Hi all,
First post here, I am wondering if I can have a delay between taking subs so I can let the sensor cool down a little in my Canon 700D. I’ve trying looking through all avenues in SGP and googled to my fingers bled with no real answer. I’m hoping someone can help with an answer or two.
Thanks in advance.
Karl
See the SGP manual, chapter ‘Sequencing’, ‘Delay and Ordering Options’.
Bernd
Thank you to you both for your help, I feel somewhat the fool at the moment to how I over looked something so simple.
Karlos
Hi Karl,
You can also click the Pause Sequence button. It gives you the option of pausing after the current frame is completed or aborting. Definetly do no choose abort. When the frame is finished the sequence is paused until you click on Resume Sequence button. I often do this to do a manual refocus when the temperature drops. Just another option for you.
Clear skies!
Phil
A couple of other practical things - try and turn off the camera’s LCD and fold it out, so that it does not warm the camera body. You could also try using a battery eliminator, so the battery itself does not warm the camera. These are passive things, the last thing is to put a fan on it - with the risk of vibration though.
I suspect you won’t see an improvement in your images after a delay. The image exposure time is a pause because the sensor only generates heat during the image read cycle.
While it may be true that the camera sensor only ‘generates’ heat during read cycle surely it is also passively heating during the course of an exposure as a result of absorbing the radiant energy of the photons collected during the exposure - comparable to the way a metal dustbin lid heats up if left in the sun!
My understanding of the purpose of a delay between exposures is to allow time for some/all of the energy collected and generated during an exposure cycle to dissipate. If the heat is not dissipated then the exposures become increasingly noisy as a result of increasing kinetic energy of the electrons in the sensor material.
If I recollect correctly this kinetic noise doubles for every 6° C increase in sensor temperature.
Allowing it to delay will help reduce the sensor temperature over the whole course of the night, considering at the moment we still have summer heat.
The other thing is keep the exposures short. Today’s modern CMOS sensors have low read noise and the penalty of combining multiple frames-worth of read noise may be better than the random noise element of the dark current during an extended temp. If you think about it, a camera sensor in a 20C ambient is probably about 35C, rather than say -15C in an astro camera. That is 50C difference, or about 322x less dark current, equating to 18x less random dark noise. Best thing is to measure the characteristics of dark and bias frames and work out the contributions.
