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M8, the Lagoon Nebula and M20, the Trifid Nebula in Sagittarius rises high in the summer for northern hemisphere observers. The nebulae are surrounded by brown dust near the core of the Milky Way galaxy.
Technical. This image was obtained with a stock Canon EOS 90D DSLR Camera and 500 mm f/4 L IS lens (Newer model: Canon EF 500mm f/4L IS II USM Lens) at f/4 and ISO 1600. Raw conversion with photoshop ACR. No dark frames, no flat fields, and no bias measured because they were not needed. The camera suppresses dark current, Bias is a single value for all pixels and is stored in the EXIF data with each image, and the flat field is in the lens profile used in the raw converter (photoshop). Exposure was 19 frames at 90 seconds each (28.5 minutes total exposure time). Daylight white balance. The exposure was tracked on a Losmandy G11 equatorial mount with an autoguider. Mean RMS tracking accuracy was around 0.5 arc-second. Full resolution image is 1.32 arc-seconds/pixel. This image is at 1/3 that resolution (3.96 arc-seconds/pixel) and shows the full field.
Post processing: stretched with rnc-color-stretch then star reduction applied. Also see Astrophotography Image Processing Basic Work Flow. The stretch settings followed this article: Black Point Selection in Astrophotos which used the same are converted images.
This is a natural color image. The raw data were converted with Photoshop Adobe Camera Raw (ACR) with full calibration that included the color correction matrix and hue corrections usually skipped in the traditional astro workflows. Color managed workflow in Rec2020 color space. Stretched with rnc-color-stretch, and final adjustments in photoshop. This is a highly calibrated image, presented in sRGB color space.
The Exposure Factors, CEF, CEFA are measures of the relative amounts of light received from a subject. It can be used to fairly compare wildly different lens/telescope apertures and exposure times. For this image:
Modern DSLRs like the 90D include on sensor dark current suppression and low fixed pattern noise at ISOs around 1600 and higher, making no need for dark frame subtraction.
To learn how to obtain stunning images like this, please visit my Extensive Articles on Photography .
Keywords to this image = astrophoto-1 nebula Messier low-light digital_astro canon_90d NEW
Image ID: m8,m20-500mm-09-04-2021-acr-IMG_0944-63-av19-rs4.e-0.33xs.jpg
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Last updated September 17, 2025