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11-12-2010, 03:02 AM   #1
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How about if we go the other way?

It isn't as stunning of a demo as my underexposed dog shot but...

77 minutes of the earth rotating past the stars (I'll explain the exact setup later), Exif in tact, out of camera JPG.

http://www.rolleiman.com/Photos/K5JS0658.JPG

Fixed as best as I can get (from DNG) by dialing the exposure down 4 stops and adjusting contrasts and such.







Last edited by JeffJS; 10-22-2011 at 05:54 AM.
11-12-2010, 03:42 AM   #2
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FOr some reason those images took waaay too long to download.
But not bad after the fix...
Clear, but obviously overcooked in the original exposure...
11-12-2010, 04:14 AM   #3
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Onko kyseessä stattinen sähkö ilmiö jossa kamera jumittuu.

Minulla on tehnyt usein K20D. Ihmettelin vikaa ja irotin Batterin,
taas toimi senjälkeen. Manualin mukaan Ainakin Nikon on sama vika.
Kiusallinen vika, menee monta tilannetta ohi suun.

En tiedä onko K-5 saatu jo tämä korjattua.
11-12-2010, 05:09 AM   #4
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Looks like there's plenty of headroom at the other end of the histogram...
K-5......the Dynamic Range is downright cruel.....

11-12-2010, 08:59 AM   #5
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QuoteOriginally posted by Ash Quote
FOr some reason those images took waaay too long to download.
But not bad after the fix...
Clear, but obviously overcooked in the original exposure...
Those are full sized JPGs, one straight out of the camera. No resizing of the original and the one linked from Flickr is "original" sized. Click them to view the full sizes.

I know it's way 'overcoocked'.. Part of what I'm wondering is how This,

https://www.pentaxforums.com/forums/pentax-k-5-forum/121834-k5-startrail-what...ing-wrong.html

was done. He reports his is 105minutes with a wider aperture (different lens of course) vs mine at 78 minutes. I know my lens and camera are working.



---------- Post added 11-12-10 at 11:02 AM ----------

QuoteOriginally posted by 30v iPentax Quote
Onko kyseessä stattinen sähkö ilmiö jossa kamera jumittuu.

Minulla on tehnyt usein K20D. Ihmettelin vikaa ja irotin Batterin,
taas toimi senjälkeen. Manualin mukaan Ainakin Nikon on sama vika.
Kiusallinen vika, menee monta tilannetta ohi suun.

En tiedä onko K-5 saatu jo tämä korjattua.
If I understand, you are saying your K20d locks up (hangs) in some situations and only removing the battery cures it. I have never had this happen but to get a real answer you may want to ask your question in a thread of your own. That is, If I understand you correctly.

QuoteOriginally posted by kittykat46 Quote
Looks like there's plenty of headroom at the other end of the histogram...
K-5......the Dynamic Range is downright cruel.....
That it is

11-12-2010, 09:16 AM   #6
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QuoteOriginally posted by JeffJS Quote
I know it's way 'overcoocked'.. Part of what I'm wondering is how This,

https://www.pentaxforums.com/forums/pentax-k-5-forum/121834-k5-startrail-what...ing-wrong.html

was done. He reports his is 105minutes with a wider aperture (different lens of course) vs mine at 78 minutes. I know my lens and camera are working.
Light pollution

On another note, this example measures the signal, i.e., the SNR at the particular luminance level.

Subtracting a gradient background (or a median-value blurred version of the foreground) should do even better.

Subtracting such massive amount of offset luminosity (which is a contrast boost) reduces the SNR. But all modern sensors have a relatively high SNR at low ISO and high luminosities. DxO has full curves and one could compare cameras for their ability to do what you just did. Except that banding and pattern noise are another important consideration here.
11-12-2010, 09:24 AM   #7
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QuoteOriginally posted by JeffJS Quote
It isn't as stunning of a demo as my underexposed dog shot but...

77 minutes of the earth rotating past the stars (I'll explain the exact setup later), Exif in tact, out of camera JPG.

[IMGTall]http://www.rolleiman.com/Photos/K5JS0658.JPG[/IMGTall]

Fixed as best as I can get (from DNG) by dialing the exposure down 4 stops and adjusting contrasts and such.


[IMGTall]http://farm5.static.flickr.com/4112/5168553085_38b4c96084_o.jpg[/IMGTall]
Did you do this one last night? I noticed that the moon is getting fuller and although it is low later in the night sky it is producing a lot more light than the night before and as Falk says it may be that you have light pollution that your naked eye is not picking up.
11-12-2010, 10:04 AM   #8
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This was done this morning, begun at 2:45 am (or thereabouts). It's entirely possible that there is too much light pollution and I hadn't really considered that although I'm well aware it factors in. This is phase of the moon the previous day (taken before dusk) but it's long out of sight at this point



There are also city lights so the sources of stray light are plentiful. It's possible that a hood would have helped but I think if I really want to do this, it's going to have to be multiple exposures. Something worth playing around with now that DFS can be turned off.

The way this was done was my camera was mounted on the side arm of my tripod and passed out of the second floor window of my house. I didn't want to sit outside and babysit the camera for an hour+. It was very securely locked to the tripod just in case the mount failed (Think $2900 15' drop to the concrete OUCH!!!!!). A wireless remote used with the 3 second delay. If you look at the large versions you'll see movement at the beginnings of the traces where I had to walk past the tripod and slightly moved the floor. Come to think of it though, even the room light seeping through the window blinds may have caused part of this. Hmmmm.. That's easy enough to cure. I'll have to try this again if it's another clear night but modify the setup slightly..



3700


Last edited by JeffJS; 11-12-2010 at 10:12 AM.
11-12-2010, 10:08 AM   #9
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OP, your images are simply WAY TOO BIG and take FOREVER TO LOAD.
Suggest you post a link to the photo rather than the have the actual photo inserted.
11-12-2010, 10:11 AM   #10
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QuoteOriginally posted by creampuff Quote
OP, your images are simply WAY TOO BIG and take FOREVER TO LOAD.
Suggest you post a link to the photo rather than the have the actual photo inserted.
I would but since the links have been quoted, it won't help.



Last edited by JeffJS; 11-12-2010 at 10:38 AM.
11-12-2010, 10:20 AM   #11
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Jeff, did you think to cover the eye cup? I've had stray light enter the the few long night exposures I've taken. I never even thought of it but a friend of mine pointed it out

NaCl(tho I imgine that if you do this sort of photography frequently, covering the eyecup is a given)H2O
11-12-2010, 10:40 AM   #12
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No, I didn't cover the eye cup but it certainly could be another factor. In this particular situation however the area below the camera is pretty dark but with a 78 minute exposure, who knows...

11-12-2010, 10:52 AM   #13
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Well it can't hurt and with a dark area I assume that a fix could be a simple flap of some opaque tape, like electricians tape or the like.

NaCl(just to cover all the bases as it were)H2O
11-12-2010, 12:46 PM   #14
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Long exposures need clear and clean skies, as Falk alluded to.
Light pollution in urban areas precludes you from going over a few minutes without flooding the sensor with stray light, regardless of the eyecup being covered.
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