How I Got This Photograph

Photograph of Jupiter and Saturn
Conjunction of Jupiter and Saturn, 12/21/2020

One of the most publicized celestial events of the year, the conjunction of Jupiter and Saturn. The closest these two planets have appeared from earth in 800 years.

Here’s how I got this photo.

I captured this photograph using a Nikon D500 and the Nikkor 200-500mm VR lens shortly after sunset at 5:22:57 PM MT on December 21st, 2020.

I’ve seen a number of photos of this and many of those shots seem to be missing some of the detail I managed to capture with my camera setup. I’m not saying that my shot is all that great, but I did seem to get something many photographers missed, and I can share what I did different and what makes a difference when you are working at the very edge of your camera’s capability.

The shot isn’t that complicated nor challenging, if you know what to do. I’ll explain how I squeezed every bit of capability from my gear with the hope that someone out there may find it useful the next time they try such an extreme image.

The first challenge was the weather. I was lucky enough to have a perfectly clear sky this evening. Both planets were quite visible with the naked eye about 10-15 degrees above the south western horizon shortly after sunset. I had a perfectly clear straight line of sight from the front porch of my house. My front porch is boxed in, meaning there was a wall behind me and to my left and a roof over my head. This kept the risk of wind creating vibrations by blowing my camera around to an absolute minimum. My biggest concern was the low angle on the horizon, as atmospheric distortion from the earth could play a big role in how well I could capture these tiny specs of light. The closer your look angle to the horizon, the more distortion you will get. The trick was to catch this scene early, not late in the cycle as the earths rotation was pushing these subjects closer to the horizon with every second wasted, thus making the shot more difficult to obtain as time passed.

I used a Slick heavy duty tripod with a ball head mount. The lens was mounted directly to the ball head in a gravity centric location and I could reposition the look angle easily and securely. Everything about the mount was rated for far more weight than my rig presented. At a 32 lb weight rating, my camera and lens weighed less than 10 lbs. Nice and sturdy, very minimal potential for excessive vibration.

My porch is made of 6 inch thick concrete. This gave me a very secure and stable mounting point for the tripod with no vibration coming from the ground.

I played with a couple of different cameras and concluded that my Nikon D500 was the best camera in my kit for getting this photo. I could choose between the Nikon D850, D810, D750 and D500. My initial test shots were with the D850 but I wasn’t happy with the results. When I switched to the D500, things improved. I ruled out the other two cameras, as they were not likely to give me as good of a result as the D850, and the D850 wasn’t quite getting it done.

Common logic indicates that full frame cameras are going to give you a better image file than a crop sensor camera. In a lot of cases that thinking is true, but understanding what I was trying to do, capturing a very clear and detailed image of a very very small dot in the sky was going to result in an image where the subject matter was going to be extremely magnified by cropping. The more pixels I could throw at the image subject, the better off I was going to be getting fine detail of the rings around Saturn and of the most visible moons orbiting Jupiter. The photo you see here is cropped to 445 x 297 pixels. Not a lot of image left over once I zoom in on the subjects. Every pixel counts in these situations. The best way to throw more pixels at the subject is to use the camera that has the smallest pixel size, thus giving me more pixels per unit of measure. Here’s what I had to choose from.

Nikon D750 pixel pitch = 6.0 µm

Nikon D500 pixel pitch = 4.2 µm

Nikon D810 pixel pitch = 4.9 µm

Nikon D850 pixel pitch = 4.3 µm

Pixel pitch is the physical size of each pixel on the sensor and is measured in micrometers. The lower number the pixel pitch, the more pixels that are crammed into a given unit of sensor size. As you can see, the D500 has the smallest pixel pitch, thus it was going to give me the most pixels to work with at an extreme crop. The D850 is very close in pixel pitch to the D500, but other factors led me to choose the D500 over the D850, which I’ll explain later. I’m using the camera that is going to give me the most raw detail at a microscopic level. Every little tiny difference is going to count in this situation.

Exposure requirements aren’t exceptionally difficult here. I’m photographing sunlit objects in low light. The light coming from the planets is reflected light, not transmitted light. It’s the sunlight bouncing off the planets and returning to earth. Exposure times should not be extreme. Since I was using a 500mm focal length with a 1.5x crop factor, I use the rule of 500 to calculate the maximum shutter speed I can use to freeze the stars in the scene before the earth’s rotation cause the planets to noticeably move in the frame during exposure and thus removing detail from the tiny specs of light.  The rule of 500 is divide 500 by the focal length (field of view) to give me the maximum exposure time I should use. In this case, it was 500/750 = .66 seconds. I came up with the 750 by multiplying my lens focal length by the 1.5x crop factor of the sensor (500mm x 1.5 = 750), which is the actual field of view of the lens in this situation.

Focusing on the planets is probably the most critical aspect of this shot. I tried using autofocus through the viewfinder, manual focus through the viewfinder, autofocus using live view and manual focus using live view. My best focusing result was using autofocus in live view on the D500. I just called up the scene on the LCD screen, zoomed in to maximum magnification and touched the screen on Jupiter, and the camera used contrast detection to focus the image. It was consistent and gave me the best results. Interestingly, the D850 live view autofocus doesn’t seem to be as good as the D500. Both cameras use the same autofocus system, but they obviously aren’t dialed in identically. I suspect it has to do with how well the camera can focus in low light, and the D500 proved to be superior in this case. Manual focus was a waste of time. It’s impossible to keep the image steady at extreme magnification while you handle the lens focus ring. Too much jiggle to get it sharp as a tack. The viewfinder focusing wasn’t as good either. I’m really impressed at the capability of the Nikon D500 to get shots other cameras can’t get. Don’t be fooled by it being a crop sensor camera. Operationally, it’s a cut above just about every other camera I’ve ever used. The D850 will shoot in crop mode and is very close to the D500 in functionality and resolution, but there is a difference, be it tiny, and that tiny bit makes a difference here.

I’m using DSLR’s but some of you may have mirrorless cameras. There’s no reason a mirrorless couldn’t do just as well or even better. Mirrorless use contrast detect focusing at the sensor, similar to a DSLR in live view, and perhaps even better. It’s going to come down to your sensor pixel density and the ability of the mirrorless camera to focus in low light. Not all cameras are the same, so your mileage may vary.

Your lens is going to play a big part in how much detail you can squeeze out of a scene like this too. From a practical standpoint, I think you’ll need at least a 500mm lens focal length. Anything less and you just won’t get the magnification and detail you’ll need to see the rings around Saturn. The quality of your lens optics will play a role here too. Better lenses are sharper with less optical distortions. I’d estimate that any modern super-zoom such as the Tamron 150-600, Sigma 150-600, Nikkor 200-500 or other newer, similar lenses will get it done. I think you’ll struggle at 400mm and anything less will not get you there optically.

One could try a teleconverter to increase magnification, but I tend to shun teleconverters in general as you loose some sharpness and the increase in magnification doesn’t mean you’re getting a sharper image. I didn’t try using one on this scene, but you may have success using one if you have a very sharp 500mm or longer lens with a lot of pixels to throw at the image.

My camera settings for this shot were as follows. I’ll throw in an explanation for each setting as well.

Aperture = f/8.  I used this aperture because that’s about the sharpest aperture for the lens I used. Depth of field is meaningless in this photo because the planets are millions of miles away and there is no foreground or background. I wanted as sharp an image as the lens could generate and f/8 is the sweet spot.

ISO = 100.  Best image quality is going to be at base ISO on any camera. You can shoot up to ISO 1600 without introducing a lot of digital noise into your shot, but at base ISO, you are using the full well depth of each pixel and capturing the most dynamic range of color and frequency response of the light. Set your camera up to get the absolute best result. Noise in the image is not an issue at ISO 100.

Focal length = 500mm. I’m zoomed in as far as the lens will go.

Shutter speed = 1/5 second. That’s 200 milliseconds. That keeps me below the .66 second exposure time limit and the faster your shutter speed, the less movement you’ll see in your planets due to the earth’s rotation. I could have probably cut the exposure time to 1/10 of a second by using ISO 200 and it would have worked okay. But, this is where I ended up.

Vibration reduction on the lens was disabled. Some lenses can be used on a tripod with image stabilization enabled as they will shut themselves off but I’ve seen image stabilization cause problems at a microscopic level even if they detect the tripod and in some cases it can completely ruin a photo, just by running those tiny little motors and generating micro-vibrations. Turn your VR off, and that included the in body stabilization too. The camera doesn’t need to be controlling image stability in any way to get this shot if you have a good stable tripod to shoot from.

Take the camera strap off your camera. All it will do is wiggle around and cause vibrations.

Use a remote shutter release or set the camera timer for 30 seconds. Even touching the remote shutter release will generate vibrations in your camera, so secure it and don’t let it move in the least when you snap the shutter button. I’ve also seen images where even 30 seconds delay isn’t enough for vibrations to dampen out. Use mirror lockup on your DSLR or use Live View, as in live view the camera’s mirror is already out of the way and won’t be moving when the shutter fires.

Focus the planets as close to the center of the frame as possible. That’s the sweetest part of your lens and you’ll need every tiny bit of sharpness for this shot.

My technique using live view.

Frame the subjects slightly away from the center so that the center of the frame is where the planets are moving towards, use live view to autofocus on the planets then disable autofocus. You don’t want your camera to refocus when you take the shot, it could screw it up. Allow the camera to sit while the planets move closer to the center of the frame, then gently push the remote shutter release without tugging on it or letting it flop around. Be as still as possible during the entire process. Let the camera vibrations dampen out before touching the shutter button and don’t move the release while the camera fires its shot.

Post Processing.

I edited this image in Adobe Lightroom. Nothing fancy was done here. I made a few tweaks to exposure, contrast, highlights and tone curve, added some sharpening and cropped it down to a .2 megapixel original.

I hope this gives you an idea of how to get a shot like this.