Pros...how to get the planet on the chip?

[Camelopardalis]

The other night I had a lot of "fun" getting the subject on the chip once the Barlow was inline. I tried getting the planet centred first with an eyepiece, but on my SE even switching the eyepiece for the camera was enough to throw it out :sadeyes:

So what does it take to easily get the planet on the chip...

Pier mounted scope in an obsy
Expensive mount with accurate goto
Careful setup and star alignment
Luck of the draw


With the SE, it's a single arm under mounted for the C8, so I can forgive it. And I was pretty stoked with what I got. Tonight, weather permitting, I'll be trying with the C11 on the EQ6.

If you've got any hints, tips or tricks please feel free to share :D

[BlackWidow]

Its a real pain in the rear.... I don't focus prior so that I am looking for a change in light or a donught.. That way is see it better over the full field of the chip. Then I slowly focus and re-center until I have it on target.... I have found that my Image source camera seems to be spot on with my eypiece, but all my others seem to be way out....

Oh don't start hair pulling as it will end up very bad for you!

Mardy

[Merlin66]

I have similar problems getting target objects (small) onto slit gaps (even smaller!!) with small (ish) CCD chips....
For me I found the solution was to use an ol' flip mirror in front of the camera and a 12mm eyepiece in the other port.
I could then position the "target" as required (relative to the xwires) and with a "no movement to camera/ scope" flip of the mirror it was pretty much dead bang on the middle of the chip!
HTH

[Amaranthus]

I used the single fork arm 8SE too. First I centre with my reticle 12mm EP.

Then I use the maximum resolution in my imager (NexImage 5), and ideally have that pre-focussed (try to mark a point on your focusser). Also turn the gain right up.

Doing this I had no problem getting Mars in the FOV at f/10, and a moderately easy job at finding it at f/25. You can turn the gain/rez back once it's centred. Oh, and turn your imager such that left is left and top is top on your HC - makes life much easier :P

[Astro_Bot]

It's not easy, but I make sure my finderscope is well aligned at the start of the session, then insert Barlow/Powermate and use the "unzoomed" view in Backyard EOS to begin. The target is usually in the FOV when "unzoomed" as long as it's well centred in the finderscope.

With a small-chip high-speed camera, unfortunately, you don't have that luxury. :shrug:

[JB80]

I agree with much of what has been said, it can be a real task at times and it has defeated me on occasion in the past but I can say that with practice it becomes much easier or at least routine.

I think while points 1-3 on your list would be quite helpful they are by no means essential and point 4? Well at times it really just seems like that is the case but you do get into a routine.
I use a 150mm/1200mm scope on an EQ3-2 and this is probably one of the most unstable pairings around and it definitely offers up more of a challenge.

Unless I am feeling fancy I don't really polar align, just point the tripod in the right area and it is generally good enough for planetary. Good practice probably says to polar align and well you would be better off for it I suppose.
I also only use the R.A?(I get muddled :p) motor for the mount leaving the DEC free for manual adjustments. I find this to be more tactile than using both the motors.

I tend to start off making sure the eyepiece and finder scope are aligned as best as I can eyeball, I then remove the EP and add the cam and generally the planet is there or thereabouts and just needs focusing.
Then bang it in focus, centre it on screen and as mentioned turn the gain right up and remove the cam and put the x2 barlow in and repeat.

This is where having the DEC free for adjustments comes in handy as you can watch the bright patch on screen whizz past over and over until you can slow it down and centre it and focus.
Then repeat the process for a x3, etc...

Sometimes you do lose the planet altogether and may have to drop back down to the previous field of view to find it again which is frustrating but normal.
Before I remove say the x3 to drop it back down to a x2 though I always just remove the cam first and look through the barlow, often you can see the brightness from the planet in the barlow and you can kind of get a feel for where the edge is, try to guesstimate centre like that first and replace the cam. Quite often that gets you very close and the fine adjustments will get you back on screen.

Now if things are going well enough I just use that last method of eyeballing through the barlow but that assumes you are close to begin with.

[Camelopardalis]

Thanks for all the info folks. Getting it on the chip at f/10 wasn't a problem, but adding the Barlow into the train caused the fun and games.

Flip mirror looks like it should do the trick then...on the wish list it goes :)

[Camelopardalis]

All good stuff chaps, thanks for all the tips.

I setup the EQ6 in daylight yesterday as the forecast looked half promising (compared to rain, I'll take it!) and stuck the C11 out to acclimate once the Sun had set.

Still need to go through my data for the evening, but I made a couple of tweaks to my finderscope which helped and I also used an alternative eyepiece to help centring the subject before swapping out for the cam. I also swapped my Click lock diagonal for a conventional compression ring one, as I think the twisting operation might have contributed (on top of the single arm mount I was using the other night). The chip gives about the same field as a 7mm eyepiece, so this already fun with a native focal length of 2800mm, before I start thinking of Barlowing :D

With the subject centred, I carefully watched out for drift (backlash?) and adjusted to make sure it stayed centred, to give me a fighting chance of getting it on the chip! For the most part, it worked. A bit of a fumble, but the experience is good.

[Amaranthus]

When I was imaging last night, I tried 4x4 binning. If your camera can handle that, it makes life much easier, because you can see the whole chip on screen which means that you're using the full FOV. I found it much easier to get Mars centred that way - after which I switched back to 1x1

Another trick - I typically do planetary stuff on moonlit nights, because DSO is out. This has a big advantage - you can get excellent focus on the moon, and then switch to your planet of interest. I've found it MUCH easier to get a precise focus on lunar features vs tiny planetary discs...

[Camelopardalis]

Good tips Barry, thanks!

I've got a Bahtinov mask for focusing, which gets pretty interesting with the C11 on the EQ6 looking at something with reasonably high altitude with the dew shield on :lol:

Will try the binning too - though I think my cam only has a 2x2 binning as it's relatively low resolution.

[Amaranthus]

I find it hard to get my NexImage 5 to be bright enough on point sources to be able to use my Bahtinov effectively.

[raymo]

I realise that most of you are talking about CCD cameras, but I have the
same problem with my webcams. I have tried every trick and method
known to man, but still cannot even get a flash of the target passing through the F.O.V. when using a barlow. I have spent around about
5-6 hours over several sessions. It's doubly frustrating, as I am a very experienced observer and film imager. When an object is precisely
centred in a reticle EP, and then defocussed to about twice it's normal apparent size, how is it possible that very careful slight sweeping back and forth and up and down shows no sign of it.
I'm not looking for suggestions; I have already received many of them
from several members. I am, I suppose, just expressing my what has
become rage. Last time out I ended up throwing one of my webcams
at the fence and smashing it. There, rant over.
raymo

[Amaranthus]

raymo, when out of focus, the planetary discs can look really dim on your computer screen! So make sure you turn the gain to maximum, and set the exposure to, say 1 second - this really brightens up the image. Then get it centred and focused without the barlow. Then put in your barlow as the last step.

I have found that binning also really helps. My planetary imager is a CMOS 'webcam', not a CCD - though designed specifically for planetary work (Neximage 5).

[raymo]

Thank you Barry for your advice. As I said in my post I have had lots of help from lots of people, including your tips, and have tried them all, and got nowhere, and was not looking for more help, just having a rant.
I have gone back to DSO imaging. Your thoughtfulness is much appreciated.
raymo

[Camelopardalis]

The other thing is the webcam will have a really narrow FOV...the chip on your 1100D is a lot bigger, could be worse things than trying that :confused2:

[raymo]

I tried that; took several vids of Mars and Jupiter, using EP projection
because the image at prime focus was much too small. even with a barlow. Registax doesn't recognise Canon movies of course, so I converted them to AVI. Registax accepted them and aligned them, but
wouldn't stack them. A dialogue box came up and stated that I was
trying to do some "illegal" thing or other. I don't remember exactly what it said.
raymo

[Amaranthus]

Probably ran out of memory. You should use the brilliant 'Castrator' to cut your video size (reduces to the planetary disc and small edge):
http://www.astrokraai.nl/castrator.php

[raymo]

Thanks Barry, I'll give it a go.
raymo

[Poita]

I use a zoom eyepiece to get the planet pretty much centered perfectly, and then swap out the camera. I never really had any trouble with a C9.25 or meade 10" with 2.5 or 5x barlow.

I started off doing low mag until I got used to the camera.