Is there any way to take away the guess work from long exposures

What is it that you are trying to take pictures of ? Its sooo variable on subject, camera, personal taste etc etc. I suppose a light meter will help to an extent ... but I imagine that would give you a ballpark area from which you're likely to vary from anyway.

Similarly, take the time out to try different settings to see what you like, note down the settings that work best for your scenes and generate a quick referral cheat list of settings. i.e. a small card you can refer to.
 
Practice/Trial & Error is the best piece of advice I'm afraid. Presumably if you're shooting int these sorts of scenarios you have time to set up your tripod etc so should have time to fire off a couple of test shots?

Or are you shooting with film?
 
The issue I was having was one in which my A7 display reads bulb indicating an exposure of over 30 seconds is required but fails to indicate the length of exposure- which in a scene consisting of next to no light could be anything plus the time it takes to process. Once you need to go above 2 minutes it becomes a pain.

I suppose the other way to do this would be to take the exposure when there still remains a little bit of light to work with. However some Olympus cameras have a function called live bulb mode but the Sony doesn't making things a little harder.
 
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ethan said:
The issue I was having was one in which my A7 display reads bulb indicating an exposure of over 30 seconds is required but fails to indicate the length of exposure- which in a scene consisting of next to no light could be anything plus the time it takes to process. Once you need to go above 2 minutes it becomes a pain.

I suppose the other way to do this would be to take the exposure when there still remains a little bit of light to work with. However some Olympus cameras have a function called live bulb mode but the Sony doesn't making things a little harder.
Click to expand...

I would change the iso until it reads below 30 seconds and then you can work it out from there.

EG. Say you have to adjust by 3 stops to get your camera meter to stop reading Bulb and reads 22 secs instead. Then put iso back to what you want to shoot out and your shutter speed would be 22 x 2 x 2 x 2 = 176 seconds. Simples.
 
Use a calculator app on your phone.

Set the photo up with a very high iso. Input those into the calculator and then adjust for a low iso and it will give you the exposure time.
 
I know this doesn't help/answer your question but I quite like the 'trial and error' creative element of long exposure work. I've got little interest in applying anything methodical or being scientific about it. You usually get the right image after a few attempts.
 
I don't know if this will help you but I taught myself about long exposure times a few weeks ago. Basically keep increasing the ISO until the exposure meter is correct, then once you know how long the exposure should be, put the ISO back to 100 and then take the picture.

Below I've pasted my own words that I wrote into my photography notes on my phone to remind myself how it works. Then based on those notes I calculated bulb exposure times for every ISO and wrote out my own cheat sheet which will save me having to calculate when I'm actually out and set up with the camera on a tripod. I don't know about with ND filters, so these calculations are mostly for night time with no filter. I hope my notes below make sense :p


MY NOTES

'To calculate exposures longer than 30 seconds (mostly at night) so that the photo is not under or overexposed:-

Set 1SO to 100 and shutter speed to 30 seconds. It should be underexposed at this point. For each full stop of ISO I increase by, double the shutter time.

So 200 iso is 1 full stop and is doubled from 30 secs to 1 minute. 400 iso is 2 stops and doubles from 1 minute to 2 minutes. 800 iso is 3 stops and doubles from 2 minutes to 4 minutes. 1600 iso is 4 stops and doubles to 8 minutes. 3200 iso is 5 stops and doubles to 16 minutes, etc.

So if for example my exposure meter was correct at 3 stops (iso 800), I'd set bulb timer to 4 minutes. I'd then bring the ISO back down to 100 before starting the 4 minute exposure.

For thirds of a stop, take the difference between stops and divide by 3. So for example, the difference between 400 and 800 iso is 4 minutes minus 2 minutes = 2 minutes.
2 minutes × 60 = 120 seconds.
120 seconds ÷ 3 = 40 seconds.
So 2 and a third stops is 2 min 40.'

..............

My ISO CHART BULB TIMES

100 - 30 secs
125 - 40 secs
160 - 50 secs

One stop and thirds
200 - 1 minute
250 - 1 min 20 secs
320 - 1 min 40 secs

Two stops and thirds
400 - 2 minute
500 - 2 mins 40 secs
640 - 3 mins 20 secs

Three stops and thirds
800 - 4 minutes
1000 - 5 min 20 secs
1250 - 6 min 40 secs

Four stops and thirds
1600 - 8 minutes
2000 - 10 min 40 secs
2500 - 13 min 20 secs

Five stops and thirds
3200 - 16 minutes
4000 - 21 min 20 secs
5000 - 26 min 40 secs

Six stops and thirds
6400 - 32 minutes
8000 - 42 mins 40 secs
10,000 - 53 mins 20 secs

Seven stops
12,500 - 64 minutes
 
Merlin5 said:
I don't know if this will help you but I taught myself about long exposure times a few weeks ago. Basically keep increasing the ISO until the exposure meter is correct, then once you know how long the exposure should be, put the ISO back to 100 and then take the picture.

Below I've pasted my own words that I wrote into my photography notes on my phone to remind myself how it works. Then based on those notes I calculated bulb exposure times for every ISO and wrote out my own cheat sheet which will save me having to calculate when I'm actually out and set up with the camera on a tripod. I don't know about with ND filters, so these calculations are mostly for night time with no filter. I hope my notes below make sense :p


MY NOTES

'To calculate exposures longer than 30 seconds (mostly at night) so that the photo is not under or overexposed:-

Set 1SO to 100 and shutter speed to 30 seconds. It should be underexposed at this point. For each full stop of ISO I increase by, double the shutter time.

So 200 iso is 1 full stop and is doubled from 30 secs to 1 minute. 400 iso is 2 stops and doubles from 1 minute to 2 minutes. 800 iso is 3 stops and doubles from 2 minutes to 4 minutes. 1600 iso is 4 stops and doubles to 8 minutes. 3200 iso is 5 stops and doubles to 16 minutes, etc.

So if for example my exposure meter was correct at 3 stops (iso 800), I'd set bulb timer to 4 minutes. I'd then bring the ISO back down to 100 before starting the 4 minute exposure.

For thirds of a stop, take the difference between stops and divide by 3. So for example, the difference between 400 and 800 iso is 4 minutes minus 2 minutes = 2 minutes.
2 minutes × 60 = 120 seconds.
120 seconds ÷ 3 = 40 seconds.
So 2 and a third stops is 2 min 40.'

..............

My ISO CHART BULB TIMES

100 - 30 secs
125 - 40 secs
160 - 50 secs

One stop and thirds
200 - 1 minute
250 - 1 min 20 secs
320 - 1 min 40 secs

Two stops and thirds
400 - 2 minute
500 - 2 mins 40 secs
640 - 3 mins 20 secs

Three stops and thirds
800 - 4 minutes
1000 - 5 min 20 secs
1250 - 6 min 40 secs

Four stops and thirds
1600 - 8 minutes
2000 - 10 min 40 secs
2500 - 13 min 20 secs

Five stops and thirds
3200 - 16 minutes
4000 - 21 min 20 secs
5000 - 26 min 40 secs

Six stops and thirds
6400 - 32 minutes
8000 - 42 mins 40 secs
10,000 - 53 mins 20 secs

Seven stops
12,500 - 64 minutes
Click to expand...

interesting. Thank you.
 
Kei said:
That only applies to film as digital has a linear response to exposure. In a film data sheet, there is a always a section on it and the necessary corrections that need to be applied depending on the metered exposure time.
Click to expand...
Wow, did not know that. Shows I'm old school taught :rolleyes:

Checkout this 8 minute exposure with some funky stuff going on I can't scientifically explain. I was experimenting with a 10stop ND plus CPL.
With the Nikon D610 being an old camera I had to remote expose the image using an app by a live USB feed.
oDsoRzi.jpg
 
Merlin5 said:
I don't know if this will help you but I taught myself about long exposure times a few weeks ago. Basically keep increasing the ISO until the exposure meter is correct, then once you know how long the exposure should be, put the ISO back to 100 and then take the picture.

Below I've pasted my own words that I wrote into my photography notes on my phone to remind myself how it works. Then based on those notes I calculated bulb exposure times for every ISO and wrote out my own cheat sheet which will save me having to calculate when I'm actually out and set up with the camera on a tripod. I don't know about with ND filters, so these calculations are mostly for night time with no filter. I hope my notes below make sense :p


MY NOTES

'To calculate exposures longer than 30 seconds (mostly at night) so that the photo is not under or overexposed:-

Set 1SO to 100 and shutter speed to 30 seconds. It should be underexposed at this point. For each full stop of ISO I increase by, double the shutter time.

So 200 iso is 1 full stop and is doubled from 30 secs to 1 minute. 400 iso is 2 stops and doubles from 1 minute to 2 minutes. 800 iso is 3 stops and doubles from 2 minutes to 4 minutes. 1600 iso is 4 stops and doubles to 8 minutes. 3200 iso is 5 stops and doubles to 16 minutes, etc.

So if for example my exposure meter was correct at 3 stops (iso 800), I'd set bulb timer to 4 minutes. I'd then bring the ISO back down to 100 before starting the 4 minute exposure.

For thirds of a stop, take the difference between stops and divide by 3. So for example, the difference between 400 and 800 iso is 4 minutes minus 2 minutes = 2 minutes.
2 minutes × 60 = 120 seconds.
120 seconds ÷ 3 = 40 seconds.
So 2 and a third stops is 2 min 40.'

..............

My ISO CHART BULB TIMES

100 - 30 secs
125 - 40 secs
160 - 50 secs

One stop and thirds
200 - 1 minute
250 - 1 min 20 secs
320 - 1 min 40 secs

Two stops and thirds
400 - 2 minute
500 - 2 mins 40 secs
640 - 3 mins 20 secs

Three stops and thirds
800 - 4 minutes
1000 - 5 min 20 secs
1250 - 6 min 40 secs

Four stops and thirds
1600 - 8 minutes
2000 - 10 min 40 secs
2500 - 13 min 20 secs

Five stops and thirds
3200 - 16 minutes
4000 - 21 min 20 secs
5000 - 26 min 40 secs

Six stops and thirds
6400 - 32 minutes
8000 - 42 mins 40 secs
10,000 - 53 mins 20 secs

Seven stops
12,500 - 64 minutes
Click to expand...

When I used film this the method I use for dark scenes.
By doubling the ISO up you can count how many seconds you need to count for the exposure when you reset back to ISO
 
juno_first said:
Wow, did not know that. Shows I'm old school taught :rolleyes:

Checkout this 8 minute exposure with some funky stuff going on I can't scientifically explain. I was experimenting with a 10stop ND plus CPL.
With the Nikon D610 being an old camera I had to remote expose the image using an app by a live USB feed.
oDsoRzi.jpg
Click to expand...

ND plus CPL is probably the culprit. Due to the way they work SFAIK they don't always play nicely together. Can you confirm what kind of filters?
 
Did you cover the viewfinder before taking the photo?
I've had similar odd results with light leak through the viewfinder.

As for the original question, set the iso to 256000 and calculate from there.
 
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