:55 PM	#8
Benjamelon Junior Member Posts: 7 Karma: 10 Join Date: Dec 2021 Device: none	Glad to hear they've implemented it well! That settles my decision then, I'm going with the Libra 2. I appreciate all help!

12-28-2021, 07:33 PM	#9
Quoth the rook, bossing Never. Posts: 11,156 Karma: 85874891 Join Date: Jun 2017 Location: Ireland Device: All 4 Kinds: epub eink, Kindle, android eink, NxtPaper11	Yes, white LEDs don't exist. All are Blue, violet or UV with at least a yellow emitting phosphor mix. Most phosphors, except some blues used in instrument CRTS and flying spot scanner CRTs for mono film have lag. It's easy to give them more lag than the R G B on a colour CRT. OLEDs are actually using phosphors and dye filters as they are really diode-like electroluminescent dots and not true LEDs. There isn't usually any phosphor on red, yellow or orange LEds used to tint front lights, but 1kHz is high enough that it would be unlikely to visibly flicker with normal movement.

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