Bahtinov Mask Test with Seestar S50: Does it Really Improve Focus?

Many have claimed that a Bahtinov mask might not be necessary when using the Seestar S50, as it already features an effective autofocus system. To explore whether this accessory could provide additional benefits, we conducted a real-world test to assess its usefulness in astrophotography with the Seestar S50.

Testing the Bahtinov Mask on Seestar S50

We performed the test by pointing the Seestar S50 at Delta Lyrae, located near the zenith, on a clear late summer night with minimal jet stream interference in a Bortle 4 sky.

Initial Autofocus Results

First, we initiated the Seestar's autofocus, which locked in at a value of 1598. We took the first picture with a standard exposure of 10 seconds.

Using the Bahtinov Mask

Next, we placed our Bahtinov mask on the lens and observed the diffraction pattern. While the initial pattern was acceptable, it wasn’t perfectly centered. We adjusted the focus manually, fine-tuning it to a value of 1605, and then took another photo with the same 10-second exposure.

Mask Installation Ease

Our model of Bahtinov mask is designed for ease of use, allowing for quick installation and removal without disturbing the telescope’s position. This functionality ensures that you can test and fine-tune your focus easily without affecting your setup.

Test Results: Visual Differences

The images we used for comparison were single shots with 10-second exposures, with no post-processing applied. This method allowed us to evaluate the focus on the faintest background objects, ensuring we only compared the focus itself. We avoided stacking or processing images of deep-sky objects, which would have introduced variables affecting the test's conditions.

Initially, the two images seemed identical when viewed on a smartphone. However, a more detailed analysis on a computer revealed subtle differences in focus, particularly in the clarity of faint background objects.

The optimal focus value we achieved using the mask didn’t differ significantly from the autofocus result. However, the improvement in sharpness was clear, indicating that the mask provided a noticeable benefit, especially when evaluated on a larger screen. The improved focus also enhances the final results from longer tracking sessions.

Conclusions from Our Test

Our test showed that while the autofocus feature of the Seestar S50 works very well, there is still room for improvement. A well-designed Bahtinov mask, like the one we offer, can fine-tune focus and enhance the precision of your astrophotography, especially for more discerning photographers aiming for perfection.

For serious astrophotographers, the slight focus improvement offered by a mask can make a significant difference. It’s important to ensure that the mask is specifically designed for your telescope, as a poorly designed mask could have the opposite effect.