Sony alpha A55

[Allam2009]

I don't do astrophotography with either a specialized astro cam or a DSLR but lots of people do. I remain too be convinced as to an EVF's usefulness in seeing faint things like Nebula and Galaxies, how much does an EVF interfere with your night vision?

One of the other guys that was in the demo session is into Astrophotography and (based on the quick play that we had) said that the EVF would not work for him.

[KevinBarrett]

I guess it's a good thing they introduced two OVF cameras at the same time then... a7XX cameras they ain't, but that camera is till coming.

[bfitzgerald]

I will be a good thing if they put MLU in there..if that's missing then that kills it off completely lol

[David Kilpatrick]

Greg - you could never do astro work with the 'translucent' models - you would get a sky full of binary stars.

David

[WaltKnapp]

Greg - you could never do astro work with the 'translucent' models - you would get a sky full of binary stars.

David

The apparent offset has been pointed out in some of DPReview's samples. 11 pixel offset. In one photo there's a double offset. A triple star, except it's just outdoor lighting. Be interesting if that is confirmed with shots from other sources.

And yes EVF will take out night vision in my experience with night photography of wildlife. And it can take 20-30 minutes to come back.

Walt

[Greg Beetham]

Hmm if a camera can't replicate a point source without splitting it in two however good and diffraction limited the lens or telescope is it's mounted on won't make any difference, you'll just get a mess....Thing is if the camera is unable too accurately register a point source what's the use of it? a photo of anything consists of millions of points.
Greg

ps. Anyway DK it's been estimated that most stars in the sky are actually double star systems of one sort or another, we were lucky, Jupiter could be a failed dwarf star, just needed about 6 times more mass and it would have been a star.
So I guess in a sense if the camera splits all the stars up into doubles artificially, it's pre-empting and saving you the bother of buying a bigger telescope ha ha, go Sony go....what a weapon.

[bakubo]

I recall that when the Canon 50D came out there was a very big uproar because of a problem with point source lights. It took awhile, but I think Canon fixed it in a firmware update. I don't recall the exact problem, but it was a big deal for some time.

[KevinBarrett]

Anybody see this video showing the transparent mirror being manually raised, followed by shutter actuations? I wonder if the camera is trying to record image files right then, or if there would be any clearance issues with the mirror raised up that way.

[agorabasta]

In principle, those reflections can be cancelled out by subtracting an appropriately attenuated (and shifted/stretched) copy of the image from the original. They seem to sit about 6-7 stops below the main image intensity, so one iteration should be enough to shift any residue out of any practical DR.

But it looks like back to drawing board for Sony engineers... But then again, those cams are so cheap...

[OneGuyKs]

, Jupiter could be a failed dwarf star, just needed about 6 times more mass and it would have been a star.

6 times? no way. More than 80 times more mass would have been needed to turn jupiter into a star. Jupiter is 1000 times less massive than the sun.

[Greg Beetham]

O B A F G K M - R N S from memory are the classifications of main sequence stars....last I looked that is, and I'm sure I read in J Kayler's book 'Stars' that Jupiter only needed 6 (could have been times more masses too become a brown dwarf, possibly an S class, it's also been said that Jupiter already produces enough heat in the core too remove the electrons off the atoms that are there, so you are talking serious temperature and pressure just as it is.
Greg

[dynax800si]

Anybody see this video showing the transparent mirror being manually raised, followed by shutter actuations? I wonder if the camera is trying to record image files right then, or if there would be any clearance issues with the mirror raised up that way.

Kevin I was wondering exactly the same thing yesterday when I saw this video.
Without AF maybe it's possible.

[dynax800si]

OK, I have asked a user that have a33 and he answered that the camera take photos with mirror raised!

But in the video mirror sticks out of the bayonet So I don't know.

(sorry for the English)

[bfitzgerald]

They probably made the mirror oversized to minimise the light loss to the sensor.
I'm tempted to say that in the long term phase detection off of the sensor (note Fuji's F300exr) will likely be a more suitable solution for cameras of this type.
The fixed position mirror brings some advantages but also has some issues as well which is why other makers have probably not adopted it.

[dynax800si]

Update, Sorry for the misinformation.

The guy with the a33 told me that you can't attach a lens. That is Pity.