Post your low light long exposures

J

J-see

Senior Member
I went out for some shots and after too long a walk while setting up I noticed I indeed had the tripod plate attached to the cam but sadly not this one.

I didn't really feel like going out for a second try.

A good time to practice some more blending different ISO shots. I now process one into multiple versions using a different WB and exposure for each and blend those together with the other ISO. I'm still not satisfied but it's going into the right direction.

_DSC2275-Edit-Edit.jpg
 
J

J-see

Senior Member
wornish said:
I had the same thought. So @J-see what is the goal ?
Click to expand...

I simply combined things I was experimenting with in this shot.

I'm still trying to find the best method to maximize my quality at night. During the day it's easy but during the night I need to find out how I can get the best color and details while minimizing noise.

I was shooting different ISO settings to compare the shots and check if there was improvement or not. But since it was very windy, I decided to simultaneously take shots in which I could combine those clouds while on top of that blending temperature differences to enlarge the color palette.

I prefer to do multiple things at the same time when possible since that saves me a lot of time/work and I still learn what I wanted to learn.
 
B

Blacktop

Senior Member
J-see said:
I simply combined things I was experimenting with in this shot.

I'm still trying to find the best method to maximize my quality at night. During the day it's easy but during the night I need to find out how I can get the best color and details while minimizing noise.

I was shooting different ISO settings to compare the shots and check if there was improvement or not. But since it was very windy, I decided to simultaneously take shots in which I could combine those clouds while on top of that blending temperature differences to enlarge the color palette.

I prefer to do multiple things at the same time when possible since that saves me a lot of time/work and I still learn what I wanted to learn.
Click to expand...

Can you do ISO or WB bracketing with the D750?
 
J

J-see

Senior Member
Blacktop said:
Can you do ISO or WB bracketing with the D750?
Click to expand...

I do everything the old fashioned way; manual. The cam is on a pod so the static part of the scene remains identical and the time in between my shots ensures the clouds, and the light cast on them, are entirely different. That's how I do the ISO.

WB I do in post since that's much easier.

The reason I test this is because the night skies of a single shot too often have a very limited color palette while in reality the light is in constant change and so are the colors. By enlarging the palette I try to artificially add some of that change into my shots.

Here's one of those previous shots with auto-WB. As you see, the sky is very dull and even if I change the WB, it will remain rather limited color wise. That's one of the problems with night skies. During the day colors are not an issue but during the night and during one exposure, they too often come in one version.

_DSC2316.jpg

It's the same for that previous shot. Here's one of them normally processed.

_DSC2275.jpg
 
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J

J-see

Senior Member
Blacktop said:
Can you do ISO or WB bracketing with the D750?
Click to expand...

I just checked the bracketing options and the D750 can bracket exposure, flash level, active D-Lighting and WB. I personally don't really need any of them at the moment. Exposure however might come in handy one day.
 
J

J-see

Senior Member
RON said:
What you talkin. My Congressman says that there is no such thing as pollution, and even if there was, it would be good for me. You must have just fogged your lens somehow.:anonymous:
Click to expand...

It must have been a farmer with a flashlight who's hobby is annoying photographers. ;)

While experimenting with blending multiple copies of the same shot, I noticed I can increase the brightness of the stars even when their brightness is too low in the original. It provides the advantage I don't need to shoot higher than 200-400 ISO to get all I need. A couple more test runs and I should be able to do shoot nightsky + landscape in one shot without losing much of both.
 
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J

J-see

Senior Member
wornish said:
Very nice.
How many shots / layers did you merge in this ?
Click to expand...

This is one shot I started with. I first processed it in two different versions; one for the landscape and one for the sky and then used both in PS. Those I copied several times and then blend them together, first trying to remove as much light pollution as possible and then increasing the brightness of the stars. That's the hardest part.

The landscape is easy and once that is done, I simply use layer mask and erase it in the new layers while working at the rest.

All in all this one was not more than three of four copies blended of both different versions. Some eight layers blended most having masks and some erasing at different opacity. Not as many as some of the previous shots.

Multiple shots is nice if I want more detail for the landscape but for stars it doesn't work too well since they travel while I'm shooting and I have to realign the stars while removing the rest if I want to blend those. Best is finding the correct settings to do it in one shot. That's not easy if you want sharpness, minimal vignetting, wide aperture and a long enough duration to grab enough photons.
 
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J

J-see

Senior Member
I need to figure out what to do with ISO.

I had this idea that changing ISO changed the sensor's sensitivity to light but apparently that's not correct. It's not like film where a different ISO implied an actual difference in sensitivity to light. From what I read, the sensor remains as is regardless which ISO setting. The change in sensitivity is mainly a conversion where increasing the ISO doubles the photon count of a pixel, or halves it when going down a stop, while converting the signal to digital.

If that is true, it makes me wonder if I can't just as easy do in post what the cam does when changing ISO.

I guess I need to read up even more. It never ends.
 
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J

J-see

Senior Member
I just checked it with a shot taken at ISO 100.

The only thing that affects the light I capture is the lens' aperture and the cam's shutter speed. With my 24mm that's between f/22 at 1/4000th as a minimum and, ignoring the bulb and timer, f/1.4 at 30s. ISO has zero effect on that.
That should imply that when I can capture my scene without clipping at the native ISO (100), it is better to increasing brightness levels in post than increasing ISO which only results in more noise since it does multiple the existing noise.

This is a shot I took at ISO 100, f/1.4 at 30s. The histograms show there is minimal clipping. Only the blue channel suffered some minor clipping.

iso.jpg

I increased exposure in post to see what data was there:

_DSC2329.jpg

I apparently have all I need and that was provided solely by the aperture/shutter combination. More ISO would not have added anything beneficial. Only noise.

Evidently, when clipping occurs, it becomes another story. During night shots that is often the darker part of a shot and to avoid that, decreasing the shutter duration should be prioritized over increasing ISO.
 
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