Which is the best FE body for nightscapes?

Hello E-mount folks! I'm an A-mount user and it looks like it's finally time to transition to E-mount. I mostly use my A900 still. I love the simplicity and it takes great photos. However, I'd like a body that is better for nightscapes including astrophotography. I was considering the A99II and staying A-mount for a while longer, but it looks like the high ISO noise performance isn't very good. I could go all the way to the A1, but it also appears to produce too much noise. It looks like the A7III has the best high ISO noise performance of any full frame camera according to DXOMARK. The A7S isn't far behind, but I don't want to go down to 12 MP. Third place appears to be the A7RIII. The higher MP would allow for more cropping, but longer star trails if I'm not mistaken. Is there any reason I should chose the A7RIII over the A7III for this kind of photography? Is the Pixel Shift feature useful for this?

Here's a high ISO noise comparison between A1, A99II, A7III, and A7RIII.

I would also be using the LA-EA5 adapter until I procure a collection of E-mount glass. I don't need autofocus for nightscapes, but it would be nice to have autofocus for some of the screw drive lenses for other types of photography. I suppose there's no way to know if Sony will release a firmware update for the A7III or A7RIII, or if there will be an A7IV soon and if the noise performance will be as good as the A7III.

The A99m2 has the same 42mp sensor as the A7r2 and A7r3 and it still is one of the best sensors. It is a third of a stop (or was it half a stop?) behind the E-mount cameras because of the SLT mirror, but it still is much, much better then the A900.

How much AF do you do? If you're primarily a nightscapes including astrophotography shooter, the Ar2 might be a good option. It has the same sensor as the A7r3 for a fraction of the price. Or go all the way and have the bells and whistle's of the A7r4 like Matthew said.

There are rumours for an A7 IV this year, but nothing for certain.

MisterAndrew wrote: In the DP Review studio image comparison the noise levels of the A7R2 and A99II look similar at 6400 ISO, but the A7R3 is noticeably cleaner (about 1 stop better), so there must be more contributing to reduced noise than just the sensor. I haven't thought of removing the mirror on the A99II, but I don't think that would give me an advantage over the A7R2 or A7R3 and it's more expensive.

DPReview found/admitted their studio scene was not consistent over time. They supposedly addressed the issues, but I don't think they redid all the past testing.There is a little blub in the A7RIV review about one issue.

These cameras all have dual gain. There is no noise advantage to using other ISO settings other than their two base ones. All you get from using other ISO settings is highlight clipping and reduced dynamic range in the raw files.

Edited by QuietOC - 19 May 2021 at 12:16

Compared to your A900 anything will be two stops better at least. For me, the A900 at stopped being fine at 1000-1200iso. With the A99m2/A7r2/A7r4 I am happy with 3200iso and fine with 6400iso. I find the A7r4 the best of the three, but the differences are small.

Oh, never used the A1, but seems that one is good at everything. So, indeed, go for it

MisterAndrew wrote: I found this thread below on DP Review that discusses the noise difference between the A7R3 and the A7R4. People are saying it's not really a big difference and the images look about the same if the A7R4 images are downsampled to match the resolution of the A7R3. So perhaps the A7R4 would be the best choice for me since it has the better ergonomics, it's newer, and fully supports the lens adapter. The A1 is nice, but I think it's a little overkill for my needs and more expensive. For the price difference I could get a few nice lenses for the A7R4. https://www.dpreview.com/forums/thread/4529045

You can check this on dpreview's studio comparison thingy you linked in OP. If you click on the "comp" option instead of "full" in the top right corner it'll show crops at the same resolution i.e. downsized. It's better to compare noise this way.
A7RIII is tiny bit better than A7RIV. Having had both I would say so also. But the difference is so small that it's not really worth taking into consideration as one of the aspects for making your decision over.

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

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. Like Anand said, differences are small. Any is a huge update. There are real improvements with the A7r4, but you pay for those. Whatever you decide on, I am sure you will be happy!

Couldn't agree more and A7RIV is very slightly worst in these areas at high ISOs compared to A7RIII.

I think the reason here is once again Sony have recycled their processor but increased the resolution and AF capabilities i.e. calculations and number of points compared to previous generation.
So it takes a small hit in the IQ department. something has to give.

I'd still pick an A7RIV over A7RIII if money is of no concern. A7RIV is nearing 2 years now. I think they kinda released it in a hurry so they weren't the seen as the lowest resolution offering among all the other high res offerings.

I imagine there will be a new A7RV with new processor and updated AF and a new A7IV with new sensor, processor and updated AF to go against canon R5/6. These will probably come later this year.