Newbie Long exposure

[Jack]

I know there has been given some advice and information about long exposure . But it’s better to talk about it on dedicated thread.

So back to the subject, how you can take pictures longer than 30 seconds, yes I’ve noticed Bulb option next to 30seconds, but never decided to try. If I choose bulb, for how long I can leave the shutter open? Obviously with my current ND filter.

Would this affect my pictures if the shutter camera will be left for long time?

 

[Andy Smith]

In Bulb mode you can leave the shutter open as long as you want. If you have a remote cord or wireless remote you can use that instead of pressing the shutter release button, to ensure there is no camera shake.
You can buy intervalometers if your camera doesn't have one built in, which let you set the exposure time and will automatically open & close the shutter. or if you just have a simple remote cord without timer, you can use a timer on your phone.
You have to calculate exposure times to ensure the pictures are exposed correctly with long exposure anyway, so in your case your images are only affected by the smoothing out of movement.
With your ND filter and example would be:
without filter exposure settings - f/8.0, ISO 100, 1/5s
with 10 stop ND filter - f/8.0, ISO 100, you would need the shutter open for 3min 25s to get the same exposure.

Astro long exposures are different as you are opening the shutter for long periods to enable more light to hit the sensor, and catch the faint details of stars, nebula or galaxies etc.
I use an intervalometer for astro, so shoot without any filters but have exposure lengths of 3 - 5 minutes sometimes, so I set my intervalometer to shoot 64x frames at 3 minutes each frame. Then press start and walk away for a few hours while it does it's job.

 

[Jack]

In Bulb mode you can leave the shutter open as long as you want. If you have a remote cord or wireless remote you can use that instead of pressing the shutter release button, to ensure there is no camera shake.
You can buy intervalometers if your camera doesn't have one built in, which let you set the exposure time and will automatically open & close the shutter. or if you just have a simple remote cord without timer, you can use a timer on your phone.
You have to calculate exposure times to ensure the pictures are exposed correctly with long exposure anyway, so in your case your images are only affected by the smoothing out of movement.
With your ND filter and example would be:
without filter exposure settings - f/8.0, ISO 100, 1/5s
with 10 stop ND filter - f/8.0, ISO 100, you would need the shutter open for 3min 25s to get the same exposure.

Astro long exposures are different as you are opening the shutter for long periods to enable more light to hit the sensor, and catch the faint details of stars, nebula or galaxies etc.
I use an intervalometer for astro, so shoot without any filters but have exposure lengths of 3 - 5 minutes sometimes, so I set my intervalometer to shoot 64x frames at 3 minutes each frame. Then press start and walk away for a few hours while it does it's job.

Thanks for information. Would the image quality be affected if the shutter will be left for more minutes?

Not sure if can set my camera to take pictures every x minutes. 🤔 Probably will have to check it out.

 

[Andy Smith]

Thanks for information. Would the image quality be affected if the shutter will be left for more minutes?

I don't think there would be any image quality problems Jack, I have never had any and have never read or heard of any problems arising from long exposures.

 

[panos_adgr]

Thanks for information. Would the image quality be affected if the shutter will be left for more minutes?

Not sure if can set my camera to take pictures every x minutes. 🤔 Probably will have to check it out.

Hello Jack

Very long exposures have an inevitable negative effect regardless of camera brand and price tag. And that is 'hot pixels' which are identified in the dark areas more intense. This can be avoided by turning on 'long exposure noise reduction' in camera but it will take the same time of processing as the long exposure lasted. In example if you use an one minute exposure then when you take the picture an indication will tell you that the camera is 'processing'. What happens is the camera is taking one more dark exposure and then from the noise pattern it produces it removes the noise from the first exposure.

It is more intense in summer due to higher ambient temperatures. Hot pixels are mostly intense in very long time exposures over 1-2 minutes. Hot pixels are caused form sensor overheating when long exposures are performed. They can be removed in photoshop with some effort or with some special techniques known to astro-photographers.

Personally, in order to avoid this problem I make 9 exposures of 30 seconds when possible and then I stack them in Photoshop in Mean mode. Noise has a random pattern and when you stack the photos in Mean or Median modes, noise is 'cancelled'.

It isn't something to worry about that much but hot pixels is a 'consequence' of long exposure which occurs at circumstances. So if you make one day a veeeery long exposures and you see green, red, blue or white dots here and there (in the photo) you will know what it is.

 

[Jack]

I don't think there would be any image quality problems Jack, I have never had any and have never read or heard of any problems arising from long exposures.

Thanks Andy Smith, I thought there could be some image issue if left for long time.

 

[Jack]

Hello Jack

Very long exposures have an inevitable negative effect regardless of camera brand and price tag. And that is 'hot pixels' which are identified in the dark areas more intense. This can be avoided by turning on 'long exposure noise reduction' in camera but it will take the same time of processing as the long exposure lasted. In example if you use an one minute exposure then when you take the picture an indication will tell you that the camera is 'processing'. What happens is the camera is taking one more dark exposure and then from the noise pattern it produces it removes the noise from the first exposure.

It is more intense in summer due to higher ambient temperatures. Hot pixels are mostly intense in very long time exposures over 1-2 minutes. Hot pixels are caused form sensor overheating when long exposures are performed. They can be removed in photoshop with some effort or with some special techniques known to astro-photographers.

Personally, in order to avoid this problem I make 9 exposures of 30 seconds when possible and then I stack them in Photoshop in Mean mode. Noise has a random pattern and when you stack the photos in Mean or Median modes, noise is 'cancelled'.

It isn't something to worry about that much but hot pixels is a 'consequence' of long exposure which occurs at circumstances. So if you make one day a veeeery long exposures and you see green, red, blue or white dots here and there (in the photo) you will know what it is.

Thanks panos_adgr , bit late reply here. So are you saying that is better to take multiple pictures taken with 30 seconds and then stack them together ?

 

[panos_adgr]

Thanks panos_adgr , bit late reply here. So are you saying that is better to take multiple pictures taken with 30 seconds and then stack them together ?

Hi Jack!
As long as you expose well (I mean sensor saturation) and your exposure time is about 3-4 minutes you will not have significant issues.

 

[Jack]

Hi Jack!
As long as you expose well (I mean sensor saturation) and your exposure time is about 3-4 minutes you will not have significant issues.

If the shutter is opened for longer, is a chance that the quality of the photo will be affected?

 

[MartinF]

If the shutter is opened for longer, is a chance that the quality of the photo will be affected?

I have not seen any of those negative effects when doing 3-4 minute exposures. If there should be a dead pixel or two you can clone them out in a minute. I find for landscapes it is easier with one long exposure. For astro, it´s a whole other deal
See attached image, it had a 4 minute exposure for the foreground. No problems there.

 

[panos_adgr]

If the shutter is opened for longer, is a chance that the quality of the photo will be affected?

No. Don't worry about this matter.

 

[panos_adgr]

Great example M MartinF .

Jack as you see from the above photo of Martin the quality is not affected. You can also clearly see the hot pixels on the lower part of the image. They can be removed in post processing though.

 

[Jack]

Great example M MartinF .

Jack as you see from the above photo of Martin the quality is not affected. You can also clearly see the hot pixels on the lower part of the image. They can be removed in post processing though.

Can't notice any hot pixels 🤔. Maybe because I'm browsing from my phone.

 

[Jack]

I have not seen any of those negative effects when doing 3-4 minute exposures. If there should be a dead pixel or two you can clone them out in a minute. I find for landscapes it is easier with one long exposure. For astro, it´s a whole other deal
See attached image, it had a 4 minute exposure for the foreground. No problems there.View attachment 419

Might sound stupid question, but what do you mean by dead pixel?

 

[panos_adgr]

Can't notice any hot pixels 🤔. Maybe because I'm browsing from my phone.

They are identified as red dots or green or blue. They are on the part of the image where the rocks are.

Anyway, the photo of Martin is amazing!

 

[Jack]

They are identified as red dots or green or blue. They are on the part of the image where the rocks are.

Anyway, the photo of Martin is amazing!

Thanks for the info panos_adgr . I will know that now.