Any astrophotographers out there?

[ChrisPBacon]

I recently attended a training program at an observatory and the conversation eventually got around to our choices of cameras.

if you are an avid astrophotographer, I’d be interested to hear from you.

1. What DSLR camera do you utilize? Make and model, please.

2. Has it been modified at all to eliminate IR filters? If so, where, and/or by whom?

3. Do you load your photos to a laptop from a telescope, or do you take photos with your DSLR camera through the telescope?

4. Assuming you utilize a Canon camera, what lenses do you use?  What prime lenses? What telephoto?  What wide-angle or telephoto zoom lenses?

5. What photo processing software do you use, such as RegiStax or StarTools?  Post processing software, such as Lightroom. Adobe, or DPPS?

Would love hearing from you.

Thank you.

[TCampbell]

Chris,

I use a Canon 60Da, a ZWO ASI128MC-Pro, and a ZWO ASI174MM-Cool for my cameras (I also have an ASI174MM-Mini that I use as a guide-camera).

The Canon is a special edition of the 60Da that is pre-modded by Canon for astrophotography.  A normal camera cuts the reds quite a bit becuase human vision isn't particular sensitive to reds (there's a lot more red in the world than we actually see).  The key band is the Hydrogen alpha wavelength.  Around 90% of all ordinary matter in the universe is hydrogen.  This means loads emission nebulae glow in Ha.   Traditional camera is blocking around 75-80% of the light at that wavelength.  A modded camera tries to allow nearly all of it to pass.  If you're imaging Ha objects (horsehead nebula, rosette nebula, lagoon nebula, etc. or even wide-field stuff like Barnard's loop) you would have to collect a lot more data to get the reds to show up vs. the modded astrophotogrpahy camera.

The ASI128 is a full-frame color camera with a cooling system that can chill the image sensor down to 40°C below ambient temp to reduce thermal noise.  The "pro" in the name means it has an internal DDR buffer so that it can "read out" the sensor much faster (even if the computer can't keep up) to reduce "amp-glow" problems.

But full-frame cameras are risky for astrophotography.  Few scopes can delivery a flat-image field large enough to fill a full-frame sensor.  My TeleVue requires a large-field corrector.  I've got a PlaneWave 12.5" CDK on order (PlaneWave can project a flat field roughly 70mm across).  I don't use the full-frame camera in very many scopes -- usually using the Canon.

But I also have the ASI174 ... that camera has a smaller chip, it's also a "cooled" camera, but it's monochrome.  The main reason I bought it was for solar imaging through my Ha solar telescope (Lunt).  The camera has a "global" electronic shutter.  Most cameras have "rolling" electronic shutters which means the read-out happens row-by-row.  A "global" shutter camera can read out the whole sensor (all rows) in parallel.  This gives it a very fast frame rate.  At full resolution it can do 162 frames per second.  In planetary and solar imaging, you typically shoot a few seconds of video frames and stack those (it's very different than deep-sky astrophotography).  A solar Ha telescope is monochrome anyway (it only allows the 656.28nm band to pass ... so you see just one color... red).  For solar Ha imaging there's no point using a color sensor (and you can't have CA when there's only one wavelength of light).

I can use it for color imaging by using the filter wheel.  A filter wheel is typically loaded with R, G, B, & L filters (L = Luminance channel and this is really just a filter that does UV & IR blocking but allows the full visible spectrum through.)   You capture some sample data with each filter and then combine to produce a full-color image.

The ZWO cameras are dedicated astrophotogrphy camera that can only be controlled via a computer.  The cameras have no controls on them of any kind (just a USB port ... and a place to plug in a 12v power source to running the cooling system.)

Most of the guys I know start with a Canon DSLR.  Canon is pretty good about having an open SDK so any software developer can write software to control the camera.   Consequently there is tons of software out there for Canon.  Nikon opens the SDK if you own a D5xxx series or higher model, but not for the D3xxx series (there are those who have reverse-engineered the protocol to hack their way in).  Consequently there's less software out there for Nikon.  Sony is usually avoided because of their "star eater" problem.  Sony "RAW" images aren't really RAW.  They process out noise to get better scores and this results in faint stars vanishing becuase the camera though it was noise.  So far as I am aware, there is no way to get around that problem with a Sony.  (Some Nikon models also have the "star eater" problem ... but not all.)

If you want a "new" Canon camera that has been modded (since you can't buy a new 60Da anymore), look to Astro Hutech (hutech.com).  They are an authorized Canon dealer ... but they offer to do the mod on a new camera and they'll honor the warranty.   If you buy from anyone else and send it out for modification, you basically just blew the warranty by modding it. 

I often have to shoot through light pollution filters (I prefer to avoid them becuase you get wonky colors when part of the spectrum is being blocked) but sometimes I have little choice.  I've used the Astronomik CLS filter in the EOS-Clip version (designed to clip into EOS APS-C cameras).  They make CLS and CLS-CCD versions.  The "-CCD" version is meant for cameras that have NO filtering at all (not even IR).  The CLS version assumes the camera still blocks IR.

I have a few ways of imaging. 

I do own a tracking head (Losmandy StarLapse system) which I bought specifically for "travel" (I can take in on an airline ... where I wouldn't trust the airline baggage handlers with my telescopes).  When I do this, I typically use an intervalometer to run the bulb-mode and the images are call captured to the memory card.  I unload them later when I'm ready to process.

But when I use a telescope, I usually either use a StellarMate appliance OR I use image capture software on the computer.  In which case the images are captured to the computers and not the memory card.

For PC users of Canon cameras, "Backyard EOS" is the popular program to remotely control camera image-acquisition.  I don't use a PC, but on the mac it's "AstroDSLR" that does this (there are many choices, but that's my favorite).  It's made by cloudmakers.eu.

But I also use a StellarMate appliance.  This is a Raspberry Pi (a Raspberry Pi is a tiny single-board computer about the size of a deck of playing cards).  It controls EVERYTHING.  It's crazy how automated it is. 

If you had a permanent observatory (I do not) you can tell it what targets you want to shoot on the following night (you do this in the middle of the day) and do the image "sequencing" (tell it how many of each type of image to capture, etc.) and then just start it running.

It will

1. Wait until it gets dark enough (it calculates the end of astronomical twighlight when there is no remain light pollution from the sun).
2. Open the observatory roof
3. Unpark the mount and send it to the first object
4. Automatically focus the telescope.
5. Perform a "plate solve" to align and start tracking
6. Calibrate and start the auto-guider
7. Start the image acquisiton process while...
8. Monitoring the weather and any clouds ... if any clouds show up (it knows this by monitoring the auto-guider quality) it will suspend imaging until the clouds clear, and then resume.  If the weather degrades (too windy, too cloudy, etc.) it will automatically close the observatory and park the mount.
9. It also knows to stop imaging if moonrise creates too much light pollution, etc. or stop imaging if an object altitude gets too close to the horizon.
10. When it finishes with your first target, it moves on to the second target for the night and repeats all that (plate-solving, guiding, image acquistion).
11. When it's completley done, it parks the mount and closes the observatory.

What do you do?  You go to bed and wake up in the morning to check your data.  Honestly ... it feels like cheating.

The list price of the Raspberry Pi computer is $35 USD.  that doesn't include the case, power supply (it runs on a 5v 2.5a power supply ... basically what you might use to charge a cellphone), or memory card (a 32GB memory card is less than $15). The StellarMate OS software is $50.  You can buy the whole package as an appliance for $150 (but I already had a Raspberry Pi so I just paid the $50).  The appliance version comes with a bunch of accessories.

When I use just the camera (tracking head) I'm often using my Canon EF 135mm f/2L USM.  But I do have several other lenses.  I don't have to worry about exposure duration because my camera is tracking and I'm not including landscape.  

It is easier to learn with shorter focal lengths (I know guys who have tried to learn by going staright for a big SCT with a long focal length (e.g. 2000mm or longer) and that's tough.  Long focal lengths will show every mistake.

I do most of my processing with PixInsight (€230 - works out to around $260 USD depending on the exchange rate) and then finish it with Lightroom & Photoshop.  

[iris]

Ted, based on what I just read here I thought perhpas you'd be just the guy to answer my question. I have a Canon 5D Mark iv.

I've come to love nightscapes and astral photography....recently I tried to used the "internal intervalometer" on my Canon 5D Mark IV...I wanted 15 shots at 4 secs apart...and I think I had set the exposure time to 10 maybe 15 secs....The first set went great....however tht was the only set I got....for ever after it would take 4 in a row then stop....Unfortunately each time a set is taken you have to go back into the menu and re  enable the intervalometer......

Can you think of any reason why my Canon 5D Markiv didn't provide me with the numbers of lights, darks and flats that I need..

Other people on ine tell me they do 20 or more sets a night...taking hundres of shots...but I couldn't get one complete set of lights, darks and flats??

[Waddizzle]

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@iris wrote:

Ted, based on what I just read here I thought perhpas you'd be just the guy to answer my question. I have a Canon 5D Mark iv.

I've come to love nightscapes and astral photography....recently I tried to used the "internal intervalometer" on my Canon 5D Mark IV...I wanted 15 shots at 4 secs apart...and I think I had set the exposure time to 10 maybe 15 secs....The first set went great....however tht was the only set I got....for ever after it would take 4 in a row then stop....Unfortunately each time a set is taken you have to go back into the menu and re  enable the intervalometer......

Can you think of any reason why my Canon 5D Markiv didn't provide me with the numbers of lights, darks and flats that I need..

Other people on ine tell me they do 20 or more sets a night...taking hundres of shots...but I couldn't get one complete set of lights, darks and flats??

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I think your intrval needs to exceed your shutter speed.  

When you set the 15 shots at 4 seconds apart, that will be roughly 60 seconds of shooting before the interval expires.  If your shutter speed is 15 seconds, then it would take about 60 seconds to capture 4 shots.

[TCampbell]

I just grabbed my 5D IV to test it... I didn't experience any issues (I set the interval to 5 seconds and told it to take 3 shots.  Each shot was 1/10th sec. in Manual mode).

Out of curiosity... did you happen to have the lens set to the 'AF' position?  (It wont take the next shot until it can confirm that it re-focused)

Normally in astrophotography everything is manual anyway because metering and auto-focus don't work in such low light conditions so you have to manually dial in the exposure (and manually focus.)

[Waddizzle]

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@TCampbell wrote:

I just grabbed my 5D IV to test it... I didn't experience any issues (I set the interval to 5 seconds and told it to take 3 shots.  Each shot was 1/10th sec. in Manual mode).

Out of curiosity... did you happen to have the lens set to the 'AF' position?  (It wont take the next shot until it can confirm that it re-focused)

Normally in astrophotography everything is manual anyway because metering and auto-focus don't work in such low light conditions so you have to manually dial in the exposure (and manually focus.)

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Right.  Now try that again with a 20 second shutter speed.  Pick any shutter speed that is longer than the interval.

[TCampbell]

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@Waddizzle wrote:

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@TCampbell wrote:

I just grabbed my 5D IV to test it... I didn't experience any issues (I set the interval to 5 seconds and told it to take 3 shots.  Each shot was 1/10th sec. in Manual mode).

---

Right.  Now try that again with a 20 second shutter speed.  Pick any shutter speed that is longer than the interval.

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Tried it with 20 seconds... it takes only 1 shot and no more (everything otherwise Identical to my prior test... only the exposure length changed).

So I increased the interval between shots to 10 seconds... that time it took the first AND second exposures... but NOT the third (I told it to do 5).  

That looks like a firmware bug to me.  My firmware is (was) 1.1.2.  I'm updating the body to 1.2.1 to re-test.  If that fails, I'll contact Canon and report it as a bug.

Yep - confirmed it is definitely a firmware bug.

When you start the sequence, the LCD panel on top has the word 'timer' blinking ... the entire time.  The first shot ends... the word timer continues to blink... then it starts teh second shot... timer message still blinking.  But a few seconds into the second exposure, the 'timer' message stops blinking (the timer software has crashed) and you never get a nother shot.

There's no rational reason why it should not work.  This isn't an issue of the camera keeping up (if you use the external Canon TC-80N3 intervalometer it works fine and I generally don't give it more than about 5 seconds between shots (it probably *needs* about 3 seconds but I give it a couple more just to be sure that it is ready.)

I never noticed this before because in astrophotography, I mostly use computer software to control the camera (via USB cable) and have never actually used the in-camera intervalometer.)

[Waddizzle]

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@TCampbell wrote:

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@Waddizzle wrote:

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@TCampbell wrote:

I just grabbed my 5D IV to test it... I didn't experience any issues (I set the interval to 5 seconds and told it to take 3 shots.  Each shot was 1/10th sec. in Manual mode).

---

Right.  Now try that again with a 20 second shutter speed interval.  

Pick any shutter speed that is longer than the interval.

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Tried it with 20 seconds... it takes only 1 shot and no more (everything otherwise Identical to my prior test... only the exposure length changed).

So I increased the interval between shots to 10 seconds... that time it took the first AND second exposures... but NOT the third (I told it to do 5).  

That looks like a firmware bug to me.  My firmware is (was) 1.1.2.  I'm updating the body to 1.2.1 to re-test.  If that fails, I'll contact Canon and report it as a bug.

Yep - confirmed it is definitely a firmware bug.

When you start the sequence, the LCD panel on top has the word 'timer' blinking ... the entire time.  The first shot ends... the word timer continues to blink... then it starts teh second shot... timer message still blinking.  But a few seconds into the second exposure, the 'timer' message stops blinking (the timer software has crashed) and you never get a nother shot.

There's no rational reason why it should not work.  This isn't an issue of the camera keeping up (if you use the external Canon TC-80N3 intervalometer it works fine and I generally don't give it more than about 5 seconds between shots (it probably *needs* about 3 seconds but I give it a couple more just to be sure that it is ready.)

I never noticed this before because in astrophotography, I mostly use computer software to control the camera (via USB cable) and have never actually used the in-camera intervalometer.)

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Please, excuse me.  I had that backwards.  Pick any interval that is longer than the shutter speed..  

I don't think that it is a firmware bug.  As I explained to the OP, his 15 shots at 4 second intervals would take roughly 60 seconds.  He was able to capture 3 or 4 exposures at 15 seconds each, which adds up to the same minute.

The interval program doesn't take shutter speed into account.  All that it seems to do is to blindly "press the remote shutter" button at the regular intervals that you have configured.  It sets intervals between triggers, not intervals between exposures.

If you are taking long exposures, then you must make sure that your intervals are longer than your exposures.

[TCampbell]

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@Waddizzle wrote:

The interval program doesn't take shutter speed into account.  All that it seems to do is to blindly "press the remote shutter" button at the regular intervals that you have configured.  It sets intervals between triggers, not intervals between exposures.

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INTERESTING!  That may be it.  When I use the Canon TC-80N3 intervalometer, the categories are "SELF", "INT.", "LONG", and "FRAMES". 

SELF - is the self-timer... the delay it will wait before taking an exposure.  This typically isn't used with the other three settings.

INT. - is the interval to wait *between* shots (ignoring exposure length).   

LONG - is the length of the exposure in HH:MM:SS

FRAMES - is the number of exposures to take.

If I wanted 5 exposures, each 30 seconds long, and a 5 second delay between them, I would use those very values in on the TC-80N3 intervalometer.

But you're saying that to do this *same* thing in camera, I'd do

5 exposures with a 35 second intervals on the interval timer.  But on the camera exposure (not defined in the interval timer) I'd set a 30-second exposure with a 5-second interval between exposures because the camera is just "blindly" activating the shutter every 35 seconds.

This makes sense (even though it's a bit confusing and not the same way that it works on an intevalometer).  Most photographers are taking sub-second exposures and aren't likely to run into this issue.  

But I think they key message is it "blindly" presses the shutter button every XX seconds with no awareness as to the actual exposure duration of each shot.  Hence the interval is the interval between "pressing" the shutter button... not the interval between the end of the last exposure and the start of the next exposure.

Thanks!!

[Waddizzle]

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@TCampbell wrote:

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@Waddizzle wrote:

The interval program doesn't take shutter speed into account.  All that it seems to do is to blindly "press the remote shutter" button at the regular intervals that you have configured.  It sets intervals between triggers, not intervals between exposures.

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INTERESTING!  That may be it.  When I use the Canon TC-80N3 intervalometer, the categories are "SELF", "INT.", "LONG", and "FRAMES". 

SELF - is the self-timer... the delay it will wait before taking an exposure.  This typically isn't used with the other three settings.

INT. - is the interval to wait *between* shots (ignoring exposure length).   

LONG - is the length of the exposure in HH:MM:SS

FRAMES - is the number of exposures to take.

If I wanted 5 exposures, each 30 seconds long, and a 5 second delay between them, I would use those very values in on the TC-80N3 intervalometer.

But you're saying that to do this *same* thing in camera, I'd do

5 exposures with a 35 second intervals on the interval timer.  But on the camera exposure (not defined in the interval timer) I'd set a 30-second exposure with a 5-second interval between exposures because the camera is just "blindly" activating the shutter every 35 seconds.

This makes sense (even though it's a bit confusing and not the same way that it works on an intevalometer).  Most photographers are taking sub-second exposures and aren't likely to run into this issue.  

But I think they key message is it "blindly" presses the shutter button every XX seconds with no awareness as to the actual exposure duration of each shot.  Hence the interval is the interval between "pressing" the shutter button... not the interval between the end of the last exposure and the start of the next exposure.

Thanks!!

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Exactly!

The key difference being the shooting mode that the camera is in.  You are using Bulb mode with the TC-80N3, which defines the "LONG" parameter for shutter duration.  

With the internal interval program you are not using Bulb mode.  Shutter duration/speed is defined by your exposure settings.