Seestar S50 Pro vs. S50: How Much Better Is It Under Bortle 8 Skies?

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    When ZWO asked me to put the new Seestar S50 Pro to the test, my first thought was to compare it with the S30 Pro, the other model currently in production. However, after reading the questions and comments I received, I realized that the most interesting comparison was actually a different one: how much of an improvement is the new S50 Pro over its predecessor, the S50?

    An important note: the photographs you are about to see are in no way intended to represent the true potential of these smart telescopes. I carried out the tests from my balcony, under Bortle 8 skies, with fairly high levels of ambient light and an 80% illuminated Moon. To give you an idea of the conditions under which the tests were conducted, I’m also including a photograph of my balcony.
    The integration times were deliberately kept relatively short and, in no case, exceeded one hour.
    I also chose to focus more on the raw stacks, straight out of the Seestar, rather than on external post-processing.
    So, please consider these images solely as a direct comparison between the two instruments, rather than as a demonstration of their full potential.

    Technical Specifications

    The S50 Pro features a 4-element APO optical system, like the S30 Pro, whereas the S50 used a 3-element APO. It has a focal length of 260 mm and a 50 mm aperture.
    The S50 Pro also features two 4K cameras with a resolution of 2160 × 3180 pixels, or 8.29 MP, twice the resolution of the S50, which means four times as many pixels.
    The field of view (FOV) of the wide-angle camera is 63°, while the telephoto camera has a 2.8° FOV, again twice that of the S50. With mosaic mode, the field of view can be expanded even further, effectively doubling it again.
    The sensor has characteristics similar to those of the S30 Pro, both for the main and wide-angle cameras, with some differences that favor the new model.
    Another major improvement is the battery: capacity has increased from 6,000 mAh on both the S50 and S30 Pro to 10,000 mAh on the S50 Pro.
    Internal storage has also doubled compared to the previous model.
    The tripod has been redesigned as well. It can extend and spread wider than the S50’s tripod, providing greater stability, especially when the telescope is used in equatorial mode. The S50 Pro will also come with a solar filter, which covers the wide-angle camera as well, just like the other ZWO smart telescopes.
    In particular, I consider the addition of the wide-angle camera to be a major improvement. It is not only useful for making the pointing process easier, but also opens up new possibilities for astrophotography, from Milky Way and nightscape photography to meteor capture, time-lapses, and star trails.

    Field of View (FOV)

    The wider field of view compared to the S50 is one of the most interesting strengths of the new model.
    It makes it much easier to frame large, extended objects without having to create mosaic after mosaic. To give you an immediate idea of the difference, below I’m showing the field of view of Andromeda with the S50, S50 Pro, and S30 Pro. Keep in mind that the field of view can be doubled using mosaic mode if desired.

    Aperture and Image Quality

    With the same integration time, aperture still makes a difference: when it comes to fine detail, the two 50 mm models outperform the S30 Pro.
    However, the S50 Pro also shows clear improvements over the previous S50. Fainter details appear sharper, colors are more pleasing and, in my opinion, more accurate, while noise is significantly better controlled compared to both the S50 and the S30 Pro.
    The stars also look cleaner and more pinpoint, including toward the edges of the field of view.
    (In order: raw S50 stack, raw S50 Pro stack, processing with the Seestar app, and processing with PixInsight. No mosaic. 40 minutes of integration, under a full Moon and Bortle 8 skies.)

    Tracking Performance

    Another aspect that particularly impressed me is the improvement in tracking performance.
    In EQ mode, I experienced almost a 0% rejection rate, while in alt-azimuth mode, with 30-second exposures, less than 10% of the frames were rejected.
    With the S50, by comparison, I rarely went beyond 10-second exposures, and even then, the number of rejected frames was relatively high.

    Moon

    I also tested the S50 Pro on the Moon.
    The wide-angle camera is particularly useful for pointing and can be a great help if the automatic GoTo fails to center the target on the first attempt.
    The S50 Pro offers a wider field of view, while the level of detail, under the same conditions, remains essentially comparable to that of the S50. However, the improved optics reduce aberrations and produce an image with better contrast and sharper details.
    The color rendition also appears different compared to the S50: I found the Pro’s color calibration to look more natural and pleasing.
    Here are three unprocessed images, straight out of the Seestar.

    Portability

    When it comes to size, the S50 Pro is only slightly larger than the S50 and weighs around 300 grams more. The S30 Pro remains the true champion of portability, thanks to its compact dimensions and a weight of just 1.6 kg.

    Image Processing

    Like its predecessors, the S50 Pro offers several image-processing options directly within the app.
    You can use tools for star removal and reduction, noise reduction, cropping and rotation, as well as image optimization and background extraction using DBE, which helps improve background uniformity.
    It is also possible to download the individual raw frames and stack and process them using dedicated astrophotography software such as Siril or PixInsight. Dark frames are subtracted automatically; it would be great to have the option to access them separately in the future.
    Personally, this is the workflow I prefer, as it gives me much greater control over the final result. However, I appreciate that Seestar offers different levels of flexibility, allowing even users who do not want to spend time on post-processing to achieve satisfying results directly within the app.
    And, of course, the S50 Pro retains all the main strengths of the other Seestar smart telescopes:
    • ease of use;
    • simplicity;
    • portability;
    • an affordable price considering what it offers.

    Conclusions

    In summary, I consider the S50 Pro a truly significant improvement over its predecessor, the S50. The improved optics, capable sensor, image quality, wider field of view, addition of the wide-angle camera, and improved tracking make it, in my opinion, one of the most complete smart telescopes in its class.
    If I had to choose just one smart telescope, I would have no hesitation in choosing the S50 Pro. If I could add a second instrument, however, I would choose the S30 Pro — not so much for its performance, but for its outstanding portability, which makes it the ideal companion when size and weight are a priority.
    I’ll leave you with a selection of images captured with the S50 Pro and subsequently processed in PixInsight. Once again, integration times did not exceed one hour, with the exception of the Veil Nebula, and all the images were captured under Bortle 8 skies.
    The images have also been cropped, but no mosaics were used.


    Author: Emma Pezzi


     

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