mono imaging,advice, new minicam 5f

[Chris Murray]

Hi all, i just recieved my little mini cam from Bern, many thanks Bern. i got this camera as a cheap way into narrow band, for me its a gamble as ive tried using I telescope and can,t make any sense putting rbg together, but if i mess about with my own gear then i can make it work. so im looking for advice on capture times, i will look at 5 minute subs  for each filter, whats the best ratio or is that dependant on target, as in, ha 5 mins, o3 5 mins, s2 5mins, or should i have more ha or o3 ect... been busy with my qhy8l for 4 years so know the way it all works but this mono i think is the only way to cut through the light polution, any sugestions and advice?

chris 

[riklaunim]

When you want to use a CMOS based cooled camera you must forget how CCD DS imaging is being done... as those CMOS cameras behave differently (although MiniCAM with Micron sensor isn't as specific as ZWO with Sony sensors).

You can do few minute exposures with MiniCAM, but some noise will show up, including random horizontal line noise and leftover FPN. It's better to capture more frames at shorter exposures - to average the noise and limit the effect of amp glow on the frames (that's mostly for Sony ZWO cameras). I would keep the exposures no longer than 2-3 min for start, and then you can compare it with longer, 5+ min exposures. Targets like Rosetta in H-alpha should easily work at 3 or less min exposures. Some experts of image processing (like Emil) use even 1s exposures and thousands of frames

[Chris]

It's a tricky one because CMOS cameras prefer lots of short exposures (as said above), but you need longer exposures with narrow band filters to pick up enough stars for stacking. 

It might take a bit of trial and error with sub length, my guess would be like what Rik said (2-3 minutes).

I've been gearing up for experimenting with CMOS imaging of DSO's. I've purchased a ED80 + 0.6 reducer making a 360mm f4.5 system, and plan on taking hundreds of 10-20 second of luminance exposures with my ASI120mm to begin with. I'm hoping the very high 75% QE will help make this happen, I've read a few threads on CN where people have been getting really good results with short exposures. We'll see..    

[Chris Murray]

thanks guys, i made a cooler for my asi 120mcs which stopped all that noise but i need to cool the chip not the whole camera, if the minicam can do as well as my cooler, (should be better) i think il be ok, as said a bit of trial n error, its the narrow band bit i have to work on, should i expose all the same lenth or change for different filters, cheers

chris