Ask a question and a thousand different answers come up.....

[GaryA]

Hi All,
I went into the archives and was looking for answers to what Barlow I should be using with My SCT CPC 800 and there was no real answer. Maybe this was because their gear was slightly different to my setup- dunno!
Anyway as you can see I have a collection of toys
1) Celestron CPC 800 Alt- Azimuth, 200mm apeture 2035 focal length F10
2) Canon 400D DSLR with tele extender
3) DMK 21AU04.AS CCD
4) Filter wheel
5) 2x Celestron Barlow and a selection of Plossl Celestron lenses.

My questions. There is a fair bit of intricate gear missing with the above toys to take quality Pics to work with, and could you help me to fill in the gaps to improve the quality and size with the shots of the planets and also deep space?
I don't need to worry about the Stacking program and also Photoshop, just the proper gear to take quality shots first up, as I see in the pics of different astro photography shots taken on this Forum sites.
Questions on Barlows versus Powermate and what size I should use to get the best quality would be of advantage.
You see I do not have the luxury of running down to the local astro shop as there are none around locally or in this state. I am asking for help before I just go out to buy something on the net I don't really need as there are plenty of sharks out there just willing to suck the money bag dry.. If you get my drift? Thanks

[peter_4059 (Peter)]

Gary, There's no one right answer but here's my thoughts:

For planets I was using a 10" f5 newt with a 5x Powermate and a Neximage webcam. This combination (ie fl 1250 x5 = 6250 mm) and the original Neximage (I think it is 640x480 pixels) gave quite good image scale for Jupiter and Saturn.

As your scope already has 2m focal length and the DMK is also 640x480, a 3x Powermate would be a good fit. I think that camera is mono so you'll need to use the filter wheel and some RGB filters if you want to take a colour image or purchase a one shot colour camera (the ZWO ASI120MC seems quite popular for planetary imaging). One shot colour will be a lot easier to do planetary imaging than mono with a manual filter wheel.

I think you are going to find that combination of optics, camera (DSLR) and mount quite tricky for deep space imaging. Alt/az it is going to make it hard to avoid field rotation when you try longer exposures. Also, 2m focal length and f10 is going to make quite a small field of view (probably around 0.5 arc minute with the 400D) so the bigger/brighter objects will be twice the size of your field. CCD calc is a free app you can use to check the scope fl/camera combination to see the fov vs a number of deep space objects:
http://www.newastro.com/book_new/camera_app.html

At f10 with an unmodded DSLR you will need some reasonably long exposures to capture deep space objects. You might be able to get a reducer for your Celestron to make it f6.3 and this should help with both the fov and the exposure length.

Finally at some stage you will want to be autoguiding. I'm not sure how successful that is on an alt/az mount.

Hope that helps,

Peter

[Shiraz (Ray)]

http://www.iceinspace.com.au/forum/s...d.php?t=105057

[GaryA]

[QUOTE=peter_4059;1200903]Gary, There's no one right answer but here's my thoughts:

For planets I was using a 10" f5 newt with a 5x Powermate and a Neximage webcam. This combination (ie fl 1250 x5 = 6250 mm) and the original Neximage (I think it is 640x480 pixels) gave quite good image scale for Jupiter and Saturn.

As your scope already has 2m focal length and the DMK is also 640x480, a 3x Powermate would be a good fit. I think that camera is mono so you'll need to use the filter wheel and some RGB filters if you want to take a colour image or purchase a one shot colour camera (the ZWO ASI120MC seems quite popular for planetary imaging). One shot colour will be a lot easier to do planetary imaging than mono with a manual filter wheel.

I think you are going to find that combination of optics, camera (DSLR) and mount quite tricky for deep space imaging. Alt/az it is going to make it hard to avoid field rotation when you try longer exposures. Also, 2m focal length and f10 is going to make quite a small field of view (probably around 0.5 arc minute with the 400D) so the bigger/brighter objects will be twice the size of your field. CCD calc is a free app you can use to check the scope fl/camera combination to see the fov vs a number of deep space objects:
http://www.newastro.com/book_new/camera_app.html

At f10 with an unmodded DSLR you will need some reasonably long exposures to capture deep space objects. You might be able to get a reducer for your Celestron to make it f6.3 and this should help with both the fov and the exposure length.

Finally at some stage you will want to be autoguiding. I'm not sure how successful that is on an alt/az mount.

Hope that helps,

Peter[/QUO

Thanks Peter, I have done a bit of research and it looks like I will need a wedge as taking long exposures does cause a headache with the 400d.
The CCD camera Filter wheel is coloured and was recommended I go this way first. Still waiting for that to arrive at this moment. As I said being here in WA things take a long time to get here.
I am going over to Singapore at the end of the month and will have a look over there so I can get an idea The Powermates are only at 2.5x. Will that be ok to use? As you say a f6.3 reducer I may have to invest in as well.
At the moment the Pics taken by the 400d are total crap and I thought buying the tele extender would have been an advantage. Anyway I have still a long way to go.
BTW Thanks for the App

[dannat (Daniel)]

the 400d is for deep sapce -for that cam you need to look at the reducer f6.3 as suggested, no barlow or tele-extender

the tele-extender is for use with the dmk which is for lunat planetary

[JB80 (Jarrod)]

I can't really speak for the DSO side of things but I think for planetary, lunar and solar you have some good gear already to get on your way.
I agree with Peter mostly, you already have a x2 barlow and the DMK so you won't need anymore than that to get started and produce some good planetary images with that.
Personally I would prefer to use a filter wheel and a set of RGBLs to image planets than a colour camera, it's a bit more faff but doesn't take long to get used to and seeing as you already have the DMK you may as well use it.
I also agree that a nice x3 barlow with your scope will be a good fit too, between the x2 and x3 you wouldn't need much else.

[Paul Haese]

Just a couple of things here. 3x barlow will produce nearly 4x the focal length once the filter wheel is put in place. This spacing has a multiplying effect from the rear of the barlow glass to the sensor, so you will need to consider this if using a filter wheel. I use a 2x and it gives me about 3x on a 3910mm focal length scope. So I image near 12m.

You should think about 8m as your maximum focal length for your size scope.

A 2.5x powermate does not have the multiplying effect a barlow does. It in fact has the reverse effect. The further away the sensor is from the rear of the glass the less magnification is applied. So be wary of buying this powermate. The 5x does not have this problem.