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Canon EOS 550D Astro Modification


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Hi all,

 

Apologies for the long post, but I'd though I'd share my experiences modifying a recently purchased ancient EOS Rebel I picked up for a song.

 

I wasn't looking for the latest and greatest DSLR (not really a requirement for my version of LRGB), just a laptop-controllable replacement for my old Baader modified T3 I regretfully sold a while back.

 

Having previously "naked sensor" full-spectrum modified a Micro Four Thirds body some years ago, I wanted this Rebel to be somewhat useable with refractive optics, without the star bloat associated with your typical LPF1-only and Clear Glass Astro-mod conversions most folk tend to go for. Also, with a custom white balance, It might fill the role as a spare body for regular photography. 

 

So, I purchased a third party 400-700nm LPF-2 filter (at a fraction of the cost of an identical-spec Baader BCF), to replace the stock Canon item and followed Life Pixel's and Gary Honis's online Canon Ha modification guides.

 

Well, I stripped the perfectly good camera down to a pile of parts, swapped out the old filter for new (sadly, I couldn't remove it without irreversibly damaging it) and set about the unenviable task of re-assembly.

 

All the guides warn that the hardest part is calibrating focus and keeping dust at bay.

 

They're not joking.

 

The way I tackled it was to fill the room with steam (a boiling saucepan to trap as many airborne dust particles as I could, without turning my kitchen into a sauna) and scribing timing lines across the three spring-loaded adjustable sensor mounting screws before disassembly. Also counting exactly how many turns are required for each screw to "bottom out", plus as a final backup measure, recording the length of the protruding mounting lugs near the screws using a Vernier gauge.

 

Outer casing removed, mainboard and rear sensor assembly pictured.

 

Canon EOS 550D Ha Astro Modification

 

 

Spring-loaded sensor mounting and tilt adjustment screws pictured.

 

 

Canon EOS 550D Ha Astro Modification

 

Canon EOS 550D Ha Astro Modification

 

Final sensor positioning, post filter swap.

 

Canon EOS 550D Ha Astro Modification

 

All seemed to go well, with all parts, ribbon cables and sensor repositioned to the best of my ability and so I powered the camera on. A flashing power light, then nothing. Dammit! 

 

So, I stripped open the camera again, checked all cables were fully seated, but I didn't see anything obvious I'd missed. About to throw in the towel, I'd just noticed that the only ribbon cable buried behind the main board (dust shaker circuit, at a guess) looked slightly unseated. So, more disassembly ensued, and I re-seated the cable and put it all back together.

 

Powered on, camera appeared to come to life, but the rear screen failed to power on. Now what? 🤔

 

I pressed the display button, and sure enough, the display lit up. Sounded like maybe the eye sensor broke during the modification, so the price to pay is having to manually switch on the LCD display after every power up. When starting an imaging run, I usually switch it off anyway, so not the end of the world.

 

I was ready to leave it at that, as the camera was fully functional apart from that small issue, but I know for a fact, little issues like that would eventually drive me round the bend.

 

After a firmware update failed to fix it, I thought about Googling the problem and there was an old article about certain Eye-Fi cards causing this very issue. Sure enough, the camera had a FlashAir card installed, so, I swapped it out for a regular SD card. Would you believe it, the camera was back to being fully functional. 

 

It's always the simplest things, eh! 🤣

 

I have taken both daylight shots and done a short, calibrated Astro test imaging run. Serendipitously, infinity focus seems attainable with manual lenses, there doesn't seem to be any tilt to a degree that bothers me, and the stars are in focus corner to corner. 

 

An impromptu 8-minute test integration of NGC 1499 - Background Extracted, no further processing.

 

550Da first light

 

 

If you stretch the Masterflat to insane levels, there seems to be a few tiny dust motes here and there , but these seem to calibrate out fine, and are totally invisible with daylight pictures. I haven't cleaned the front LPF-1 sensor glass since reassembly, but to be honest it's probably pointless ATM with proper calibration.

 

 

TL;DR - for a simple life, send your camera to Juan at Cheap Astrophotography for modification! 😁

 

 

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Well done Kev. Brings to mind my conversion of my 1000d some years back. I put it all back together after modding and switched on, nadda, zilch. Stripped it again, remade ribbon cable plugs, reassembled and thankfully it all worked

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Hats off to you Kev 👍🏼

 

Its only when you strip it down like that you realise the complexity of whats inside.

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Excellent work, FYI there was a chap on sgl in classified selling a 3D printed holder for canons that takes 1.25 filters for £5 which can be very useful in that you can use filters that you have I snapped one up at the time .

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8 hours ago, philjay said:

Well done Kev. Brings to mind my conversion of my 1000d some years back. I put it all back together after modding and switched on, nadda, zilch. Stripped it again, remade ribbon cable plugs, reassembled and thankfully it all worked

 

Yes Phil - if just one of those tiny ribbon connections aren't fully seated, camera more often than not won't power on.

 

I don't think I've ever nailed it with my very first attempt!

 

Cheers,

 

Kev

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6 hours ago, Bino-viewer said:

Hats off to you Kev 👍🏼

 

Its only when you strip it down like that you realise the complexity of whats inside.

 

Yes, it's quite something, Rob. It's not exactly a state of the art body either.

 

Makes what they manage to cram in modern smartphones all the more impressive, too.

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2 hours ago, Bottletopburly said:

Thingyverse link to 3D file https://www.thingiverse.com/thing:4306640/comments should you want to print one, the chap had professionally printed due to the fine threads .

 

Interesting find, David. Thanks for that!

 

Would a 1.25" filter be able to cover an APS-C sensor without vignetting though?

 

My 31mm unmounted filters are barely the smallest I can get away with, using my 4/3 mono setup. Even that requires perfect calibration on my part.

 

Cheers,

 

Kev

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1 hour ago, 8472 said:

 

Interesting find, David. Thanks for that!

 

Would a 1.25" filter be able to cover an APS-C sensor without vignetting though?

 

My 31mm unmounted filters are barely the smallest I can get away with, using my 4/3 mono setup. Even that requires perfect calibration on my part.

 

Cheers,

 

Kev

Regards vignetting not sure Kev purchasing coincided with me getting a zwo533mc so not used yet .

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I did a 1000D a good few years ago and as I was getting towards the end the phone rang just as I had got one of the many screws on the end of the screwdriver.

 

I think I found the screw somewhere in Northern Australia.

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