An XPan Retrospective

I spent six years as the caretaker of a Hasselblad XPan, one of the most unique cameras ever made. It was a rangefinder camera that used 35mm film to capture a frame roughly 2x the size of a standard 4:3 ratio frame.

A Hasselblad XPan

Instead of 36mm x 24mm negative, you got a 65mm x 24mm negative. This is the same height as any standard 35mm negative, but the extreme width made for an utterly unique perspective in a single frame. The 45mm lens gives what you roughly expect to see from a 50mm lens—and this is reinforced by the vertical tightness of the frame—but then you get more context on either side.

Through the terminal window at JFK Airport

JFK Airport

It was an absolute joy to compose with because of this, composing the widest possible frame that containing and suggesting an otherwise familiar field of view, and because you’re doing this through the viewfinder, focusing with the rangefinder.

Copenhagen

Copenhagen

Souring on film

The only problem—and I stress, the only reason I stopped using this gem of a camera as much as I should’ve—is film. I know film has been having a renaissance moment, but—and I say this as someone who got his start in a black and white darkroom—I’m kind of done with it.

Traveling with film is annoying, and won’t stop any time soon. X-ray scanners and worse are increasingly proliferating. Sure, you can come up with all kinds of logistics around it, mailing your film to avoid unfriendly airports, etc, but that adds more overhead.

Then you’ve got to scan it, and scanning film is either really expensive or as terrible experience to do by hand. I’m just… done.

Stockholm on x-ray damaged film

Stockholm, on x-ray damaged film. You can mitigate this in post, mostly, but it’s a pain.

This is why I sold my XPan. It is a camera that deserves to be used, not to sit around because I can’t be bothered with film. But oh it was such a joy, especially in composition.

A digital XPan?

It’s unlikely any company would put a 65mm x 24mm sensor into any camera, so digital options are limited to cropping. You can crop any image to that 65:24 ratio, of course, but part of the experience of the XPan is framing that way in-camera—learning to see the familiar frame wider.

There are a few cameras that let you do this: the two modern mirrorless medium format mainstays, Fujifilm’s GFX cameras and the Hasselblad X cameras with their 44mm wide sensors. But there is one option that I don’t see talked about very much: Panasonic’s Lumix S series cameras and their 36mm wide sensors.

A Panasonic S5II without lens, showing the sensor

The S5 II is about as working class a camera as you can get—there’s nothing approaching the sexiness of the XPan about it. It is supremely comfortable in the hand, it must be said; the ergonomics are great.

It is definitely not a rangefinder either; it’s a DSLR-styled mirrorless camera. You’re not composing through a separate optical viewfinder. But it has a native 65:24 crop, allowing you to see the XPan-sized frame and to compose within it.

The duality of early spring over the Rip Van Winkle Bridge

And… this is enough for me. Pairing a Panasonic Lumix S5 II with the Sigma 24mm f/2 prime lens gives the same field of view as the XPan with its 45mm lens (and the Sigma is two stops faster too).

A Panasonic S5II with the Sigma 24mm f/2 lens

The Sigma 17mm f/4 will give the same field of view as the XPan’s 30mm wide angle lens—which is exceptionally rare, expensive, and required a separate viewfinder for the XPan.

The only downside is the megapixel cost: the S5 II is 24MP natively. When you apply that 1.8x crop you end up with a 13MP image. Not terrible, especially in the modern world of machine learning-based upscaling, but not ideal.

The S5 II does have a handheld high resolution mode that can capture 96MP, but this doesn’t offer you an XPan 65:24 crop, unfortunately. You could theoretically compose a 24MP 65:24 frame, then take the composition with the high resolution mode, and crop it in post to match for 53MP image.

An S1R might be a better choice here. Its 47MP sensor would give you 26MP images when cropped to 65:24. But it’s a substantially larger camera.

Of crops and composition

But, you might ask, why use an XPan-ratio crop when the point of the XPan was exactly the opposite; it was nearly two 35mm frames wide, not a crop of a 35mm frame.

Frederic Edwin Church’s Olana

I think it is, because the final composition doesn’t care about real estate, on film or otherwise. No one is going to admire a 65mm-long frame more than a 36mm-long one. No, the impact that the XPan framing has is in the composition: what is inside the frame, and how it is arranged, as with all photography. The S5 II lets me compose in that frame, which is what I want to do.

I’m not totally happy with the look I get from the Panasonic files yet, but I’m still learning how I want to process them — certainly they have a different vibe than film, but what I’m looking at for the purpose of this post is the experience of taking the photograph.

As for the other thing I enjoyed about using XPan, the rangefinder, well… that’s another post.

I hadn’t had opportunities to observe a total solar eclipse before 2017, but I knew I wanted to try my hand at photographing it. And photograph it I did!

Composite of the total eclipse of August 2017

Before that though, I did some research and captured notes and a simple, fine-grained order of operations, because I didn’t know what I was doing and it’s not something you can really try over again if you fail. Plus, I actually wanted to enjoy the moment without fiddling with my camera, and having a concrete plan helps with that.

There are a few different images I wanted to try to capture, because there are multiple aspects of the sun that are visible during an eclipse that aren’t normally. In brief, we can observe the sun’s chromosphere, any prominences it might have in the moment, the corona, and, at totality, we can see earthshine on the moon. These can all be composited together to form an image like the one above.

For this eclipse, I was traveling with my tripod, Polarie tracking mount, and Fujifilm X-T2 and 100-400 lens, so figuring out the exposures for each of these phenomenon would happen in terms of the ISO+shutter speed+aperture settings best for that combination of equipment. Jerry Lodriguss has a fantastic write-up that forms of the basis of what I decided to do.

Based on this I settled on using an ISO of 400, an aperture of 5.6 (the widest that lens was at 400mm), and chose shutter speeds from there.

Phenomenon Shutter Speed ISO Aperture
Chromosphere 1/8000s 400 5.6
Prominences 1/4000s 400 5.6
Corona 0.1 Rs 1/1000s 400 5.6
Corona 0.2 Rs 1/250s 400 5.6
Corona 0.5 Rs 1/60s 400 5.6
Corona 1.0 Rs 1/15s 400 5.6
Corona 2.0 Rs 1/8s 400 5.6
Corona 4.0 Rs 1/4s 400 5.6
Corona 8.0 Rs 1s 400 5.6
Earthshine 2s 400 5.6

This became my sequencing for during the eclipse: I would take an exposure at 1/8000s, then 1/4000s, 1/1000s, etc, all the way up to 2s, then do the same in reverse, from 2s down to 1/8000s. To eliminate the number of things that could go wrong, I decided to manually set the shutter speed (with the X-T2’s physical dial, perfect for this use-case) rather than relying on any automation.

The other decision I made was to use exposure bracketing in camera at ±1 stop. So, I would set the shutter speed above, and the camera would take 3 exposures. This wold maximize the range of possible data I’d have to work with.

I also wanted to get some photos before totality as the moon is moving across the sun’s face. For those there’s a lot more time to experiment.

⚠️ For any photography of the sun outside of totality itself a solar filter specifically designed for observing the sun is absolutely required. I keep seeing advice around the internet to just use ND filters. This is wrong and dangerous.

The core decision I stuck to here was just to follow the same exposure list, with bracketing, I had for totality. Again, this gives me a maximum range of exposure data and is an opportunity to practice.

As I said at the beginning of this post, what I wanted was a straight-forward, fine-grained order of operations I could follow on the day to ensure I was spending as little time as possible fiddling with my camera, and the most time enjoying the experience of the eclipse with my family. Here is the list I ended up with:

Before totality:

  1. Put new batteries in Polarie
  2. Set up tripod and Polarie
  3. Align Polarie
  4. Put new battery in camera
  5. Put camera and lens on Polarie
  6. Put solar filter on lens
  7. Attach cable release
  8. Set manual focus
  9. Set ISO 400
  10. Set BKT drive mode
  11. Set 5.6 aperture
  12. Put solar glasses on face
  13. Position on sun
  14. Focus
  15. Set shutter speed 8000

Partiality:

  1. 8000
  2. 4000
  3. 1000
  4. 250
  5. 60
  6. 15
  7. 8
  8. 4
  9. 1s
  10. 2s
  11. Repeat as desired

Totality:

  1. Remove solar filter
  2. 8000
  3. 4000
  4. 1000
  5. 250
  6. 60
  7. 15
  8. 8
  9. 4
  10. 1s
  11. 2s
  12. Gawp
  13. 1s
  14. 4
  15. 5
  16. 15
  17. 60
  18. 250
  19. 1000
  20. 4000
  21. 8000
  22. Put solar filter on lens

Overall, this made for a satisfying and enjoyable eclipse, with results I’m pleased with. I did knock the manual focus ring on the lens slightly out of focus when removing the solar filter for totality, and so my totality shots are that little bit out of focus. But that’s fine. Other people got sharp, in focus photos of this eclipse. But this is mine, where I was, and with my family as we observed it.

I love a good star chart. Maybe because I got started with astronomy and astrophotography with visual observation and a box full of star charts when I was in high school, and I’ve never really found digital planning as satisfying as laying out a physical chart on a table. But that’s not what this post is about.

What it’s about is that I want to generate star charts for this website based on my images, mostly because it seems like an interesting problem, and because I want to control the aesthetics of the charts, which means they need to be in SVG (or otherwise stylable). So, this requires two things, first to plate solve the image, and second to use that information to generate the chart.

ASAP, the Astrometric STAcking Program is a fantastic tool for offline plate solving, and my tools (like N.I.N.A) already use it. ASTAP, when invoked from the command-line, can take an image file, and plate solve it for a given FOV and search radius. For my latest Orion Nebula, it gives the following output:

$ /Applications/ASTAP.app/Contents/MacOS/astap -r 180 -fov 0 -f orion_nebula.jpg
Solution found: 05: 35 04.6	-05° 17 54	 Solved in 19.2 sec.	 Δ was 83.8d.	 Used stars down to magnitude: 12.7
Warning inexact scale! Set FOV=1.71d or scale=1.9"/pix

This gives me the RA, DEC, and FOV of the iamge (if you use -fov 0 to have ASTAP automatically solve that as well — since this is a final image over two sessions, with cropping, the FOV isn’t necessarily going to match exactly what my Canon 6DM2 and AT115EDT provide).

Next, I’ve discovered a tool that generates some really nice star charts in Dominic Ford’s StarCharter used for the charts on in-the-sky.org. StarChater takes a configuration file for the chart to generate. What I wanted to see is if I could take the coordinates that ASTAP returns and put them into a configuration file for StarCharter:

CHART
title="Great Orion Nebula"
output_filename=test.svg

# RA and DEC as decimals
ra_central=5.5844
dec_central=-5.2981

# Go about twice as wide as the image FOV, give some context
angular_width=4

aspect=1.5
ra_dec_lines=1
axis_label=0
mag_min=7
constellation_boundaries=1
constellation_sticks=1
coords=ra_dec
projection=gnomonic
star_names=1
star_flamsteed_labels=0
constellation_names=1
plot_galaxy_map=1
plot_equator=1
plot_ecliptic=1
plot_galactic_plane=1
font_size=1.2
magnitude_key=0
great_circle_key=0
dso_symbol_key=0

And then run it:

starchart.bin test.sch

This gives me a star chart that corresponds to the image:

I’m going to wrap this up with some automation and I’d like to have it as part of my workflow and my astrophotography gallery.

As a minor aside, ASTAP can also add annotations to the image, with the -annotate argument. I’m not sure I’ll use this, but it’s a neat discovery with… possibilities.

I wrote about my return to using my German Equatorial Mount, refractor, and Canon DSLR in my last blog post. Since then I’ve refreshed both my mount and my reactor. In many way’s it’s the opposite of the lightweight setup I wanted a year ago, but what I realized I wanted was simpliciy. This gives me that, of a sort:

  • Losmandy GM-8 German equatorial mount with Gemini 2
  • Astro-Tech AT115EDT 115mm ED triplet refractor with 0.8x reducer/field flattener

The Losmandy mount is substantially heavier (even with their lightweight tripod) than anything I’ve used before. But it’s modular, comes apart easily, and is—in my experience so far—rock solid, feature rich, and a joy to operate.

The same can be said for the 115mm refractor, it is much heavier than my ED80, but what I gain for the added weight is a faster optic (f/5.6 with the reducer) with a larger aperture that can capture more in less time.

My first light with this setup was actually limited. I got 30 minutes of the Horsehead and Flame nebulas before they went behind a tree and clouds rolled in:

The Horsehead and Flame nebulas

The Flame nebula and the Horsehead nebula. 30x60s, Canon 6D Mark II, Astro-Tech AT115EDT, 0.8 focal reducer. AstroBin

Shortly after that I got to capture a 1:23 of the Orion nebula over a couple nights:

The Orion Nebula

The Great Nebula in Orion. 83x60s, Canon 6D Mark II, Astro-Tech AT115EDT, 0.8 focal reducer. AstroBin

I’ve had no complaints, no struggles, nothing so far with the mount — it is an utter joy to use. And because it’s upgradable, it could be the last mount I’ll ever own. I’m not sure I’d ever need to upgrade — I don’t anticipate putting anything on it heavier than the AT115EDT at present.

The AT115EDT is a beautiful telescope, with superb optics. I will say, figuring out that the camera rotator actually was two pieces, and you have to take one off to attach the reducer/flattener was a bit frustrating. But that’s a minor, one-time thing.

Look for more from this setup in the future.

After my experiments with a lighterweight astrophotography setup ended in a bit of failure, I’ve gone back to a fairly tried-and-true setup for myself:

  • Orion SkyViewPro computerized German Equatorial Mount
  • Orion ED80 APO 80mm refractor
  • Orion StarShoot Autoguider
  • Sky-Watcher 0.85 focal reducer for ED80

I’ve been able to control the telescope and autoguider from a computer (both using laptop and a Raspberry Pi attached to the telescope), but where I’ve struggled in the recent past is in controlling my Fujifilm cameras from that same computer. I would usually use the built-in interval timer separately on the camera.

This has a few disadavantages, first that I can’t check progress, tracking, whether any obstructions have gotten into the frame, etc while the timer is running. Before I switched to Fujifilm cameras, I would use BackyardEOS with my Canon DSLR to control my exposures. It had the added bonus of being able to use the laptop screen to frame, preview, and focus, which works much better than the back screen on any camera.

So, what I decided to do was pick up a second-hand Canon 6D Mark II to dedicate to astrophotography and go back to using BackyardEOS. A dedicated camera I can also get modified for Hydrogen-alpha. This made me happy.

So, I tried to take some photos of a couple easy targets this time of year to see how things go:

The Pleiades

The blue whispies of the Pleiades. 60x60s, Canon 6D Mark II, Orion ED80, 0.85 focal reducer. AstroBin

Andromeda

The Great Galaxy in Andromeda. 26x60s, Canon 6D Mark II, Orion ED80, 0.85 focal reducer. AstroBin

Things went well.

The software stack I’m using is, in macOS, PHD2 for autoguiding and SkySafari 6 Pro for controling the telescope; in a Windows VM, BackyardEOS, set up to drizzle with PHD2. For post-processing I’m using Siril and then importing into Capture One for my regular photo workflow.

This worked really well. I have some new targets in mind for the next clear night.

I wrote earlier this year that my biggest blocker to regularly engaging with my astrophotography hobby 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.

This inspired me to rethink: what if I assembled a lighter-weight, more portable, less cumbersome astrophotography setup using my (beefy, carbon fiber) camera tripod, a polar mount (first the Vixen Polarie I’ve had for a while, then the iOptron SkyGuider Pro), maybe throw my autoguider on there, and hey presto! A setup that should be less effort to set up and take down on a little more of a whim, that I could set up and carry out whole. Or that was the theory.

What I’ve found in practice is that… it doesn’t solve the problem I set out to solve: my laziness. This is why I haven’t updated this series with any resulting photos yet, or attempts to travel, or just generally anything. The setup just doesn’t work for me. This isn’t to say it won’t work for someone else, but I’m more used to the conveniences of a computerized German Equatorial Mount workflow, where I can have software do a lot of the work for me.

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

This might be where I’m going next. Stay tuned.