DIY Ideas to Help Get Into Planetary Imaging

[Gina]

I can hear the comments "Oh no!  Gina's starting yet another project "  Well this is only a germ in my head ATM and takes lower priority to the widefield imaging system and associated mini obsy.

To lay the ground... this stems from my aborted purchase of a C11 scope and not wanting to abandon the prospect of planetary imaging entirely.  The idea now is to make use of my MN190 and use a Barlow or Powermate to magnify the image.  I have various Barlows but not a Powermate as yet.  For the camera I have a Philips SPC900NC with thoughts of investing in a mono camera later.

Now to the point of this thread.

I think there may be a problem with getting the planet in the FOV of the webcam though I don't know if AstroTortilla could be used for this.  I know I could go the manual route of putting an eyepiece on the scope initially and swapping this (or using a zoom) to gradually centre the object in the view and then swapping for Barlow and camera.  OR I could use a camera instead of an eyepiece and centre the object that way and swap cameras or add Barlow.

But as most on here know, I'm not really into manually swapping imaging gear and prefer remote control or automation.

What I'm thinking is that I could make a flip-mirror to put in the optical path and flip the light beam out to the side and into a camera to give a wider FOV.  I already have ready-made flip mirrors from the many DSLRs I have cannibalised for other projects, so I think this project would be quite feasible.

As usual I welcome comments and suggestions   I don't even mind people saying "You're a nut-case" etc.

[hobsey]

I have recently been reading up on flip mirrors as I purchased one the other day.

I think the problem you are going to have is not enough inward travel to allow for the extra length of the flip mirror with that particular scope design (newtonian).

[kev]

Gina, why cant you simply use a small piggy back scope with another phillips as a finder?

Kev

Sent from my iPhone so excuse the typos!

[nmoushon]

Flip mirrors and barlows should get you to where you want. Not quiet the FL of the C11 but pretty close. But as Anthony said, and i agree with, i think you might have problems with focus. Maybe not though. But if you have to take out the flip mirror I personally would just put an EP in and get it center and swap out more mag if needed till i get it centered. It wouldnt take more than a couple minutes at most to do. And how often are you going to be doing planetary imaging? If its not that often or just when you feel like it, I think swapping EP wouldnt be to much of a pain.

[pete_l]

What I'm thinking is that I could make a flip-mirror to put in the optical path and flip the light beam out to the side and into a camera to give a wider FOV.

Why go to the trouble of flipping anything?

Instead of a mirror, use a dichroic long pass filter to split the light coming out of the telescope into the visible portion that is fed to the webcam and the I.R. component that is fed to the wide FoV camera. This is how on axis guiders work and will allow you to both image the planet in the visible spectrum and find it in the wide view of the other camera in the infra red. No moving parts and simultaneous views.

Alternatively you could capture the I.R. images as well and stack them into the visible images to give a unique view of planets.

[andyboy1970]

I have never managed to do planetary imaging without swapping in the barlow.

If you put the flip mirror between the barlow/powermate and the camera you will have no probs with focusing and gain extra magnification.

I often use extension tubes between the barlow and camera to gain that extra bit of magnification.

I find it very hands on compared to deep sky.

[JamesF]

Oh no!  Gina's starting yet another project 

I'm really not sure the Astrotortilla solution would work.  The field of view is so small that you're really short of stars so you'd need a shorter focal length image to work from and if you did that I'm not sure you'd get the accuracy you need by that method alone.

I'm inclined to believe that you'd struggle for focus with a flip mirror unless you could make it very short (and obviously you could motorise the "flip"), but what might work would be to use AT to get close using a second shorter focal length OTA and then centre separately if the image is on the main camera, or use EQMOD's spiral search feature to hunt for the target otherwise?  I imagine having both the finder and imaging cameras on-screen at the same time with a reticle overlaid on each and adjusting the OTA alignment to be spot on might make life easier.

How accurately can you place an OTA using AT?  I reckon that at 5m focal length an SPC900 sensor is about 3 arcminutes across the diagonal.  Do you think you could get that close?

James

[Davey-T]

There's a thread on planetary imaging using Canon DSLR some of them have a crop video mode that uses the centre of the chip at 1 to 1 resolution, had a go earlier in the year with not too bad results using 60da. Will have a look for it.

Dave

http://stargazerslounge.com/topic/208610-planetary-imaging-with-dslr-video-mode/?hl=%20crop%20%20mode

There you go

[Gina]

Thank you everyone - plenty there to think about   I'll give more detailled replies later

[JamesF]

There's a thread on planetary imaging using Canon DSLR some of them have a crop video mode that uses the centre of the chip at 1 to 1 resolution, had a go earlier in the year with not too bad results using 60da. Will have a look for it.

I don't know if it's still true, but my recollection is that the DSLR video method at least used to only produce the data after lossy compression which isn't ideal.  On the other hand, the smaller pixel size helps by reducing the desirable focal length.  It's equally true that the SPC900 uses lossy compression to varying degrees depending on frame size and frame rate, so they may well end up comparable.

James

[Davey-T]

Some Canon DSLRs can do proper 640X480 video.

Dave

[JamesF]

Some Canon DSLRs can do proper 640X480 video.

You get full 640x480 raw RGB frames out?  That's quite handy.  I didn't know that.

James

[Gina]

I'll have to check my DSLRs.  I imagine the best will be the latest model I have which is an EOS 1100D.  If a DSLR will do the video alright I can swap modes to give me a wider FoV for aligning.  Could be the answer

OTOH using the MN190 means that I have the Esprit that I can use as a finder (if I carefully align the two scopes). 

[Gina]

Using the MN190 for planetary imaging will fit in nicely with my grand master plan   I aim to do planetary when I'm not using my main rig for DSO imaging.  I will have my widefield triple imaging rig on the NEQ6 and SW pillar mount protected by wooden box and roll off roof when not in use (what I've called my Mini Widefield Imaging Observatory).  That will use camera lenses and three 460EXs - I'm drawing the limit at three in my present plan

The main site and full sized observatory, has the EQ8 on concrete pier with MN190, Esprit 80ED and will have two Evostar 80EDs.  Eventually I would like to replace the Evostars with Esprits but that's probably a good way into the future.  The MN190 provides for small DSO imaging such as galaxies with single 460EX and filter wheel.  The three refractors cover medium size DSOs with three 460EXs using the MN190 for guiding.  I have already tested the efficacy of this arrangement with single 460EX and FW on the Esprit.

[Gina]

Gina, why cant you simply use a small piggy back scope with another phillips as a finder?

Kev

Sent from my iPhone so excuse the typos!

I have an Esprit 80ED that I can use as a finder - good idea   Thank you :

[Gina]

Why go to the trouble of flipping anything?

Instead of a mirror, use a dichroic long pass filter to split the light coming out of the telescope into the visible portion that is fed to the webcam and the I.R. component that is fed to the wide FoV camera. This is how on axis guiders work and will allow you to both image the planet in the visible spectrum and find it in the wide view of the other camera in the infra red. No moving parts and simultaneous views.

Alternatively you could capture the I.R. images as well and stack them into the visible images to give a unique view of planets.

That looks a very interesting idea - thank you

[Gina]

I have never managed to do planetary imaging without swapping in the barlow.

If you put the flip mirror between the barlow/powermate and the camera you will have no probs with focusing and gain extra magnification.

I often use extension tubes between the barlow and camera to gain that extra bit of magnification.

I find it very hands on compared to deep sky.

Thank you for the suggestion   I plan to use an extension tube but hadn't thought of putting a flip mirror in that position - wonder if it would work

[Gina]

Oh no!  Gina's starting yet another project 

I'm really not sure the Astrotortilla solution would work.  The field of view is so small that you're really short of stars so you'd need a shorter focal length image to work from and if you did that I'm not sure you'd get the accuracy you need by that method alone.

I'm inclined to believe that you'd struggle for focus with a flip mirror unless you could make it very short (and obviously you could motorise the "flip"), but what might work would be to use AT to get close using a second shorter focal length OTA and then centre separately if the image is on the main camera, or use EQMOD's spiral search feature to hunt for the target otherwise?  I imagine having both the finder and imaging cameras on-screen at the same time with a reticle overlaid on each and adjusting the OTA alignment to be spot on might make life easier.

How accurately can you place an OTA using AT?  I reckon that at 5m focal length an SPC900 sensor is about 3 arcminutes across the diagonal.  Do you think you could get that close?

James

AT indicates by it's UI that it can get to one minute of arc - I wonder if it can.  It certainly gets the image spot on as seen with a 460EX and Esprit 80ED but that's a long way off the 10x more magnification of the MN190 plus Barlow/Powermate and the much smaller sensor size of a webcam.  OTOH I do think there's a good chance that AT used with the Esprit could get the planet in the FOV of the webcam.  I agree that AT would struggle with the webcam image.

[Gina]

There's a thread on planetary imaging using Canon DSLR some of them have a crop video mode that uses the centre of the chip at 1 to 1 resolution, had a go earlier in the year with not too bad results using 60da. Will have a look for it.

Dave

http://stargazerslounge.com/topic/208610-planetary-imaging-with-dslr-video-mode/?hl=%20crop%20%20mode

There you go

Now that's a very interesting idea if it works with one of the DSLRs I have.  I presume wider fields are also available and that could be useful for findiing the planet

[Joe_L]

Gina,

I had a problem with finding the image using an spc900nc on my NExstar6SE so I added a second video camera as a finder by piggybacking half an old pair of 8x40 bins.  With careful alignment and using the crosshairs on sharpcap I can sit indoors and steer the scope remotely, lining up on the viewfinder cam and can take the main cam to the right place. I can share one sharpcap and two serials for scope control and LX mode over one USB cable but the second camera needs a second USB cable as two cameras is too much bandwidth for a single USB cable.

Joe

[Gina]

Some very interesting new ideas (new to me that is) have been proposed which would be much simpler than making a flip mirror.  The possibility of using a Canon EOS camera in cropped video mode I find hugely interesting, particularly if it's anywhere near as sensitive as the Philips webcam.  But that's the rub with that idea - the Philips webcam has a reputation for being particularly sensitive and DSLRs haven't

Using the Esprit as a finder is another great idea.  I might decide to keep my one remaining Atik 314L+ to use for that in conjunction with AT.  In fact I'm keeping it at least until I get the third 460EX - I only have two ATM.  I can use the 314L+ on the Esprit and the two 460EXs on the Evostars to make a triple imaging rig.  With the different focal lengths and image sensor sizes the coverage is quite close.

[Gina]

Gina,

I had a problem with finding the image using an spc900nc on my NExstar6SE so I added a second video camera as a finder by piggybacking half an old pair of 8x40 bins.  With careful alignment and using the crosshairs on sharpcap I can sit indoors and steer the scope remotely, lining up on the viewfinder cam and can take the main cam to the right place. I can share one sharpcap and two serials for scope control and LX mode over one USB cable but the second camera needs a second USB cable as two cameras is too much bandwidth for a single USB cable.

Joe

Thank you Joe   BTW I have had three astro cameras on a USB2 powered hub fed through just one cable to the laptop.  These were two 314L+ and one 460EX mono CCD cameras.

[John1980]

I must admit it is very easy on a canon dslr as long as the model has movie crop mode. You can centre the image in normal video using the full 1920x1080 and then select the movie crop mode that only uses the center portion of the cmos sensor and gives an output of 640x480 at 50fps.

Its like having 5x zoom. You then use EOS utility to give a nice big picture on the laptop. Then you can change between the two movie modes without even touching the camera one for centering image and one for recording. The 50fps is nice as well lots of frames to stack.

[Joe_L]

Thank you Joe   BTW I have had three astro cameras on a USB2 powered hub fed through just one cable to the laptop.  These were two 314L+ and one 460EX mono CCD cameras.

Interesting. I tried with two spcs, it almost worked but was unreliable. I wonder if different cameras require different bandwidths. BTW mine was on a 15M cable so that may also have been a limitation. Or maybe depends on the quality of the drivers.

Joe

[JamesF]

Interesting. I tried with two spcs, it almost worked but was unreliable. I wonder if different cameras require different bandwidths. BTW mine was on a 15M cable so that may also have been a limitation. Or maybe depends on the quality of the drivers.

Joe

On a 15m passive cable I'd not be surprised if you run into problems to be honest.  USB wouldn't be expected to be reliable over that kind of cable length.

James