Photo123abc wrote in post #16264225
Yeah, but I dont mean stacking them. I mean single exposure. I took yesterday couple shot with 7 minute exposure time, f/5.6, ISO 800. Is there a way to calculate correct exposure, for example with f/8 ISO 100?
There is no way to calculate correct exposure without a starting point. The quickest way to calculate a long exposure is to set your ISO at it's highest and shoot until you get the exposure you're looking for. Once you have your data, work backwords towards ISO 100. It's all math once you have somewhere to start. Every scene is vastly different though, even at night.
3200 ISO - f/2.8 - 1 sec shutter
1600 ISO - f/2.8 - 2 sec shutter
800 ISO - f/2.8 - 4 sec shutter
400 ISO - f/2.8 - 8 sec shutter
200 ISO - f/2.8 - 16 sec shutter
100 ISO - f/2.8 - 32 sec shutter
Brian is right.
bsp wrote in post #16264004
... but this shot is most likely a collection of photos stacked together to form one image. I have one similar and to create it I combined multiple photos, each taken with a 30 second exposure.
If you are trying to replicate the shot you posted, it is most definitely a stacked image of multiple star shots. Lincoln Harrison spends lots of time shooting star trails, but he does so with multiple exposures and then once you blend them all together, they get that blurred look. Also, the foreground and horizon of that shot was taken at dusk. He blended it in with the night sky to get the overall look.
If you simply want to take long exposure shots, nothing wrong with that, I just want you to know it's now how the shot was achieved.