How to see all stars & other small details on pics?

Started 2 months ago | Questions
Thomas1975 New Member • Posts: 2
How to see all stars & other small details on pics?
1

I´m in trouble with my 7RIV.

It cleans a lot of stars, when I take night shots. Also, photographing colourful patterns with a lot of small details, my camera "swallows" details.

I´ve used different lenses, so this is no lens problem. The previuos published "star eater phenomenon" should´nt be existing with the 7RIV, Sony service told me.

I´ve switched off all picture improving things.

Anyone some tipp for me?

Thanks

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JimKasson
JimKasson Forum Pro • Posts: 27,469
Chomp, chomp
4

Thomas1975 wrote:

I´m in trouble with my 7RIV.

It cleans a lot of stars, when I take night shots. Also, photographing colourful patterns with a lot of small details, my camera "swallows" details.

I´ve used different lenses, so this is no lens problem. The previuos published "star eater phenomenon" should´nt be existing with the 7RIV, Sony service told me.

The a7RIV eats stars:

https://blog.kasson.com/a7riv/sony-a7riv-raw-spectra-vs-shutter-speed/

Jim

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Lan Senior Member • Posts: 1,379
Re: How to see all stars & other small details on pics?
2

Jim is correct; as usual.

However, please can you post some samples Thomas? It's possible that you're suffering from heavy handed high ISO NR, or shake issues. Star eater only generally eats faint stars, for most non-astro uses star eater shouldn't be noticeable? I photograph landscapes with an A7R4, and there's plenty of fine detail.

Astrophotographer 10 Forum Pro • Posts: 13,379
Re: How to see all stars & other small details on pics?
1

Thomas1975 wrote:

I´m in trouble with my 7RIV.

It cleans a lot of stars, when I take night shots. Also, photographing colourful patterns with a lot of small details, my camera "swallows" details.

I´ve used different lenses, so this is no lens problem. The previuos published "star eater phenomenon" should´nt be existing with the 7RIV, Sony service told me.

I´ve switched off all picture improving things.

Anyone some tipp for me?

Thanks

I don't know that any Sony eats any stars since A7iii. What it mainly seems to do now is turn faint stars that are pinpoints, green.

I use an A7riii often for nightscapes. Its still very capable. But I prefer the EOS R Canon because despite a bit more noise which goes with stacking, the star colours are a lot better than with the Sony.

But using 4X pixel shift and a tracker with LENR turned. HI ISO NR turned off, IBIS off, uncompressed RAW and manual focus with auto white balance I get more colour.

Star colour is very vulnerable to overexposure. If you are getting all white stars then turn the ISO down and boost in post until you have stable star colour.

The theory was A7riv may be less effect of the star eater because there are more pixels per star now with 61mp (50% more than A7riii). Whether that is true would have to be confirmed.

The main issue with A7riv is the extra noise but handled by taking several shots and stacking them same as with any camera.

As far as small details in daylight shots, I have never seen that. There are plenty of posts about the need to use faster shutter speeds with the A7riv so perhaps that is your issue.

Post some photos so we see this post is genuine.

Greg.

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sharkmelley
sharkmelley Senior Member • Posts: 2,320
Re: Chomp, chomp
2

JimKasson wrote:

Thomas1975 wrote:

I´m in trouble with my 7RIV.

It cleans a lot of stars, when I take night shots. Also, photographing colourful patterns with a lot of small details, my camera "swallows" details.

I´ve used different lenses, so this is no lens problem. The previuos published "star eater phenomenon" should´nt be existing with the 7RIV, Sony service told me.

The a7RIV eats stars:

https://blog.kasson.com/a7riv/sony-a7riv-raw-spectra-vs-shutter-speed/

Jim

Thanks for confirming the usual raw filtering behaviour. That's an interesting additional effect taking place horizontally in the blue channel. I wonder if it is related to the PDAF rows? Over on Nikon Z Mirrorless Talk, Jack Hogan recently showed similar horizontal blue channel behaviour in the PDAF rows of the Nikon Z7.

To the OP, are your image exposures 3.2sec or more, which is when the raw data filtering kicks in? Sony service will certainly tell you that the star eater issue is fixed in such long exposure images. But in reality Sony replaced the algorithm with a less aggressive one which tends to attenuate the brightness of sharply focused stars and turn them green. It can also has the side effect of reducing contrast in sharply defined tiny details of regular (i.e non-astro) long exposure images.

Mark

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Magnar W
Magnar W Senior Member • Posts: 4,356
Re: How to see all stars & other small details on pics?

Thomas1975 wrote:

I´m in trouble with my 7RIV.

It cleans a lot of stars, when I take night shots. Also, photographing colourful patterns with a lot of small details, my camera "swallows" details.

This is about what "Star Eater" do with the A7rIII when pixel peeping. The spatial filtering should probably have less effect on A7rIV files since this sensor has smaller pixels.

https://www.dpreview.com/forums/post/61784964?image=0

I´ve used different lenses, so this is no lens problem. The previuos published "star eater phenomenon" should´nt be existing with the 7RIV, Sony service told me.

Are your lenses focused manually and very precise? Most lenses will focus "beyond" infinity when relying on hard stop. And are you using very high ISO, or pushing the files a lot at post processing?

I´ve switched off all picture improving things.

Jpg or raw should not make any noticeable difference.

Try some exposures at 3.2 sec, pointing the camera close to the Polar star to avoid stretched stars caused by Earth's rotation. Thenb do the same with 4 sec exposure. Then you should be able to see the difference between no "star eater" and "star eater".

Anyone some tipp for me?

Would be very helpful if you posted some sample photos!

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Magnar W
Magnar W Senior Member • Posts: 4,356
Re: How to see all stars & other small details on pics?

Astrophotographer 10 wrote:

I don't know that any Sony eats any stars since A7iii. What it mainly seems to do now is turn faint stars that are pinpoints, green.

They do, but the effect seems to be less noticeable.

I use an A7riii often for nightscapes. Its still very capable. But I prefer the EOS R Canon because despite a bit more noise which goes with stacking, the star colours are a lot better than with the Sony.

Color is about profiles, unless you are looking for Hydrogen Alpha response (near-infrared). In this regard the new A7 cameras are better than previous models.

The main issue with A7riv is the extra noise but handled by taking several shots and stacking them same as with any camera.

About 1/3 more than the A7rII, which is excellent, should hardly be noticeable when comparing final work.

Post some photos so we see this post is genuine.

Sure. Without samples we can't help that much.

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Trollmannx Senior Member • Posts: 5,875
Re: How to see all stars & other small details on pics?
5

First post from a new members - most likely a hoax, but might be wrong...

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Have an astromodded Canon 6D - a highly acclaimed astronomy camera.

Have an unmodded Sony A7III (which has a worse star eater issue than the A7RIV)

And guess what:

The Canon recordi a bit more Ha light, after all it is modded to do that.

Both cameras record about the same limiting magnitude using the same lens and the same exposure under identical conditions!

Some very faint stars turn greenish with the A7III, but only very faint stars. This is obviously a result of how RGGB data passing the Bayer matrix is processed.

Some of the very faintest stars disappear but those stars are close to the detection treshold anyway and should not be vital for any amateur astronomy image anyway.

Professionals and serious amateurs stay away from ordinary digital cameras when doing spectroscopic and photometrically work - then other tools are needed.

Yes - the star eater issue is real, but the impact is far less than most imagine.

Sony A7III image:

Even my astromodded Canon 6D did NOT capture the stars missing here...

Astrophotographer 10 Forum Pro • Posts: 13,379
Re: How to see all stars & other small details on pics?
1

Magnar W wrote:

Astrophotographer 10 wrote:

I don't know that any Sony eats any stars since A7iii. What it mainly seems to do now is turn faint stars that are pinpoints, green.

They do, but the effect seems to be less noticeable.

I use an A7riii often for nightscapes. Its still very capable. But I prefer the EOS R Canon because despite a bit more noise which goes with stacking, the star colours are a lot better than with the Sony.

Color is about profiles, unless you are looking for Hydrogen Alpha response (near-infrared). In this regard the new A7 cameras are better than previous models.

The main issue with A7riv is the extra noise but handled by taking several shots and stacking them same as with any camera.

About 1/3 more than the A7rII, which is excellent, should hardly be noticeable when comparing final work.

Post some photos so we see this post is genuine.

Sure. Without samples we can't help that much.

The star colour issue with the Sony's isn't about profiles its a direct result of the star eater that suppresses blue and red leaving excess green. You get a lot of green faint stars on an image with pinpoint stars.

So far the astro images I have seen (admittedly not many) from the A7riv are disappointing.

Did you know QHY are selling a mono cooled version of this sensor (61mp)?

Apparently it has low noise and no amp glow.

Its also an expensive camera, a lot more than an A7riv.

Greg.

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Magnar W
Magnar W Senior Member • Posts: 4,356
Re: How to see all stars & other small details on pics?

Astrophotographer 10 wrote:

The star colour issue with the Sony's isn't about profiles its a direct result of the star eater that suppresses blue and red leaving excess green. You get a lot of green faint stars on an image with pinpoint stars.

I have never claimed that the faint green stars have anything with profiles to do.

This is Bayer Matrix sensors, and for single pixel recording you get ... a single filter color. But stars will never cover a single pixel, due to light spread. And those green stars are so faint that they do not affect final work to a noticeable degree.

Did you know QHY are selling a mono cooled version of this sensor (61mp)?

Yes, and there is also a Bayer matrix version that is used in specialized, cooled astro cameras.

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OP Thomas1975 New Member • Posts: 2
Re: How to see all stars & other small details on pics?

Thanks for all the replies.

The problem seems to be an hardware-issue. Exposues over 2 seconds are all unsharp, as sometimes the IBIS begins to shake - even in manual focus and switched off. Also the sensor does not capure all light available (tried to get some night shots in urban places) black spots are appearing.

So it has been sent to Sony last week.

I´ll do some shots when it comes back and post them here.

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