Trouble with bracketing (Nikon D500)

[jgoldshlag]

Having a couple problems with trying to change over the script to use bracketing to capture the corona, which mostly works, except:

A five shot 1EV bracket from 1.3 doesn't give what I would expect: I get 1/6, 1/3, 1/1.6, 1.3, 2.5, which is stop lower than I would have expected. It seems like something doesn't like to go up to 5 second exposures, not sure if this is a Nikon problem or a SEM problem. Not a huge deal, but a little odd.

My 2nd problem is more annoying. This test script illustrates the issue:

Code: Select all

SETBKT,C2,-,00:22.5,D500, , ,0, , , , ,Deactivate bracketing
CHGCSSL,C2,-,00:21.5,D500, , ,0, , , , ,Set to maximum burst frame rate
EXPMODM,C2,-,00:22.0,D500, , , , , , , ,Set camera to Manual (M)
BKTDATA,7,1.0EV,u0o

LVPSTART,C2,-,00:20.0,D500, , , , , , , ,Start Lv
LVPSTOP,C2,+,00:25.0,D500, , , , , , , ,Stop Lv

SETBKT,C2,-,00:15.5,D500, , ,1, , , , ,Activate bracketing for the burst
TAKEBST,C2,-,00:15.0,D500,1/100,8.0,100,7,RAW,None,Y,Solar corona Rs = 0.1-0.5
TAKEBST,C2,-,00:12.0,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0

# workaround for bracketing issue
SETBKT,C2,-,00:03.5,D500, , ,0, , , , ,Deactivate bracketing for the burst
SETBKT,C2,-,00:03.0,D500, , ,1, , , , ,Activate bracketing for the burst

TAKEBST,C2,-,00:02.5,D500,1/100,8.0,100,7,RAW,None,Y,Solar corona Rs = 0.1-0.5
TAKEBST,C2,+,00:00.5,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0
SETBKT,C2,+,00:10.5,D500, , ,0, , , , ,Deactivate bracketing


If I don't have the middle lines flipping bracketing off and back on, I see the 3rd burst only take 2 shots (1/13 and 1/25). It doesn't matter if I space things out a bunch, but inserting the SETBKT lines fixes things. I'll probably just run with that for this eclipse, but it would be nice to fix in the future. Also, generating the default script with bracketing bursts like this seems like a pretty good win, it gave me an extra 15 or so seconds of time during totality to mess around with.

[xjubier]

A five shot 1EV bracket from 1.3 doesn't give what I would expect: I get 1/6, 1/3, 1/1.6, 1.3, 2.5, which is stop lower than I would have expected. It seems like something doesn't like to go up to 5 second exposures, not sure if this is a Nikon problem or a SEM problem. Not a huge deal, but a little odd.

I would need to check, right now it is too late for the eclipse. Do upgrade to SEM 1.8.6v2 if you haven't yet (it will unlikely solve your issue).

My 2nd problem is more annoying. This test script illustrates the issue:

Code: Select all

SETBKT,C2,-,00:22.5,D500, , ,0, , , , ,Deactivate bracketing
CHGCSSL,C2,-,00:21.5,D500, , ,0, , , , ,Set to maximum burst frame rate
EXPMODM,C2,-,00:22.0,D500, , , , , , , ,Set camera to Manual (M)
BKTDATA,7,1.0EV,u0o

LVPSTART,C2,-,00:20.0,D500, , , , , , , ,Start Lv
LVPSTOP,C2,+,00:25.0,D500, , , , , , , ,Stop Lv

SETBKT,C2,-,00:15.5,D500, , ,1, , , , ,Activate bracketing for the burst
TAKEBST,C2,-,00:15.0,D500,1/100,8.0,100,7,RAW,None,Y,Solar corona Rs = 0.1-0.5
TAKEBST,C2,-,00:12.0,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0

# workaround for bracketing issue
SETBKT,C2,-,00:03.5,D500, , ,0, , , , ,Deactivate bracketing for the burst
SETBKT,C2,-,00:03.0,D500, , ,1, , , , ,Activate bracketing for the burst

TAKEBST,C2,-,00:02.5,D500,1/100,8.0,100,7,RAW,None,Y,Solar corona Rs = 0.1-0.5
TAKEBST,C2,+,00:00.5,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0
SETBKT,C2,+,00:10.5,D500, , ,0, , , , ,Deactivate bracketing


If I don't have the middle lines flipping bracketing off and back on, I see the 3rd burst only take 2 shots (1/13 and 1/25). It doesn't matter if I space things out a bunch, but inserting the SETBKT lines fixes things. I'll probably just run with that for this eclipse, but it would be nice to fix in the future. Also, generating the default script with bracketing bursts like this seems like a pretty good win, it gave me an extra 15 or so seconds of time during totality to mess around with.

Here is the explanation. You have
BKTDATA,7,1.0EV,u0o
which is a global setting and expect a 7-bracket burst. But there
TAKEBST,C2,-,00:12.0,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0
you only take 5 out of the 7 frames, so the next time it fires the remaining two. The reason why it work by deactivating the bracketing and reactivating it is that this operation resets the bracketing.

Now there is one thing you're doing I don't understand: you're shooting coronal exposures before/at 2nd contact. This doesn't make sense. What is visible during that time-frame is Diamond ring and Baily's beads which both require shorter exposures.

[jgoldshlag]

A five shot 1EV bracket from 1.3 doesn't give what I would expect: I get 1/6, 1/3, 1/1.6, 1.3, 2.5, which is stop lower than I would have expected. It seems like something doesn't like to go up to 5 second exposures, not sure if this is a Nikon problem or a SEM problem. Not a huge deal, but a little odd.

I would need to check, right now it is too late for the eclipse. Do upgrade to SEM 1.8.6v2 if you haven't yet (it will unlikely solve your issue).

OK, like I said, not a big problem.

My 2nd problem is more annoying. This test script illustrates the issue:

Code: Select all

SETBKT,C2,-,00:22.5,D500, , ,0, , , , ,Deactivate bracketing
CHGCSSL,C2,-,00:21.5,D500, , ,0, , , , ,Set to maximum burst frame rate
EXPMODM,C2,-,00:22.0,D500, , , , , , , ,Set camera to Manual (M)
BKTDATA,7,1.0EV,u0o

LVPSTART,C2,-,00:20.0,D500, , , , , , , ,Start Lv
LVPSTOP,C2,+,00:25.0,D500, , , , , , , ,Stop Lv

SETBKT,C2,-,00:15.5,D500, , ,1, , , , ,Activate bracketing for the burst
TAKEBST,C2,-,00:15.0,D500,1/100,8.0,100,7,RAW,None,Y,Solar corona Rs = 0.1-0.5
TAKEBST,C2,-,00:12.0,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0

# workaround for bracketing issue
SETBKT,C2,-,00:03.5,D500, , ,0, , , , ,Deactivate bracketing for the burst
SETBKT,C2,-,00:03.0,D500, , ,1, , , , ,Activate bracketing for the burst

TAKEBST,C2,-,00:02.5,D500,1/100,8.0,100,7,RAW,None,Y,Solar corona Rs = 0.1-0.5
TAKEBST,C2,+,00:00.5,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0
SETBKT,C2,+,00:10.5,D500, , ,0, , , , ,Deactivate bracketing


If I don't have the middle lines flipping bracketing off and back on, I see the 3rd burst only take 2 shots (1/13 and 1/25). It doesn't matter if I space things out a bunch, but inserting the SETBKT lines fixes things. I'll probably just run with that for this eclipse, but it would be nice to fix in the future. Also, generating the default script with bracketing bursts like this seems like a pretty good win, it gave me an extra 15 or so seconds of time during totality to mess around with.

Here is the explanation. You have
BKTDATA,7,1.0EV,u0o
which is a global setting and expect a 7-bracket burst. But there
TAKEBST,C2,-,00:12.0,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0
you only take 5 out of the 7 frames, so the next time it fires the remaining two. The reason why it work by deactivating the bracketing and reactivating it is that this operation resets the bracketing.

Now there is one thing you're doing I don't understand: you're shooting coronal exposures before/at 2nd contact. This doesn't make sense. What is visible during that time-frame is Diamond ring and Baily's beads which both require shorter exposures.

Should I not have the global setting? How else can I set the stops between the brackets?

The timing is just because I was testing, and it is easier to just set up everything to run around C2 so I can just reset the simulated time to C2. My real script has them at the right time...

[xjubier]

My 2nd problem is more annoying. This test script illustrates the issue:

Code: Select all

SETBKT,C2,-,00:22.5,D500, , ,0, , , , ,Deactivate bracketing
CHGCSSL,C2,-,00:21.5,D500, , ,0, , , , ,Set to maximum burst frame rate
EXPMODM,C2,-,00:22.0,D500, , , , , , , ,Set camera to Manual (M)
BKTDATA,7,1.0EV,u0o

LVPSTART,C2,-,00:20.0,D500, , , , , , , ,Start Lv
LVPSTOP,C2,+,00:25.0,D500, , , , , , , ,Stop Lv

SETBKT,C2,-,00:15.5,D500, , ,1, , , , ,Activate bracketing for the burst
TAKEBST,C2,-,00:15.0,D500,1/100,8.0,100,7,RAW,None,Y,Solar corona Rs = 0.1-0.5
TAKEBST,C2,-,00:12.0,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0

# workaround for bracketing issue
SETBKT,C2,-,00:03.5,D500, , ,0, , , , ,Deactivate bracketing for the burst
SETBKT,C2,-,00:03.0,D500, , ,1, , , , ,Activate bracketing for the burst

TAKEBST,C2,-,00:02.5,D500,1/100,8.0,100,7,RAW,None,Y,Solar corona Rs = 0.1-0.5
TAKEBST,C2,+,00:00.5,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0
SETBKT,C2,+,00:10.5,D500, , ,0, , , , ,Deactivate bracketing


If I don't have the middle lines flipping bracketing off and back on, I see the 3rd burst only take 2 shots (1/13 and 1/25). It doesn't matter if I space things out a bunch, but inserting the SETBKT lines fixes things. I'll probably just run with that for this eclipse, but it would be nice to fix in the future. Also, generating the default script with bracketing bursts like this seems like a pretty good win, it gave me an extra 15 or so seconds of time during totality to mess around with.

Here is the explanation. You have
BKTDATA,7,1.0EV,u0o
which is a global setting and expect a 7-bracket burst. But there
TAKEBST,C2,-,00:12.0,D500,1.3,8.0,100,5,RAW,None,Y,Solar corona Rs = 1.0-6.0
you only take 5 out of the 7 frames, so the next time it fires the remaining two. The reason why it work by deactivating the bracketing and reactivating it is that this operation resets the bracketing.

Now there is one thing you're doing I don't understand: you're shooting coronal exposures before/at 2nd contact. This doesn't make sense. What is visible during that time-frame is Diamond ring and Baily's beads which both require shorter exposures.

Should I not have the global setting?

You do but since the previous 7 frames bracket wasn't complete, it completes with the next as the camera was waiting.

How else can I set the stops between the brackets?

By resetting the bracketing state just like you discovered.

The timing is just because I was testing, and it is easier to just set up everything to run around C2 so I can just reset the simulated time to C2. My real script has them at the right time...

Fine, I do the same.

That said for the solar corona it is better to use exposure ramps (RAMPUP, RAMPDN and/or RAMPSUD) as you need to cover a range of 12 to 13 stops and even the Nikon cameras which always had a better bracketing capability than the Canons can only cover 9.

[jgoldshlag]

How else can I set the stops between the brackets?

By resetting the bracketing state just like you discovered.

Would it work if I just set the global state to 5 shots? I guess I can try that.

The timing is just because I was testing, and it is easier to just set up everything to run around C2 so I can just reset the simulated time to C2. My real script has them at the right time...

Fine, I do the same.

That said for the solar corona it is better to use exposure ramps (RAMPUP, RAMPDN and/or RAMPSUD) as you need to cover a range of 12 to 13 stops and even the Nikon cameras which always had a better bracketing capability than the Canons can only cover 9.

I found that the RAMP commands were much slower between shots. I can try them again, but that is why I switched to bracketed shots.

[xjubier]

How else can I set the stops between the brackets?

By resetting the bracketing state just like you discovered.

Would it work if I just set the global state to 5 shots? I guess I can try that.

I would say so, try.

The timing is just because I was testing, and it is easier to just set up everything to run around C2 so I can just reset the simulated time to C2. My real script has them at the right time...

Fine, I do the same.

That said for the solar corona it is better to use exposure ramps (RAMPUP, RAMPDN and/or RAMPSUD) as you need to cover a range of 12 to 13 stops and even the Nikon cameras which always had a better bracketing capability than the Canons can only cover 9.

I found that the RAMP commands were much slower between shots. I can try them again, but that is why I switched to bracketed shots.

Slower yes yet quite efficient and with a D500 you can certainly execute two ramps up and two more down which means 48 pictures.