Star trails in the city?

Hey all,

So I just bought myself a timer-like device, you might know what it's called but I just call it a shutter timer/long exposure timer. So I don't go out often, well I barely go out to the open wilderness and fun stuff/places like that, and I'm pretty much condemned in my room most of the time. I live in San Francisco and I either stayed in my room to test a shot that always turns out to be pure black or pure white and it's getting annoying.

Usually I try ISO 100, 20 mins, f/4-5. I turn off my lights in my room and open my window, but I feel it's all wrong.

Since I live in the city (SFO) and this is my first time doing star trails, I need a ton of help!

Thank you!

It's called an "intervalometer", and it might help if you explained what the problems are you're experiencing in a little more detail or posted a sample pic.

EDIT: Okay, I didn't see the "all black or all white" comment you posted. Well, if it's all black, it's not getting exposed enough, and if it's all white, it's getting overexposed

Star trails are not something you can do in large 20 minute intervals like that. It's not like the old film days.

The link I posted in my next post will explain the proper procedure (or at least a procedure that should work). Now, in the middle of the city, you may run into some difficulties due to light pollution. That might make it difficult to do ANY star trails. I don't know that I've ever seen any successful star trails from a city.

This link is what I use for star trail info, btw (Google, as always, is your friend):

http://www.jamesvernac​otola.com …ar-Trails/12233655_V7cX4D

Alright, let's see how I should star(t). I just had to say that.

So I'm using a Canon 7D, a 70-200mm f/4 non IS, or a 50mm f/1.4 or a 16-25 f/2.8. I tried using the 70-200 just to get close to the stars.

The lights in my room have been turned off, and my camera is IN my room. I think this is a bad idea but I try to keep it as dark as possible. So my problem is, do I have to go out to a dark spot at night or can I adjust the exposure and shutter speed to get rid of getting pure black or white photos.

The link I posted tells you the answer to all your questions about star trails

Yeah dude you're gonna have to get out of the city to get a decent star shot. It won't work where you live 'cause all the light from the street is overpowering the sky.

Go to Marin or somewhere near Sutro tower, somewhere where it'll be darker than normal. The hills in the bay are always good at being dark.

I'll head out to the beach and point outwards and see how that is. ALSO, I just found out that other technique, the 30 second exposure for as long as possible and stacking the photos on Photoshop. I was going to check that out and attempt that in my room and see how that goes.

I'm still very curious about the long exposure method as well and I don't quite know how to do it. I'm pretty scared that I might mess up. I checked a couple site almost all of them explained the 30 second technique a lot better than the one long exposure technique. HELP AGAIN?

The link posted above is a good explanation. You can use the program mentioned in that article, photoshop or the free startrails.de to do the stacking. Most people use the free one.
The long exposure method is difficult to do with a digital camera because it simply works too well. It catches every photon that comes through the lens and also catches the heat from within the camera. Even if you leave the lens cap on in a darkroom and do a long exposure, you'll end up with something other than black.
Film works differently from a digital sensor and is insensitive to very low levels of light and heat so the background stays black in a long exposure.
You won't do any harm to your camera with the long exposure method but you're not likely to get the best results either.

make sure to turn off long exposure noise reduction or else there will be 30 second gaps in all your photos.