Welcome to our Milky Way astrophotography pre-workshop info page.
We look forward to seeing you at the event and encourage you to read though this page and watch the videos which discuss taking photos without needing expensive lenses plus the software used for post processing those photos. We have photographers of all abilities attending and I’ll be on hand to help everyone set up, answer any questions throughout the evening, and distribute equipment for those wanting to borrow our lenses and astro filters (please use the available equipment disinfectant and hand sanitizer at our event).
This page provides an overview of some issues encountered in astrophotography compared to standard landscape photography which is good to be aware of in advance, such as focussing in the dark or star trailing due to longer shutter speeds.
- Camera and wide angle lens (in the 10mm to 35mm fulle frame equivalent range – we use 14mm and 24mm for most of our own shots)
- Tripod – preferably sturdy!
- Remote shutter release – we prefer a wired trigger as it saves battery over using your phone with wifi/bluetooth or a wireless trigger.
- Spare camera battery – the multiple long exposures taken during astrophotography and the cold evenings will reduce battery life.
Please note: We’ll be using manual exposure mode so we have full control over our camera’s ability to capture as much light as possible. You’ll need to disable autofocus on the lens or camera so that the camera isn’t trying to refocus with each shot. We also recommend turning off Long Exposure Noise Reduction on your camera (if not, the camera will take a second exposure without opening the shutter – effectively halving your shooting time at the location).
Camera Settings – we need light and lots of it!
Aperture – wide open (ie the lowest number) to gather as much light as we can. If you’re lucky enough to have a f/1.4 or f/1.8 lens then you could consider stopping down to increase sharpness and reduce vignetting but otherwise keep that aperture as wide open as it will go.
Exposure length – (The 500 Rule…or not!)
If we want as much light as possible then we can just open the shutter for longer…right? Well, unfortunately with increasing exposure time we’re at risk of having the stars trailing on our image. So how do we calculate what our ideal shutter speed to get pinpoint stars for a particular focal length?
The 500 Rule was a way to calculate the shutter speed to limit stars trailing. For a full frame camera, we divide 500 by the focal length of our lens to get our suggested shutter speed (eg 500/24mm = ~20 seconds. Note, an adjustment is still needed for cropped sensor cameras). The formula was developed for use with 35mm film but modern camera sensors have much greater resolutions so this formula is now outdated and using it will result in our stars trailing. We suggest starting with the “400 Rule” and zooming in to check star trail length on your image and decrease your shutter speed according to personal taste. What shutter speed you are happy with will depend on if you’re simply shooting for social media or planning to view or print the image much larger. We recommed taking a series of images at different shutter speeds and making the decision at home on a larger, clearer screen.
For example for a full frame camera:
500 Rule 24mm = (500/24) = 20 seconds, 14mm = (500/14) = 35 seconds
400 Rule 24mm = (400/24) = 16 seconds, 14mm = (400/14) = 28 seconds
300 Rule 24mm = (300/24) = 12 seconds, 14mm = (300/14) = 21 seconds
For a crop sensor camera, divide the exposure time by the crop factor, eg 1.5 for Nikon DX or 1.6 for Canon APS-C.
A more accurate & complicated formula exists, the NPF Rule, which is available on several apps but to start we suggest using the 400 Rule and adjust the shutter speed downwards.
ISO –The ISO setting is our main variable as we generally have our aperture and shutter speed set to gather as much light as possible without significant star trailing. We’d suggest ISO 1600 as a starting point and adjust up or down from there.
White Balance – Most modern cameras have excellent auto white balance and any deviations can be fixed easily in post processing by making all pics the same white balance with a couple of clicks. If you are shooting JPG or not wanting to post process, I’d suggest setting a white balance of ~4000K to start and adjusting according to taste as each situation will be different due to the amount of light pollution in the area.
Focusing – We can’t rely on the infinity mark on most lenses so there are options to make life easier.
a) Pre-focus in daylight and tape lens so it won’t move
b) Pre-focus in dayight and gently mark (crayon, Tipex/Liquid Paper, gold marker, etc)
c) On location (either illuminating foreground subject or on distant object such stars/streetlights) – most common method but can be difficult at times so marking/knowing where the infinity focus is located is an advantage.
When other photographers are on location at night it is good practice to not be constantly lighting up the foreground subject to refocus as some people may be doing timelapses so other methods are encouraged.
There are multiple ways to photograph landscape astro shots and we can do multiple methods on this event.
- Single shot – generally require expensive “fast” lenses and a semi-pro camera with a high performance sensor.
- Combine multiple shots – take multiple shots at exactly the same settings and combine with software – allows use of a “slower” lens, shooting at a higher ISO to compensate, then combining the 5-10 shots in software to reduce the noise. This works as noise is random so by combining multiple shots the randomess of the noise is eliminated. Note: 5-10 shots combined is considered enough as there is diminishing returns with more than 10 shots.
- Combine two shots – 1 x shot for foreground + 1 x shot for sky then combine in software. Generally we’ll shoot 1 x long exposure at a lower ISO for foreground (can use ambient light or light paint with a torch – this shot will have star trailing) then combine with an exposure for the sky using a star tracker (tracks the movement of the sky allowing a longer exposure time, eliminates star trailing effect and allows lower ISO – but will have a blurry foreground due to star tracker movement). We can then combine the sharp foreground in our first image with the sharp stars in our second image in software such as Photoshop.
1) “Noise-Free Milky Way Photos by Stacking Multiple Exposures (Sequator)”
“Tips for cleaner Milky Way images using a slow lens”
Sequator (Windows, free) – https://sites.google.com/site/sequatorglobal/download
Starry Landscape Stacker (Mac, £38.99) – https://apps.apple.com/gb/app/starry-landscape-stacker/id550326617?mt=12
The same principals we learn at this event can be used to capture photos of meteor showers.