That’s a bug, not a feature!
Ideally, a star should be rendered as a featureless point. But, many things prevent that - lens aberrations, diffraction, sensor artifacts, and motion due to the spinning of the earth, to name a few. The lens I was using is very, very good - it’s the Nikon 20mm f/1.8, considered one of the sharpest, fastest wide-angle lenses available. But, wide-open it still has some astigmatism and coma, which combined with the star’s motion, creates the points on the star.
Ooh, f1.8–I’m jealous!
What does that equate to in terms of light gathering aperture, as in the way one would speak of the objective in a telescope?
I grew up as one of those kids with the telescope in the back yard, and I still get confused by the fact that in photography lenses tend to be described by their focal length, while in astronomy it’s by their diameter.
It turns out not to be an simple question for wide-angle lenses.
But, no lens is ever fast enough for wide-angle astrophotography. Since the camera can’t be tracked (would cause foreground blurring), the faster the lens (and bigger the sensor), the better.
Here is a fun one for star folk, ~ 100 degrees horizontal (14mm ff), Nothern hemephere in December 2015.
Pleiades (M45) are in the upper right hand corner, note the direction that is looking.
Spectacular!
Since I posted this, I’ve acquired a Nikkor 50mm f/1.8 fixed lens, which has seriously pumped up the impact of my astrophotos. Though I do need to get something with a wider angle, too.
Cancer and the Beehive
The diffraction spikes were added in post-processing. The star colors should be relatively accurate although the entire spectrum is probably shifted. I rarely use the full f/1.8 aperture, so this was probably stopped down to f/2.2 or 2.5.
Subscribed.
All of you have done impressive work – it’s inspirational! rat avatar, your pic took my breath away.
I was recently given a hand-me-down Canon Rebel EOS XSi, an older camera, obviously. It’s my first “real” camera other than a little Nikon Coolpix point-and-shoot. I’m excited to learn more about photography.
The camera I received is just the camera body and has no lens. I started to research lenses but quickly became intimidated. I know nothing. I hope to take a basic online photography class offered through our local community college starting on March 13th, but I’d love to play around with the thing sooner than that!
Any suggestions/information, particularly with respect to beginner’s lens recommendations, gratefully accepted. Meantime, I’ll enjoy seeing all of your work!
Check out my beginning posts in this thread where I described the lens I was using at the time. “18-55mm” means the focal length is adjustable; the higher the FL, the greater the optical magnification and the narrower the field of view. I see that Cancer was also in the photo I linked to in my ETA post #2. Obviously it’s not nearly as good as the 50mm lens, but it’s still a reasonably good everyday lens.
Fixed lenses arre said to perform better, but you sacrifice some flexibility.
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Look into some of the Rokinon manual lenses. You can get some fast, wide-angle lenses for relatively cheap (24mm f1.4, 14mm f2.8). These get very good results, and have very little coma which causes a smearing affect that gets more pronounced as you move towards the edge of the frame. They are fully manual, but you should be doing that when shooting at night anyway.
Here my astrophotography album:
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And if anyone is interested, my partner and I give night photography workshops. PM me for info.
On the 24mm f1.4 I’m guessing you don’t use the f1.4 setting for astro; if so, what do you stop it down to?
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Usually 2.0 or 2.2.
BTW, I have a Samyang (Rokinon) 20mm f 1.8, Nikon mount. It is optically excellent - I am selling it because I have the Nikon, and I don’t need two 20mm lenses (I bought it to have two for the 2017 Eclipse.
If anyone is interested, PM me.
Man, that is fucking desktop PC wallpaper worthy! Very nice!
I really like the photo of the cemetery under that star formation, with the crosses seemingly beseeching the night sky like skeletal arms.
Nah, The Long Road is it.
I’ll put up a couple tonight (or tomorrow).
Tempting…
There’s a SDMB Flickr group that got started several years ago, but hasn’t seen much traffic lately:
That’s a 2.5 minute exposure for the car trail, composited with a 30 second exposure for the stars, all shot under the full moon.
Thank you. I had read that part of your OP with much interest, and have managed to suss out that the 18-55mm is a fairly standard starting place lens. Your hearty approval of it and your own successful photography using it encourages me in that direction, for sure. I read elsewhere that the Canon EF 50mm f/1.8 II was also a great beginner’s lens but really don’t understand why. Still trying to learn the ground floor basics. Thanks for your patient reply!
A 50mm f1.8 fixed lens is a good general purpose lens for beginners, pros and everyone in between. It’s a lot faster than the 18-55mm f3.5 that usually comes with an entry/enthusiast level DSLR. From the perspective of a beginner who may not yet feel ready to spend many hundreds of dollars on another lens, the 50mm f1.8 is usually modest in price. Mine was a Nikon and it cost me about $132 on Amazon, plus tax and brand new.
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Where did you take this?
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