New to Planetary Imaging with C11 - help please

[Gina]

I will shortly be getting a Celestron C11 with a view to trying planetary imaging again.  My previous attempts were several years ago with the a cheap Celestron Astromaster 130EQ MD Newt and simple webcam.  I could see the rings of Saturn but no detail

Now I'm about to try planetary imaging again with a dedicated planetary scope with 2800mm v 650mm focal length.  I have 2x and 3x Barlows and initially thinking of using an MS LifeCam Cinema HD webcam for imaging.  I expect to upgrade to a better camera later.

I have the choice of two piers/mounts - best is the EQ8 on a solid concrete pier in my observatory but I also have an NEQ6 on a SW pillar mount.  The latter was set up for widefield but I have wondered about putting the C11 on it rather than hauling the big kit off the EQ8.

Now to my questions...

 

1. Would the NEQ6 setup be any good for this or would I be best advised to use the EQ8 with its much better tracking and stability?

2. What about guiding?  I don't imaging tracking alone would keep the planet in the FOV.  Options are separate guide scope and camera or OAG on the C11.  From my DSO imaging experience, an OAG works a lot better.  I have Lodestar and Lodestar X2 guide cameras. 

3. In the future I've no doubt I shall want to upgrade to a better camera.  I have been looking at the Celestron Neximage 5 Colour camera with its high resolution and small pixels but not seen mention of this in any planetary imaging posts.  The DMK 21AU618.AS cameras seem to be used a lot but are only 640x480 pixels.  Are they worth the extra significant cost?

I've seen Stephen's comparison between colour and mono imaging of Jupiter with the clear improvement with mono so this would seeem to be the ultimate aim.  I have the requisite filter wheel and filters so it would just be a case of buying a mono camera.

[Bizibilder]

The NEQ6 will carry a C11 (mine does!) and is fine for planetary.  You don't need to guide - actually it would be counter-productive as planets move about (very slowly), unlike the stars which remain "fixed".  Your total exposure time for a "movie" is likely to be under 5mins so good PA will easily keep a planet in the middle of the fov for that length of time.  The experts may say different but in UK skies I have found a 2x barlow is the limit on a night of excellent seeing and often find I am limited to prime focus.  I have a 2.5x Powermate that I have not been able to use so far - its just too long a focal length to get a decent image.

[Grotemobile]

http://www.firstlightoptics.com/celestron-skyris/celestron-neximage-burst-solar-system-imager-camera.html

I think this is the latest camera from

Celestron.It looks better than the basic

Celestron Neximage 5 Colour camera .I

never used a barlow with my C11.I

live in a town,so it was no good.

If you have a dark site,a 1.5 barlow

might be good.Have fun.

Steve

[Tinker1947]

I had my C11 on the NEQ6, it seemed to work ok with a reducer, ramping up the FL with Barlows ect might just be to much, a more stable mount would be a better.......and adding a Feather Touch makes it a doodle to focus...

[jambouk]

Yes, neq6 will be fine. Good polar alignment should keep the planet on the sensor for sometime. You could guide on the planet itself i guess (bit bright and blobby though) or a star if you wanted but i don't think many planetary imagers bother. I have thought about it more than once as an academic exercise but the need just isn't there for me.

Damian peach has that new dvd out, maybe worth a look at. There was a thread about it but i've not read any of it.

I do find my flip mirror very helpful in getting the planet on the sensor, but others get by fine without them.

Good luck

James

[riklaunim]

1. Would the NEQ6 setup be any good for this or would I be best advised to use the EQ8 with its much better tracking and stability?

I used C11 with HEQ5 that had extended counterweight shaft. EQ6 can handle C14 the same way. C11 is not a problem for it.

 

2. What about guiding?  I don't imaging tracking alone would keep the planet in the FOV.  Options are separate guide scope and camera or OAG on the C11.  From my DSO imaging experience, an OAG works a lot better.  I have Lodestar and Lodestar X2 guide cameras.

No guiding for planetary needed. You can either tune planet position between AVIs or play with FireCapture "self guiding" option that uses slowest mount motions to keep the planet within FOV.

 

3. In the future I've no doubt I shall want to upgrade to a better camera.  I have been looking at the Celestron Neximage 5 Colour camera with its high resolution and small pixels but not seen mention of this in any planetary imaging posts.  The DMK 21AU618.AS cameras seem to be used a lot but are only 640x480 pixels.  Are they worth the extra significant cost?

Pixel count doesn't mean resolution. Both cameras are limited by telescope resolving power. Even C14 can't exceed 640x480 on Jupiter in general due to that limitation. DMK21AU618 is a good camera but it's to expensive when compared to ASI120MM, which is similar/better in performance, yet it costs around half of DMK. Neximage 5 is a "low end" camera, not very good.

You will also need a motocryford or a cryford SCT focusr with motofocus - that will dramatically improve focusing on the planets.

[Gina]

Thank you everyone   The C11 I'm getting has been fitted with a Crayford focuser but I don't know how good it is.

I'll look into camera upgrade later on - options may have changed by then   The Celestron Neximage Burst Imager in mono looks interesting but I'll also look at the ASI120MM.  Funds are booked for other things before I consider this.

I shall have to think long and hard about making my second roll off roof accomodate the C11 - it's a big step up from accommodating the WF imaging rig.  No decision until I get the C11 anyway

[Owmuchonomy]

Hi Gina, as above, guiding definitely not required and the mount is fine and is not so critical to planetary imaging. The big hurdles are ( in no particular order):

Wind

Focussing

Image scale

Seeing; this moves the image around far more than any errors in tracking

Waiting for planets to come round and get closer. It's not great at the moment or for the foreseeable future.

I've not tried barlows and use EP projection on my 9.25 with a 8 or 15 mm EP instead.

[Gina]

Thank you Chris

Wind would probably be reduced if I put it in my observatory on the EQ8 mount rather that the totally exposed second pier and NEQ6.

Focussing will be with a stepper motor.

I know the image of the planets is pretty small - I've been looking at FOV sites.

Seeing is a definite problem for amy imaging.

I'll just have to make do with the planets as they are - no control over that   Or should I stop the purchase of the C11?

[Zakalwe]

Planetary imaging uses short movies. Wind isn't that much of an issues as stacking software will just centre the planet. Anyway, if it's that windy the seeing will probably be manky anyway.

A motorised Crayford (even a chepo Crayford) will be a million times better than the standard C11 focuser.

Don't forget the weight issue Gina...the C11 is a pretty heavy, unwieldy beast.  I have mine mounted in tuberings with an extra Vixen dovetail on top....it makes it easier to heft about, but it still means lifting 12Kg (2 stones) onto the mount.

The Celestron cameras looked way overpriced to me.....One uses a similiar chip to the Chameleon Blackfly but is (from memory) 25-30% more expensive.

[Tinker1947]

Take a look through Stellarium will give you a idea when the best views will be......

[Gina]

Planetary imaging uses short movies. Wind isn't that much of an issues as stacking software will just centre the planet. Anyway, if it's that windy the seeing will probably be manky anyway.

A motorised Crayford (even a chepo Crayford) will be a million times better than the standard C11 focuser.

Don't forget the weight issue Gina...the C11 is a pretty heavy, unwieldy beast.  I have mine mounted in tuberings with an extra Vixen dovetail on top....it makes it easier to heft about, but it still means lifting 12Kg (2 stones) onto the mount.

The Celestron cameras looked way overpriced to me.....One uses a similiar chip to the Chameleon Blackfly but is (from memory) 25-30% more expensive.

Yes, the weight could well see me using it on the EQ8 where I have a motorised hoist for lifting and lowering heavy scopes (or assemblies).  The NEQ6 is out in the open without any sort of "sky hook".  I'm thinking perhaps I should stick with lighter items on the no.2 mounting. 

As for cameras, there must be a very good reason I see no mention of Celestron cameras - that sounds like the reason

[Gina]

Planetary imaging uses short movies. Wind isn't that much of an issues as stacking software will just centre the planet. Anyway, if it's that windy the seeing will probably be manky anyway.

A motorised Crayford (even a chepo Crayford) will be a million times better than the standard C11 focuser.

Don't forget the weight issue Gina...the C11 is a pretty heavy, unwieldy beast.  I have mine mounted in tuberings with an extra Vixen dovetail on top....it makes it easier to heft about, but it still means lifting 12Kg (2 stones) onto the mount.

The Celestron cameras looked way overpriced to me.....One uses a similiar chip to the Chameleon Blackfly but is (from memory) 25-30% more expensive.

Yes, the weight could well see me using it on the EQ8 where I have a motorised hoist for lifting and lowering heavy scopes (or assemblies).  The NEQ6 is out in the open without any sort of "sky hook".  I'm thinking perhaps I should stick with lighter items on the no.2 mounting.   I thought the mounting method of the C11 looked a bit poor and may well do the same.

As for cameras, there must be a very good reason I see no mention of Celestron cameras - that sounds like the reason

Take a look through Stellarium will give you a idea when the best views will be......

Thanks   I don't have Stellarium ATM - maybe I should get it

[JamesF]

There's at least one video somewhere on on that youtube showing how to mount a large SCT such as a C11 on an EQ mount without having to heft it around.  Basically you stand the scope on a stool or chair and then move the mount to it, not the other way around.

I think it's probably fair to say that the ASI120MM is the planetary camera of choice for the moment.  I believe even Damian Peach is using one.  I think the ASI120MM-S is better, but it's also a fair bit more expensive.  The mono cameras blow the colour models into the weeds, really.  I was amazed at the difference between the image from an OSC camera and that from combined RGB frames from a mono camera.  Of course it does require a filter wheel and suchlike, so it's hardly a cheap option.

As has already been said, guiding isn't required, but Firecapture can control the mount to keep the target on the sensor if required.  It's not a big deal for the target to move around a bit (remember we're talking about monster focal lengths compared with what you're used to for DSO imaging here).

WIth planetary imaging it's desirable to match the resolution of the camera to the resolution of the OTA which is fairly basic trig that I imagine you could handle yourself, but with the 3um pixel size of the LIfecam I'd suggest that a focal ratio any higher than f/15 is probably overkill.  You can't rely on the stated focal length of the OTA though.  The nature of the SCT design is that the stated focal length only occurs with the primary mirror (or the focal plane if you want to look at it that way) in one given position.  Move away from that position and it changes (and quite rapidly, too).  When it knows the target and a few other bits of data, Firecapture will attempt to calculate the effective focal length and focal ratio and drop that information in its output file.  If you still have your SPC900s I'd certainly give one of those a whirl.  My gut feeling is that it may out-perform the Lifecam.  You'd be looking for a focal ratio nearer f/35 or perhaps even f/40 with that though (I did say monster focal lengths, didn't I?  I struggled to get the Lifecam to work as well as my SPC900 though I've seen better images from others.  I posted a comparison some time back.  I really wouldn't discount it.

As others have said, sensor size really isn't an issue for planetary.  Even Jupiter at opposition is not going to make much more than 300 pixels across on most planetary cameras.  Once you've reached the "optimal" focal ratio you can't extract any more detail by increasing the focal length or reducing the pixel size.  You just get a larger, dimmer image.

Whichever kit you end up using, rest assured that I will be badgering you to test oacapture on Linux at some point

James

[JamesF]

Here's my Lifecam vs. SPC900 posting, if you're interested:

http://stargazerslounge.com/topic/168060-spc900-vs-xbox-live-webcam-vs-lifecam-cinema/

James

[Gina]

Thank you for posting all that interesting and useful info James

I have several SPC900NCs, one of which has been modified for AP, with nosepiece, little box and YesYes long exposure option.  Not that the latter will apply to planetary imaging   I agree that these webcams are very good and very controllable.  The MS webcams are notoriously uncontrollable and I have had problems with that in the past.  Good for their intended purpose but not really for AP. 

I can understand from my DSO imaging that there's no point in trying to get more detail than the sky will allow.  For instance, I usually find I need to bin 2x2 with the MN190 and 480EX.  Many times I even find I need 2x2 binning with my Esprit 80ED.  So yes, I can see that you have the same with planetary imaging.  Seems that using the C11 without a barlow will be the way to go - certainly at first.

A mono camera will certainly be my upgrade path with such a difference in results   No problem with filter wheel and filters as I already have them, though I shall have to find out how the FW is controlled from planetary software - I know that imaging runs are limited with Jupiter due to its rotation.  I use the Atik Artemis Capture software for DSO with the Atik cameras and FW, which has all this built in.

As for your oacapture software, I am certainly very interested and will definitely try it

[Zakalwe]

Unless you are aiming for Lunar shots Gina, then you will need a Barlow. f10 just isn't long enough to get anywhere "near" enough for planetary. I get decent results with a Powermate 2.5 when using a DMK21au618.

[url=https://flic.kr/p/k9rPNj]

[JamesF]

A mono camera will certainly be my upgrade path with such a difference in results   No problem with filter wheel and filters as I already have them, though I shall have to find out how the FW is controlled from planetary software - I know that imaging runs are limited with Jupiter due to its rotation.

FireCapture can talk to the ASCOM driver to control the filter wheel.  It's just a case of telling FC how you want the exposure sequences to work and it will move the filter wheel accordingly.

Time on Jupiter is tight, but there is also WinJupos, which attempts to "derotate" the data to account for the movement of the planet.

James

[JamesF]

Unless you are aiming for Lunar shots Gina, then you will need a Barlow. f10 just isn't long enough to get anywhere "near" enough for planetary. I get decent results with a Powermate 2.5 when using a DMK21au618.

The SPC900 should need the same focal ratio as the DMK I think.  The Lifecam has much smaller pixels I believe (3um, from memory), so you can work at almost half what you'd be after for the DMK.

James

[Gina]

Unless you are aiming for Lunar shots Gina, then you will need a Barlow. f10 just isn't long enough to get anywhere "near" enough for planetary. I get decent results with a Powermate 2.5 when using a DMK21au618.

[url=https://flic.kr/p/k9rPNj]

That's a great image Stephen   As I said I have a couple of 2X Barlows and a 3X so I could easily get 2.5x with a 2x Barlow and extension tube.

There seems to be some controversy about the possible magnification with the seeing in UK skies.  I'll just have to see how it goes

[Gina]

FireCapture can talk to the ASCOM driver to control the filter wheel.  It's just a case of telling FC how you want the exposure sequences to work and it will move the filter wheel accordingly.

Time on Jupiter is tight, but there is also WinJupos, which attempts to "derotate" the data to account for the movement of the planet.

James

That's good to know James   And yes, I've seen mention of WinJupos

[JamesF]

There seems to be some controversy about the possible magnification with the seeing in UK skies.  I'll just have to see how it goes

It's certainly a little different from DSO imaging and partly I think that's down to the fact that you can capture thousands rather than tens of images to process.  I'd say the fundamental thing is to arrange your optics so the camera sensor and OTA are matched, regardless of the state of the atmosphere.  If you're capturing tens or even hundreds of thousands of frames during the course of a night's imaging then at some point you're likely to get the best that was available.

I've heard it said that often the C11 (and even the C14) won't beat the C9.25, for example, because on average nights in the UK the seeing just isn't good enough.  But on those fleeting occasions when it does come right, if you have the camera and OTA properly matched, you'll get the best there is and that's when the larger apertures come into their own.

James

[Gina]

The SPC900 should need the same focal ratio as the DMK I think.  The Lifecam has much smaller pixels I believe (3um, from memory), so you can work at almost half what you'd be after for the DMK.

James

Yes that's right and why I was thinking of trying the LifeCam but the problems make it far less attractive.  The only advantage I can see now is that it gives a bigger FOV and the image can move about a lot more without causing problems.  If there is a problem, of course, which it seems not   How easy it is to find the planet and get it on the sensor remains to be seen   One possibility is what I was thinking of last time I was thinking of planetary image and that's a flip mirror and eyepiece.  OTOH AstroTortilla might solve the problem as it has for the smaller DSOs.

[JamesF]

With a decent mount (ie not my EQ3-2 I've found it relatively easy to keep a planet on a 1/4" sensor as long as the mount alignment is fairly good, even at focal lengths of four metres plus.

Generally I start by going to the target in CdC, then tweaking the alignment to get bang in the centre of the finder crosshairs (a game control is excellent for this), and then start with eyepieces, stepping up the magnification until I reach the barlow combination I'm going to use with the camera and re-centre the target each time.

I did try a Vixen flip mirror, but in the end decided the amount it added to the effective focal length when combined with a secondary focuser was excessive (remember the focal plane has to move backwards when you add the flip mirror, and refocusing increases the effective focal length), so I went back to the awkward method.  If I could find a decent 1.4x or 1.5x barlow then I might be able to make it work ok.

James

[Gina]

Yes, I don't see there being any problem with the EQ8 - the PA is pretty good already though could be better I think, it's currently a minute of arc or so out according to AT.  I reckon I should be able to get it within 10 or 20 seconds

I usually start with CdC for DSOs if I haven't already got an image I can use with AT and get some of the image in the frame straight away.  With the much brighter planets they should show in an eyepiece.  Or maybe use a larger size camera for centring the image.

I'll see how things go but I suspect it will be easy enough to get the planet in the view without a flip mirror.  Should get a nice bright image with a C11