What interval between photos is recommended for shooting meteors?

Question

I plan on shooting the Perseid meteor shower in one of the next nights (probably August 11-12). It is my first time (purposely) taking photos of meteors.

I will be using my 18-55mm kit lens (this is the widest I can currently go), which results in the following exposure settings:

Shutter Speed: 11 seconds
Aperture: f/3.5
ISO: ~3200-6400

I want to create a composite with many meteors in one frame and thus plan on shooting a series of many images (probably several hundreds) with my intervalometer.

How many seconds should elapse between two frames taken? Is one second (i.e. an interval of 12 seconds) fine? Of course, you want to minimize the possibility of a meteor not being captured, but (of course), I don't want to damage my camera due to the sensor overheating through (almost) permanently being active.

Is the latter a problem in modern cameras (mine is a Nikon D5300)? If so, which interval (or which time between two exposures) is recommended?

Answer 1

Cameras wouldn't offer continuous burst modes if they were harmful to the camera in any significant way. There's no more risk or stress placed upon the sensor in a series of 400 ten-second exposures than there is in a single 67 minute exposure. Your camera can handle both without any problem. Sensor heat is something we have to accept will happen when doing any kind of astrophotography (or when doing anything that requires the viewfinder to be on with a mirrorless camera).

Of course the shutter mechanism will receive the wear and tear of 400 actuations versus the wear and tear of a single actuation, but modern DSLRs are pretty good about shutter longevity even at the entry level, where one can expect to get well in excess of 100,000 "clicks" on average.

I want to create a composite with many meteors in one frame and thus plan on shooting a series of many images (probably several hundreds) with my intervalometer.

I wouldn't use an intervalometer at all. I'd use a cable release with a button that locks down. I'd then set the camera on "Continuous" shooting so that as long as the shutter button on the wireless remote is locked down the camera will continuously take one frame after the other with only the minimum gap that the camera is capable of between each frame.

How many seconds should elapse between two frames taken? Is one second (i.e. an interval of 12 seconds) fine?

If you don't have a cable release available, set your intervalometer to the shortest possible delay between shots.

• If your intervalometer allows you to set the time from the end of one shot to the beginning of the next, set it to zero, if available, or to one if zero is not available.
• If your intervalometer requires you to set the interval from the time of the beginning of one shot to the beginning of the next shot, then set the interval to one second more than the exposure time. Then TEST it ahead of time.

Especially for exposures over one second, the actual exposure time may be a power of two, rather that the designated exposure time. Many cameras expose for 16 seconds when the exposure time is set to 15 seconds and expose for 32 seconds when set to 30 seconds. This is because many shutter time values on the commonly used list are rounded from actual powers of two to easy to remember round numbers. 1/60 is really 1/64, 1/125 is really 1/128, 1/250 is really 1/256, and so on. (By the way, aperture values based on the odd powers of the square root of two are also similarly rounded. f/22 is really f/22.62741699796952... which is actually closer to f/23 than to the number that we use to represent it.)

Shooting meteors is a numbers game. It's a low return numbers game, too. You'll need to take hundreds of frames to catch a handful of meteors.

As other existing questions here point out, the optimal technique for shooting meteors is a bit different than the optimal technique for shooting other types of astronomical phenomena. In some ways, it's almost like doing flash photography when ambient light is also present. The stars and all other light sources are the ambient light. They are "on" for the entire length of the exposure. The meteor is like the "pop" from a flash. It lasts a much shorter duration that the total exposure time, particularly when one is considering the comparative time on pixels between the stars and the meteors. The stars stay in the same place (or within just a few pixels) for the entire exposure while the meteors spend very little time on any given pixels as they move across the field of view.

The longer each exposure is, the dimmer the meteor will appear relative to the stars.

To capture meteors you need to:

• Increase sensitivity (ISO) until the light gained is offset by the increase in noise. For most current full frame cameras this might be somewhere around ISO 6400. For current APS-C cameras, it's probably around ISO 3200. You can experiment using a night sky before the meteor shower to find where your particular camera's limits, combined with your post processing workflow, are.
• Increase aperture as much as possible without losing significant sharpness. For some lenses this will be wide open, for others it might mean stopping down anywhere from 1/3 stop to a full stop or more.
• Decrease the amount of time the shutter is open from the 1/500 or 1/600 rule of thumb to around 10-20 seconds.

Answer 2

I wish had more time to offer a proper response but I realize that we are currently at the peak and you need some information now.

Exposure

When I do DSLR astrophotography with a camera lens (no telescope), I'm usually shooting using an f/2 lens (at f/2) ISO 800, and typically 1 minute exposures. But I'll also shoot some shorter exposures (for HDR combination) and some of those exposures will be as short as 1-3 seconds depending on the subject.

That aside, since your 18-55mm lens is probably a variable f/3.5-5.6, I'm going to guess that your wide-open aperture is f/3.5 and that this is only available if you are at the 18mm focal length. Given these assumptions, I'll assume you will plan to use 18mm f/3.5.

Your Nikon has a crop-factor of 1.5x. That means if you use the 500 rule, it's

exposure-duration = 500 ÷ crop-factor ÷ focal-length

So for you that's

500 ÷ 1.5 ÷ 18 = 18.5

You can't accurately make an 18.5 second exposure so you'll likely set your camera to a 15-second exposure. You should also cheat it up a bit to a 20 second exposure.

I normally find I get good sky exposure with 1 minute at f/2 and ISO 800 and I get away with this because I have a tracking head (I have a Losmandy StarLapse head -- which is no longer sold. These days the Sky Watcher "Star Adventurer" head or the iOptron "Sky Guider Pro" head are the popular models.)

You'll need to adjust ISO to compensate for your shower exposure duration... in this case, doubling the ISO to 1600 (from my 800) would compensate for going from a 30 second exposure to a 15 second exposure. But we also have to compensate for your f/3.5 focal ratio (vs. my f/2). This would get you to roughly ISO 5000.

My guess is that using ISO 5000, f/3.5, and 15 second exposure durations will probably be pretty close.

Interval

Make sure you understand the nuances of your interval timer.

I usually use a computer (via USB connection) to control my camera, but I do have a physical wired-remote with an internal timer and my camera has a built-in interval timer (via the menu system). They all work a bit differently.

When I use the physical interval timer, it assumes the camera is in Bulb mode. The interval timer is programed for

1. The delay before activating (usually I set this to zero since I am not touching the camera to trigger the shutter)
2. The number of frames I want to capture (e.g. 100)
3. The duration of a single frame (e.g. 15 seconds ... or 1 minute, etc.)
4. The wait-time AFTER the shutter closed from the previous frame BEFORE beginning the next exposure.

The main message to the above description is that the "interval" in the case of this specific timer, is the time between the END of one exposure and the START of the next.

If I use the camera's internal interval time (it's not a Nikon so it's likely not the same), the built-in timer is ... not as smart.

1. The number of frames
2. The time interval between the START of exposures.

This timer doesn't care about exposure duration. You have to work out the math on your own. E.g. if the exposure durations are 15 seconds and I set an interval of 15 seconds it's probably that I'll have dropped frames because the camera wont quite be done and ready for the start of the next exposure when the camera tries to trigger the shutter. So for this particular timer, I have to pad... e.g. suppose I set a 20 second interval. That would give the camera 15 seconds to take the shot and a 5 minute padded buffer time until the next shot begins to make sure the camera is ready (and sure I could probably cheat that down a couple of seconds shorter).

Other Resources

There is a decent article on PhotographingSpace.com on Meteor Shower photography. You can find it here: https://photographingspace.com/beginner-meteor-photography/