night sky photography

[jdconner]

i have been trying to shoot some star trails and night sky stuff over the past few weeks but it seems that i have a lot of noise in the darker areas even at iso 100 and if i shoot for too long (bulb) the sky appears blue... i have a nikon d700 and i can't program it to shoot longer than 30 sec other than bulb... any suggestions on how to not have a blue sky at night on the pictures... and how i can program my d700 to shoot for more than 30 secs other than bulb... my old f5 could be programmed to shoot for minutes... any suggestions on how to shoot great star trails? thanks..

[mseigafuse]

Do you have a locking remote/cable release? I put my Pentax in continuous shooting mode and then lock the shutter with the camera set to manual and exposure set to 30 seconds. The camera takes one 30 second exposure after another without any attention. I then stack them using startrails.exe. As for noise, I wish I had an answer for you ... I get too much noise too

[jdconner]

i don't have a cable release... i have a mac so startrails.exe won't work for me... and do you think that aperture or photoshop would be needed to get rid of the noise or should i turn the in-camera noise reduction all the way up... i've always heard that you need to leave it set to normal or off...

[dcclark]

Can you post an example with some noise in it? I'm a bit surprised... your D700 should be pretty good at those ISO levels. For very long exposures (around 5+ minutes), you may get "amp noise" -- which appears as purple clouds around the edges of the photos -- but that looks very different from ISO noise.

[navcom]

Digital sensors heat up with use and affect pixels, which is where you are getting your noise. The longer the exposure, the better chance you are going to get noise as the sensor gets hotter from use. It has nothing to do with ISO noise...it's different. I've used Nikon's, Canon's, and Pentax DSLRs to make star trails and they all do it....some worse than others.

Most cameras have a noise reduction feature that eliminates most of it. You may want to check if it's turned on. I'm not familiar with the D700. The side effect of noise reduction is that in order to reduce the noise, the camera usually takes a second photo (with shutter closed I believe) after the shutter closes on your first one (usually the same time length). It then "combines" this black photo together with the first one to get a clear picture. At least that is how it works in laymen's terms. I'm not up on how it's done technically.

This is why on every digital camera I've ever used for star trails, I've shut off the noise reduction feature. You can use Photoshop to get rid of the noise.

[jdconner]

how do i get a 5 min or 10 min shutter speed? the d700 goes up to 30 sec then to bulb... which holds the shutter open as long as the shutter release button is held down... i could program my f5 for 5, 10, or 30 minutes... i found a wireless remote for the shutter release but i don't want to pay 150 for it... i may just have to... and i have my noise reduction set to normal... should i just turn it off completely? thank ya'll so much for the responses...

[dcclark]

You should buy the $20 Nikon wireless remote -- press once to open the shutter, press again to close it. No need to pay $150 for a shutter release!

[navcom]

I have a generic wired shutter release that you can use as a normal shutter release or you can toggle it to stay open until you un-toggle it. Bought it for about $10 about 10 years ago.