Nikon D500/D750 interval timer question

[Destin]

Hey all! I'm having some trouble getting clear answers on how exactly to set up the interval timer on my cameras. Admittedly, this is a function I've never really used much but I'm looking to get into more star trails and time lapses, so I've gotta master it.

I have several questions here:

If I want to shoot 30 second exposures with 5 seconds in between them, how would I do this? Do I set the interval to 35 seconds? or to 5 seconds? (In other words: does the timer start when the shutter opens? or when it closes?) Either way *seems* to work, but I'm not sure what the proper way is and the manual isn't very clear here.

Also, I've run into issues in the past where the buffer hasn't been able to keep up with long exposures with short intervals; is there a way to determine how large my interval needs to be to avoid overloading the buffer? This is especially an issue when shooting star trails, as I really want my 30 second exposures to be as close together as possible to avoid the "zipper" effect in the trails.

Thanks in advance!

 

[Raddy]

On the D750, when you go to interval shooting (Menu > Photo Shooting Menu > Interval Timer Shooting), you would want to set the interval to 5 seconds, that's the time between the shutter closing and reopening. Then you set the start time and number of exposures you want.

As far as the buffer, that will depend what you're shooting and the speed of your memory card. When I shoot RAW on my D750, I have a buffer of 11 or 12 exposures and it takes 2 or 3 seconds to write each exposure to my memory cards (which are mid-grade and not particularly fast). You can measure the buffer yourself by taking a burst of shots and then timing how long until the buffer is empty again, which you can see in the corner of the viewfinder.

If you want to improve the buffer, you can reduce the quality of what you're shooting (RAW 14-bit lossless > RAW 14-bit lossy > RAW 12-bit lossless > RAW 12-bit lossy > JPEG) or you can buy faster memory cards. It seems like 5 seconds should be enough to write a full quality RAW file with common memory cards, but it will depend on your particular setup.

 

[KmH]

The camera buffer is usually the limiting factor as far as the max speed of writing to a memory card.
In other words one can wind up with a memory card that the camera buffer can't write to as fast as the memory card can be written to.

Memory card advertised speeds are usually the read speed, not the write speed.
So if you explore using different memory cards be sure to look closely at the specifications so you know if the spec speed is read, write, or if the specs have both.

 

[WayneF]

If I want to shoot 30 second exposures with 5 seconds in between them, how would I do this? Do I set the interval to 35 seconds? or to 5 seconds?

Definitely NOT to 5 seconds. The interval naturally has to be longer than the shutter duration it contains (also longer than any choice of multiple pictures per interval). If it is not longer, it will simply skip those conflicting interval steps, and wait on the next one.

Also, you should be aware that the cameras 30 second shutter is actually 32 seconds, so the least interval that can work properly with a 30 second shutter has to be about 33 seconds. 31 will be very disappointing. 35 seconds should be fine, but if you literally want 5 seconds between them, then that is a 37 second interval. It will work well when this is understood. It's easy to test this first.

The Long Exposure Noise Reduction option will be a huge complication, you have to plan for it approx. doubling your interval requirements too.

Any disbelievers about 32 seconds better first go time their 30 second shutter. The way EV works is that each EV stop is exactly 2x. So this necessarily runs 1, 2, 4, 8, 16, 32 seconds. 30 seconds is not an option. The marked numbers we see are merely convenient nominals (existing in name only, by historical convention). They don't cause error, the camera knows to do it right. More about that at Charts of camera Nominal and Exact Precise Shutter speed, f/stop and ISO values

 

[Destin]

If I want to shoot 30 second exposures with 5 seconds in between them, how would I do this? Do I set the interval to 35 seconds? or to 5 seconds?

Definitely NOT to 5 seconds. The interval naturally has to be longer than the shutter duration it contains (also longer than any choice of multiple pictures per interval). If it is not longer, it will simply skip those conflicting interval steps, and wait on the next one.

Also, you should be aware that the cameras 30 second shutter is actually 32 seconds, so the least interval that can work properly with a 30 second shutter has to be about 33 seconds. 31 will be very disappointing. 35 seconds should be fine, but if you literally want 5 seconds between them, then that is a 37 second interval. It will work well when this is understood. It's easy to test this first.

The Long Exposure Noise Reduction option will be a huge complication, you have to plan for it approx. doubling your interval requirements too.

Any disbelievers about 32 seconds better first go time their 30 second shutter. The way EV works is that each EV stop is exactly 2x. So this necessarily runs 1, 2, 4, 8, 16, 32 seconds. 30 seconds is not an option. The marked numbers we see are merely convenient nominals (existing in name only, by historical convention). They don't cause error, the camera knows to do it right. More about that at Charts of camera Nominal and Exact Precise Shutter speed, f/stop and ISO values

Based on research and playing around I’ve done in the last few days all of your info appears to be dead on accurate.

Thanks you!

 

[WayneF]

Based on research and playing around I’ve done in the last few days all of your info appears to be dead on accurate.

Thanks you!

Thanks. I think the interval timer means you're interested in the circular polar star trails, but for routine Milky Way shots, you might be interested in

Calculator to replace the 500 Rule for maximum exposure time of Milky Way Stars

about fixed tripod shots without trails.