First Saturn 30 April, 2011

[Red Nine]

I took my first avi's of Saturn last week using my 12inch and 550D at prime focus with a 2.5x and 5x Powermate stacked on each other. Finally got around to stacking it all in Registax.

Took me a while to convert the .mov file to a readable .avi file that Registax could process. Used 685 frames, so overall very happy for a first attempt.

I think my focus was a little out, however it is a good starting point as far as I'm concerned. Please critique as necessary.

Thanks, Evan :)

[asimov]

That's pretty good for a first attempt with a DSLR. Yes, you may have been a fraction out with focus however it could have been less than average seeing too.

Well done!

[iceman]

Excellent first attempt! A 5x with a 2.5x, wow that's some magnification :)

Keep an eye on Von Tom's images - he's doing the same thing as you with almost identical equipment, so I'm sure he can share some of his techniques.

[von Tom]

Hi Evan,

Excellent. Definitely a little out of focus but I can see some of the storm. 15 times magnification is huge. Were you using full HD movie mode, and do you recall the settings used?

I have found that changing the Picture Style on the 550D to Landscape, with sharpness, contrast and saturation all maxed out brings out the most disc detail.

Great work and I can't wait to see more images!

Cheers,

Tom

[Shiraz]

Good going for a first image Evan. As others have said, that's a lot of magnification - you could probably get better results by using only the 5x powermate. At the very least, it will be easier to focus if you have a bit more photon density on the chip. Look forward to seeing more. Regards Ray

[Red Nine]

Hi Everyone,

Thank you all for the wonderful feedback. Have been out again tonight so hopefully will have some more to post soon.

I have been looking at a lot of Tom's work for a while, and it has been a big inspiration I suppose in getting all of this set up to try and get some of the similar success he has been getting lately.

Tom, I'm pretty sure I used the 720p recording at 50frames per second. I haven't had a proper play around with the Picture Style yet, and have just kept it on automatic. Focusing proved to be the hardest part so far, especially as it looks to be very much in focus on the 3 inch screen. I really need to look into maybe getting a 10:1 focuser further down the track as well.

Ray, I will have to look into just using the 5x next time I'm out. I used the 2.5x and 5x together again tonight, so will make sure I give that a try next time.

Thank you all again for your advice and comments!
Evan

[von Tom]

Hi Evan,

I had my video recording for the 550D set as PAL, but then realised if I set it to "NTSC" then you can get 60fps instead of 50fps, or 30fps vs 25fps for 1080p, for no penalty.


Also, do you use the 5x and 10x display zoom when focussing? And have you tried focussing on a star to optimise your focus before viewing Saturn?

Cheers,

Tom

[Red Nine]

Thanks for those tips Tom!

I didn't know I was able to change the settings from PAL to NTSC, have changed that now so hopefully those extra frames will make a diffence next time I'm out.

I focused on a star last night prior to moving to Saturn, however think it may have been a little out again, but I'll soon find out when I process them. I'll make sure to use that zoom function more as well, used it a little bit, but found it hard to see too much with how much it was moving around, will just try the 5x Powermate next time and see how that turns out.

Thank you for all the wonderful advice, very much appreciated as some of your images have been outstanding!

Evan

[von Tom]

No worries Evan. To aid in focussing, if you modify one of the Picture Styles to maximum sharpness and contrast, you may make it easier to see the area of focus.

Also, what are you using to convert the .mov files?

Cheers,

Tom

[Shiraz]

G'day Evan. in an earlier post I suggested using only the 5x powermate - apologies, seems that was not particularly good advice. Just did some calcs for your setup and you were right - you do need a bit more than 5x mag to get fine enough sampling with what I assume are about 12micron effective pixels in 1080p video mode. Maybe Tom can chip in here with the effective fl he uses - his results are good. regards Ray

[von Tom]

Hi Ray,

Most of my images are with 4x worth of teleconverters (which I assume is equivalent to a 4x Powermate). The 12" Sky-Watcher Dobsonian is 1500mm f/5, so I assume my effective focal length is 6000mm at f/20.

Using a 2.5x and a 5x Powermate, Evan's setup is 22500mm at f/75.

Nearly all of my planet images use the central 640x480 pixels, whereas Evan has used the entire 5184x3456 sensor reduced by 4.8x to 1280x720 in camera.

As a result: 15/4.8=3.125x in 720p vs 4x in 640x480 crop mode, which seems to match the images sizes we both have.

Using the full HD 1080p mode with the 5x and 2.5x Powermate will give a 1.5x greater image size compared with using 720p, but also drop the fps to 30fps.

Using the 640x480 crop mode with the 5x and 2.5x Powermate will almost fill the 640x480 frame with Saturn's disc!

Cheers,

Tom

[Red Nine]

Hi Tom,

So far I've just converted the .mov file to .avi through Pazera movtoavi converter. However, I was not able to open the file in Registax. So I did some research, downloaded virtual dub, and have then exported the image sequences into .bmp files.

This has then allowed me to open all the files up in Registax and stack them that way. Its quite a round about way, but the codecs with windows programs are always a nightmare.

Ray, thanks for the advice anyway, it's always appreciated. Tom, wouldn't I have an f/37.5 though? If the 2.5x and 5x Powermates are stacked to give 7.5x that gives a focal length of 11250mm - or am I missing something...?

[Shiraz]

Hi Evan. I think that Tom has explained it well - that's a very versatile camera. The stacked powermates will give you 12.5x nominal and probably about 15x actual, so your fl will be over 20m. You need that much if operating the chip in full frame video mode. If you select to use only part of the chip at native pixel resolution (about 4 microns) you will need much shorter focal length and the 6m that Tom uses gives an angular pixel resolution in line with that used by others. Regards Ray