N
No account anymore
Guest
When I got some clear skies, I had to test my A7IV and the spatial filtering, better known as the Star Eater. This is part of my process of learning my camera gear to know, and also to avoid internet myths and desinformation.
Set up: Camera with Sony G 40 mm f:2.5 lens on a tracker and a Gitzo series 5 tripod for absolute sturdiness. Uncompressed RAW. All my lenses shorter than 300-400 mm will show some effect of the Star Eater. From earlier tests results, I went for the 40 mm, since spatial filtering is easiest noticed with this lens on my A7rIII. Now I am testing the A7IV.
First step on my to-do list is checking where the spatial filtering kicks in. At 3.2 sec exposure there is no filtering, but at 4 sec I could notice some background smoothing going on when pixel peeping at 100%, also affecting very faint stars.
I used manual focus, and repeated the focus setting since turbulent air will normally be an issue. The examples posted here are from the sharpest files. ISO 400, where second gain kicks in, since I never ever do night sky photography at base ISO. I can't think of others doing this either, since pushing base ISO files beyond 2. gain level will show more noise and don't offer more useable dynamic range.
With 4 sec exposure, only fainter stars than about magnitude 10 (!) was affected visibly at 100% pixel peeping. These stars are not well saturated at such short exposures anyway, with an effective aperture of 16 mm. The cropped star field presented here is part of the constellation Bootes.
For photographers using the A7IV on a tripod for night sky photography, the Star Eater means nothing at all. For astrophotographers using lenses for wide field (up to 200-300 mm focal lenght) and a precision tracker, you might lose the faintest stars, but this will not affect the visual appearance of aestethical astrophotos. With medium to long telephoto lenses, the Star Eater will not have any practical effect, due to image scale and turbulence.
Conclusion: Use your A7IV with confidence for any kind of night sky, polar light or astrophotography, no matter if the camera is put on a tripod or you are using a good tracking device.
The pictures and little animated GIF posted here supports my arguments and conclusion.
Before the Star Eater kicks in - 100% pixel.
After the Star Eater kicks in - 100% pixel.
Animated GIF 100% pixel - 3.2 and 4 sec. (To start the GIF, double-click at 100% view)
A more typical night sky exposure, 100% crop. Astrophotographers will use lots of short exposures like this one, and stack them to a long exposure file.
Set up: Camera with Sony G 40 mm f:2.5 lens on a tracker and a Gitzo series 5 tripod for absolute sturdiness. Uncompressed RAW. All my lenses shorter than 300-400 mm will show some effect of the Star Eater. From earlier tests results, I went for the 40 mm, since spatial filtering is easiest noticed with this lens on my A7rIII. Now I am testing the A7IV.
First step on my to-do list is checking where the spatial filtering kicks in. At 3.2 sec exposure there is no filtering, but at 4 sec I could notice some background smoothing going on when pixel peeping at 100%, also affecting very faint stars.
I used manual focus, and repeated the focus setting since turbulent air will normally be an issue. The examples posted here are from the sharpest files. ISO 400, where second gain kicks in, since I never ever do night sky photography at base ISO. I can't think of others doing this either, since pushing base ISO files beyond 2. gain level will show more noise and don't offer more useable dynamic range.
With 4 sec exposure, only fainter stars than about magnitude 10 (!) was affected visibly at 100% pixel peeping. These stars are not well saturated at such short exposures anyway, with an effective aperture of 16 mm. The cropped star field presented here is part of the constellation Bootes.
For photographers using the A7IV on a tripod for night sky photography, the Star Eater means nothing at all. For astrophotographers using lenses for wide field (up to 200-300 mm focal lenght) and a precision tracker, you might lose the faintest stars, but this will not affect the visual appearance of aestethical astrophotos. With medium to long telephoto lenses, the Star Eater will not have any practical effect, due to image scale and turbulence.
Conclusion: Use your A7IV with confidence for any kind of night sky, polar light or astrophotography, no matter if the camera is put on a tripod or you are using a good tracking device.
The pictures and little animated GIF posted here supports my arguments and conclusion.
Before the Star Eater kicks in - 100% pixel.
After the Star Eater kicks in - 100% pixel.
Animated GIF 100% pixel - 3.2 and 4 sec. (To start the GIF, double-click at 100% view)
A more typical night sky exposure, 100% crop. Astrophotographers will use lots of short exposures like this one, and stack them to a long exposure file.
Last edited:
