New camera, new issues...

[Tullio]

What I think is interesting is the fact that I've switched to m4/3 over two years ago and since I've had at least 4 m4/3 bodies. I haven't had a single spec of sensor dust on any of my cameras. I thought that since the sensor is quite exposed every time I swapped lenses that I'd get dust on the sensor very easily but it turns out to be the opposite. Either the dust removal system is very efficient on m4/3 bodies or the flip-flop of the mirror moves dust around causing the problem on regular DSLRs. I had several DSLR cameras and I experienced this problem on just about every one of them at one point or another.

[TCav]

Originally Posted by Marawder

BTW, how far away from a city do I need to be in order to get some decent star trails?

What matters is how much light pollution you have, not how close or far away you are from a city. Certainly, city lights are a major and common source of light pollution, but they're not the only one. And light pollution doesn't preclude getting good star trail shots.

What you want is to get as much contrast between the stars and the dark sky, and any light pollution lessens that contrast, whether it be from city lights, a full moon, or snow covered mountains.

I like what Neil deGrasse Tyson, director of the Hayden Planetarium, who grew up in The Bronx, said (indirectly) about light pollution:

I knew about the stars when I was growing up. I could see them at night from my street ... all six of them."

[Marawder]

Originally Posted by SIMON40

you're happy with the A580...?

Overall, yes, I really can't complain about anything, besides the shady RAW compression.

Originally Posted by SIMON40

I like you had an SLT model (A37) briefly- and as you,wasn't impressed...

With images from the A580 I'm seeing less noise when opening up the shadows in Camera Raw.
That 1/3 of a stop of light lost on the SLT models really does take a toll on image quality.

Originally Posted by SIMON40

It is odd, however, why one feels the need to compress RAW... shouldn't that be up to the user...?

Of course it should, but seems that Sony thinks otherwise, knowing better than the actual user what's best for him.

Originally Posted by TCav

What you want is to get as much contrast between the stars and the dark sky, and any light pollution lessens that contrast, whether it be from city lights, a full moon, or snow covered mountains.

Got it, thanks a bunch Tom!

Regarding the 25-minute exposure shot from the previous page, I have to say, even with LENR activated, I could still see some artifacts in the final image, including plenty of dead pixels.
Is that normal, or could it also be from the lossy RAW-compression?

From your experience, what would be the ideal limit so as to preserve a balance between image quality and a long-enough shutter speed for creating the illusion of mouvement?
15 minutes? Or maybe 8-10 minutes? Less than 5?

[SIMON40]

Personally, I think the 1/3 of a stop loss of light on the SLT models is somewhat misleading- I'd argue innaccurate... I reckon almost a stop with regards high iso noise was lost...

[TCav]

Originally Posted by Marawder

That 1/3 of a stop of light lost on the SLT models really does take a toll on image quality.

Originally Posted by SIMON40

Personally, I think the 1/3 of a stop loss of light on the SLT models is somewhat misleading- I'd argue innaccurate... I reckon almost a stop with regards high iso noise was lost...

DxOMark puts the difference at about 1/2 stop, between the noise in an image from an A580 and one from an A35. The SNR for the A580 at ISO 100 is 41.5 db and 38.6 db at ISO 200, while the A35 has an SNR of 40.0 at ISO 100. That splits the difference neatly in half. That difference is consistant throughout the ISO scale too, btw. (See the SNR 18% measurement.)

[TCav]

Originally Posted by Marawder

Regarding the 25-minute exposure shot from the previous page, I have to say, even with LENR activated, I could still see some artifacts in the final image, including plenty of dead pixels.
Is that normal, or could it also be from the lossy RAW-compression?

I wouldn't use Long Exposure Noise Reduction when shooting star trails, unless you know you need it, and until you try it without it, you don't know. Set the ISO low to reduce noise, set the aperture to get the sharpest image, and leave the shutter open for as long as you want the trails to be. (If it's cold, bring gloves. An aluminum tripod can get tough to handle.) What you'll see is trails for both bright and dim stars (, planets, etc.), plus any aircraft, that happen to fly through, plus any foreground. Anything that doesn't make a trail is either foreground or noise, and my guess is that you won't actually see a lot of noise.

Originally Posted by Marawder

From your experience, what would be the ideal limit so as to preserve a balance between image quality and a long-enough shutter speed for creating the illusion of mouvement?
15 minutes? Or maybe 8-10 minutes? Less than 5?

What I do is make multiple short exposures and put them together. That way, if anything flies through the frame, you can just leave out that frame and make up the gap in other ways. Also, with a shorter exposure, you're less likely to get noise. You can't do that with LENR, because it makes a black frame using the same exposure time as the exposure you made, so there will be significant gaps in the trails.

[Marawder]

Some street shots taken today with my A580...oh, the sensor is now squeaky-clean, and Sony only asked for 15 francs, very cheap:

[TCav]

Originally Posted by Marawder

...oh, the sensor is now squeaky-clean, and Sony only asked for 15 francs, very cheap:

Glad to hear it. Congratulations.

[Marawder]

Thanks Tom.

More shots taken with the A580:

[Marawder]

30 seconds at f/11, my new ND filter is fantastic: