Autoguiding with a DSLR

[keybaud]

Is it possible to get software that will use the live view output from a DSLR to autoguide, whilst it is also taking photos, or do you need a separate, brighter object to track?

[Leveye]

You really want/need a separate guidescope and camera to autoguide. I use an old Meade mono DSI CCD i found used and a 50 dollar Zhumell 9x50 scope.

[Zakalwe]

Is it possible to get software that will use the live view output from a DSLR to autoguide, whilst it is also taking photos, or do you need a separate, brighter object to track?

The camera sensor can only do one thing at a time. If it is exposing an image that means that its collecting photons. It can read those photons out, issue the image to a guiding system and still retain the photons for the image.

2 cameras are needed.

[keybaud]

The camera sensor can only do one thing at a time. If it is exposing an image that means that its collecting photons. It can read those photons out, issue the image to a guiding system and still retain the photons for the image.

2 cameras are needed.

The 70D sensor can do 2 things at once, hence my question.

[keybaud]

The 70D sensor can do 2 things at once, hence my question.

On further investigation, it looks like the dual pixel CMOS is only for autofocusing. :-(

[Leveye]

You can have 2 cameras working at the same time imaging and going to separate folders using APT but thats about it.

[brantuk]

The guide camera will be taking shorter exposures than the imaging camera in order to issue rapid mount corrections by the second as the Earth turns. Meantime the imaging camera will have it's shutter open recording the image for 5 or 10 mins at a time. Taking a long exposure and a short exposure are two discrete and mutually exclusive functions which will require two separate cameras I'm afraid.

It can be done using off axis guiding with a single scope - but not with a single camera. Hth

[keybaud]

The 70D has dual pixel CMOS, which means that each pixel has 2 sensors. I was hoping to be able to use one sensor per pixel to take the picture and the second to feed the autoguiding software, but the second feed is only used to drive the autofocus. I guess that someone may produce a hack for it in the future, but it isn't possible at the moment.

[narrowbandpaul]

It's really not a daft question. If your sensor were CCD then the answer is a definite no. These typically have just one output, so it's either integrating or reading out. Not both.

With CMOS each pixel should have its own output amplifier (active pixel) and so can be read out whilst other pixels integrate charge. I have often thought this would be a great feature, but CMOS sensors are not being applied to astroimaging as the CCD is still well and truly king.

So in theory yes, a CMOS sensor could guide and integrate at the same time, but for your Canon it would depend on the architecture of the pixel and you would have to write your own timing signals. I think that's a far bigger issue than saving for an Orion Starshoot or equivalent.

Hope that helps

Paul

[narrowbandpaul]

In fact I worked with a sensor that did just that. It had a region that could read out much faster. The technology clearly exists for this, but it needs to be CMOS for a "non-destructive readout"

[lensman57]

Is it possible to get software that will use the live view output from a DSLR to autoguide, whilst it is also taking photos, or do you need a separate, brighter object to track?

Is it possible to get software that will use the live view output from a DSLR to autoguide, whilst it is also taking photos, or do you need a separate, brighter object to track?

Hi,

The problem is not only confined to hardware but software too. Unless  the guide software is capable of communicating with the guide chip be it a  camera or something else all bets are off. There are CCDs  such as SBIG STX series that are self guiding but these are dual sensors not dual reading as in a CMOS DSLR, they apparently work very well but  I would not like to even look at the price of these cameras. A £150.00 CMOS guide camera with a 50mm finder guider does a good job, if you wish to invest in one.

A.G