Imaging the moon and processing with Registax

Gem (Grant) · #1 13-09-2011, 10:18 AM

Hi all,

Well, I tried my first reall atempt at imaging the moon with my new webcam and then stacking it. I was a bit disappointed. The single frame images from the other night were better. I was using around 30 seconds of video. I have not much idea on the wavelet side. I expected a bit better... then it occurred to me... I was not using "Lunar" tracking rates on my mount. Would this help explain the poor quality?
Any tips on Registax would also be appreciated!

asimov (John) · #2 13-09-2011, 10:27 AM

In 30 seconds, I'd doubt you'd see a lot of difference in the different tracking rates. What camera are you using again, Grant?

If the quality is poor, it could be a few things. Focus & seeing usually being the two major contributors.

mswhin63 (Malcolm) · #3 13-09-2011, 10:28 AM

I don't think it will matter that much as long as the subject is in the field of view, as Registax will compensate for the movement.

30 seconds may not be enough to get some decent frames from poor sky conditions.

asimov (John) · #4 13-09-2011, 10:31 AM

Registax tips > http://www.astroholic.com/showthread.php?t=1734

darbyvet (Carl Darby) · #5 13-09-2011, 11:08 AM

Grant,
can you send me the avi and I will try processing it for you to see what I get? Send me a PM with a link to where you store the avi online and i will download it and play around with it
Carl

Gem (Grant) · #6 13-09-2011, 11:46 AM

Wow! Thanks for the quick responses!

I am using a Phillips 880 flashed to 900. It is unmodded. The scope is a C9.25 SCT. No barlow or focal reducer (so focal length is 2350mm). I only roughly polar aligned (since it was a trial attempt), but it couldn't have been too bad since the two star alignment and calibration stars were close.
Conditions were ok, but the moon was near full so lunar contrast was minimal and, hence, focus wasn't the easiest. The moon was well up (since I have trees to the east).
I roughly followed the examples on the Registax site http://www.astronomie.be/registax/pr...singlerun.html

Gem (Grant) · #7 13-09-2011, 11:50 AM

So for lunar, how long should I be looking at? 2 minutes?

How many of the "best frames" should I include? 10% of the total?

asimov (John) · #8 13-09-2011, 11:56 AM

That's right, the flashed 880. I remember now. Yes, Shooting the moon when near full is certainly not the easiest. Even at prime focus on the 9.25 (2350mm) If everything like focus, scope close to ambient temp. the seeing etc. is not going your way, a low quality AVI will be the result. Are you using an IR/UV cut filter? It'll make shooting the moon a little bit easier.

asimov (John) · #9 13-09-2011, 11:59 AM

Quote:

Originally Posted by Gem

So for lunar, how long should I be looking at? 2 minutes?

How many of the "best frames" should I include? 10% of the total?

Shooting at 10FPS? If so I'd probably go for at least 3-4 mins. As far as stacking how many; my general rule of thumb would be if the seeing was 5/10, I'd want to stack 40-50% - That's just my version of what I think should happen though.

Gem (Grant) · #10 13-09-2011, 12:15 PM

Thanks John!
I don't have a filter... just the straight camera and adapter. This is my first tentative step into imaging after many years of observing. I figure if I can get some experience using a simple camera and processing images, I can take the step of getting a "real" camera when next year's tax return comes back...

On the plus side, a C9.25 on a CGEM is a great scope/mount combination... so any errors are 99% my fault if the images don't turn out!!

Gem (Grant) · #11 13-09-2011, 12:17 PM

Forgot to add... the scope was fine temperature wise. I set it up outside around 17:00 and didn't try to image until 22:30.

asimov (John) · #12 13-09-2011, 12:46 PM

Ok, well I reckon it's the lack of that filter that would be contributing to the quality. Even though the moon may be classified as virtually colourless, your camera doesn't like that idea much & won't concur. A rather soft image will be the result.

midnight (Darrin) · #13 13-09-2011, 03:12 PM

Quote:

Originally Posted by asimov

Ok, well I reckon it's the lack of that filter that would be contributing to the quality. Even though the moon may be classified as virtually colourless, your camera doesn't like that idea much & won't concur. A rather soft image will be the result.

G'Day John! I have a 1.25" IR/UV filter but would you recommend I use the IR/UV filter on my DBK41 on the moon? I was imaging the moon the other night but this time through my 8"SN for the 1st time (F4) instead of my 80mm refractor (F6) and struggled. Mind you the atmosphere was quite unstable (worst I've seen in a while)

Good luck Grant - I think you're philosophy of sticking to the moon with a simple camera is a good one to fine tune some skills before you move onto the more expensive stuff. It's the path I took and it's allowed me to quickly get comfortable with my new acquisitions. Good luck mate!

Darrin...

asimov (John) · #14 13-09-2011, 04:08 PM

Yes Darrin, I would recommend imaging the moon with the filter. I've tried it myself with & without the filter & yep, much better with it on, mate. A mono camera such as the DMK (IE) needs no filter.

asimov (John) · #15 13-09-2011, 04:12 PM

BTW, a few years ago I made my own filter, particularly for the moon. it works similar to an IR pass and/or similar to an R filter by cutting through the seeing. Quite simply, it's a piece of colour film that has been processed in the lab, but not exposed. Works fantastic!