Hi there! I've been a regular follower of Fstoppers for quite some time already, but only recently opened a profile. My name is Juan Carlos, and I'm an astronomer at Paranal Observatory, located in the Atacama Desert in Northern Chile.
I'd like to share with you an image that I took in my last observing shift several days ago. It shows the Milky Way imaged through a crystal ball. My idea was to make it resemble a marble, but most people have told me it looks like Orion's belt from Men in Black :-)
I bought the ball a few weeks ago in a flea market in Santiago de Chile, where I live. Once in Paranal, I placed it on the handrail of one of the entrance corridors to our lodging, and arranged the camera (Canon 6D) at angle below it, pointing to the Milky Way. I used a Rokinon 24 mm lens to get a wide enough field of view in the background.
Focusing was tricky. For "normal" astrophotography I usually focus on a bright star using the Live View mode of my camera, but that wasn't possible here. So instead I took a series of short exposures (1 sec at max ISO), changing the focus in between shots until the stars within the ball were sharp.
As for the aperture, after a few tests I settled on f/4. Even though a wider aperture would've let more light through, I found the depth of field to be too shallow, and it wasn't possible to clearly recognize the defocused stars and the Milky Way behind the ball. On the other hand, smaller apertures obviously led to much darker images, and I also didn't like the smaller bokeh.
This is a 20 sec exposure at ISO6400. I edited it in Lightroom and Affinity Photo. I hope you like it!
Really nice! Thank you for sharing.
Thank you!
saw that on APOD, en hora buena!! awesome photo, wish you would have submitted to the recent night photo contest
Thanks! Unfortunately I took the picture just very shortly before the deadline for the night photo contest, and I was working back then, so I couldn't submit it.
Bravo Juan Carlos
Thank you!
This is really incredible and I never really though in this astrophotography approach. 5* for the creativity! Is this a single exposure, right? How did you handled the noise with the high ISO?
Thanks a lot! Really glad you like the image. And yes, it's a single shot.
As for the noise, the problem is the lack of light and not the ISO itself. In fact, at fixed aperture and shutter speed, the readout noise *decreases* with increasing ISO, up to a certain ISO beyond which the noise doesn't decrease any more. This behaviour depends a lot on the sensor though; in some sensors the readout noise doesn't change much with ISO.
In my Canon 6D, the sweet spot is around ISO 3200-6400. That's the ISO that gives me the lowest noise. Higher ISOs yield the same noise, but lower dynamic range, as you start clipping the highlights. So for astrophotography I typically shoot at ISO 3200-6400.
But yeah, this image was noisier than others I've taken, because I had to use f/4 instead of wider apertures. I did the noise reduction in Lightroom in two steps: an aggressive noise reduction for the background sky, and a more conservative one for the crystal ball. Then I merged both images in Affinity Photo. So, to be clear: it's a single shot edited twice with different noise reduction settings for the outer and inner parts.
Thanks mate, for the explanation.
Anyway I don't really think this image has a lot of noise, on contrary. Now I understand your approach to noise handling in post processing. But I find the result really really good in terms of noise having in mind that you shoot this image with ISO6400!! With my camera I do not dare to go above 3200 because I will get huge amounts of noise (it is na entry level Canon EOS 1100D which I plan to change in the next months). This is why I started doing stacking and more recently I got a tracker... of course that not every scene or composition is suitable for stacking or even tracking, and also this techniques usually require a lot of work on post processing!
But anyway, this is a great shot which I find really Creative and technically challenging, and you mastered it really well. Congrats.
This is the type of photographs that inspire others.
Yeah, I stack sometimes, but as you say not every scene is suitable for that. And at the end of the day, a bit of noise is not a problem. It's all about the composition, I think :-)
Thanks again for your kind words!
I joined this group, just so I could tell you I love your picture! Its amazing! I wonder....is there anyway to get this shot without the black post its sitting on in the shot? And who cares about noise...some pictures are worth the bit of noise you might have to put up with! Amazing idea Juan!
Thanks so much! I think one way to get this shot without the post would be to have the ball standing on a tripod, take the image, then immediately remove the ball and its tripod, and take another image just with the background. Then blend both images. Not sure how to do this with a single shot!
Hey, I just saw your photo in an article! Way to go! I'm so excited for you! Can't wait to see your next ones! Congrats!
Thanks! Which one? I'm curious!
This photo, I'm can't remember which publisher but I instantly recognized your photo!
Knowing that you actually imaged the MW through this ball rather than composite it in is epic. That is really, really awesome and well done. Thank you for all of the background story as well.
Thanks Ryan! I really enjoyed the challenge of getting this in one single shot. Really glad you like it!