ZWO ASI290 MM + Filter wheel or MC? For Planets

[cjdawson]

Hi all.

I've just ordered myself a ZWO ASI290MC I've done this after lots of thoughts about capturing planets and deciding that in the end it's more important to work quickly, than to work with the extended workflow needed for LRGB.

My main thought here is in creating timelapses of Jupiter so that over several hours, I can create lots of image stacks, process each to make a frame, then use those frames to create the timelapse movie.

 

Already Owning the 290MM, I did think about using this, however, I decided against it as to capture a colour image, I'd have to capture 3 (RGB) or 4 (LRGB) sub frames per frame which would mean that I would have to capture smaller stacks and there would be much more data to process.

 

I'm going to keep the 290mm, as I'm also thinking about making an All Sky camera.

[Pete Presland]

With the seeing in the UK being at best variable, a OSC camera is a "good call" If you do happen to be lucky and experience some good seeing fleetingly during your session, at least you have captured all three channels at once rather than having to rely on capturing RGB in three separate runs. OSC cameras are getting better all the time, the Asi224mc is excellent! 

I have also had some limited success using an ADC as well.

[newbie alert]

For getting maximum out of your photon capture, mono wins hands down

[Adam J]

14 hours ago, newbie alert said:

For getting maximum out of your photon capture, mono wins hands down

Yes but for planets your have to consider other factors like rotation of Jupiter between filters and variable seeing between filters. Mono in terms of solar system imaging is best used for the moon and sun. 

Edited June 20, 2019 by Adam J

[cjdawson]

22 hours ago, Adam J said:

Yes but for planets your have to consider other factors like rotation of Jupiter between filters and variable seeing between filters. Mono in terms of solar system imaging is best used for the moon and sun. 

Yep.  That's exactly the reason why I decided to switch away from a Mono planetary camera.   Whilst mono might also be best used for the moon, I've decided that if I'm going to do that, I'll use my ASI1600MM-Pro, rather than the ASI290's.    My ASI290MM is going to become an allsky camera.

[CraigT82]

On 19/06/2019 at 21:11, newbie alert said:

For getting maximum out of your photon capture, mono wins hands down

Any reasons why mono wins hands down?

[newbie alert]

On 21/06/2019 at 09:59, CraigT82 said:

Any reasons why mono wins hands down?

Nice cropping..

If you read the bit before it says to maximise your photons captured ..

A Bayer matrix has a group of 4 pixels to shoot through.. rggb usually so a red or blue wavelengths aren't going to be red or blue once they hit the sensor.. 

[CraigT82]

7 hours ago, newbie alert said:

Nice cropping..

If you read the bit before it says to maximise your photons captured ..

A Bayer matrix has a group of 4 pixels to shoot through.. rggb usually so a red or blue wavelengths aren't going to be red or blue once they hit the sensor..

Cropping? I quoted your entire post. 

Thanks for the bayer matrix lesson. So please elaborate and tell us how that means mono wins hands down for planetary imaging.  

[cjdawson]

8 hours ago, newbie alert said:

Nice cropping..

If you read the bit before it says to maximise your photons captured ..

A Bayer matrix has a group of 4 pixels to shoot through.. rggb usually so a red or blue wavelengths aren't going to be red or blue once they hit the sensor.. 

Sorry, I don't see that, I only see the version that you say was cropped, but that was the whole post.

 

Yes, the root of this topic is bayer matrix vs time needed for filter wheel.   Whilst it's true that the bayer matrix is mean that not every pixel is used for every wavelength, the thing is that the capture time of the pixels will be roughly the same (I know the green will have 2 pixels so will get double, that's a whole seperate subject).   One of the issues with Planets is that they rotate fast enough that the time needed to capture an LRGB dataset will mean that the planet will have moved, so that the images are actually a different part of the planet surface, rather than taken in Sync.

This is the balance that I'm looking at, the filter wheel and a longer workflow to capture a stack of planet images, or a colour image and the bayer matrix.

 

For me, ultimately, I have the choice of both options.  But I'm settling on the idea of using the colour camera for short exposure planetary work, and the LRGB for the deek sky work.

[newbie alert]

 In my and other peoples opinion to maximize your photons captured mono does win hands down, either on planetary or deep sky....

As for rotation I only ever see effects of rotation on Jupiter and mars.. with rapid frame rate camera's you can get a fair few frames captured in a 30 sec avi, so even all 4 channels can be captured in a short space of time .. look at what the top planetary imagers are doing..Christopher go,Damien peach etc they all use mono cameras..

While it's true that you can get a decent image from a colour camera, you be able to get a better image from a mono one..

[CraigT82]

I agree with the assertion that with all other things being equal, a mono camera would produce a planetary image which is a more truthful representation of the real image than an OSC, however all other things are rarely equal. Peach and Go etc... generally use C14's under steady sub arc-second-seeing skies at latitudes that puts the planets overhead and as such can actually reap the benefit of mono cameras for planetary imaging.

For the real world average Joe UK planetary imager who has an ADC available to them*, variable 2-3 arc second seeing and lowish planetary latitudes I think it'd be nigh on impossible to tell the difference between a mono planetary image and an OSC one.  And the OSC will be more productive, producing more images per session with less processing time. Of course if you or anyone else in the UK has taken mono/OSC comparison images on same night, same kit etc. I'd be very happy to see them.

 

* The ADC is crucial when shooting with an OSC camera for a UK planetary imager, else the image will suffer with the smearing of fine detail due to atmospheric dispersion. Of course mono cameras will suffer too but to a much lesser extent, thanks to narrower band pass RGB filters (compared with the RGB filters built into an OSC camera) and also post process channel alignment.

[cjdawson]

The ZWO ADC is the next piece of kit on my astronomy shopping list.

[CraigT82]

You wont regret buying one... can be tricky to get set up for minimum dispersion but the results are well worth it!

[Stub Mandrel]

4 hours ago, newbie alert said:

As for rotation I only ever see effects of rotation on Jupiter and mars.. with rapid frame rate camera's you can get a fair few frames captured in a 30 sec avi, so even all 4 channels can be captured in a short space of time .. look at what the top planetary imagers are doing..Christopher go,Damien peach etc they all use mono cameras..

I've done both mono and OSC on Jupiter.

In my experience,  you have to use WinJUPOS to derotate mono images, and the result is indistinguishable from OSC, at least with Jupiter at its present elevation. Things may change when it gets higher again

This GIF has lost most detail converting to 256 colours, but it shows how rapidly Jupiter changes in two runs of 5,000 frames started just 50 seconds apart.