Photography anyone?

[sound1]

Now enjoy some flowers

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beautiful photographs brother

 

[arunvenkats]

Really incredible.
I would like to know more about the workflow if possible.
Thanks

Thanks

Regarding deepsky astrophotography, there are 3 phases
1. Data acquisition
2. Image stacking (combining multiple exposures into one long exposure)
3. Image processing

The first phase is data acquisition. Deep sky objects are very very dim. Many of these objects are rather large, but dim. For example the Orion nebula I shared is actually a little bigger than the full moon, but is so dim, we cannot see with our naked eyes. Dim objects require long exposures to be captured by the camera's sensors. 4-12 hours of exposure is common based on how dim the object is. We cannot take very long exposures with a regular tripod or telescope mount because of earth's rotation. If you point your camera to a star and expose it for long time, the star would have "moved" away because of earth's rotation (same reason why the sun, moon and stars rises in the east and sets in the west). We are constantly rotating on the surface of the earth. To compensate for this rotation, we need a "tracking" mount which will keep pointing the camera to the same location despite earth's rotation.

No tracking mount can track forever and cameras have their own maximum exposure times. So we do what is called as stacking. Take multiple long exposures and combine them together using a stacking software. For example, take 100 5 minute exposures and stack them into a single 500 minute exposure. Each 5 minute exposure records the photons for 5 minutes. Even after 5 minutes, if we open the image, it is not possible to see the object because it is so dim. We need to "stretch" the histogram to see the object. Just like audio noise, we have different types of noise associated with image acquisition. And signal to noise ratio SNR is very low because the signal is so faint. Stretching with noise make the image very bad. Stacking allows us average out the signal, reduce noise and increase SNR substantially.

Even after stacking, the resultant image is just black because of how faint the objects are. Making the object pop out is half science half art. We spend many hours processing the image. Stretching the histogram and then doing a variety of image processing steps to get the final image.

Regards,
Arun

 

[yogibear]

One more, Exotic Saraswati Temple ! BITS Pilani campus, Nikon D90.

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