Summer Triangle and Cygnus

[Vega]

Managed to get out of the light pollution and take this at a dark site.

Really pleased with it considering the short exposure time taken.

Modded Canon 1000d, 18-55 mm stock lens @ 18mm

3x 3min exposures, ISO 800, f/4.5

Custom white balance

The histogram is quite far to the left on the raw files (although no data touching the far left edge), does anyone know how I would correct this next time round? From an image capture point of view? Or is this expected for this part of sky?

Thanks for looking, all feedback welcomed

[wxsatuser]

Very nice image, well done.

The RAW histogram will no doubt be further to the left compared to the in camera histogram.

The in camera histogram is of a jpeg and you should aim to get that around 20>40%.

I normally aim for 25%, your sky brightness will dictate how quick you reach this mark.

On average here I get 5min subs at iso 1600 for a 25% histogram.

[Pete Presland]

excellent image, lots of nebulosity showing as well.

[Pete Presland]

Very nice image, well done.

The RAW histogram will no doubt be further to the left compared to the in camera histogram.

The in camera histogram is of a jpeg and you should aim to get that around 20>40%.

I normally aim for 25%, your sky brightness will dictate how quick you reach this mark.

On average here I get 5min subs at iso 1600 for a 25% histogram.

when you say 25% does this mean 25% of  the scale from white to black full?

[Vega]

I was referring to the histogram in the camera. I've not looked at the histogram in the stacked raw image or post processed image. Will be interesting to compare. I need to start using the histogram more in processing... Tut tut. The uncropped image did look clipped at the top of the frame. It was just too black. Probably the way I stretched it in ImagesPlus' digital development tool.

[wxsatuser]

when you say 25% does this mean 25% of  the scale from white to black full?

Canon's in camera histogram is divided into 5.

Get the mountain peak of the histogram just past the first line from the left.

This gets the data out of the read noise but does'nt push it to far right, upto 40% is ok.

[Pete Presland]

like this

[wxsatuser]

like this

09_60d_histogram__hero.jpg

Thats it.

[Vega]

Canon's in camera histogram is divided into 5.

Get the mountain peak of the histogram just past the first line from the left.

This gets the data out of the read noise but does'nt push it to far right, upto 40% is ok.

Thanks for the advice. Do you know how I would achieve this. Does it simply mean taking longer exposures / changing the ISO to 1600 ?

Regards

Here is the histogram for the finished image, its very close to being clipped. Worse than the original histogram on the camera which featured a much narrower mountain but slightly more to the right in comparison.

[jgs001]

Looks good Matt

Something to bear in mind with the histogram... it's showing 256 levels of data... 8 bit... but the camera raw is 12 or 14 bit, so you have some leeway...

probably doesn't make too much difference for this sort of thing though... Realistically, the only way to move the histogram to the right, is to expose for longer. Upping the ISO just increases the gain/amplification of the signal on the sensor read, better to have longer exposures where possible. As you're able to get 3 minutes at 18mm you're tracking, so push it up to 5 minutes.

[wxsatuser]

Thanks for the advice. Do you know how I would achieve this. Does it simply mean taking longer exposures / changing the ISO to 1600 ?

Regards

Here is the histogram for the finished image, its very close to being clipped. Worse than the original histogram on the camera which featured a much narrower mountain but slightly more to the right in comparison.

Set whatever ISO your going to use and  take a few test shots,

Check each exposure with the camera histogram, like the image bunnygod shows above.

I normally start at 1min exposures and work my way up until the histogram peak lies around 25%.

I can normally guess what my exposure will be by looking at how bright the sky is.

The average here is 5minutes with the ISO at 1600.

Sometimes when it's been really dark here I have pushed it to 10minutes

[Vega]

Thanks for the advice guys. I did wonder if it was exposure time that affects it. Like you have said, I'll just do a couple test shots, review them in the camera and work my way up. :-) Hoping to have another go at the milky way towards the end of the month once the moons back to waning crescent.

However it will be a horizon shot with Sagittarius and friends reflecting off a lake... wish me luck with that one! Histogram will definitely be a different shape!