Need a lens for Astrophotography

[WNG]

Huh I got Minolta w.rokkor 28mm f3.5 for some astro shoots as soon weather gets a bit better.

Will that lens do job?

If I think it's the Minolta MC W.Rokkor-SG 28mm f3.5, then it's a lens I have and my two cents is that it's performance is somewhat weak and will not be optimal for night skies.
Although the lens has good resolution, it lacks sharpness. And the corners reveal some red chromatic aberration on top of the softness at the edges. The center is clean, but needs to be stopped down to f/8 for an acceptably sharp result. The MC coating is also not their best.
Compared to other 28mm f/3.5 models, the Olympus OM Zuiko and Konica Hexanon AR are significantly superior. Both are super sharp, contrasty, and nil distortion wise.
28mm f/2.8 and f/2.0 are will be better still for more light.

Can you get star captures on a 28mm? Yes, it's just wide enough on full frame as mentioned. Try it out and see. Maybe your copy is better than mine.
Wider is better as it allows you more shutter time to gather the light.
But if you are on a budget, search for a 24mm f/2.8. The Canon nFD Olympus OM Zuiko, and Tokina RMC are very good and budget friendly. If you can afford it, get a Nikon Nikkor AIS 24mm f/2.8. Want wider? The Canon nFD 20mm f/2.8. These more desirable legacy lenses may push your cost into the modern manual-focus range.
And a new Samyang-Rokinon 14 or 21mm may make more sense in the low $300s.

 

[robotiqus]

It is MD W.Rokkor, not so sure but think MD are even older than MC

E5823    ---    4mm    f/2.0    1/32s    ISO 500

Anyway this is probably bad example of what I managed to capture

   ---            

I know it was wide open on f3.5, iso 200 as that is lowest i can go on nex 3n and shutter speed was 8" or 10"

But definitely it's not really sharp in low light , but if weather is nice it actually perform quite good

   ---            

   ---            

 

[Ad Dieleman]

It is MD W.Rokkor, not so sure but think MD are even older than MC
View attachment 89828
Anyway this is probably bad example of what I managed to capture
View attachment 89829
I know it was wide open on f3.5, iso 200 as that is lowest i can go on nex 3n and shutter speed was 8" or 10"

But definitely it's not really sharp in low light , but if weather is nice it actually perform quite good

View attachment 89830
View attachment 89831

Minolta introduced your lens model in 1977 and it was superseded by a lighter and smaller version in 1978 with the same optical design; check Dennis Lohmann's list for a complete overview. The MC versions are definitely older, this optical design was introduced first in 1975 as an MC W.Rokkor 3.5/28 which has a very similar build. I'm not surprised that you find it's not great at f/3.5 and decent at f/8 or f/11.

 

[WNG]

As Ad pointed out, the MD are newer versions. You daylight images show your MD is significantly better than my copy of the MC.

Those long shutter times will give you star trails. If that's not desired, you can always stack images. Use the lowest ISO again and shorten the shutter to 1 sec.
The other alternative is to create your own DIY barn door tracker.

 

[robotiqus]

Oh it is fine as long as shutter is less than 15-20" I'm not getting any startrails.
That picture with trails is done with startrails application (around 40 pictures stacked,and they were all shoot trough window as part of my overnight timelapse) .

Apparently weather is about to get better soon so I'll be able to test it properly

 

[Hin Man]

Not quite as wide as the other lenses being discussed, but another possibility might be the Tokina Firin 20mm F2. $799 new.

But I might be biased. Mine is in transit.

I have great interest on the Tokina, please tell us more about the lens and your impressions.

Hin