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core
Pooh-Bah
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Reged: 02/23/08

Loc: Mostly in Norman, OK
iPhone 'SQM' app available soon ... your thots?
      #5692565 - 02/21/13 11:32 AM

Came across this soon-to-be-released app for iPhone - Dark Sky Meter.

Their reasoning being that they are coding and calibrating for a only a couple of devices (4/4s, 5?), it should work reasonably well. Does iOS allow for complete control of the camera h/w? I presume setting the focus point to an arbitrary 'near' to spread out the incoming light, and having complete control of the camera's exposure/gain settings is along the lines of standardizing a reading.

fwiw, for comparison:

SQM FOV for HWHM is 42
SQM-L FOV for HWHM is 10
iPhone 4 FOV ~60x47
iPhone 4s FOV ~56x43

No relation to the app or anyone involved, just very curious; if it works it would be a great app/equipment, and the sudden jump in crowd-sourced 'SQM' reading would be fantastic.


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wolfman_4_ever
Pooh-Bah


Reged: 07/15/11

Loc: El Segundo, Ca, So. Cal
Re: iPhone 'SQM' app available soon ... your thots? new [Re: core]
      #5692779 - 02/21/13 01:37 PM

I have a Unihedron SQM... I'll have to compare when the app comes out..

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microstar
Pooh-Bah


Reged: 01/05/08

Loc: Canada
Re: iPhone 'SQM' app available soon ... your thots? new [Re: wolfman_4_ever]
      #5692817 - 02/21/13 01:55 PM

Looks interesting! I'll be following this one. Thanks for posting.
...Keith


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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: iPhone 'SQM' app available soon ... your thots? new [Re: microstar]
      #5692879 - 02/21/13 02:37 PM

When is it going to be available? Only SQM app I found was a controller for some other one.

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hbanich
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Reged: 06/17/05

Loc: Portland, Oregon
Re: iPhone 'SQM' app available soon ... your thots? new [Re: Raginar]
      #5693034 - 02/21/13 04:12 PM

Sounds interesting but my initial thought is that looking at the screen of the iPhone, even with its screen as dim as possible, and with a red cover, will involve some loss of dark adaptation. That's one of the reasons I like the Unihedron SQM - one only has to look at the illuminated readings, not a full screen.

But my reservations are only imagined at this point and the app may have taken care of all this so I'm eager to see what it's really like.


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GlennLeDrew
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Re: iPhone 'SQM' app available soon ... your thots? new [Re: hbanich]
      #5694021 - 02/22/13 04:47 AM

My concern is this. Can these cameras obtain an image of a fairly dark sky which is not mostly noise? The chip's pixels are awfully small, and moreover are reduced in efficiency because of the Bayer mask. One must have some minimum signal to noise ratio in order to derive a meaningful measurement allowing to discriminate brightness differences to the desired degree.

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ahopp
sage


Reged: 05/24/12

Re: iPhone 'SQM' app available soon ... your thots? new [Re: GlennLeDrew]
      #5694087 - 02/22/13 06:56 AM

I wonder if they might be binning the chip with a lot of pixels. Maybe 50x50 or more. This might do it.

Tony


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Chucky
sage
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Reged: 04/16/10

Loc: Dublin, Ohio
Re: iPhone 'SQM' app available soon ... your thots? new [Re: ahopp]
      #5694092 - 02/22/13 07:03 AM

Wonder if this will be more of a gimmick? In the meantime, I'll just peer skyward with my good old eyes to estimate magnitude and compare results with my astro buddies. KISS principle.

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johnpd
sage


Reged: 04/13/08

Re: iPhone 'SQM' app available soon ... your thots? new [Re: core]
      #5695011 - 02/22/13 03:41 PM

I have been testing the app. As of the last test I ran a few days ago, it's results are under what the SQM gives you. The developer says that there is a difference between what the iPhone4 and iPhone5 camera gives you. Hopefully this evening I can try the latest release to see if its results are more consistent with the SQM.

JohnD


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starrancher
Carpal Tunnel
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Reged: 06/09/09

Loc: Northern Arizona
Re: iPhone 'SQM' app available soon ... your thots? new [Re: johnpd]
      #5695091 - 02/22/13 04:23 PM

What is a "thots" ?

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Jason D
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Reged: 10/21/06

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Re: iPhone 'SQM' app available soon ... your thots? new [Re: Chucky]
      #5695232 - 02/22/13 05:30 PM

Quote:

Wonder if this will be more of a gimmick? In the meantime, I'll just peer skyward with my good old eyes to estimate magnitude and compare results with my astro buddies. KISS principle.




Well-said

After all, these days there is an app for everything including an app for a mirror -- referring to the one that shuts off the screen so you can see your reflection.

Maybe I should consider an app for collimation!!!


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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: iPhone 'SQM' app available soon ... your thots? new [Re: Jason D]
      #5695249 - 02/22/13 05:40 PM

Jason,

A collimation app would be kind of neat. You could have circles for the various rings and just line them up visually. No guess work involved?


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GlennLeDrew
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Re: iPhone 'SQM' app available soon ... your thots? new [Re: Raginar]
      #5695302 - 02/22/13 06:02 PM

Of greater interest to me is not the fact that currently this app is "under" the SQM reading, which I presume to mean is a consistently lower (brighter?) reported value, but whether the readings track reasonably closely. And whether the level of discrimination is reasonably fine. And whether the readings are reasonably repeatable. And whether results extend to at least moderately dark sky levels.

Down to about 21 MPSAS, to be useful at all the 1-sigma error should not exceed 0.2 magnitude.


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BPO
sage


Reged: 02/23/10

Loc: South Island, NZ
Re: iPhone 'SQM' app available soon ... your thots? new [Re: Jason D]
      #5695338 - 02/22/13 06:22 PM

Without specifically addressing the quality of the iPhone app, I would like to mention that SQM are used for many reasons. My observatory uses two SQM-LE for full-time monitoring purposes; To provide info on current conditions to active observers, and also for generating long-term records.

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Chucky
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Reged: 04/16/10

Loc: Dublin, Ohio
Re: iPhone 'SQM' app available soon ... your thots? new [Re: BPO]
      #5696113 - 02/23/13 06:46 AM

<< Maybe I should consider an app for collimation!!! >>

Seriously Jason, you really, really should consider this. It would be a great way to share your knowledge. I'll look for it on ITunes soon.


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Nop
Vendor (iPushto)


Reged: 02/12/06

Loc: Netherlands, Valkenburg
Re: iPhone 'SQM' app available soon ... your thots? new [Re: Chucky]
      #5708640 - 03/02/13 11:46 AM

We are developing the app. The app will hit the app store as soon as all devices with a decent camera are supported. The devices with good (close) results are the iPhone 4S and 5. We hope to support the 4's camera as well as the iPad 3rd gen and iPad mini cameras. We are working close with the IDA and will distribute a special 'lite' version soon. The lite version works like a SQM, but has not the Mag/square sec arc scale. It will be more aimed towards a broad audience, submitting as many readings as possible. This should (hopefully) generate a lot of useful readings. The app is more than a reader: it submits device position (aimed at the zenit), GPS and moon readings.
For amateur astronomers like you there will be a pro version (in app or separate build) with proper SQM readings, google like darkness map (pinpoints of you and other dark sky meter user with SQM readings) and a GFS based clear sky clock.
Currently we are testing and getting close to releasing the app. Hopefully in April.


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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: iPhone 'SQM' app available soon ... your thots? new [Re: Nop]
      #5708653 - 03/02/13 11:55 AM

Norbert,

That sounds like a really good app that'll have great effects on reducing light pollution. I can't wait to try it out.


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johnpd
sage


Reged: 04/13/08

Re: iPhone 'SQM' app available soon ... your thots? [Re: Nop]
      #5709790 - 03/03/13 12:29 AM

Hi Norbert,

I tried running a test from inside a closet but the SQM would not give me a reading. Guess it was too dark.

The latest results seem to be getting closer on my iPhone 5. Keep up the good work.

JohnD


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core
Pooh-Bah
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Reged: 02/23/08

Loc: Mostly in Norman, OK
Re: iPhone 'SQM' app available soon ... your thots? [Re: johnpd]
      #5709891 - 03/03/13 02:59 AM

Norbert,

Thanks for chiming in, and developing the app! If it isn't too much trouble or leaking 'programming secrets', could you share some insights into how you might have overcome some of the perceived issues using a iPhone's camera to do the work? I'm a little weary if the eventual results is subject to larger-than-expected variations due to iPhone H/W and iOS constraints/limitations, and all the data being fed to IDA ends up being affected.


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James Cunningham
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Reged: 08/07/10

Loc: Maryland
Re: iPhone 'SQM' app available soon ... your thots? [Re: core]
      #5710071 - 03/03/13 08:00 AM

What is "SQM"
Thanks.


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