[WONTFIX] Intervalometer for astrophotography

Started by moromete20ro, June 29, 2012, 07:42:58 PM

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moromete20ro

In astrophotograhpy is very important to take long exposures with the intervalometer setup like in the following example:
a) 1 dark frame of 3 minutes, than
b) a set of 5 exposures of 3 minutes each with a pause betwen them of 3 minutes, than
c) 1 dark frame of 1 minute, than
d) a set 8 exposures of 1 minute each with a pause of 30 seconds between them.

All these exposures must be taken automaticaly one after another with the DSLR "set and forget" for 1-5 hours letting the astronomer stay inside his home during winter. All this time the telescopes tracks the night sky and the DSLR takes long exposures alone.

Is it possible to extend the functionality of the intervalometer like this, for astronomers?

scrax

Not now,
some kind of workflow like this can be done when lua scripting will be supported, but then you still will have to put the cap on to take the dark frame.
I'm using ML2.3 for photography with:
EOS 600DML | EOS 400Dplus | EOS 5D MLbeta5- EF 100mm f/2.8 USM Macro  - EF-S 17-85mm f4-5.6 IS USM - EF 70-200mm f/4 L USM - 580EXII - OsX, PS, LR, RawTherapee, LightZone -no video experience-

moromete20ro

I see.

Even if we take the dark frames out of the equation (by putting manually the lens cap on), it would still be wonderful for an astronomer to have the extended functionality of the intervalometer like I presented it by being able to program a few sequences of different exposures duration one after another with different pauses between them.

I don't know if you guys know but Magic Lantern has a great potential for astronomy and that's the single reason I bought a Canon 550D (T2i) which I use often with FPSOverride On and shoot the planets with 2-10 FPS in 640x480 video mode instead of 60FPS.   

Just don't forget about this idea and implement it when it's possible because this makes the intervalometer much more useful.

Regarding strictly the dark frames, somehow Canon T2i takes dark frames alone (without lens cap) and subtracts them from a long exposure. Since I'm not a technical guy and don't understand the process, I wondered if Magic Lantern could do the same when the user asks it.

ozcancelik

Nice idea but not possible. As you know you can't use more than 30-40 second exposure without astro tracking mount. It makes star trails. So we have to use a mount for 3, 5, 10+ minutes exposure. Magic Lantern works on the camera. It doesnt control the mount.

If someone makes a application for pc and from pc, maybe it can control mount an shutter release same time with spesific commands like "take 3min x 3 bracket, stop mount for 30 sec and do it again and again".

moromete20ro

I have an astro tracking which holds my telescope so I can shoot 5-10 min without star trails.  ;)
That's why I need extended functionality for the intervalometer which I feel it has lots of potential unexploited yet, being to simple now.

ozcancelik

Quote from: moromete20ro on July 01, 2012, 09:04:23 AM
I have an astro tracking which holds my telescope so I can shoot 5-10 min without star trails.  ;)
That's why I need extended functionality for the intervalometer which I feel it has lots of potential unexploited yet, being to simple now.

I see. But magic lantern could not help. It's just camera firmware. Not a mount controller.

scrax

Quote from: ozcancelik on July 01, 2012, 12:33:40 PM
I see. But magic lantern could not help. It's just camera firmware. Not a mount controller.

I don't get why it would not work? For sync problems?
Once the mount is tracking the scene and is possible to do a 5min pic manually why this can't be done with a script in camera?

What I think about the dark frame made by the camera, when you have long exposure and Long Exp noise reduction active, camera will double the time of the exposure to save the pics for this option to take place. So i suppose that probably it's tacking the dark frame without lens cap on like you suggested.
If this is true you can accomplish sort of a. and  b. with intervallometer set to 6min and bulb to 3min.

For now is impossible to force the darkframe with ML, i think that a sort of workaround script could be to :

enable NRLEx
Take a 3min RAW+NRLEx pic
after 3min+3min (pic and dark frame)
disable NRLEx
take a 3min RAW pic each 6min. for 5 times
enable NRLEx
Take a 1min RAW+NRLEx pic
after 1min+1min (pic and dark frame)
disable NRLEx
take 1min RAW pic each 1,5min for 8 times

I think that maybe could be possible to extract the dark frame in post using the raw from the NRLEx and the first not NRLEx.
I'm using ML2.3 for photography with:
EOS 600DML | EOS 400Dplus | EOS 5D MLbeta5- EF 100mm f/2.8 USM Macro  - EF-S 17-85mm f4-5.6 IS USM - EF 70-200mm f/4 L USM - 580EXII - OsX, PS, LR, RawTherapee, LightZone -no video experience-

ozcancelik

Quote from: moromete20ro on July 01, 2012, 09:04:23 AM
I have an astro tracking which holds my telescope so I can shoot 5-10 min without star trails.  ;)
That's why I need extended functionality for the intervalometer which I feel it has lots of potential unexploited yet, being to simple now.

Now i realised you re not talking about time-lapse :) Sorry. (I thought time lapse with 3-5 minutes exposure without star trails)

Yes, it would be awesome feature. Theoretically it seems not to hard for developers but who knows :)

scrax

Found this info on canons site:

"Remember that if long exposure noise reduction is set in the Custom Functions (it should be), the effective exposure will be doubled. The second part of the exposure is a noise subtraction process and if it is a cold winter night, the process can, at a push, be achieved in the car with a lens cap on"

This confirm that the camera can take the dark frame with the cap off.
I'm using ML2.3 for photography with:
EOS 600DML | EOS 400Dplus | EOS 5D MLbeta5- EF 100mm f/2.8 USM Macro  - EF-S 17-85mm f4-5.6 IS USM - EF 70-200mm f/4 L USM - 580EXII - OsX, PS, LR, RawTherapee, LightZone -no video experience-

a1ex

A ugly hack would be to stop down the aperture (for example, f22 is 7 stops darker than f2.0).

http://a1ex.bitbucket.io/ML/states/600D-alt/sm70.htm - sbsDarkRelease might be related.

moromete20ro

Alex, that's impossible because when you attached the dslr to a telescope your remove the lens and the telescope has fixed aperture.

moromete20ro


dbunna2

Astrophotographer with a T2i here too.

Dark frame subtraction is vital.  The Canon solution of grabbing a dark frame and subtracting it with each exposure as noted leads to half the night wasted.

I'd be happy with a solution that would allow me to put on a lens cap to take a dark frame and have it stored internally in the camera.  The feature would subtracted the dark frame from every future exposure until I tell the camera to stop the feature or the camera is powered off.

This would simplify my life ;D

calypsob

Im not going to claim to be an astrophotographer but I do enjoy doing widefield astrophotography when I can.  Im happy to see some astrophotographers on here, I had some similar questions to the ones mentioned so far in this discussion.  I was out shooting the milky way last night with my T3i and I was using the canon long exposure noise reduction function, which can be turned off by the way.  It seems decently effective all the way up to iso 1300.  iso 3200+ and you need to do manual dark frames from what I understand.  I have never been very good at the whole dark frame process using digital sky stacker in post processing so I would like to contribute a few ideas to this thread.   If magic lantern could be setup in a scenario similar to HDR bracketing only, Long exposure bracketing or something to that nature I believe it may be possible to execute a process similar to this one listed here http://en.wikipedia.org/wiki/Bias_frame  If we could run a long exposure set which took the shot, a dark frame, and a bias frame, 3 images total, that would make post process so much faster.  Honestly any further research on the abilities to reduce long exposure noise with magic lantern scripting in these crop sensor canons would be HUGE for the world of astrophotography.
 
Full spectrum T2i
T3i

francescosbg

I m using my T2i ( 550d) astro modded, I d love to see an auto hdr function or intervalometer esp. for astro things as u mentioned above..... just imagine to shoot the m42 nebula with auto hdr.... well for now I enjoy the zoom function, iso boost, display lv gain, mirror lockup  e.g. so much fun ;-)

k1uhf

I have just put ML in my 50D primarily to try and use the intervalometer for astro photographs.  I am on a tracking mount with either a 450 1300 or 2300 mm F/L telescope on the camera.

I am hoping that the intervalometer will do 6 to 20 shots at 30 sec to 10 min exposures.  My first attempt at setting it up it seems to only go down to 100 exposures and I did not see a way to set the long bulb exposures.

Hopefully if it doesn't do this it will be a updated feature soon.  I will look into scripting it although I am not a programmer.

Thanks for ML and in advance for any replies I get about this.

Francis

Quote from: k1uhf on April 23, 2013, 04:18:34 AM
I have just put ML in my 50D primarily to try and use the intervalometer for astro photographs.  I am on a tracking mount with either a 450 1300 or 2300 mm F/L telescope on the camera.

I am hoping that the intervalometer will do 6 to 20 shots at 30 sec to 10 min exposures.  My first attempt at setting it up it seems to only go down to 100 exposures and I did not see a way to set the long bulb exposures.

Hopefully if it doesn't do this it will be a updated feature soon.  I will look into scripting it although I am not a programmer.

Thanks for ML and in advance for any replies I get about this.

Someone else just asked about very specific needs for the intervalometer and I gave them this demo script. Scripting is very accessible even if you have no programming experience. Some minimal research goes a long ways. The demo scripts in the API post are very helpful as well.