Sony A7III - real life star eater images

Tristimulus · Apr 30, 2018

Just sharing two star eater images from the A7III.

Tracked stars, CZ 2/135mm lens at f/8 (bright sky here now, am a northener). This is from the JPG series, but the RAW files look just the same (star eater affected).

Yes - the star eater issue is there.

NOTE: This will be a non issue for ordinary images and wide angle astroscapes. The ones affected are demanding astrophotographers with first class optics!

Have no intention to start a discussion - just showing real life as it is.

Test image 1: Sony A7III 3.2 sec exposure at ISO 800 - 100 % crop.

Test image 2: Sony A7III 4.0 sec exposure at ISO 800 - 100 % crop.

The Davinator · Apr 30, 2018

interesting. I do a bit of astrophotography and this would be an issue.

JimKasson · Apr 30, 2018

Trollmannx said:
Just sharing two star eater images from the A7III.

Tracked stars, CZ 2/135mm lens at f/8 (bright sky here now, am a northener). This is from the JPG series, but the RAW files look just the same (star eater affected).

Yes - the star eater issue is there.

NOTE: This will be a non issue for ordinary images and wide angle astroscapes. The ones affected are demanding astrophotographers with first class optics!

Have no intention to start a discussion - just showing real life as it is.

Test image 1: Sony A7III 3.2 sec exposure at ISO 800 - 100 % crop.

Test image 2: Sony A7III 4.0 sec exposure at ISO 800 - 100 % crop.

The color shifts are the big gaveaway for me, and, I think for most folks, more of a problem than the luminance differences.

Jim

--

the last word the last word - Photography meets digital computer technology. Photography wins -- most of the time.

Photography meets digital computer technology. Photography wins -- most of the time.

blog.kasson.com

sharkmelley · Apr 30, 2018

Thanks for that - a useful experiment!

It's quite obvious when blinking the 2 images.

Mark

Sugasmune · Apr 30, 2018

What about doing 100 shots with electronic shutter at 1/30 and blending them together?

The Davinator · Apr 30, 2018

Sugasmune said:
What about doing 100 shots with electronic shutter at 1/30 and blending them together?

Aside from being more work, the final signal to noise won't be as good.

sharkmelley · Apr 30, 2018

Sugasmune said:
What about doing 100 shots with electronic shutter at 1/30 and blending them together?

In other words, suffer 100 contributions of read noise for a 3sec total exposure?

Mark

--
Takahashi Epsilon 180ED
H-alpha modified Sony A7S
http://www.markshelley.co.uk/Astronomy/

bclaff · Apr 30, 2018

Fun, perhaps this animated GIF makes it even clearer:

You must view as 'original size' to see the animation.

Regards

--
Bill ( Your trusted source for independent sensor data at PhotonsToPhotos )

rgwaller1 · Apr 30, 2018

You are right. I can not see the missing stars. The question I have is how I would know the stars are missing if I can not see them to start with.

The Davinator · Apr 30, 2018

sharkmelley said:
Sugasmune said:

What about doing 100 shots with electronic shutter at 1/30 and blending them together?

Click to expand...

In other words, suffer 100 contributions of read noise for a 3sec total exposure?

Mark

sharkmelley · Apr 30, 2018

The Davinator said:
sharkmelley said:

Sugasmune said:

What about doing 100 shots with electronic shutter at 1/30 and blending them together?

Click to expand...

In other words, suffer 100 contributions of read noise for a 3sec total exposure?

Mark

Click to expand...

sharkmelley · Apr 30, 2018

rgwaller1 said:
You are right. I can not see the missing stars. The question I have is how I would know the stars are missing if I can not see them to start with.

You wouldn't necessarily know stars are missing.

But if you were a lover of astronomy you would find the purple, pink and green blobs left behind by the spatial filtering algorithm to be very strange. Hint - real stars are never this colour!

But star eating and remnant coloured blobs are the most obvious effects of the spatial filtering. Other effects are a general loss of detail (i.e. blurring) and a characteristic worm-like noise pattern.

To be honest, only the most discerning imagers are likely to notice these effects - i.e. the type of imagers that might pay $2000-$4000 for a camera body.

Mark

--
Takahashi Epsilon 180ED
H-alpha modified Sony A7S
http://www.markshelley.co.uk/Astronomy/

Sugasmune · Apr 30, 2018

The Davinator said:
Sugasmune said:

What about doing 100 shots with electronic shutter at 1/30 and blending them together?

Click to expand...

Aside from being more work, the final signal to noise won't be as good.

Is there even software that can blend 100 shots together? A lot work, but maybe for the a7III the sky would show more stars.

AstroDan · Apr 30, 2018

Stacking 100 frames is intensive, but isn't an issue for most dedicated astrophotography suites.

I typically use my 6D for astro, but if we can get some clear nights here I will try and add a few frames at 3250mm with my a7iii for context for the 'star eater' on an oversampled field.

Dan

The Davinator · Apr 30, 2018

sharkmelley said:
The Davinator said:

sharkmelley said:

Sugasmune said:

What about doing 100 shots with electronic shutter at 1/30 and blending them together?

Click to expand...

In other words, suffer 100 contributions of read noise for a 3sec total exposure?

Mark

Click to expand...

Click to expand...

sharkmelley · Apr 30, 2018

The Davinator said:
Better computer time than my old days of manually guiding 90 minute exposures on hypered Tech Pan

I admire folk like you who used to do it the hard way - film cameras and manual guiding!

I've had it easy - I didn't start astrophotography until the age of digital cameras.

Mark

Tristimulus · May 1, 2018

sharkmelley said:
The Davinator said:

Better computer time than my old days of manually guiding 90 minute exposures on hypered Tech Pan

Click to expand...

I admire folk like you who used to do it the hard way - film cameras and manual guiding!

I've had it easy - I didn't start astrophotography until the age of digital cameras.

Mark

JimKasson · May 1, 2018

Sugasmune said:
What about doing 100 shots with electronic shutter at 1/30 and blending them together?

I see no advantage in reducing exposure times below 3.2 sec in these circumstances.

No account anymore · May 2, 2018

Good, then we know!

Would be great to see pictures of stars tracked for 3.2 sec, 4, sec, 8, sec, 15 sec, 30 sec, and Bulb up to 60 seconds, and also stacked versions from all settings to a total of 60 seconds. ;-)

Tristimulus · May 2, 2018

Magnar W said:
Good, then we know!

Would be great to see pictures of stars tracked for 3.2 sec, 4, sec, 8, sec, 15 sec, 30 sec, and Bulb up to 60 seconds, and also stacked versions from all settings to a total of 60 seconds. ;-)

Bright nights here for now, but the asked for images will pop up after a wonderful summer fade away and give room for those cozy dark autumn nights - then...

Sony A7III - real life star eater images

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