beginner- simple Dobsonian photos help please

[Raymo]

Hello forum,

I reciently aquired a Skywatcher 250PX and I 'm was trying to take some still images of Jupiter last night.

I have a camera tube adapter which allows me to photograph behind the eyepiece.

attached is my still image capurred with a Canon 5D MK3

To the naked eye, I could see a bit more detail that is shown in the still image, but I suspect this is due to eye/brain processing vs a still image captured at 1/100th of a second, the eye/brain wins.

 

So my questions are as follows:

Im using the standard Possle 10mm eyepiece for this shot.... could I expect better detail and contrast from a higher quality/more expensive EP?

If I purchased a 5mm EP, I know it would be twice the size... but would it be ay clearer... ?

Lastly, can I stack DSLR images which have the planet at different locations for each frame, i.e. can a stack program correct for drift/rotation observed with on a Dobsonian?

any tips/advice with using my 5DMk3 would be welcome, like camera settings etc

 

many thanks

Ray..

 

 

 

[darknight]

ok, if you get whats called a tpiece for your dslr, fleabay are cheapest, then take out the epiece and the holder held in by 2 thumbscrews, then that piece will unscrew, attach that to your camera and itl be used like prime focus, use liview.

stick to very short exposures as you cant guide, but take oh roughly 30, then stack them

sorry quick reply, didn't realise time gotta go

[Owmuchonomy]

Hi Ray, the most widely adopted method for imaging solar system objects is to use a technique labelled 'lucky imaging'.  This involves taking short, high shutter speed videos of your target.  This is accomplished without the use of the eyepieces in the imaging train.  This is why the camera of choice is a high speed planetary camera such as (in my case) a ZWO ASI 174 or 290 cam.  That said, I used to use my Canon 60D using the true movie crop video mode set at 60 frames per second.  This isolates a region of interest on the sensor allowing for fast video capture.  You could try the video modes of your 5D Mk 3 but thats a BIG sensor so you may capture tons of unwanted data.  Next you have to match the focal ratio of your scope with your camera.  I believe your scope is f/5 so as a rule of thumb you need an f/ of 5x your sensor size which is around f/20 I believe.  So you would benefit from a 4x Barlow or Powermate.  Finally, there are lots of freeware packages that will stack your video frames.  I use Autostakkert AS!2.  Check the planetary imaging section for what folks use.  Good luck.

[Raymo]

1 hour ago, darknight said:

ok, if you get whats called a tpiece for your dslr, fleabay are cheapest, then take out the epiece and the holder held in by 2 thumbscrews, then that piece will unscrew, attach that to your camera and itl be used like prime focus, use liview.

stick to very short exposures as you cant guide, but take oh roughly 30, then stack them

sorry quick reply, didn't realise time gotta go

Thanks darknight, I think I already have that part. but when I use it at prime focus the image is tiny! Thats why I added the 10mm ep.

and when I try to stak the 22mp files... Autostakker freezes...

[Raymo]

1 hour ago, Owmuchonomy said:

Hi Ray, the most widely adopted method for imaging solar system objects is to use a technique labelled 'lucky imaging'.  This involves taking short, high shutter speed videos of your target.  This is accomplished without the use of the eyepieces in the imaging train.  This is why the camera of choice is a high speed planetary camera such as (in my case) a ZWO ASI 174 or 290 cam.  That said, I used to use my Canon 60D using the true movie crop video mode set at 60 frames per second.  This isolates a region of interest on the sensor allowing for fast video capture.  You could try the video modes of your 5D Mk 3 but thats a BIG sensor so you may capture tons of unwanted data.  Next you have to match the focal ratio of your scope with your camera.  I believe your scope is f/5 so as a rule of thumb you need an f/ of 5x your sensor size which is around f/20 I believe.  So you would benefit from a 4x Barlow or Powermate.  Finally, there are lots of freeware packages that will stack your video frames.  I use Autostakkert AS!2.  Check the planetary imaging section for what folks use.  Good luck.

Thanks Vacume, I'll try the video mode on the 5DMk3, but I think your correct about the full frame CCD... there will be loads of wasted pixles. a 1.6 body would be better for this.

And I'll check out the x3 Barlow.

[darknight]

ok, yes will be a bit smaller but hopefully better quality and be able to made larger later, if you get the t piece you can attach a barlow to it, itl produce hopefully a better pic otherwise you could make something to hold the camera over the eyepiece

[Raymo]

ok, so a bit more homework was done last night and I managed to make my 5DMK3 produce RAW video at x3 Crop factor using a 3rd party firmware called Magic Lantern.

I can now effectively zoom in 3x and record .MOV video in HD resolution.... this is a big step forward !!!

Then I can convert .MOV to .AVI in PIPP, export the best frames and then stack in Autostakker 3.... I'm learning fast!

Now I just need a clear night to test it out.

 

Darknight, I already have the T-adapter which can hold a 1.25mm ep or I can go direct and record prime focus.

I shall try  the 3x crop video recording and see if he is better with Prime Focus or with a 25mm EP... but I think the 10mm EP and 3x Crop will be way too unstable with my Dob mount.

 

Laters... 

[happy-kat]

That will be interesting. Look forward to seeing your first go.

[Davey-T]

Hi Ray, what have you got the capture set to in the camera, ALL1 captures "uncompressed" video while IPB compresses it on the fly.

The 5DMk111 doesn't seem to have the useful (for solar system imaging) 640X480 crop video mode although it does have an assortment of video modes.

Dave

[Raymo]

25 minutes ago, Davey-T said:

Hi Ray, what have you got the capture set to in the camera, ALL1 captures "uncompressed" video while IPB compresses it on the fly.

The 5DMk111 doesn't seem to have the useful (for solar system imaging) 640X480 crop video mode although it does have an assortment of video modes.

Dave

Hi Dave,

agreed, I found the standard Firmware from Canon does not provide much flexability on video formats.

However Magic Lantern is a user-developed non-approved firmware which enables RAW video capture at x3 crop and in 1920 x 1080 ... this still produces large files in .MOV format but at least the image will be x3 times larger...

and since it's RAW I can adjust the exposure & colour balance etc in post processing.

Once these clouds clear I hope to test it out... perhaps during the week.

 

Ray

 

[Davey-T]

It should be able to capture 1280 X 720 @ 60fps uncompressed video with the Canon firmware, somewhat similar to a dedicated CCD colour camera except for some variation in pixel size.

Dave

[Raymo]

1 hour ago, Davey-T said:

It should be able to capture 1280 X 720 @ 60fps uncompressed video with the Canon firmware, somewhat similar to a dedicated CCD colour camera except for some variation in pixel size.

Dave

Hi Dave,

yes just found it.. the Video menu allows 1280  x 720 @ 50 FPS uncompressed, I didnt see it earlier as this option only appears when in Video record mode...

So is faster FPS an advantage with astrophotography stacking ?

I'm guessing here, but has it got something to do with gathering more images while the object is in the sweet spot?

 

 

Ray

 

 

[Davey-T]

Just now, Raymo said:

Hi Dave,

yes just found it.. the Video menu allows 1280  x 720 @ 50 FPS uncompressed, I didnt see it earlier as this option only appears when in Video record mode...

So is faster FPS an advantage with astrophotography stacking ?

I'm guessing here, but has it got something to do with gathering more images while the object is in the sweet spot?

Ray

 

Generally yes, the faster frame rate the better, especially with Jupiter which is rotating comparatively rapidly, then the stacking software can sort out the best frames to use.

Dave

[Raymo]

Ah, got you.. makes sense.

I'll try both approaches, Canon 1280 x 720 @ 50 FPS uncompressed and then the MagicLantern X3 crop factor @ 24 FPS RAW.

I suspect the X3 crop will help when recording at Prime Focus and might even work well with my 25mm Possel...

Forecast looks like I'll get some clear skies here on Monday.

[Raymo]

ok so after a few nights with semi-clear skies I managed to get something recorded.

I used my 10mm possel from Skywatcher, an ebay T-adapter and tube to holdthe Eyepiece.

then I used the Canon 5DMk3 set to x3 crop and recorded Raw video.

Saved the frames and stacked...

here is the result using a dobsonian mount and my first "Lucky imaging"..

What ya think folks?

I'm fairly happy with this given how crappy my first images were...

 

Ps, this was about 20 seconds of video at 24 fps, stacked the best 20%

 

[orion25]

1 hour ago, Raymo said:

ok so after a few nights with semi-clear skies I managed to get something recorded.

I used my 10mm possel from Skywatcher, an ebay T-adapter and tube to holdthe Eyepiece.

then I used the Canon 5DMk3 set to x3 crop and recorded Raw video.

Saved the frames and stacked...

here is the result using a dobsonian mount and my first "Lucky imaging"..

What ya think folks?

I'm fairly happy with this given how crappy my first images were...

 

Ps, this was about 20 seconds of video at 24 fps, stacked the best 20%

 

Nice work! What a difference!