Vacation Time with the Nifty Fifty

Something To Look Forward To

Things have been quite busy for me lately but one thing we've always prioritized as a family is getting away for a week or two every summer together.  This year, my wife booked us a cottage in the Northern village of Kopalino, Poland which sits a little over a mile away from the Baltic Sea.

I love being around the water so I was already pretty excited about getting away.  But imagine my enthusiasm when I discovered that Kopalino is located in a Bortle 4 zone.  This is a significantly darker location than where I am used to shooting, so I need to make the most of this opportunity - skies willing.

That is why I decided to take the plunge and go ahead and purchase my first new lens.  For this, I went with the very affordable Canon 50mm f/1.8 STM.  Now, before we hit the road, I have a couple of days to get out and learn how to use it.

Why the 50mm?

I know, I know, my immediate temptation is to go longer here.  But 50mm is a great utility focal length that once again, I'll be able to find a use for outside of astrophotography.  Besides, the main decision criteria for my first prime lens is speed.  And for just North of $100 brand new, the price was right.

Vacation Goals

Weather permitting, my main goal during vacation is to get some serious imaging time with Andromeda.  I didn't mention this, but I shot a handful of test shots the other night on the 18-135mm lens while just playing around and was surprised at how easy Andromeda was to find in the sky even just outside of Krakow.

50mm will be a great focal length to take my first serious images of Andromeda.  But before we get to the seaside, I need to put this lens to the test.

Testing the 50mm

With just two nights before we hit the road, I needed to get a sense of how this lens will perform.  In order to do this, I created a plan to take a series of 10-shot photos at different apertures and ISOs to hopefully begin to tease out some sweet spots.  Here's what I spent the night shooting:

Of particular interest to me in this testing is to gauge the lens aberrations at different aperture settings.  This lens is notorious for coma distortion.  However, I don't expect that will be much of a problem for me if I know where in my shot this effect (and others) will appear.  Besides, I'm going to be cropping my photos down anyway, so as long as I can frame and keep my target in the sweet spot, I should be alright.

For this testing, I decided to just step onto my back porch to take pictures.  I wasn't overly concerned about the light pollution and accepted that I might have a more significant gradient to deal with in my photos.  So be it.  This was just going to be more comfortable for me.

It should come as no surprise that I wrapped my shooting up pretty quickly which gave me plenty of time to go ahead and start processing the shots that evening.  

The coma at the low aperture settings was immediately obvious.  To give you a sense of what coma is:

These are your stars (Deneb)

These are your stars on coma

As you move away from the center of your shot, your stars begin to look like they've been drinking excessive amounts of Red Bull.  Now, where this distortion begins to appear is very much dependent on your aperture setting.  The coma is almost unnoticeable once you get beyond f/4.  But at f/4 and lower, you need to mind your target framing.  

Below is a full stop comparison of coma impact.  The light circles are where the stars appear crisp and outside of the light circle is where the coma effect becomes apparent. As you can see, there is quite a trade off in the field of view.

f/2
f/2.8
f/4

I'm really glad I went through this exercise as tedious as it was.  This is knowledge that I can use.  Nothing would have been more disappointing than to have spent a good night imaging only to see in post that the lens effects ruined the photo.

I mentioned that I was also sweeping the ISOs.  I wish I had more to talk about here, but the truth is that finding the appropriate ISO setting to image with is still a bit of an enigma to me.  

First Impression

I'm already loving this lens for a number of reasons.  First, it's light.  Second, the speed of the lens allows me to gather a lot more light than with the kit lens and the difference is definitely noticeable - even after only one session.  Third, it wasn't terribly expensive.  Fourth, the field of view is wide which allows me to take pictures of larger regions of the sky, and it makes finding my targets a lot easier.  Finally, the images and colors are really crisp.

Now, everything that I just mentioned is relative.  You need to remember that just a couple of months ago, I didn't know the first thing about photography.  What I can easily observe is that this prime lens is a big step up for me from my kit lens.  Of course I'll still be using the kit lens, but I'll now be thinking more about what I'm trying to do when I image and determine which of my lenses would be more fit for purpose.

The only thing I need to do now is get to the seaside and start shooting!