31 replies to this topic

[photobookie]

I'm considering purchasing either the Sony a7RV or a Nikon Z8 (or possibly the upcoming Nikon Z6III) and have read on this forum that the Sony a7RV may not have the 'star eater' problem. I'm wondering if it has the polygon ring / posterization problem caused by anti-vignetting lens adjustments regardless of whether or not those adjustments are turned on or off.

Are there users out there with a7RV camera for long exposure astrophotography? If so, I'd love to know how you are liking it and what your experience has been. It's great that there's now a NINA plugin for Sony cameras with ASCOM support. 

 

Thanks! Rick

[whwang]

It is confirmed that A7R5 does not have star eater.  See this post and other posts in that thread.

 

As for the polygon ring problem, I think it is gone too.  I used A7R5 and Sony FE 135/1.8 (at F1.8) GM to conduct the test suggested by Mark.  Here are the results:

 

 

The top row is B divided by G of flats (after bias subtraction).  The bottom row is R divided by G of flats.  The three columns are three different exposures.  The difference between two adjacent exposures is 8x.  So there is a total of 64x in the dynamic range.

 

As you can see, there may be weak horizontal banding or very low level non-uniformity (only barely visible in the rightmost column, the highest exposure ones).  However, there are no concentric or polygon structures.

 

I also took some deep-sky images with the lens.  From the stacked image, I don't see evidence of polygon or concentric banding either.  Unfortunately the stars from the lens isn't very good (I think I got a bad copy).  So I didn't bother further processing that image and I can't show it here.

 

I think we can conclude that A7R5 is a perfectly fine camera for astrophotography.

[cometguy]

The fellow that runs the YT channel "Fervent Astronomy" posted some images up to 60 seconds with an A7R5 and a Viltrox 16mm f1.8.  Look specifically at the tracked images - which are excellent.  What is not excellent though is having to spend $4000 for a Sony body to get non-mangled stars

 

Here is the link:  https://ferventastro...eviews/YouTube/

[photobookie]

Thank you both. Yes, I just watched the ferventastro video this afternoon and have read the threads that  Whwang posted. Sounds like great progress is being made by Sony for astrophotographers.  

But I'm about to give up on Sony. I have an a7RII and I first tried my 35mm Zeiss Loxia which is just terrible with bad coma/astigmatism in the corners when used at night. So, after doing a lot of research, I bought a 24mm G-Master lens to try out, after watching several rave YouTube reviews. One reviewer said it was perhaps the best 24mm astro DSLR or mirrorless lens every made.

In the daytime the lens appears to be spectacular, great size and weight and super sharp edge to edge stopped down. A pleasure to use and hold. But at night, wow, that's a different story. 

 

The chromatic aberrations on my copy wide open were terrible. I used a bahtinov mask and when stars were perfectly in focus, they had a magenta/purple ring around them. Then if I minutely adjusted focus on either side of perfect focus, stars got even more magenta or in the opposite direction, cyan, which destroyed the warm Betelgeuse star color of red giants. Focus is super critical on that lens, with the stars changing color drastically with just a very, very slight rotation of the focusing ring around perfect focus. I'm pretty sure the super sensitive focus can't be relied upon during temperature drops. 

So I bought another copy of the lens, and ugh, it too has the same chromatic aberrations! 

Then a friend of mine and I tested the Nikon Z 20mm f1.8 S on his Z8 camera and it was a revelation. Stars were so much closer to their proper colors. No shift in color coming and going past perfect focus. Yes, there is some astigmatism in the corners wide-open, but it's not bad at all.  The thing I hate about the Nikon Z lenses is that they don't have an aperture ring and instead they use aperture selection by wire, just like focusing. They're also significantly bigger and heavier than the Sony wide-angle lenses.

But... I'm pretty sure I'm going to send the second copy back of the G-Master 24mm and go for the Nikon 20mm even though it has some optical distortion being that wide of a lens. Sony's 20mm is supposed to be good too, but I'll believe that with my own eyes. Haven't heard such good things about Nikon's 24mm though.

Trying to hold out for the upcoming Z6III camera (hopefully it won't have an anti-aliasing filter on the chip), but may go for the Z8 if I can't wait. 

Also, I may also get the Voigtlander 50mm f2 APO-Lanther Z lens, hopefully its reputation will hold up to star-time use. 

I'm hoping the Nikon ASCOM driver works like a champ when using NINA to control their camera as I'd like to piggyback it on top of a telescope. The Sony plugin for NINA 2.0 works great!

Rick

Edited by photobookie, 01 February 2024 - 11:39 AM.

[whwang]

Interesting.  I am also a Nikon user, so I won't stop you from going to Nikon.  I used the Sony 24/1.4 a couple of times, like this one:

https://flic.kr/p/2kZe1ZE

I never thought that I would use this lens wide-open.  The above picture was taken at F3.5, and I have pretty much nothing to complain.

 

The new Nikon Z lenses have good reputation.  I just hope the circular banding problem can be resolved.

[photobookie]

Interesting.  I am also a Nikon user, so I won't stop you from going to Nikon.  I used the Sony 24/1.4 a couple of times, like this one:

https://flic.kr/p/2kZe1ZE

I never thought that I would use this lens wide-open.  The above picture was taken at F3.5, and I have pretty much nothing to complain.

 

The new Nikon Z lenses have good reputation.  I just hope the circular banding problem can be resolved.

When does this circular banding occur? Is it only on exposures longer than x? 

[MJ Wunderlich]

I'm also considering a Sony a7rv, and weighing it against a ZWO ASI6200MC.

The price difference is negligible. The camera has the benefit that it can be used standalone or with an onboard computer like the ASIAir. However, the ASI6200 is cooled, and doesn't need to be modded.

I wonder how the a7rv unmodded compares with the ASI6200MC, especially for galaxies and other broadband dso targets.

Edited by MJ Wunderlich, 01 February 2024 - 07:23 PM.

[photobookie]

I'd go with the ASI6200 MC, but it really depends upon what kind of compromises you are comfortable with. The deep sky results you'll get from a cooled astronomy camera will be significantly better in most cases, but it will be a single purpose solution. The Sony could do both, but it won't be as good for deep sky astrophotography as it will have more noise and possibly other issues that I'm not familiar with.

 

Also, I'm not sure what you mean by saying the ASI6200MC doesn't have to be modified. The Ha response from a mono camera ASI6200MM with a good Ha narrowband filter is far better than filtering an ASI color camera, though you will get some nice results from doing it.  Rick

[whwang]

The Sony will only be more noisy if you image in a warm place. In a cold place, cooling is not needed (unless your sky is extremely dark, or you use a narrower-band filter).

[calypsob]

I'm also considering a Sony a7rv, and weighing it against a ZWO ASI6200MC.

The price difference is negligible. The camera has the benefit that it can be used standalone or with an onboard computer like the ASIAir. However, the ASI6200 is cooled, and doesn't need to be modded.

I wonder how the a7rv unmodded compares with the ASI6200MC, especially for galaxies and other broadband dso targets.

the 6200mc with an asi air and the phone ap is just as convenient as the A7rv imo, only you get precision temp controlled calibrated frames with the 6200

[Jack’sDad]

Just wanted to jump in quickly and ask a quick, semi-related question about the Sony’s.

I was thinking about using my A1 and a telephoto. Does the A1 suffer from some of the issues mentioned above? If there are any threads specifically about Sony cameras and these issues, specifically ones that may compile a list of models, please share a link.

Thanks!

[whwang]

https://www.markshel...ra_summary.html

 

Also search for Mark's (sharkmelley) comments in this forum.

 

I had used A1 a few times:

The star eater problem is still there, but better than earlier models.  I think it's almost acceptable to me.  Unfortunately I haven't put a Sony lens on it to take deep pictures, so I can't comment on the polygon banding issue.

[Jack’sDad]

Thank you! I was hoping to use it with the 600mm f/4 and the 1.4x & 2.0x teleconverters. Time to hit the books.

[Digitaliz.se]

My Sony A7R4, which is 3 years older than A1, has no major banding issues with either Sigma 85/1.4 DG DN nor Samyang 135/1.8 AF. So A1 should be fine.

 

/Stefan

 

Just wanted to jump in quickly and ask a quick, semi-related question about the Sony’s.

I was thinking about using my A1 and a telephoto. Does the A1 suffer from some of the issues mentioned above? If there are any threads specifically about Sony cameras and these issues, specifically ones that may compile a list of models, please share a link.

Thanks!

Edited by Digitaliz.se, 02 February 2024 - 03:50 PM.

[whwang]

I probably can only believe it if you use it with a Sony lens.  Chance is good that your A1 did not know what raw correction to apply to the Sigma or Samyang lenses and skipper it, rather than not trying to do something bad regardless of the lenses.

[Digitaliz.se]

Fair enough. Here's the Sony A7R4 with Sony 20/1.8G. Single shot and stars removed to easier see presence of banding.

 

/Stefan

 

 

I probably can only believe it if you use it with a Sony lens.  Chance is good that your A1 did not know what raw correction to apply to the Sigma or Samyang lenses and skipper it, rather than not trying to do something bad regardless of the lenses.

 

Attached Thumbnails

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[whwang]

It looks good. But please allow me to be nitpicking here, given the important nature of this issue. The brightness distribution in the example you showed is dominated by the sky gradient, which can overwhelm the color banding. In another camera that own, the color banding issue only shows up after the large scale gradient is removed. So it will be better to try to remove the gradient and to conclude.

Edited by whwang, 03 February 2024 - 05:13 AM.

[Digitaliz.se]

Ok, cropped out the foreground and removed the gradient. To me, it still looks ok. Remember that this is a 60s single image. A stacked DSO one will have much higher s/n ratio. And also, this is wideangle shot. Using a longer FL will reduce the light pollution gradient.



 

It looks good. But please allow me to be nitpicking here, given the important nature of this issue. The brightness distribution in the example you showed is dominated by the sky gradient, which can overwhelm the color banding. In another camera that own, the color banding issue only shows up after the large scale gradient is removed. So it will be better to try to remove the gradient and to conclude.

 

Attached Thumbnails

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Edited by Digitaliz.se, 03 February 2024 - 07:30 AM.

[whwang]

I feel there is some color gradient toward the rightmost edge, but I can't confirm this because of the JPG image quality.  I would say it's good to see this, but it remain inconclusive.

[Digitaliz.se]

There are blotches of color noise since the s/n ratio is not as high as you might want it to be and on top of that, I just cancelled out the light pollution gradient which will pronounce it even more. The stars are removed which normally conceals noise.

Since this is a DSO group, typically, you use longer FL which makes the lighpollution gradient not as harsh as a wideangle lens. You also stack multiple images to increase the s/n ratio and make the impact of removing the gradient less visible.

If I turn on the lens correction in camera, hell breaks loose… And stacking will make it worse. Typicaly I get newtonian rings artifacts.

 

/Stefan 

 

I feel there is some color gradient toward the rightmost edge, but I can't confirm this because of the JPG image quality.  I would say it's good to see this, but it remain inconclusive.

Edited by Digitaliz.se, 04 February 2024 - 05:10 AM.

[whwang]

I mentioned gradient because it can hide the problem of color banding, not because it induces color banding.  So this has nothing to do with the less gradient under long focal length.  The polygon color banding is induced by lens correction, so long lenses recognized by the camera can still have color banding.

[sharkmelley]

It is confirmed that A7R5 does not have star eater.  See this post and other posts in that thread.

 

As for the polygon ring problem, I think it is gone too.  I used A7R5 and Sony FE 135/1.8 (at F1.8) GM to conduct the test suggested by Mark.  Here are the results:

I reviewed whwang's A7R5 raw files and agree with the conclusion that there is no evidence of the dreaded colour polygons (Sony FE 135/1.8 GM) with the lens corrections disabled.  In addition, there is nothing strange about the histograms e.g. spikes or gaps caused by channel scaling etc. This is good news at last from Sony!

[sharkmelley]

I have added the good news about the Sony A7R5 to my online camera summary

[photobookie]

I have added the good news about the Sony A7R5 to my online camera summary

Thank you! I've ordered a used a7RV and am looking forward to testing it. 

Edited by photobookie, 09 February 2024 - 11:06 AM.

[sharkmelley]

Coincidentally I now have some test results from the Sony A74 (not the A7R4) taken with my test protocol using the Sony FE 85mm F1.8 and Sony FE 24-105mm F4 lenses.

 

There was no evidence of the dreaded polygons with both data compression and lens corrections switched off.

 

Unfortunately both the A74 and the A7R4 have the usual raw data filtering (a.k.a. star eater) that is destructive to small tightly focused stars.