With a cmos camera actually in your hand it's possible to adjust the ISO (gain) to match the circumstances. The use of unity gain as the default setting on these remote cameras is a necessity, although I note that requests to change this might be considered.
I've seen much when it comes to astrophotography supporting the case for lots of short exposures. I can appreciate that using this approach will in many cases be the way to go. However, I would appreciate a bit of guidance on this. It It is in the interest of no-one to place a booking for say 960 x 15 seconds exposures, 4 hours total, to save you the math. Options might be 240 x 60 seconds or 48 x 300 seconds.
Is it the case that one exposure time could be used for everything outside of the solar system, or would it be better to have a very small range to choose from? In the latter case could someone suggest a recommended time for say 3 types of target. In simple terms, bright, say m42, average, if there is such a thing, and dim. Maybe the Crescent or Bubble nebulae would qualify as average and dark nebula as possible dim. I appreciate that this is not an ideal solution but from my personal point of view it would assist greatly.
To whoever replies thanks for your great words of wisdom.
Cheers,
Ray
I've seen much when it comes to astrophotography supporting the case for lots of short exposures. I can appreciate that using this approach will in many cases be the way to go. However, I would appreciate a bit of guidance on this. It It is in the interest of no-one to place a booking for say 960 x 15 seconds exposures, 4 hours total, to save you the math. Options might be 240 x 60 seconds or 48 x 300 seconds.
Is it the case that one exposure time could be used for everything outside of the solar system, or would it be better to have a very small range to choose from? In the latter case could someone suggest a recommended time for say 3 types of target. In simple terms, bright, say m42, average, if there is such a thing, and dim. Maybe the Crescent or Bubble nebulae would qualify as average and dark nebula as possible dim. I appreciate that this is not an ideal solution but from my personal point of view it would assist greatly.
To whoever replies thanks for your great words of wisdom.
Cheers,
Ray
Ray
Roboscopes Guinea Pig
0
Undo
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Rather than a general reply I'll be happy to receive recommended exposure times just for the new camera on pier 6. This could just be carried out as an amendment to the relevant equipment page, which still gives recommendations based on the previous ccd camera. It also states that dark frames are available, which would be nice too.
Cheers. Ray
Cheers. Ray
Ray
Roboscopes Guinea Pig
Hi Ray,
As I am only technical amd know nothing about imaging, or even how the equipment works so I don’t reply To topics that relate to such. But any technical queries I get rectified as soon as possible.
I have asked Pete to drop a reply in for you.
Phil.
As I am only technical amd know nothing about imaging, or even how the equipment works so I don’t reply To topics that relate to such. But any technical queries I get rectified as soon as possible.
I have asked Pete to drop a reply in for you.
Phil.
Phil McCauley
Roboscopes Website Admin
Hi Ray,
Cmos is here to stay and as larger sensors become more available and the pixels get bigger they will eventually replace the CCD. We have all gotten used to the idea that longer the exposure the better as it brings the signal further away from the noise floor. Cmos is slightly different as the noise floor is so much lower. As you increase the exposure the signal rapidly gets to the point where the signal and noise hit a point where there is no advantage in doing longer subs. There is a huge advantage in doing lots of subs where signal is concerned....This is also true for CCD but with CCD the subs need to be much longer.
With new technology there is always a learning curve and the saying 'you cant teach and old dog' certainly does apply to me!! the idea of another variable (gain control) makes this complicated persecute even more so. So to take the pain out of it we have made the decision of pre-setting the gain to a something that will cope with a much wider range of exposures. Ideally 60s to 180s, you would rarely use anything longer than that. If you are not sure just let us know what you are trying to image and we can help you with the exposure choices.
If someone wanted to a unique gain setting this would change the whole characteristic of the camera.... new Darks and Flats would be required for each data set. This would be impractical as we would have to stop the automation system to set the camera. The problem then becomes even bigger as individual data sets are taken over several nights at different times throughout the observing session. So It would mean turning off the automation and taking over manually every time the object was in the optimal position. The other disadvantage is handling large data sets, Setting the Gain to Unity is a midway point where you keep the data from bringing your PC to a grinding halt!
(Sorry for the long winded exploitation it was more for those who are new to Cmos)
I hope this answers your question.
Peter
Cmos is here to stay and as larger sensors become more available and the pixels get bigger they will eventually replace the CCD. We have all gotten used to the idea that longer the exposure the better as it brings the signal further away from the noise floor. Cmos is slightly different as the noise floor is so much lower. As you increase the exposure the signal rapidly gets to the point where the signal and noise hit a point where there is no advantage in doing longer subs. There is a huge advantage in doing lots of subs where signal is concerned....This is also true for CCD but with CCD the subs need to be much longer.
With new technology there is always a learning curve and the saying 'you cant teach and old dog' certainly does apply to me!! the idea of another variable (gain control) makes this complicated persecute even more so. So to take the pain out of it we have made the decision of pre-setting the gain to a something that will cope with a much wider range of exposures. Ideally 60s to 180s, you would rarely use anything longer than that. If you are not sure just let us know what you are trying to image and we can help you with the exposure choices.
If someone wanted to a unique gain setting this would change the whole characteristic of the camera.... new Darks and Flats would be required for each data set. This would be impractical as we would have to stop the automation system to set the camera. The problem then becomes even bigger as individual data sets are taken over several nights at different times throughout the observing session. So It would mean turning off the automation and taking over manually every time the object was in the optimal position. The other disadvantage is handling large data sets, Setting the Gain to Unity is a midway point where you keep the data from bringing your PC to a grinding halt!
(Sorry for the long winded exploitation it was more for those who are new to Cmos)
I hope this answers your question.
Peter
Peter Shah - Collimation & Telescope servicing.
Visit my personal imaging website at astropix.co.uk
For Image Processing Tutorials
Contact: pete@ccdimaging.co.uk
We can supply your new high quality Newtonian or Dall Kirkham Astrograph
Visit my personal imaging website at astropix.co.uk
For Image Processing Tutorials
Contact: pete@ccdimaging.co.uk
We can supply your new high quality Newtonian or Dall Kirkham Astrograph
Peter Shah
Roboscopes Observatory Controller
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