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Nexus 7 Sky Safari Screen Brightness Disappointing

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#1 _Z_

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Posted 07 February 2013 - 09:42 PM

I downloaded Sky Safari Pro to my Droid Charge with an AMOLED screen a few months back. The single core phone was a little slow but ran it and the charts looked beautiful. More importantly, it didn't impact night vision when I used ScreenDim in conjunction with the red mode because the screen's overall brightness could go to pure black if I wanted. The black background did not emit light, it was just black.

I recently got a Nexus 7, mainly to use for Sky Safari Pro, because of the larger screen and dual processor. Since it's not AMOLED, the screen always has a glow to it. In Sky Safari Pro the sky is black in regular mode, but switch it to red mode and the background sky actually turns to a brighter gray! It The stars are red, but the grey background ruins your night vision. The regular screen brightness was at the minimum value.

So I turned on ScreenDim, set the screen brightness to the minimum and the contrast to the minimum value. You can't see anything in Sky Safari, but the entire screen still glows a grey color. There's almost nothing being shown on the screen yet it can't get darker or redder.

If you hold the Nexus 7 and Droid Charge near a wall, there is a pure red glow coming from the Charge and a white glow from the Nexus 7, it's not even close to real night vision.

I tried running another screen filter app i've used on the Droid Charge with some success and that didn't help at all either.

Short of red film, can this glow actually be removed, or is the lack of a LED screen going to cause it to hurt night vision more than my phone no matter what I do? It's a shame too, because the Sky Safari + ScreenDim combo on my phone was down right impressive.


#2 ccs_hello

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Posted 07 February 2013 - 10:53 PM

Per your description, it's the LCD technology issue (quite common). The only fix is to use a red film to cover the entire screen or to get a new device :).

Clear Skies!

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#3 rmollise

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Posted 08 February 2013 - 08:03 AM

Forget "short of red film. I have never seen _any_ tablet or phone that didn't need red film to preserve your night vision.

#4 _Z_

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Posted 08 February 2013 - 08:15 AM

You ought to try looking at an AMOLED screen with Sky Safari then. The blacks are just pure black because they are turned off. Then using ScreenDim you can turn the brightness of the red down so much the screen is nearly completely off. It's still easy to read it when it's dim.

The Nexus 7's screen however is an issue. I wonder if instead of applying a generic red filter in SSP, which brightens the background, if they could keep the background black, but change the color of everything else to red? That could potentially help.

#5 Sorny

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Posted 08 February 2013 - 10:12 PM

Forget "short of red film. I have never seen _any_ tablet or phone that didn't need red film to preserve your night vision.


Try a "retina" iPad running SkySafari. It can dim it to where I can't see anything and it doesn't ruin my night vision. Mind you, I never leave the SkySafari app once I start using it, but it works just fine w/o film. Auto-brightness in the system settings of the iPad disabled, screen brightness all the way down, and the brightness slider in SkySafari has to be up a tick in night-vision mode to be usable; more, obviously, if the moon is up.

Obviously not a solution for someone with a Nexus 7, so I'll have to echo everyone else who says to get some red film for the screen.

#6 _Z_

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Posted 08 February 2013 - 10:27 PM

I contacted Alex who made ScreenDim. He had an idea but I don't know enough programming to give it a try.

One could recompile the Linux kernel, though, on your device with finer-grained PWM support for the backlight.

#7 Jon Isaacs

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Posted 09 February 2013 - 06:46 AM

Forget "short of red film. I have never seen _any_ tablet or phone that didn't need red film to preserve your night vision.


My phone doesn't affect my night vision as long as I keep it in my pocket. :)

I personally think a red screen is necessary to protect against the possibility of accidentally ending up outside of Sky Safari without it's red screen.

Jon

#8 rmollise

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Posted 09 February 2013 - 08:19 AM

Yep. And if you have an iPhone, you will wind up at that consared Lock Screen every time. :mad:

#9 demiles

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Posted 09 February 2013 - 10:16 AM

An ipad with retina display is still way too bright to use without a film over it. I've tried them.

#10 lamplight

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Posted 11 March 2013 - 11:13 AM

I just found an app on the google play store called "Lux" that dims the actual backlight .. (That gray light you describe even when everything is turned down) There's a free version.. It's daytime now so I can't say for sure how well it will work.. but I think this may do the trick. I have a nexus 7 too and yes it's waaaay too bright..

#11 mark03

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Posted 12 March 2013 - 08:03 PM

I just stumbled onto this thread after experiencing similar behavior with my Nexus 10. Almost none of the replies to the OP are correctly understanding the issue, so maybe I can help.

There are two contributors to the amount of light coming from an LCD display: (1) the backlight intensity, and (2) the pixel values on the screen. The pixels are like valves, controlling how much of the backlight is exposed. Even a completely black screen will emit a fair amount of light from the backlight. This ultimately sets the "contrast ratio" of the LCD display.

The issue with Skysafari's night mode, at least on the Nexus 7 and 10, is that while it changes the pixels to shades of red, it simultaneously TURNS UP the backlight. Actually, I did some experiments which suggest that it is setting the backlight to a fixed level, so if you start out with a really bright screen, the backlight gets dimmer, but if you start out with it set to minimum, night mode makes it a lot brighter.

Of course, you will likely need some Rubylith filter material in the field anyway, but the high backlight setting in night mode makes the contrast lousy, so I actually get a more usable field display in non-night-mode with a double layer of Rubylith. It's not perfect, as blue and green text is [obviously] really hard to read through the red filter, but it's still better than night mode.

So, the reason this is an issue, is that it is entirely preventable (at least in theory). I can't think of any reason why Skysafari should be fiddling with my backlight intensity. I sent a support request a few weeks ago but didn't hear back. They're usually very responsive so I guess I just need to try again.

BTW, I also corresponded with the author of ScreenDim and it turns out that the Nexus 10 is somewhat unusual in allowing you to turn the backlight all the way down to 1/255 in the OS settings. Thus, ScreenDim doesn't help. No other app can help either, because they are just scaling the pixel values, and as the OP points out most of the light is coming from the black pixels. We just need Skysafari to not sabotage the very nice backlight control on these devices, and things will improve markedly.

#12 btschumy

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Posted 12 March 2013 - 09:26 PM

I can guarantee that we are not fiddling with the backlight intensity. If it is changing then it must be a side effect of something else. I can try to take a look at it. Can an app even adjust the backlight intensity without being rooted?

Sorry if we didn't respond to an earlier inquiry. Sometimes thing fall through the cracks.

#13 mark03

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Posted 12 March 2013 - 11:04 PM

Hi Bill,

Thanks for your reply. I'm fairly confident the backlight level is in fact going up. I might have had some residual doubt at first but zeldaboy101's observation seems to confirm it. The black areas are definitely getting [much] brighter when night vision is activated.

I wish I knew more about Android internals, but my experience only goes as far as standard Linux. Perhaps it's an undocumented side effect of some system call? I hear that's a problem on Android (:

If there's anything I can do to assist in testing, I'd be happy to.

Regards,

Mark

#14 Jon Isaacs

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Posted 13 March 2013 - 08:03 AM

I can guarantee that we are not fiddling with the backlight intensity. If it is changing then it must be a side effect of something else. I can try to take a look at it. Can an app even adjust the backlight intensity without being rooted?

Sorry if we didn't respond to an earlier inquiry. Sometimes thing fall through the cracks.


Probably Alex could answer that one but I do use his Screen Dim with Sky Safari. With my HTC Incredible, I did some experiments using Screen Dim and SSP. I had Screendim set at 4.7% brightness, 100% contrast.

I zoomed way in until there were no stars or objects in the field of view, then I went into a closet, allowed my eyes to dark adapt a short while and then switched between night and normal while observing the brightness/darkness of the background. I could see no change.

Jon

#15 mark03

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Posted 13 March 2013 - 12:19 PM

Could the issue be unique to Jelly Bean? Which Android version do you have on the Incredible? It would be interesting to get some more data points.

I have ScreenDim installed, but ended up not using it, becausse minimum backlight in ScreenDim turns out to be the same level as minimum "brightness" under the Android Settings menu. Apparently the Nexus tablets are somewhat unusual in that regard.

#16 Jon Isaacs

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Posted 13 March 2013 - 01:23 PM

Could the issue be unique to Jelly Bean? Which Android version do you have on the Incredible? It would be interesting to get some more data points.

I have ScreenDim installed, but ended up not using it, becausse minimum backlight in ScreenDim turns out to be the same level as minimum "brightness" under the Android Settings menu. Apparently the Nexus tablets are somewhat unusual in that regard.


The Incredible runs something like 2.3.7.

The Screendim documentation says it adjusts the backlight brightness in "many LCD devices"

Jon

#17 CarolG

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Posted 13 March 2013 - 07:57 PM

Perhaps you have already tried this free app. I downloaded it today, and it seems to work much better than ScreenDim. It's Night Mode by Bruno Barao. You can find it at Google Play. It really dims the screen of SSP, in fact if you turn it all the way down, the screen is black.

#18 mark03

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Posted 13 March 2013 - 10:23 PM

You probably have an OLED screen. Just scaling the video data will reduce the OLED light output very effectively. On an LCD, the app you referenced will not reduce the light output at all, once you are already at the point where all the light is coming from the black pixels.

#19 lamplight

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Posted 14 March 2013 - 11:15 AM

hi

some nexus 7 observations (I also have a android phone to try later):

i cant see any increase in brightness when skysafari comes on either.

when using "Lux" night mode doesnt even do anything(isnt needed) in sky safari...

lux has a couple extra night mode options that basically turn everything red.. i found it easier to not use this and have sky safari still on color maps..

screendim actually dims the navigation buttons (home, back) whereas lux and "Night mode" annoyingly doesnt. i bought screendim because of this.. personally any of these will be a super improvement from what it was like before..

and will help compensate for those few screens where full brightness still pops up in sky safari (entering descriptions/keyboard etc.. )

and for the record these apps make the screen way WAY dimmer than an ipad turned all the way down (although i dont know if there are any advanced brightness/dimming apps for retina display ipads).

#20 mark03

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Posted 14 March 2013 - 12:47 PM

Did you try this with the Nexus 7 brightness (under Settings->Display) set to minimum, and auto-brightness disabled?

Then you spent at least a few minutes in a completely darkened room, with Skysafari in normal mode and zoomed in so most of the screen was black, and only then turned night mode on?

If you did all this, but didn't see an obvious jump in screen brightness when night mode was enabled, I'm at a loss to explain the differing observations :question:

In Screendim have you left contrast at 100% or are you turning it down too?

#21 lamplight

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Posted 14 March 2013 - 02:44 PM

Hi

I always have auto brightness off and have it down a bit.

On screen dim I have the top slider all the way down and the bottom slider at about 40% ands that as good enough in daylight indoors.

I went under some covers in bed (thanks for the excuse BTW) and found I could turn down the bottom slider to pretty much zero.

Started up Ss , zoomed so only 1 major star (Capella), turn eds on night mode and no jump in brightness. It also made the SS display invisible.. So I think I'm going to be pretty happy using screen dim and SS without night mode.. Of course there's the actual field testing I've not yet done but I can already tell that the light output has decreased many time s over and that these apps do appear to dim the backlight, to a point .

#22 Jon Isaacs

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Posted 15 March 2013 - 07:39 AM

Hi

I always have auto brightness off and have it down a bit.

On screen dim I have the top slider all the way down and the bottom slider at about 40% ands that as good enough in daylight indoors.

I went under some covers in bed (thanks for the excuse BTW) and found I could turn down the bottom slider to pretty much zero.

Started up Ss , zoomed so only 1 major star (Capella), turn eds on night mode and no jump in brightness. It also made the SS display invisible.. So I think I'm going to be pretty happy using screen dim and SS without night mode.. Of course there's the actual field testing I've not yet done but I can already tell that the light output has decreased many time s over and that these apps do appear to dim the backlight, to a point .


They do dim the screens but to really preserve dark adaptation, a red screen is a necessity, i don't think there is any way around it.

Jon

#23 skyquest25

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Posted 15 March 2013 - 07:56 AM

I have this running on a Toshiba 10" Excite and I have no issues with it. Sky Safari in Night mode is completely red and no white lite or strange colors. All I do on that tablet is turn down the brightness all the way,since it's more than significant in night mode.

I love it !! :thewave:

#24 lamplight

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Posted 16 March 2013 - 08:23 AM

They do dim the screens but to really preserve dark adaptation, a red screen is a necessity, i don't think there is any way around it.

Jon


No doubt and its already many magnitudes dimmer already. Makes me wonder how much my dark adaptation has been affected so far not knowing... I plan to get some from scopestuff.com along with some other stuff.

I noticed screen dim doesn't control the android navigation button brightness on my phone though it does on the tablet. That's one thing I don't like about android there are so many devices you never know what's going to happen on any given one with the same software... But at least I can use the stock OS to turn off the backlight entirely for the nav buttons.

#25 mark03

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Posted 19 March 2013 - 12:13 AM

Ok. As a good friend of mine is fond of saying, "photos! or it didn't happen." So I set my camera on a tripod and took a picture of Sky Safari in (1) normal mode, and (2) night mode. Screen brightness is set to minimum, auto-brightness off. No third-party "dimmer" apps, as I haven't found any that change the results of this experiment.

Exposure is identical for both shots: 25s f/5.6 at ISO 200.

Normal mode (zoomed in to black sky):

Posted Image

Night-vision mode:

Posted Image

This is a Google Nexus 10 with Jelly Bean. Stock kernel and ROM with latest update to 4.2.2.

Sorry for harping on this, but with all the [well-meaning] posters here, I just wanted to re-iterate what may have gotten lost, which is that this is definitely a bug in the software. It could well be an issue in Android itself, but as the Nexus 10 is Google's flagship demonstrator for 10-inch Android tablets (read: iPad competitors), I really hope a fix can be found.

If someone with a Nexus 7 would like to run the same experiment (using whatever settings they think work best), it would be interesting to see the results.






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