Photography Thailand Forum

[David Procter]

Recent full moon pic from Koh Tao shore.
I tried several exposures - this one 30s f/5.6 at 10.0mm iso200
You can see over 30secs the moon has moved.
what do you think?

If i had wanted to take a picture of the moon with its detail preserved in this scene - hoe could you do it? Would you have to make two exposures and over lap them?

[David Procter]

i dont think that came out very optimised!

[canon]

Hi David,

I used to stay on Koh Tao for some time and was wondering where you shoot the pic. I've never seen
so many rocks in one place around the beaches of KT. Did you merge or superimpose the image, retouch
it in PS? it doesnt look like you smart blurred the channels in the image much considering the grains on there.

[David Procter]

Thansk for the interest - Its from Au leuk Bay. Its basically as shot. Yeah the grain is terrible here. the original is much better. I was trying to optimise the file for the web and it went a bit wrong. The one on my site is better.
http://www.pbase.com/dravlinbood/sea
I've never smart blurred the channels, can you tell me more! I just learnt yesterday that the blue channel holds the most noise and that would explain the amount of noise here.

[canon]

Hi David,

I'm a newbie too so please correct me if I'm wrong. I find more noise in the blue channel too and this goes
for close up  portraits also. I took yr pic and used the lasso tool to select the area around the stone and then
checked each channel in the layers palette. The blue had most noise and abit in the green then I
went to filter/blur/smart blur and blurred the blue and green channel by a radius of 6.5 and 3.2 with theshold
set at 30. I used the spot healing brush to fix the white spot in the sky and then sharpend the image with
unmask at 30pct. It looks like this.

 

[Marc Schultz]

A few questions come to mind David:

How long was the exposure on this image?

What was the ISO setting on the camera?

Do you have the original RAW file or did you shot this as JPG?

Did you do any sort of post porcessing on the image that might have accentuated the noise, like pushing up the levels in the highlight area too high?

More information would be good and maybe we can then at least help to isolate the cause of the noise, possibly retrace the steps in post procesing to avoid it, and/or advise how to shoot better next time in this type of lighting situation resulting in less noise.

Hope this helps...

[David Procter]

I tried several exposures all shot in RAW- this one 30s f/5.6 at 10.0mm iso200
The post processing invloved changing the WB in raw mode and a slight exposure change also in raw.
I converted to a JPEG, then adjusted the levels. I also had to get rid of all the mess from my dirty sensor (previous post!).
My post processing is pretty limited at the moment and i've only scratched the surface with PS.
Yes i still have the original - i'm keeping it til i learn more.
thanks for the interest

[Marc Schultz]

Thank you for the additional information David. A couple of initial observations come to mind:

1 - Any long exposures, meaning anything over 2-3 seconds should be shot at ISO 100 to minimize noise.

2 - Exposures over 10 seconds typically will result in some noise in the shadows. It is the nature of digital cameras trying to find enough light to make an exposure in dark areas within low light situations.

3 - Any overexposure typically results in noise in the shadows and it would appear to me this shot probably did not need to be exposed that long. Seems maybe you tried to take a dark setting and expose it long enough to make a bright image out of it. Probably 10-15 seconds would have been enough exposure to get somehting out of this shot. Photography is often a series of compromises I found and in this case one might have to accept it was already too dark to do such a long exposure and get it just right. Another solution would be to reshoot it another night before it gets dark or settle for a darker exposure given the low light sitaution as this helps to hide more of the noise that is occuring in the shadows.

4 - As I said in my previous message, you might have tried bringing out some of the shadows so much, either during exposure, post processing, or both that is resulted in a lot of revealed noise. You could try redeveloping the RAW file in PhotoShop and reducing the amount of exposure compensation. The result will be a darker image, but possibly it will take on another moddier atmosphere and with less noise.

5 - I would also convert from RAW to TIF first, do all your post production work on the TIF file, which holds more color and pixel data, and then convert to JPG at the last step of your workflow after you downsize the image for web purposes.

Do you happen to have any shots you took that night with say only a 10-15 second exposure? It might be interesting to see one of those.

Also, Kurt in the Photoshop corner might be able to shine a bit more light on this (no pun intended) from a technical side since a lot of the issues I mentioned realte to digital post processing.

Anyway, hope this helps to clarify things a bit and not confuse things any further.