how to get the image from the eyepiece onto the ccd imager

[alcol620]

Hi folks

Me again, the newbie.

Can someone provide me with the easiest way to get a planetary image onto the ccd imager with a 2x barlow. 

I am lining up the planet onto the center of the field of view with a 10 mm eyepiece and a 2X Barlow. Then removing these and inserting the CCD imager. It seems a bit hit and miss to then find the image of the planet, it may simply be out of focus or is no longer within the field of view on the laptop screen. Last night I managed to get Saturn onto the screen simply inserting the ccd imager after initially finding the planet with the 10 mm lens and 2x barlow. But when I tried to go one better to get a larger image, by inserting a 2x Barlow with the ccd imager I never managed to get an image on the screen and eventually gave up after 10/15 minutes

The ccd imager is said to be equivalent to a 6 mm eyepiece. I would have thought that once I have aligned the planet with the 10 mm lens and the 2x barlow it only remains that I pop the ccd imager in and the image would be there! Obviously not as easy as that.

Views please.

[Helen]

As well as making sure the planet is right in the centre of the filed of view before you switch I'd try upping the gain/gamma and lengthening the exposure on the ccd.  Particularly with a barlow the image can become quite dim, and when out of focus as well even dimmer.  At least with upped gamma etc you should see it!  Once you've got it you can turn it back down to properly focus and avoid overexposure.  You could also get a parfocal ring, which you can add to an eyepiece to make the eyepiece and ccd in focus 9or close to) at the same point on the focuser.

HTH

Helen

[Kirscovitch]

Like Helen said, it needs to be spot on in the center of the EP. Once you start adding barlows, it really narrows the FOV and can be hard to find on the cameras sensor. I usually use a 12mm reticle EP to get the planet perfectly centered then center it with the reticle and the barlow, then add the imager.

[knobby]

You could try practising in the day time on a very distant pylon or tree? You can then work out how many turns of the focuser and in which direction you need to get the camera in focus

[Kirscovitch]

I just took a sharpie and marked where the focus was with and without my barlow.

[alcol620]

 Matt

Excuse my ignorance, what's a sharpie?

[knobby]

Matt

Excuse my ignorance, what's a sharpie?

Its a marker pen that can write on anything (allegedly)

[Leveye]

Get a Powermate and the proper ring adaptor. Easy as pie.

[Kirscovitch]

As knobby said it's a permanent marker. After getting focus with the camera I just draw a line on the focuser tube. Next time you go out just extend the tube until you hit your mark and you should be pretty close to focus. Might have to tweak it a bit but you should be pretty darn close.

[alcol620]

Hi Matt

I have a 8SE Celestron so presumably I don't have a focusing tube but simply a twiddly knob (lol).

[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.

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 ) 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.  

[knobby]

Hi Matt

I have a 8SE Celestron so presumably I don't have a focusing tube but simply a twiddly knob (lol).

Then count the turns :-)

[alcol620]

Thanks everyone for your helpful and encouraging comments.

Can't wait to put them into practice

[Helen]

Make a fine focuser for your C8 - either a peg attached to the knob, or cut a hole in the top of a Marmite jar and slot over.  That way you get fine focus (because you can more easily make smaller movements of the focuser) and you can get some reference too for adjustments

Helen

[PeterCPC]

I have had this very issue and got over it by making sure that the finder scope and main scope were very accurately aligned.  If you do this you can use the finderscope to centre the target even when you change the eyepiece for camera. Works for me.

Peter

[ryandsimmons]

On my C8 I know that the focus for my camera is 1/8th of a clockwise turn from the focus of my 9mm EP with a barlow.

So when I want to use my camera I focus with my EP and just swap them,.

[wxsatuser]

I have had this very issue and got over it by making sure that the finder scope and main scope were very accurately aligned.  If you do this you can use the finderscope to centre the target even when you change the eyepiece for camera. Works for me.

Peter

Same here......align finder/guider and scope accurately.

I use PHD to get target dead centre in guider and the target is then normally smack in the centre of my dslr frame.

This is how I do it for eyepiece projection without removing the dslr.

My scope tube is marked for each position of my Hyperion zoom and the field flattener so intial focus is near on to start with.

This is how I imaged the 'Double Double' last night.

Image taken with SW 80ED Pro....Baader Hyperion Zoom 8mm....Canon 60Da, Astronomik CLS CCD,  eyepiece projection.

Exposure 1second @ ISO6400

Seeing was poor and I just took a few shots for a lucky hit.

[alcol620]

Helen, I like the idea of using a peg for fine adjustments and as you say it makes counting revolutions much less difficult.

[alcol620]

Hi everyone

Had a chance last night to put Helen's idea into action. I attached a cut down allen key with a jubilee clip to my 8SE Celestron focuser knob, see attached image. this worked a treat and provided an excellent method of turning the focuser without getting hold of it. the focuser could be turned with 1 finger, including even the back of a finger. Significantly reduced movement of the scope when turning the focuser.

Many thanks to Helen for an excellent idea.

Managed on one occasion to get the 2X Barlow inline with the ccd imager and found the laptop image. As someone said, a significant reduction in the brightness of the image, some of this being caused, I think by high levels of ambient light. Presumably at a dark sight the image would be brighter???

[Helen]

Pleased to see you're making progress  With the barlow remember that when you make the image bigger you are spreading the same incoming light over a wider area (no extra light is gathered), so it will get significantly dimmer.  Going from a 1mm x 1mm image to a 2mm x 2mm image reduces the brightness by a factor of 4

Helen

[alcol620]

Thanks Helen, that explains it. If I was imaging with exactly the same set up, but at a much darker site, with less light pollution would this provide a brighter image, or is the amount of light the same?

[knobby]

The light will be the same but your eyes may see it brighter on the screen as dark adapted eyes are better at seeing in the dark :-)

[alcol620]

Thought I had achieved something but getting the 2X Barlow in on the act, but the spreading of the same amount of light over the larger area of the camera chip (as you explained to me) has led to a larger but inferior stacked image.

Presumably I shall have to satisfy myself with a slightly 'bigger than a pea' image of Saturn?

Stacked images with and without the 2X Barlow are attached

saturn2xbarlow 16_05_2014 22_36_28_pipp.bmp

saturn16_05_2014 22_30_02_pippfinal.bmp