CCD Imaging with a Skywatcher Pro 180 Maksutov

[paybelb]

Hello everyone

I'm new to astronomy and enjoying every minute of it so far. I have recently purchased a Skywatcher Pro 180 Mak (gold tube) and I would like to do some CCD imaging with it. I have a Meade LPI and a Philips SPC900N.

A few nights ago I pointed the scope at Saturn and dropped in both CCD's into the diagonal attached to the scope. I had each CCD connected to my laptop running MAxim DL and also the Meade Autostar Suite. I was unable to get an image using either CCD or either program. However with my Skywatcher Explorer 200P I did get an image.

Is this to do with the Explorer being f/5 and the 180 Mak being f/12?

Basically I want to know how to image with the 180 Mak (if possible) and what other extras I then require eg. reducers etc. I would rather use the Mak as it gives much better visual images of the planets and it is more compact and lighter for my LXD55 mount.

Any help would be greatly appreciated.

Richard

[riklaunim]

The mak has much longer focal length so the object is darker - you need longer exposure than at f5 in Newtonian. Second if you connect the camera and the focus point isn't close - you may not see the planet until you get closer to the focus point And third - it has to be in the centre of your FOV with eyepiece (as the webcam is small).

Play with SPC900N and some target that is easy to keep in the field of view like moon (or some far building at day) - check when it is in focus compared to you eyepieces for easier focusing on planets at night.

Meade LPI is a CMOS sensor and is less sensitive than CCD in the webcam. Will require longer exposures.

[Cornelius Varley]

You should definitely be able to get a image with the 180 Mak, although personally I would attach the camera directly to the visual back of the telescope and not use a diagonal.

Peter

[red dwalf]

don`t use the diagonal when imaging and turn the gain settings up on the software to help you get an image and then change the setting to suit,

it is difficult at first as i found it almost impossiable using a 3x barlow to get an image onto the laptop as the camera sensors are so small, but keep trying, also try imaging the Moon first to get some experiance.

the 180 mak should be great on planets being a f15 scope.

[michael8554]

At 3x F15 = F45 you will find getting a planet onto your CCD chip with your current setup very hit-and-miss and frustrating.

You will need:

1) a flip mirror

2) a 9mm or 12mm reticle eyepiece, ideally with moveable cross hairs.

3) The eyepiece, and the CCD + Barlow, need to be parfocal when you flip the mirror.

Setup in the day on a distant object until you can consistantly move to the object and flip between the eyepiece and CCD.

Even then you may not get your planet on chip straight off. Wind the CCD gain way up so that when you search in Dec or RA and the planet wizzes across the CCD, you catch a big white blur across your screen.

If you tweak focus and you have typical Mak mirror flop you may loose your target again!

Sounds like hard work and it is, but with practice it becomes easier!

Cheers

Michael

[paybelb]

Many thanks for all your advice everyone. Sounds like it's going to take a bit of work, which I don't mind.

What are your thoughts on using a focal reducer to aid my CCD imaging? If I bought a 0.5 focal reducer would that not bring me down to about f/7.5 and thus reduce my exposure times?

[riklaunim]

Focal reducer is good to start - as it will be easier to center the object in the eyepiece and catch in the camera. Moon is getting bigger so it will be a good first target.

[SteveP]

Hi Richard

I occasionally use my Mak 180 for planetary imaging with my SPC900 in confunction with a 2.5x Powermate. The one thing it takes is patience. Whilst the long focal length is fantastic in getting in close, it unfortunately means that the FoV is very narrow and combined with the small chip of the SPC900, it's difficult to get the object on the chip. Consequently your mount's pointing has to be quite accurate. I do it by using a low mag, wide angle EP in the Powermate to help get the object centred before swapping it for the camera and then refocusing knowing that the object is there ... somewhere.

Like others have said, don't use a diagonal

Steve

[A McEwan]

Just out of curiosity, what is the argument against using a diagonal?

[ollypenrice]

One more optical surface? One more source of flexure?

Olly