I've received a bunch of questions about my photo of the Neowise comet over the sand dunes. So I wanted to write up some quick details about the shot. This is not meant to be a step-by-step. Just a capture of some of my settings and the process. Also, this is meant for photographers who understand how to use manual mode on their camera.
To start with, my gear. I was using a full frame digital camera. For the lens, I wanted to use a fast aperture and I don't have many options. So I choose an 85mm f/1.8 lens. Which would help also with the size of the comet. For instance, at 100mm, I wasn't able to get the dunes in the same frame with the comet. And with my wide-angle options, the comet would look too small.
For the photos, I took three primary sets of photos while I was at the location. The sky frames, foreground and "dark" frames. Besides the primary photos, I took a ton of test shots. I really needed to spend time dialing in how long I could expose for and what the ISO needed to be for the exposure length.
I landed at f/1.8, ISO 4000 and seven seconds of exposure for the sky photos. I took eight of the exact same photos with no time gap between them. The primary reason for seven seconds, was that I didn't want star trails. I took eight photos so I could stack them to reduce noise. Ten photos would have been better though.
Foregrounds that are too dark, blurry or noisy don't look good to me. So, I wanted to be able to see the foreground as clear as possible, even though it was completely dark out. The dunes were roughly 300 feet away, so lighting them up with a flashlight was not an option. I took more photos, but I ended up using six of them. The settings were f/1.8, ISO 2500 and 91 seconds. To achieve 91 seconds of exposure, I set the camera in bulb mode and used a timing device.
The dark frames are required for stacking in star stacking programs. They help reduce noise. The settings for dark frames should be exactly the same at the light frames (or the sky in this case). However, you put the lens cap on and make sure no light can get into the lens while taking the frames. Also, this needs to be done right after the light frames, and preferably on location so the sensor temperature is the same.
There are a lot of details that going into processing, maybe I will get into that another time. But basically, I stacked the foreground photos and edited the resulting TIF for just the foreground of the photo. Then I used a program to stack the sky photos and edited the resulting TIF. Finally, I blended the two TIF files so the good foreground and the good sky were in one photo.
My last piece of advice is that every camera and lens combo will be different. And every situation, lighting, scenery, foreground, time of night, etc, will be different. So you should expect to experiment a bunch with your camera settings in order to get the shot you want.
The final result is below.
Until next time, clear skies!