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01/08/2007 06:16:58 PM · #1 |
So With the D70, there is a heated element that lies close to the sensor causing purple marks on long shutter speeds.
//www.dancespencerdance.com/images/places1.jpg
This was 15 minutes.
At around 15 minutes, what are your cameras doing?
Are there any cameras that dont do this?
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01/08/2007 06:19:07 PM · #2 |
It isn't so much a heated element as where the power rails attach to the sensor. As the sensor is on for so long, it actually heats up itself.
Some cameras are better than others. In particular, Canon's CMOS sensors are much better than Nikon's for long exposures. This is one of the few significant differences between Canon/Nikon.
I've done a few several hour exposures without much blooming like that. I'm not sure how the Rebel's and the like do, but I've heard good things about all the 1D bodies and 5D. This one was about 10 minutes as a comparison.
This next one was screwed up in quite a few ways but was about 30 minutes, with the sky boosted quite a bit (which pulls out a lot of extra noise and has encouraged a bit of purple blooming.
Most night shooting I've done has been at temps of around 30F or below. I seem to be stupid about that.
Forgot to mention, mine above were shot at ISO400.
Message edited by author 2007-01-08 18:28:35.
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01/08/2007 06:22:42 PM · #3 |
I've had purple blooms at about 10 minutes on my 5D, however it was in temperatures of 30 degrees (which may make some relative difference). I also did not use the blind for the eyepiece and that may have contributed as well.
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01/08/2007 06:23:56 PM · #4 |
Originally posted by DrAchoo:
I've had purple blooms at about 10 minutes on my 5D, however it was in temperatures of 30 degrees (which may make some relative difference). I also did not use the blind for the eyepiece and that may have contributed as well. |
30C or 30F ? 30C might not help, 30F should reduce it.
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01/08/2007 06:26:35 PM · #5 |
| I haven't noticed any blooms on my XT, so far. I haven't done anything longer the 15-20 minutes, though. |
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01/08/2007 06:31:47 PM · #6 |
I've done quite a few half hour exposures with the D70 and I haven't been really happy with any of them because of the purple (so I don't have any uploaded to post). The long exposure noise reduction option and a hue/sat adjustment layer made it acceptable on the computer screen but still looks horible when printed out. The only real option is to compose the photo realising that you will have to crop the top left corner out.
The D80 seems to have even more trouble with amp noise
From Thom Hogans review of the D80 www.bythom.com
Message edited by author 2007-01-08 18:33:03.
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01/08/2007 06:32:35 PM · #7 |
what do oyu use to hold it down for so long?
i dont understand |
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01/08/2007 06:34:58 PM · #8 |
Originally posted by fallingretina:
So With the D70, there is a heated element that lies close to the sensor causing purple marks on long shutter speeds. |
Dark frame subtraction should eliminate this (and any hot pixels that might appear in a longer exposure)
Take another 15 minute exposure immediately after the real one, but with the lens cap on. Then in photoshop overlay the second shot on top of the first one and set the blend mode to 'Difference', I think. Adjust the opacity as necessary.
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01/08/2007 06:38:35 PM · #9 |
Originally posted by Elmakias:
what do you use to hold it down for so long?
i dont understand |
I believe the Nikons still accept the standard cable release. For the Canon cameras, you will need the appropriate remote release. It lets you open the shutter and lock it open.
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01/08/2007 06:49:35 PM · #10 |
Originally posted by Spazmo99:
Originally posted by Elmakias:
what do you use to hold it down for so long?
i dont understand |
I believe the Nikons still accept the standard cable release. For the Canon cameras, you will need the appropriate remote release. It lets you open the shutter and lock it open. |
The D70 has a remote control which you can use to trip the shutter and do long bulb exposures. It can also be connected to a laptop and controled using the nikon software on the computer
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01/08/2007 06:57:20 PM · #11 |
Originally posted by Elmakias:
what do oyu use to hold it down for so long?
i dont understand |
A remote cable release, like this |
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01/08/2007 10:43:51 PM · #12 |
Any one got a d2x that they want to share with us?
Message edited by author 2007-01-08 22:51:58. |
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01/09/2007 05:52:17 AM · #13 |
Originally posted by dr_timbo:
I've done quite a few half hour exposures with the D70 and I haven't been really happy with any of them because of the purple (so I don't have any uploaded to post). The long exposure noise reduction option and a hue/sat adjustment layer made it acceptable on the computer screen but still looks horible when printed out. The only real option is to compose the photo realising that you will have to crop the top left corner out.
The D80 seems to have even more trouble with amp noise
From Thom Hogans review of the D80 www.bythom.com |
I read somewhere that the early models of the D80 were pretty bad and that it has been improved on ones with serial #'s higher than 3050000. |
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