After Roblas Butte, my next astrophotography goal for the summer was to photograph the Milky Way over Knoll Lake.
Knoll Lake is one of my favorite places to go up on the Mogollon Rim (or simply the Rim as it’s referred to around here). Despite being 2 hours from Phoenix, plus another hour of dirt roads for the last 22 miles, the area is usually busy, even more so on holiday weekends. It’s a lovely place to hang out for the day. I’ve never been out to the lake at night, but I imagined the view of the Milky Way would be spectacular. I was not wrong.
As with Roblas Butte, timing is tricky. Once late June rolls around, odds are the monsoon is picking up which means almost daily late afternoon and evening thunderstorms up on the Rim. These storms start tapering off towards the end of August or early September so there aren’t a lot of clear sky opportunities. If it’s an especially dry year you can also run into forest closures. April and May are the best months.
May 2022 worked out well since the weekend with the best viewing wasn’t Memorial Day weekend and the weather was mostly clear. The area was still busy, but I easily found a dispersed camping site close to the lake (camping at the lake is prohibited). I turned in early to get what sleep I could and then headed out to the lake around 2 in the morning.
When I arrived, I was surprised at the number of vehicles parked at the lake and dismayed that someone set up a tent close to the shore with a fire (despite the general fire ban due to dry conditions and the fact that fires are always prohibited by the lake). Upon seeing me the camper quickly extinguished the fire and retreated inside the tent, so I’m pretty sure they knew they weren’t supposed to be there. Aside from the lone camper I appeared to have the lake all to myself despite the number of vehicles present.
Conditions were perfect. The lake was very calm and reflected the night sky beautifully. There were a few clouds on the horizon, but the rest of the sky was clear. The Payson light dome was obscured somewhat by the trees in the foreground, so I had a great view of the Milky Way with minimal light pollution. The only issue was the illicit camper on the shore. He left a light on in his tent, so not only did it show up bright blue among the trees but there was a clear reflection in the lake as well. I worked it out of the composition the best I could, but there was little I could do. I ended up removing it in post processing.
To maximize the lake the composition I got as close to the shore as I could. This was a little tricky in the dark since I had to work my way down the side of the earthen dam which was quite rocky. But I got everything setup without incident and got to shooting. The Milky Way was an impressive site, standing vertically over the lake.
For the foreground I took one 2-minute exposure at 20mm, ISO 500, and f/1.8. For the sky I took 15 30-second exposures at the same settings. For both sets of exposures I used daylight white balance to keep the colors true. Sky images were stacked in DeepSkyStacker, edited in Capture One, and combined in Affinity Photo. Combining the sky and foreground ended up being trickier than expected. I didn’t move the camera as much to avoid the issues I ran into with the Roblas Butte which helped, however I ran into problems with the reflections in the lake. Because I used a tracker for the sky images but not the ground, the stars reflected in the lake are trailing. Fortunately, there was enough movement in the surface of the water that the mismatch between pinpoint stars in the sky and trails in the lake was muted. The second, bigger complication, was the fact that the images were taken at different times. So, the stars in the sky didn’t quite align with the reflections in the lake. I had to rotate the sky a little bit to get things to line up better. There were also some clouds reflected in the lake that don’t show up in the sky. There wasn’t much I could do about this, fortunately the clouds were small, mostly obscured by the ripples in the lake, and at the far end of the lake which reflected the washed-out horizon. A minor issue was that the foreground and sky were edited as separate images, so I had to tweak the reflection in the lake to match the exposure of the sky.
Overall, I’m pleased with how the image turned out. Dealing with reflections was a new wrinkle in post processing, but I think for the most part a casual observer wouldn’t notice some of the inconsistencies. One thing that is quite noticeable is the greenish cast to the scene. This is likely caused by skyglow, both naturally occurring and as light pollution from Payson. I tried editing it out, but it ended up shifting the colors too much, so I let it be.
I’m definitely going back to try this shot again. Next time I’m going to plan for the middle of the week with the hope that fewer people will be in the area while I’m shooting.
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