As should be obvious for anyone that follows my photography, I enjoy creating images at night. As I’ve developed my skills, I have progressed from just being excited that I was able to take a decent shot at night, to trying to render the Milky Way well over a landscape, to striving to create nightscape compositions that would be compelling even if they weren’t taken at night. One aspect of this is researching locations, moon phases, star charts, and sometimes tides to get the lighting and elements that I want for my photo. Another aspect is gear.
If you want a photograph of the night sky that has pinpoint stars, you have a limited time to expose the scene. If the shutter is open too long, then the stars begin to look like small streaks in the sky rather than points. At the same time, you need to let enough light reach your camera sensor to properly expose thje photo. Using a wide lens gives you more time, since the extra field of view keeps the stars, even if they streak a little, small. A fast 14mm lens (like the Sigma 14mm f/1.8 or the Samyang 14mm f/2.4) is a popular choice and I have used both lenses a lot. However, I really like using a 24mm lens for Milky Way scenes at it keeps the landscape larger in the frame and the dense Milky Way core can take center stage in the sky.
There have not been many great choices for Canon cameras for a fast 24mm lens for night photography. Canon’s older EF 24mm f/1.4 tends to exhibit bad “coma” in the corners, rendering the stars light bat wings rather than as points. This can be improved by cropping the image or by closing the aperture somewhat, but this defeats the purpose of buying a fast 24mm lens. Most of my 24mm night photographs over the last several years have been taken with a Samyang 24mm f1.4 lens. This lens has the advantages of being small, relatively cheap, and rendering stars very well in the corners. It is also manual focus, manual aperture, tends to have quality problems, and tends to be soft with a lot of vignetting when used wide open. I almost always stop it down to f/2 to improve the image quality, but again this defeats the purpose of using this lens.
Canon has finally released a new fast 24mm lens for R-series mirrorless cameras. The RF 24mm f1.4L VCM is similar to many of Canon’s other recent offerings in that it requires digital corrections to be applied in-camera in order to bring out the full quality of the system. Early reports from people with the lens were that the result is of very high quality, with excellent sharpness and contrast. None of those reports, though, answered my main question: how does this lens render stars wide open? I decided to give it a try myself, knowing I could return the lens if it didn’t meet my needs.
Unfortunately I have only had cloudy nights since the lens arrived. I did have a brief period where I could see stars the other night so I set up and managed a few frames before they disappeared again. I’ll edit this post in the future to provide more information how the lens behaves at different apertures, but my main interest is wide open at f/1.4 so that what I used for this first test.
The image above was captured with the Canon R5 camera and the RF 24mm f/1.4L VCM lens wide open. No sharpening or noise reduction were applied although Canon’s digital profile was used. The image at the top of this post is from the same file, with some edits for color and contrast to look a little more how I might process it. At this resolution the image looks good. The real test, though, is in the corners. Below are 100% crops.
The top left corner looks good, with just a small amount of coma in the brighter stars, The right corner looks a little worse, I believe because it includes more bright stars and because it is looking more to the east, where the trailing associated with the 10s exposure would be longer than the left corner which looks more to the north.
Update to include aperture comparisons
I captured the scene below at three different apertures (f/1.4, f/2.0 and f/2.8) with all other settings the same to see how the star rendering changed as I stopped the lens down. I attempted to equalize the exposures in Photoshop since this is how I would actually use the lens for night photography – I usually shoot at the longest shutter speed that I can tolerate to avoid star movement and the ISO that gives me the best noise performance (usually ISO 1600 on my Canon R5). The images are provided below as well as a crop into the top-left corner of each. The noise increased as I pushed the exposure, as expected, but the stars looked good in all three photos. With this in mind, I would be perfectly comfortable using this lens at f/1.4.
I did get a chance to capture some purple aurora over a local barn. The image below was captured at f/1.4 and ISO 1000.
Update with Comparisons to Other Lenses at 24mm
Much has been made online of the in-camera distortion corrections necessary for the 24mm VCM lens. I decided to take a look at how it performs for sharpness and contrast relative to other lenses that I have used for night photography. The first image below was captured with the RF 24mm f/1.4 VCM lens at f/1.4 and focused on the center of the frame. No sharpening or noise reduction was applied and this version does NOT include the distortion or vignette corrections that would typically be applied by the camera. In this image you can see the warping around the corners and in heavy vignette in the extreme corners.
The same image, but with the distortion corrections applied (via Lightroom), is shown below. You can see that the field of view has been reduced (to 24mm) and the issues with the corners resolved. I did not apply any vignette corrections to this image.
Stopping the lens down to f/2.8 brightens the edges as shown below.
For comparison, the following images were captured with the Samyang 24mm f/1.4 lens (at f/1.4 and f/2.8) and the Canon RF 15-35 f/2.8 lens. Each of these had the same processing (distortion correction but not vignette correction) as the RF 24mm above.
One of my first conclusions was that I was correct in my use of the Samyang 24mm lens in that it definitely needs to be stopped down for both sharpness and vignette control. It really does not perform well when wide open. I’ve also created 100% crops in the center and the top-left corner that compare how the lenses perform at full resolution. The first image simply shows how the performance of the RF 24mm VCM lens changes as you stop down from f/1.4 to f/2.8.
Having good center performance was expected. The real question was how well do the corners hold up with that distortion correction? Here is the same series of comparisons at the top left corner of the image.
The following photos were NOT taken with this lens. They are examples of 24mm nightscapes since I like to include at least something attractive for anyone that has read this far.
I had never heard so Samyang camera. But according to its results while taking a photo means it isn’t a bad camera type as well.