Lunar/planetary Imaging Tutorial (QHY5-II Mono)

[Leon-Fleet]

Hi All,

I know there are plenty of tutorial videos out there on You Tube, some good and lots of terrible ones. Can someone, help cut through the noise and recommend a tutorial that they feel is the best? 

I will be using my QHY5-II Mono camera with my 72ED, APD 

Thanks 

[vlaiv]

Not sure about which tutorial to recommend, but I can make quick list of things that you should try out in developing your own workflow for planetary imaging.

Which model of QHY5-II do you have (there is L, M and P if I recall correctly - they are different in sensor used)?

Use x2.5 to x3 barlow with that scope and camera. Use IR/UV cut filter with that scope (or maybe narrowband filter for the moon).

Capture video using SharpCap or FireCapture in 12bit mode using ROI to frame the planet (unless doing lunar). Make sure your laptop has fast enough HDD (best if it is SSD with enough speed). Use USB3.0 port if your camera is USB3.0 (but I think that QHY5-II is only USB2.0? right?). Use SER file format to capture your movie (not avi).

Keep exposure length short - about 5-10ms, get as many subs captured as you can for about 3-4 minutes if doing planets - for moon you can go more than that.

Use higher gain settings. If you start saturating (very unlikely unless you are imaging the moon) - drop exposure length.

Capture at least dark movie as well (same settings as regular movie except you will cover your scope to block all light). IF you have flat panel, capture flat and flat dark movies as well. Aim for at least 200-300 subs in dark, flat and flat dark movies.

Use PIPP to calibrate and prepare your movie - basic calibration, stabilize planet, etc, and again export as SER.

Use Autostakkert! 3.0 (or which ever version is latest now) to stack your movie - save as at least 16bit image (32bit if possible).

Use Registax 6 to do wavelet sharpening and do final touch up in Gimp or PS or whatever image manipulation software you prefer.

[Leon-Fleet]

Thanks for the help! 

I've got the M model. 

I haven't got any filters yet, they will be next on my shopping list. ( Side note do i get in camera filters for my DSLR or a camera wheel, prob the latter) 

My laptop is pretty basic so hopefully it will be up to the task. 

3 hours ago, vlaiv said:

Capture video using SharpCap or FireCapture in 12bit mode using ROI to frame the planet (unless doing lunar). Make sure your laptop has fast enough HDD (best if it is SSD with enough speed). Use USB3.0 port if your camera is USB3.0 (but I think that QHY5-II is only USB2.0? right?). Use SER file format to capture your movie (not avi).

I don't have any idea what the above means so will have to read up and learn by trial and error. 

The rest sounds straight forward, I'll give it a go! 

[vlaiv]

1 hour ago, Leon-Fleet said:

I don't have any idea what the above means so will have to read up and learn by trial and error. 

Sorry about that, I sometimes forget that people might not be acquainted with meaning of certain abbreviations. I'll expand on that.

SharpCap and FireCapture are two pieces of software most commonly used to record planetary video for purpose of lucky imaging. Both are free (you can get pro version of SharpCap if you wish to support the product but at this stage I don't think it's necessary - free version will do the job just fine).

Planetary cameras work in two different modes - one is 8bit mode and other is in 12bit mode - that just specifies number of bits used to record data. You can record video in 8bit format and that has its own advantages (less data and faster capture), but you need to adjust gain setting accordingly for each camera model to exploit this mode properly. If you don't set gain properly you can get data truncation and that is bad thing. 12bit mode will be a bit slower, but it should work regardless of the gain, there should be no truncation that I mentioned. This is the option in capture software - you will see different modes of capture offered - go with RAW16 (that is actually 12 bit rather than 16 because the way this particular camera works).

ROI stands for Region Of Interest. With lucky imaging it is all about the speed of recording of frames. If you for example select 5ms exposure length - in theory you should be able to record 200 frames each second (200fps) as each one takes 5ms (1000ms / 5ms = 200 frames each second). There are certain technical limitations to how much data you can record, namely speed of camera/computer connection (which is USB type connection, and USB port has certain speed that it can transfer data at - version 2.0 of USB standard has lower speed than USB 3.0, this is why it is recommended to use USB 3.0 connection, but both camera and laptop has to support it - in your case you will be limited to USB 2.0 as your camera model operates on that standard) and speed of your hard drive that stores the data.

Back to region of interest - instead of writing each frame as complete image - which contains a lot of pixels, you can select small region of sensor to be read out and recorded. This means less data to transfer and less data to store. Planets are small and usually only cover very small central region of sensor - something like couple hundred pixels across and most of the image is in fact just black background that you will not need and it's a waste to record / transfer and store that data. For that reason you can select smaller size of output image - just central region which will be large enough to contain complete planet - something like 320x200 or 640x480 instead of going for full 1280x1024 image size.

If you look at the specs for QHY5II series of cameras at this page:

https://www.qhyccd.com/index.php?m=content&c=index&a=show&catid=133&id=8&cut=1

you will see that there is quite a bit of difference in achieved frame rate between full frame and 640x480 ROI, with later being much faster:

Only time when you don't want to "shrink" imaging area and use ROI is when you are shooting images of the Moon - simply because it is large enough and will usually fill the field of view and often be larger than sensor can cover (in that case you can do mosaics if you want to shoot whole lunar disk - meaning shooting separate parts of moon and then piecing separate parts in final large image).

In any case - number of captured frames is really important for lucky imaging, because you will end up throwing away most of them since they will be distorted by seeing. More frames you have, more chance you will have enough good frames to stack and your image will be better.

Last part of the equation is speed at which your laptop can record the video - it can also be a bottleneck in recording. This is why I mentioned replacing your standard hard drive with solid state drive  - these are much faster storage devices. You might not need to do it, but if you want the best possible results at some point you will want to move to laptop with SSD in the future (along with some other upgrades that I'll mention in the end).

SER vs AVI - that is just a format for storing movie. SER file format let's you record in higher bit count (above mentioned 12bit, or more than 8 bits, since M model seems to work on 10bit format unlike others models of QHY5II line, but all the same - go with highest number of bits that is available) and is simpler file format to handle - a sort of standard for planetary imaging.

In the end I would like to say that 72ED is probably worst scope for this purpose (sorry about that, and I do believe it is fine scope, just not well suited for this purpose). With planetary imaging - it is aperture that matters as resolved detail is related to aperture size. Your planets will be tiny with that scope. It is quite ok for you to start planetary imaging with such scope to get the hang of it and learn capture and processing parts of imaging, but if you are really interested in planetary imaging, you will want bigger scope soon.

It does not need to be expensive scope - something like F/8 150mm newtonian is going to be really nice and cheap planetary imaging scope. With planetary imaging unlike long exposure DSO imaging - you don't need very stable mount. As long as it can carry the scope and track with decent precision - it will do for planetary imaging. Exposures involved are so short that there is simply no way that there will be any blur due to mount not tracking properly.

For example, I did this image of Jupiter on EQ2 mount with simple DC RA tracking motor (one that you need to set proper speed with potentiometer) and 130mm newtonian scope:

(it was also taken with QHY5II - but L model and it was color camera)