If I'm not wrong it's a totally manual lens, so what the camera meter it's exactly what you'll shoot. And in this sense no, you shouldn't have this problem at all.

But given that, again, is totally manual and there is no electronic contact at all, there is nothing the lens can do to confuse the camera meter. So the only explanation that comes to my mind is that your metering is set in a way that prevent the camera to correctly measure the light, maybe like having the metering set to central spot and pointing the camera to a star...but you already excluded that.

Apart from that...it happened to me to have taken just a few shoots of the sky at night (not in sky photography at all), and they obviously have the histogram all to the left...I can't think a way to shoot at something so dark like the sky at night and have the istogram perfectly in the center. Are your shoots underexposed, or is you who are expecting something unrealistic?

Finally: no point in using Av mode, you have to shoot in M.

If I'm not wrong it's a totally manual lens, so what the camera meter it's exactly what you'll shoot. And in this sense no, you shouldn't have this problem at all.

But given that, again, is totally manual and there is no electronic contact at all, there is nothing the lens can do to confuse the camera meter. So the only explanation that comes to my mind is that your metering is set in a way that prevent the camera to correctly measure the light, maybe like having the metering set to central spot and pointing the camera to a star...but you already excluded that.

Apart from that...it happened to me to have taken just a few shoots of the sky at night (not in sky photography at all), and they obviously have the histogram all to the left...I can't think a way to shoot at something so dark like the sky at night and have the istogram perfectly in the center. Are your shoots underexposed, or is you who are expecting something unrealistic?

Finally: no point in using Av mode, you have to shoot in M.

Update after OP comment

You can try to do a small test:

1. Choose an easy subject
2. Mount the kit lens; Av mode, choose an aperture, shoot
3. Go to View mode and note down the shutter speed used. While you are there, just because "never say never", check the recorded aperture
4. Mount the manual lens, M mode, set the same aperture and shutter speed as before with the kit lens, shoot

The two images should be nearly the same, and the parameter stored in the images too.

If they are not...the lens must have some weird problem.

If I'm not wrong it's a totally manual lens, so what the camera meter it's exactly what you'll shoot. And in this sense no, you shouldn't have this problem at all.

But given that, again, is totally manual and there is no electronic contact at all, there is nothing the lens can do to confuse the camera meter. So the only explanation that comes to my mind is that your metering is set in a way that prevent the camera to correctly measure the light, maybe like having the metering set to central spot and pointing the camera to a star.

Apart from that...it happened to me to have taken just a few shoots of the sky at night (not in sky photography at all), and they obviously have the histogram all to the left...I can't think a way to shoot at something so dark like the sky at night and have the istogram perfectly in the center. Are your shoots underexposed, or is you who are expecting something unrealistic?

If I'm not wrong it's a totally manual lens, so what the camera meter it's exactly what you'll shoot. And in this sense no, you shouldn't have this problem at all.

But given that, again, is totally manual and there is no electronic contact at all, there is nothing the lens can do to confuse the camera meter. So the only explanation that comes to my mind is that your metering is set in a way that prevent the camera to correctly measure the light, maybe like having the metering set to central spot and pointing the camera to a star...but you already excluded that.

Apart from that...it happened to me to have taken just a few shoots of the sky at night (not in sky photography at all), and they obviously have the histogram all to the left...I can't think a way to shoot at something so dark like the sky at night and have the istogram perfectly in the center. Are your shoots underexposed, or is you who are expecting something unrealistic?

Finally: no point in using Av mode, you have to shoot in M.