Deep-sky photography with a camera and tracker. Step by step guide.

Equipment:
-DSLR/mirrorless camera
-telephoto lens
-tracker or motorized equatorial mount with a pole finder on a tripod
-Beginner astrophotographer.

Necessary:
Get images of a bright deep space object.

Фотообъектив Samyang 135mm f/2.0 ED + фотокамера Canon 550Da на монтировке Sky-Watcher Star Adventurer.
Samyang 135mm f/2.0 ED lens + Canon 550Da camera + Sky-Watcher Star Adventurer mount.

Before using the equipment, it is strongly recommended to study the instructions for it and remember the location of the main controls and settings.

The process of setting up and shooting STEP BY STEP

– Take all the equipment outside.
– Assembling the mount.
– Set the polar axis
– Install the camera and lens on the mount.
– Let’s check the polar axis setting again.
– Turn on tracking on the mount.
– Turn on the camera, switch it to manual shooting mode (M – Manual).
– In the camera settings, make sure that all types of noise reduction are disabled, as well as automatic cleaning of the sensor from dust. Make the camera screen as bright as possible. Check that the shooting is in RAW format.
– Open the lens aperture completely. Set the shutter speed to 20-30 seconds. ISO – 1600-3200. Turn on the self-timer for 2-10 seconds.
– Set the lens to manual focus mode (MF), turn off the stabilizer (if any).
– Point the camera at a bright star, planet or distant lantern. Rotate focusing ring for getting the minimum size of the object. If it’s too bright, set lower the ISO. After focusing, increase the ISO back.
– Approximately point the camera at the object of interest. For the first time, choose something bright for the season – the Orion Nebula M42, the open star cluster Pleiades M45, the Andromeda Galaxy M31, etc.
– Take a test shot and see the result.
– If it’s too dark, raise the ISO until the stars and the object appear. Limit the shutter speed to 30 seconds.
– If it’s too blurry, check the focus and refocus if necessary.
– If everything is ok, not too bright, not too dim, start the shooting. It will the original frames of the object (lights). Make photos the same object several dozen times without changing the shooting parameters. You can use time-lapse or programmable wire feed. Many frames are needed in order to reduce noise in the image when they are subsequently stacked together. You can’t just take one frame, copy it multiple times and put it together – the image will remain the same noisy.

Пример одиночного кадра объекта (лайт)
Example of a single frame of an object (light)


Shooting calibration frames.
These frames are needed to eliminate defects in the photodetector and phenomena caused by the characteristics of the optical system.
-After 10-50 images of the object have been taken, the mount can be turned off. Close the lens cap and take another 10-25 pictures with the same parameters. These are dark frames (darks). They are needed to eliminate defective pixels. The shooting parameters are the same as for the light ones.

Дарк
Dark

– Remove the lens cap and hold the screen of a smartphone or tablet with the brightest screen possible and a solid white image on the screen in front.
– Set ISO to minimum (for example, 100). We do not touch the aperture and focus. Set the shutter speed to 1/30 second to start with.
– Take a test photo. Look at the histogram of the resulting image. It should be filled at 75 %. If the histogram goes to the right, reduce the shutter speed. If the histogram is on the left, we increase the shutter speed. We take a test shot again and ensure that the histogram is filled out correctly. The image should not be too bright or too dim. If everything is ok, we take 10-20 such shots. These are frames of a flat field (flat). They are needed to remove vignetting and dust.

Флэт
Flat

– Close the lens cap and, without changing the shooting parameters, take 10-20 frames. These are dark frames for flat field frames (dark flats). They are needed to eliminate defective pixels in flat field frames. The shooting parameters are the same as for flats.

Дарк флэт

– Finish the captring, turn off the camera, disassemble the equipment.
– We transfer the received images to the computer and arrange them in the following folders:
1 LIGHT (frames with object)
2 DARK (dark frames)
3 FLAT (flat field frame)
4 DARK FLAT (dark frames for flat field frames, i.e. dark for flats)

Examples of the resulting images in RAW format are available HERE.
Equipment used: Samyang 135mm f/2.0 ED lens, Canon 550Da camera, Sky-Watcher AZ-GTi mount in EQ mode
Shooting parameters of the original frames: shutter speed 30 seconds, ISO 1600, aperture f/2.

Further calibration and stacking of frames is performed in a special software (for example, DeepSkyStacker):

The result will be ONE image, which is then subjected to basic processing in other programs (histogram stretch, background flatten, star removal, color correction, noise reduction, etc.)

An example of the final frame after automatic histogram stretching in the ASIFitsView software:

2 thoughts on “Deep-sky photography with a camera and tracker. Step by step guide.”

  1. Артем

    Руслан, добры вечер!
    Не совсем понял, чем отличаются дарки и дарк флеты?
    Есть ли шансы поснимать что-то в условиях городской засветки?
    Объективы Canon с фокусными расстояниями 18-55 и 55-250. Какая выдежка будет максимальная, что бы звезды не «поехали»? Есть ли шанс установить фотик на EQ2, вопрос только поможет ли ручка тонких движений для более долгих выдержек?)

    Спасибо!

    1. Добрый вечер. У дарков такие же параметры, как у лайтов.
      У дарк флэтов (ну или флэт дарков) такие же параметры, как у флэтов.
      Например: лайт 30с, ISO 1600. У дарка точно такие же параметры.
      флэт: 1\10 секунды, ISO 100. Флэт дарк – тоже 1\10с, ISO 100.

      Шансы поснимать есть, конечно. Ту же М42 попробовать, либо Плеяды.
      Предельная выдержка зависит от монтировки и точности выставления полярной оси. Для EQ2 ручка не поможет, нужен мотор, желательно с пультом (он точнее). Либо самому сделать на базе шаговика. Я думаю, выдержку 30с можно вытянуть, если полярную получше выставить.

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