Freewell 1.7X Telephoto Lens & Samsung S23 Ultra
May 28, 2024
The Freewell 1.7X Telephoto lens provides good performance as an add-on lens for the S23 Ultra smartphone using
Freewell's well designed snap-in/rotate case. Although the magnification at 1.7 isn't very high, it provides a useful
FOV between the X1 and X3 camera lenses of the S23 Ultra and the larger lens aperture means significantly more light-gathering
capability and presumably increased image resolution. It should be emphasized that the Freewell design only
makes this lens useful when used with the X1 main camera of the S23 ultra.
The results below are photos taken with a tripod of a daytime scene
with and without the 1.7X external lens, and a first shot of the Big Dipper with and without the 1.7X lens. In all
cases, manual focus in either Pro or Expert Raw/Astro mode was used to achieve the sharpest focus.
The FOV of the S23 Ultra X1 12 Mp camera alone is 57x72 °. With the Freewell 1.7X lens attached, the FOV is
measured to be 37X48 °
The daytime shot was focused on the distant roof vent near the image centers.
Image at left is the X1 camera alone. The image at right with the 1.7X Freewell lens added shows
good focus in the house roof area and the image quality is comparable to the image to the left without the external lens. The image quality is very good over the entire FOV (except of course for the blurred nearby parts of the image). Click each image for a full view of the photos):
The star photographs of the Big Dipper region below were taken on a slightly hazy evening. The lens hood (included with the 1.7 Telephoto lens) is helpful to reduce any spurious reflections from any nearby light sources. To obtain sharp star images, it is essential to very carefully adjust the
focus manually. The optimum manual focus setting for "infinity/stars" on the S23 Ultra is different for the X1 camera alone (mine is 0.90), compared to with the extra 1.7X lens (0.80 with my setup). Some trial and error helps to optimize this setting.
These photos were taken in a medium dark suburban sky (Bortle ~ 4.5).
The photos were taken at about the same time ~10:30 pm EDT May 27, 2024.
Photo at left is X1 S23 camera alone: Pro mode, ISO-800 t=8sec.
Photo at center is with X1.7 Freewell lens: Pro mode, ISO-800 t=8sec.
Photo at right is with X1.7 Freewell lens: Expert Raw/Astro mode: ISO-3200 4min/5sec (stacked).
Star images with the X1.7 lens added are quite sharp for a lens in this price range. Some vignetting is seen in the corners. Stars down to ~ Mag 11 are visible in 4 min exposure. On a clearer night, one can expect to see fainter stars as well as several deep sky objects. Overall, this Freewell 1.7 Telephoto is a respectable lens for small zoom requirements and performs nicely for wider field astrophotography with a smartphone.
Click each image for a full screen view:
