After considering my mount as part of my lightweight re-think of my astrophotography setup, I need to consider my optical and imaging setup. Currently I use an Orion ED80 f/7.5 refractor. The ED80 has a focal length of 600mm, and weighs 2.6kg. To this I add a 0.85 focal reducer/corrector that adds 320g and reduces the focal length to 510mm.

Over the past several years I’ve imaged with APS-C Canon DSLRs and Fujifilm mirrorless cameras, most recently the Fujifilm X-T4, which weights 607g with a battery. I won’t be changing the camera itself, but it’s worth including it in both setups.

With the camera, this setup had a total weight of about 3.6kg, which… could actually work with the iOptron SkyGuider Pro, theoretically. But our point here is to find a lightweight alternative to the telescope, which is going to be camera lenses!

The closest I can get to that 510mm focal length of the ED80 + 0.85 reducer is the Fujifilm XF 100-400 lens, which I have, and which I used to capture the 2017 total eclipse. That lens weighs a whopping (for something intended for hand-holding) 1.77kg! An alternative, lighterweight lens is the more recent XF 70-300mm, which is a measely 580g. That’s more like it. Both are faster too, with f-stops of f/5.6 at their maximum focal length, compared with the ED80’s f/7.5.

Total Eclipse, August 21, 2017. Single exposure. Fujifilm X-T2, XF 100-400mm.

Both of these lenses are also compatible with the Fujifilm 2x teleconverter, which would add 170g to each, but would give me focal lengths of 800mm and 600mm, respectively, at a cost of an f-stop of f/11. When I already have to do long exposures, this might be a bit much. However, because I have that flexibility, I’ll include the teleconverter in the table below.

This gives me the following possible combination and weights:

So, the X-T4 with the 100-400 and the 2x TC is still about 2/3 of the total weight of my original setup. But a setup with the 70-300 is less than half the weight of just the ED80! And in my own (non-astrophotographic) testing, the 70-300mm lens is close enough in image quality to the 100-400 that the extra weight isn’t worth it unless I need the reach.

I mentioned above that I used the XF 100-400 for the 2017 total eclipse. In that case, I used a Fujifilm X-T2 and XF 100-400 on a tripod. That experience highlights a downside to this setup when compared with a telescope: I knocked the 100-400 slightly out-of-focus when taking the sequence of exposures I wanted for stacking. That wouldn’t have happened with the ED80, where focus can be locked once obtained.

Total Eclipse, August 21, 2017. Multiple exposures. Fujifilm X-T2, XF 100-400mm.

However, the major reason I used the X-T2 and XF 100-400 for the eclipse was that I had to travel to see it. That experience already speaks to the advantage I’m trying to get out of a more thought-out lightweight setup.

Besides focus locking, there are some other downsides to a camera lens vs a telescope. Most camera lenses are optically best when stopped down from their maximum aperture, whereas telescopes are optimized at their fixed aperture. I also suspect there’s also a difference in light transmission between a doublet or triplet refractor and a camera lens with more glass and coatings in the optical path.

But, I’d like see what this looks like with some serious attempts at use, and whether camera lenses are good enough for what I want to capture, of if I need to look at a small, lightweight, dedicated refractor.

The first part of my lightweight re-think of my astrophotography setup has to be my mount. I’ve been using an Orion SkyView Pro GoTo. It’s been a good little, reasonably lightweight (as decent goto mounts go), and has done the job well — I haven’t felt it incapable of what I needed. The mount, counterweight, and tripod weigh around 17kg total when set up, and have a maximum capacity of 15kg. 17kg is… not insignificant.

I’m also a photographer, and to be sure there’s a lot more innovation in the photographic tripod space in terms of materials and features. And I have tripods and accessories. So, I thought I’d see what I could come up with.

I picked up a nice, beefy Leofoto carbon fiber tripod, leveling base (which, coming from a telescope tripod, is revolutionary), and a two-way pan head to make it easy to set-and-forget my home latitude. I already have a Vixen Polarie tracking mount for a number of years that can sit on top of this and track the rotation of the Earth. I have not used it for much more than quick-and-dirty throw-a-camera-on-it efforts up until now though. On that I’ll put the ball head that came with the tripod.

So, what is the weight and capacity of all of this?

This gives me a total weight of 3.67kg with a maximum capacity of 3.2kg (the limitation of the Polarie). About 500g of that is taken by the ball head.

Listed out, like above, , this looks more complicated than the previous setup, but I can keep certain bits assembled. More importantly, with the leveling base, I can assemble everything from the ground the Polarie inside, well before I go out a cold night. Then, when I carry it out, all I have to do is level the base, align the Polarie, attach the ball head and camera and start capturing. In theory.

I’d like to eventually replace the Polarie with an iOptron SkyGuider Pro, which weighs 4.6kg (and would therefore add 3.6kg of weight), but has a 5kg capacity. The big features it adds will be a counterweight and autoguider support (more on that later). 5kg is still only a third of the 15kg capacity of the telescope mount, but I haven’t needed anywhere close to that 15kg capacity for my telescope and imaging setup.

But the imaging setup will be another post!

Astrophotography has been an off/on hobby of mine for almost twenty years. In that time I’ve taken a few images a really like, and many I don’t. Typically I go through periods of enthusiasm and frustration, both with gear, weather, and my own limitations.

One thing that does recur is a fundamental laziness I have when it comes to setting up and taking down my equipment. This is the biggest blocker I find to just getting out and doing. I’ve thought about putting in a permanent pier, so that I don’t have to mess around as much with the tripod and mount alignment, but that’s not the only problem I have. It’s also somewhat hard to travel with my setup. I downsized about 10 years ago from an 8” Schmidt-Cassegrain to an 80mm refractor, and that helped, but given how I frequently I’ve gone out over the past few years, I thought it might be time again.

I want to rethink my setup, from my mount to the optics and imaging to the possibility of autoguiding and other niceties. Most importantly I want to be satisfied with both the level of effort involved in setup, when compared to imaging and processing, and I want to be satisfied with the quality of the images.

I’ll explore options and comparisons over a series of posts, and try to reason out what works along with what I already have — afterall, budget is a big factor, and I’m already a photographer who has a lot of equipment that could work anyway. But most of all, the test will be whether I actually get out and take astrophotos again.

After all, I’ve gotten great results with just a camera and a lens before.

The Great Galaxy in Andromeda. 22x15s, Fujifilm X-T2, XF 100-400mm.

My Slow Motion Messier Marathon has become even slower. Five years since the last update, I have another update! This one is less impressive.

• M8, The Lagoon Nebula.

This photo is actually over a year old at this point, but I was fixing some broken links and noticed I didn’t have it on here yet!

With it added, here is my updated list of Messier objects I’ve captured so far:

The full table (including all the missing objects) is also available on my Messier page.

It’s one of the quirks of the house that I live in is that I cannot easily see the end of the driveway from inside the house. This means it’s hard to tell when someone might have arrived, whether expected or unexpected. The Guardline Wireless Driveway Alarm has been a good solution to that problem, as it gives us a nice, loud, BING when its beam is crossed. It’s not perfect — deer and even neighborhood cats occasionally set it off — but I’m happier with it than I was without it.

Having other home automation projects I’ve undertaken using HomeKit (more on that another time), I decided that it would be nice to know if the alarm goes off when I’m not at home. My first inclination was to connect it to a Raspberry Pi, since I have those lying around, and I’ve used them successfully for other home proijects. The Guardline has relay connections, and I wondered if I could wire it up to a Pi and read the change in state from a GPIO pin. Clearly if the answer was no, I wouldn’t be writing this.

It turns out to be fairly simple. I chose to wire the Normal Closed contact to a pin on the Pi (GPIO board pin 37), the sensor pin and the common to a ground pin.

From there I could detect events on the sensor pin:

def motion_detected(pin):
    print("Motion detected!")

sensor_pin = 37

GPIO.setmode(GPIO.BOARD)
GPIO.setup(sensor_pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.add_event_detect(
    self.sensor_pin,
    GPIO.BOTH,
    callback=motion_detected
)

Once I knew that I was getting state change, I built a simple HomeKit accessory using HAP-Python:

import logging

import RPi.GPIO as GPIO

from pyhap.accessory import Accessory
from pyhap.const import CATEGORY_SENSOR


logger = logging.getLogger(__name__)


class GPIOSensor(Accessory):

    category = CATEGORY_SENSOR

    def __init__(self, *args, sensor_pin=3, **kwargs):
        super().__init__(*args, **kwargs)

        self.sensor_pin = int(sensor_pin)

        logger.debug('Setting up GPIO input')
        GPIO.setmode(GPIO.BOARD)
        GPIO.setup(self.sensor_pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
        GPIO.add_event_detect(
            self.sensor_pin,
            GPIO.BOTH,
            callback=self.__motion_detected
        )
        logger.debug('Subscribed GPIO events')

        serv_sensor = self.add_preload_service('MotionSensor')
        self.char_detected = serv_sensor.configure_char('MotionDetected')

    def __motion_detected(self, pin):
        logger.debug('Motion detected')
        sensor_state = GPIO.input(pin)
        self.char_detected.set_value(sensor_state)

    def stop(self):
        super().stop()
        GPIO.cleanup()

Which was easy enough to then run using the HAP-Python example. Once it’s set up in HomeKit, I get handy notifications like this:

My brief recommended reading list for a nuclear crisis, in order:

1. The Making of the Atomic Bomb, by Richard Rhodes
2. Hiroshima, by John Henessy
3. One Minute to Midnight, by Michael Dobbs
4. Essence of Decision: Explaining the Cuban Missile Crisis, by Graham Allison and Philip Zelikow
5. Nagasaki: Life After Nuclear War, by Susan Southard

My also-brief recommended reading list for North Korea, in no particular order:

• Nothing to Envy, by Barbara Demick
• Escape from Camp 14, by Blaine Harden
• The Aquariums of Pyongyang, by Kang Chol-hwan and Pierre Rigoulot