Overexposure in Deepskystacker

[pringlepowell]

Any idea why every time i use deepskystacker my final image seems to be grossly over exposed?

For instance I was concentrating on M33 the other night. I took 3 30 second exposures of the galaxy at ISO 3200 and stacked it with 20 dark shots and 20 bias shots (correct, no flats). The result in Deepskystacker was so pale everything looked washed out. Any ideas please? I'm going crazy. It doesn't seem to matter what the image is, I always get the same result.

Help!!

[jgs001]

The first thing DSS does on screen, when the stack process is complete, is perform a stretch of the image data to show you. This does not always go well, and sometimes I've had odd looking results like you describe. You could try tweaking the luminance curves and see what difference that makes. However, I save the image out with adjustments embedded and then proceed to edit the image itself from scratch... ok, it looks almost blank when loaded into PS, but I find there's a lot more fine control in the processing this way.

[pringlepowell]

So basically use the luminance controls to blacken eveything out in dss then work with the black image in photoshop?

[pringlepowell]

Could someone do me a favour and have a look in my gallery at the image called 'what's gone wrong'? It's basically a screen grab of photoshop whenever I've tried to stack the images and start processing. Ta

[RogerTheDodger]

That looks fine, but you'll need way more lights. Have a look for a DSS tutorial, and a processing tutorial, there are loads around, you'll soon see what you need to do next.

[allcart]

You could try stacking with different methods e.g. kappa-sigma instead of average or median.

[ollypenrice]

Personally I wouldn't do anything at all in DSS other than stack and calibrate. All the rest I'd do in Photoshop.

Olly

[jgs001]

Looking at the one in the gallery, looks like DSS has just overdone the base adjustments to show whats on the screen... you could have a play with the luminance settings and change the way it displays... You're biggest issue is going to be the small number of lights... don't let that stop you processing it though, the practice never hurts

So basically use the luminance controls to blacken eveything out in dss then work with the black image in photoshop?

Nope... ignore the adjustments in DSS... even the author of DSS states that the adjustments are not designed for processing the final image, only to see what's there.. When you click on save image, you get two radio buttons, save and apply adjustments, or save with adjustments embedded. Take the adjustments embedded... WHen you load the image into PS, it'll probably look almost black, but that's ok... the information is there, just buried...

Regarding the stacking mechanisms, the kappa sigma mechanism works great (it removes planes, satellites etc), but you need at least 12 light frames for it to work.

[pringlepowell]

Bizarre, I would have thought more lights would have led to more of an orange hue given the exposure. The trouble I seem to keep having is I would like the image to be black when opened in photshop, but it always has the bright over-exposed look. The tutorials I have viewed always start in photoshop with a black image, which would be great.

[jgs001]

How are you saving the images from dss ??

[pringlepowell]

They are being saved as TIFF images, with the 'adjustments embedded but not applied'. Is that wrong? I have the median kappa-sigma enabled too.

[jgs001]

Using the autosave.tif is actually opening a 32 bit image file, and I believe PS does it's best to render that to fit on the display. I don't know how well the rendering of the display can work. (sorry, couldn't see that when I looked at it on my phone the other day). If you look at the title bar to the image, you can see in brackets (RGB/32*). Try opening the saved with adjustments embedded tif and see how that looks.

[Velvet]

i had 32 bit file once and when i opened in photoshop if you go to image... mode.....you can change it to 16 bit and process from there. I hope i have understood query correctly. if not just ignore me LOL

velvet

[pringlepowell]

Right, well I had another go. I produced a stacked image of M33 using 12 lights, 20 darks, 20 bias and even 12 flat shots. It took about 2 hours to stack and when the final result appeared, it looked exactly the same. I'm wondering if it's something to do with the camera. I have a Sony Nex 3 at the moment, using an ISO of either 1600 or 3200, with 30 seconds of exposure for each image.

I must be doing something very wrong, as I simply can't think of another way to get a nice dark image.

[allcart]

start up DSS and load the autosaved tiff again. It still looks the same doesn't it. Now 'save the picture to file'

Choose the 16bit tiff option. Call it something simple.

Now open that file in photoshop. Does it still look the same?

[pringlepowell]

I've started using the Gradient plugin in Photoshop and see much better results. I don't know if all of my photographs were overexposed or whether it had something to do with excessive light pollution. Currently looking into some filters to try and combat it.