My Path to Astrophotography

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I started as a visual amateur astronomer, way back in 1984, and in the next twenty years I was more often off than on with the hobby.

Then in 2005 I decided to have a (more) serious run at it, refurbishing the old equipment and buying much new one, since in 20 years much had changed, from eyepieces to a wealth of new accessories, to the rise of GOTO mounts and of (relatively) cheap cameras for astrophotography.

The first step was a Meade LPI to be used for Lunar and Planetary Imag(ing), as per its name.

At the time the hype in the high resolution realm was all with modified webcams (like the Vesta or TouCam Pro) and the LPI was considered as lagging a bit behind, as far as performance was concerned.

However, I was able to get some satisfying (at the time) images of Jupiter, Saturn and the Moon.

My main visual scope was, since the 1980s, a Meade 826 8 inch newtonian, but for imaging I used first a second hand Meade 2045D, a rare 4 inch SCT, and later an ETX-80, a GOTO mounted 80/400 short achromatic refractor.

All of the imaging was performed using altazimuth mounts.

Late in 2006 I finally decided to give a try to DSO imaging, at the time still mainly considered the realm of rugged equatorial mounts, very expensive cameras and long guided exposures.

I tried my luck with a setup nobody at the time considered worthy a try: the second hand Meade DSI Pro I bought (I definitely was a Meade fan at the time) had received rather good reviews as an entry level CCD camera, but the ETX-80 was considered to be woefully inadequate, both because of the shaky flimsy mount and of the short achromat.

Indeed, seen today, the pictures I got at the time (2006-2007) look rather crude, noisy, with bad tracking, not always in focus and so on, but surely at the time they made me proud and feel vindicated in my choice of equipment.

And after all, having been able to image a few nice Messier object (particularly M1, M42, M52, M81 and M82) with such an equipment was something of a feat: the mount had a play in altitude which was more or less compensated by the  weight of the camera and to this day I don’t know how I was able to almost always center the DSOs in the 40’x30′ field of the camera using the basic 494 Autostar that came with the ETX-80 and which was simpler than the 497 used by more expensive Meade telescopes.

At the time my family still had a countryside house and most of my imaging and all of my visual observations were done from there.

When we sold the house in 2008, I basically gave up visual DSO observing and bought a Skywatcher MAK-90 to peek from time to time at the moon and the planets from the city where by then I lived.

I went on observing sparingly and without any further imaging, planetary or DSO, for another couple of years, then, after 2011 and a binocular parenthesis, I basically stopped any stargazing.

Somehow, out of nowhere, in early 2017, I started to think again to amateur astronomy as a viable hobby.

Living in a flat in the heart of a big city I did not have the sky for visual DSO observation, nor the space in the flat for big mounts or big scopes.

So I thought that the best way to “observe” from town was to do some sort of astrophotography, and that is at that point in time that I stumbled upon John Ashley’s seminal work “Astrophotography On The Go”.

While perhaps the book was more aimed at newbie astrophotographers who wished to move to a dark sky, it was also a very interesting reading for someone confined to a flat in town, and such case was indeed explicitly quoted in the book.

It is at this point appropriate to clarify my approach to the hobby.

I am not “confined” to the city because of some external limitation, but just because I am very much of a lazy guy who prefers to have all the commodities of his apartment at hand.

Even in 2005-2007, when I had joined an Astronomy Club, I just went once with them on the mountains, in summer.

Ten years later I could envisage the perspective of tents or lodge as a “well maybe, one of these years” thing, but you cannot seriously consider a hobby  something you do once every few years, or even months.

So I wanted to perform astrophotography from my balcony, with an as cheap and as light as possible equipment.

Hence no heavy German Equatorial Mounts, no big bore telescopes, no autoguiding and a DSLR for camera.

This kind of approach may be considered as something in between EAA (Electronically Assisted Astronomy) and old dear proper AP (Astrophotography), the basic push behind it being the desire of being able to somehow “see” what would be extremely difficult, if not outright impossible, to perceive visually from a urban site.

However, at least some of the images obtained can be considered fairly good examples of astrophotography in their own right, albeit they cannot be put at the same level of images taken with equipments that cost ten times as much.

My present urban site has a Sky Quality of 17.63 Magnitude/arcsec^2, Class 9 Bortle and all photos shown have been taken from there, unless otherwise specified.

First Season: 2017

After some reckoning and a fair amount of reading I opted for a light GEM, a Skywatcher EQ2 in a so called “Astrophoto” configuration, that is, basically, with stepper motor tracking and 1/4″ camera connection.

As for the camera, I choose a Canon EOS 1300D, an entry level, APS-C format DSLR.

I also bought a cheap Skywatcher 80/400 as the new main scope for DSO astrophotography to substitute the ETX-80.

But in the beginning, it must be said, I was very much in love with camera lenses, particularly prime lenses.

The Canon EOS 1300D came in a kit with a basic 18-55 F3.5-5.6 zoom, so in my newcomer’s enthusiasm, I rapidly bought a 55-250 F4-5.6 zoom, a 50 F1.8 prime lens, a vintage 135 F2.8 prime lens and a 1.4 teleconverter to use it also as a 185 F4 lens, and finally an unlucky Canon FD 200 F4 vintage prime lens.

I say “unlucky” because I did not know (I should have done my homework) that Canon FD lenses do not reach focus at infinity on EOS cameras without an optical adapter, so in the end I obtained a rather slow and optically debatable 250 F5 lens.

None of those lenses taken alone was expensive, but when put together they summed up at about 700 euro, not much in the field of DSLR lenses, and yet something for wannabe “cheap” astrophotography.

The camera lenses were both an useful training tool and an interesting approach to astrophotography.

The short focal lengths and the wide fields they grant are very useful to cut your teeth as a beginner astrophotographer.

The real bottleneck of my first year of this new experience in astrophotography was the mount.

The Skywatcehr EQ2 Astrophoto is a cheap mount with a promising name, but unfortunately also some flaws, at least as regards the specimen in my possession.

The mount is a light German Equatorial Mount (GEM) with a maximum payload of about 4 kg, which means that the maximum realistic payload for astrophotography is, more or less 2.8 kg, or 70% of the nominal maximum.

While you may read some favorable review of this mount on the Internet, some even claiming that it may allow 30 seconds exposures at 400 mm focal length, I never went beyond 10 seconds (basically a “4000 rule”) without noticeable trailing.

Moreover, my mount has a flaw: if you move by hand the cogwheel that provides the AR motion, you immediately notice that sometimes it moves smoothly and sometimes it is very hard to move.

Some greasing improved things a little bit, but this is a manufacturing defect that impairs the mount’s tracking capabilities.

I read about another identical case on the Internet, but unlike that guy I did not send my mount back to the dealer: I was too lazy to pack again a whole mount, especially since I had already thrown away the original packaging!

So I kept it and used it for what it was able to give.

In the end, following, as aforementioned, a “4000 rule”, I was able to obtain acceptable 10 seconds exposures at 400 mm, 20 seconds ones at 200 mm, 30 seconds ones at 135 mm and 60 seconds exposures at 50 mm, even if theoretically I should have obtained 80 seconds ones.

For some reason, the mount was able to get longer exposures at declinations around +25 and so in some instances I was able to obtain (barely) acceptable 20 seconds exposures at 400 mm.

There was, however, a constant drift, all attempts at fixing polar alignment notwithstanding, that forced me to re-center the subject in the frame every, say 10 to 20 shots. A rather tiresome practice when you are going to take hundreds of short exposures.

Second season: 2018

During the 2017/2018 winter, I reduced my activity, particularly during the coldest nights, and started to think about how to improve my equipment for the next spring/summer/autumn campaign.

I played for a while with the idea of buying an EQ3 or an EQ5 with motorization on both axes, but I was not particularly attracted by the increased storage space they would require and also worried about issues of increased distance of the mount from the balcony’s rail due to its bigger size, which could reduce the sky accessible to a telescope or lens mounted on it.

The availability of the new Skywatcher AZ-GTI mount, with its compactness and the possibility of using an app on your smartphone instead of the cable linked controller for GOTO and general management of the mount through WiFi, was enough to eventually push me to adopt an altazimuth configuration.

I bought just the mount head and not Skywatcher’s tripod because I could rely on a Manfrotto tripod, which could be quickly folded, with the head mounted in a compact  70x10x10 cm package, very easy to store at home and to carry around.

I also decide to try and revive my old Meade DSI Pro camera, which I had just very scantily used the previous year.

Finally I was attracted to a rather new Bresser product, a short achromat with, apparently, some sort of ED lens it, a quite fast 102/460 F4.5 scope sold at a bargain price with a decent 2.5″ focuser.

The addition was absolutely in style with the rest of my setup: dirt and cheap. I know many purists will absolutely despise such hardware, but I am the one who decides how to waste his own money.

Paradoxically it is true I bought some accessories, like filters, or some software I use, that cost almost as much or even more than most of my scopes, but, you know, the beauty of an hobby is that you don’t have to tackle it with the rationality expected in a professional activity.

Third season: 2019

The rather mild (in my area) 2018/2019 winter allowed me to take pictures almost without interruption, unlike the year before. I also bought some more protecting gear to keep myself warm when outside at night.

On the technical gear side, while fiddling from time to time with the idea of buying a new telescope, I eventually decided to prioritize the acquisition of a monochromatic camera of the new generation, basically to take the place of the venerable old Meade DSI Pro.

The choice fell on the ZWO ASI 178MM as a good balance between price, quantum efficiency, low read noise and (CMOS) sensor size.

Its 2.4 µm pixels are also very useful for high resolution imaging and and also on DSOs allow fairly good closeups with relatively short focal lengths.

I also decided to experiment more with filters and hence I also bought an IR PASS filter and another UHC filter, specifically for use with the monochromatic camera.

In particular, the IR PASS filter, when paired with an IR CUT filter creates a sort of poor man’s Hα filter, with a bandwidth of about 35 nm.

Such a filter was extremely useful in enhancing the imaging of emission nebulas, at the same time without it being so narrow as to penalize the relatively limited aperture optics I use.

 

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