Which is the best FE body for nightscapes?

A7S isn't actually any better or worst than A7RIV for example. if you downsize the files from A7RIV to same resolution as A7SIII you'd end up with a similar result.
you can do this comparison on dpreview's studio, you will notice there isn't much difference if any.
A7SIII has other benefits but those aren't of much consequence to OP's purpose I think.

onsplekkie wrote: I know you've said no A7s because of 12MP. But in my experience, if you looking for the BEST high iso preformance you'll have a hard time finding anything that comes close to the A7s series. I am no expert, but these youtubers seems amazed by the fact they can't see a (big) difference between a 12MP and 102MP file, either on screen or in small/big prints. I konw it's all objective, but still... https://www.youtube.com/watch?v=E8Sej2TEes4&ab_channel=ChrisHau

Link does not work for me.
Wanted to say the same thing as Anand.
The A7r4 has a 240mp pixelshift - but Facebook/Instagram destroys 90%. But still, 24mp is more then 12mp

Gerald Undone changed his A7r4 and his A7s3 for the A1. To be sure, you should do the same! (no, not really, just kidding, it is silly expensive)

QuietOC wrote: Jonas A-R wrote: addy landzaat wrote: Noise is among the least important things when it comes to high ISO, I find the decrease in dynamic range and colour fidelity much more important. YMMV. What do you think decrease the DR and colour fidelity? I think you will find that noise is the culprit The highlight clipping done at high ISO settings seems like the cause of the reduced dynamic range to me. The noise isn't increasing.

That is true. However, if your highlights are clipped, you have set the ISO too high.
If the highlights are preserved at high ISOs, the DR will reduced relatively to the base ISO. This is because the exposure (“the signal”) in the DR ratio is reduced. You don’t need a lot of bits to encode all of that noise.

In some DR metrics (photographic DR by Bill Claff for example) some photon noise is included in the definition of the lower end of the range to estimate “the useable” DR.

addy landzaat wrote: Jonas A-R wrote: addy landzaat wrote: Noise is among the least important things when it comes to high ISO, I find the decrease in dynamic range and colour fidelity much more important. YMMV. What do you think decrease the DR and colour fidelity? I think you will find that noise is the culprit If you're right there should always be a constant relation between dynamic range and visible noise. If that is true, it does not make sense that dynamic range is measured at all, since you can just measure the noise and calculate (?) the dynamic range. there is a relation between noise and dynamic range because where is noise there can be no information. But I doubt there is a constant relation. Looking at the measurements by DXO Mark, I notice that the difference between the A900 and the A99m2 in noise at any given ISO setting is different then the difference in dynamic range. Also, I feel the A99m2 and A900 useful at the same dynamic range measurement, not so with noise. And finally, I feel visible noise is seldom reason to lower the ISO setting, dynamic range always is.

You can measure the saturation capacity and noise floor and calculate the ratio. That is how it is done.

What I am trying to say: you don’t need an awful lot of DR at low exposures (expected at high ISOs) because of the noise. If you have specular, blown highlights then it is much better to keep the ISO low and raise it when the image is developed from raw. This preserves the DR of the sensor and you will generally not have a noise penalty by raising the ISO when the image is processed (compared to shooting at the higher ISO)
Typically the light level is fixed in a scene. It is good practice to set the exposure first (aperture and shutter speed) to maximize it. The ISO will fall wherever it fits and there is not much that can be done abut it unless you change the DoF or the amount of motion blur.

I think DP Review's studio images taken with the A7III and A7RIII are a little out of focus and that's why it looks like they have less noise when I select the comp option. The A7RIV and A1 images are tack sharp. So I think the noise in the images taken with the older cameras is just blending into the image and that the actual noise between the cameras at the same resolution is about identical.

They don't have a studio image taken with the A900, but they have one of the A77II and I have that camera and it seems to produce similar noise as the A900. I can see a huge difference between that one and the newer E-mount bodies. So I don't think I could go wrong selecting any of them. The main thing to consider now is that perhaps the A7RV will be released in the near future so should I get the A7RIV now and not worry about it or get one of the less expensive bodies to hold me over until then?

Perhaps the newly updated version of the A7R4 wouldn't go down in value much when the A7RV comes out, but I imagine the A7R2 wouldn't lose much value either since it has already lost most of its original value. Perhaps the A7R3 would be the worst one to buy in terms of value right now since it may drop to the A7R2 level when the A7R5 is released.

I was comparing the specs of the A7R2, A7R3, and A7R4, and I think I would be most happy with the A7R4. I think you're right that it may be a while before there is an A7R5, and it may only be a small incremental upgrade. I don't think Sony has any incentive to offer a camera right now that has some of the A1's features for half the price. So if I buy the A7R4 right now I could keep it for a couple years before I think about upgrading again.

MisterAndrew wrote: I was comparing the specs of the A7R2, A7R3, and A7R4, and I think I would be most happy with the A7R4. I think you're right that it may be a while before there is an A7R5, and it may only be a small incremental upgrade. I don't think Sony has any incentive to offer a camera right now that has some of the A1's features for half the price. So if I buy the A7R4 right now I could keep it for a couple years before I think about upgrading again.

There is some chatter about a A7iv this year, but nothing concrete. I really like my A7r4, it is a well rounded camera, not as well rounded as the A1, but great for most people I think. Even if 60mp is bit large...