First Test Image With Canon 600D - NGC3372

[rodroger (Rodney)]

Hi, Finally had the clouds clear last night to get 2 x 2minute exposures with my new Canon 600D on my 254mm Orion f3.9 Astrograph. I used APT to focus and acquire the shots, I set the IS0 at 200 and set the Camera to Colour, and used dithering in the guiding routine. I have not dark subtracted the image but did align and stack the two image in Maxim DL, cropped the image in Photoshop and processed the image in Startools, final processing I did in Photoshop.


http://www.rodroger.com/images/Astro...n600D_Test.jpg


I am very impressed considering that there is only two images in the stack and no dark subtraction or flat fields.

[SimmoW (SIMON)]

Yep, a good efficient result.

[Saturn%5 (Graeme)]

Very nice Rodney, I have just got a 600d as well i hope i can get results like yours as well

Graeme.

[acropolite (Phil)]

Rodney, exposure and noise looks quite good but there are abberations radiating out from the centre, not sure what would cause this, perhaps someone familiar with your OTA could shed some light on the problem.

[rodroger (Rodney)]

Originally Posted by acropolite

Rodney, exposure and noise looks quite good but there are abberations radiating out from the centre, not sure what would cause this, perhaps someone familiar with your OTA could shed some light on the problem.

Thanks acropolite, I am not using a coma Corrector/field flattener on the Camera and my Telescope manual said I required this filter when using it with EOS DLSR's. A friend of mine said it would fix this common problem with these type of scope/camera combinations. I am just waiting for it to turn up at the shop as it is on back order, I have also ordered a 2" 4 position motorised filter wheel (Orion) with appropriate filters. I was told also a IR blocking filter would be useful?
I have previously been using a Meade DSI II Colour CCD.

[alistairsam]

Hi Rodney

You need a coma corrector, field flatteners are used in refractors to fix the curved plane and an EOS camera or ccd camera doesnt change what is required. You have a much larger sensor in the 600d so deficiencies show up more than the dsi.

Is this cropped, I'm surprised at the relatively minor coma if this is without a cc.
Usually an f3.9 reflector would have much more severe coma, but isnt the f3.9 ratio a resultant of the coma corrector that Orion provide? Native focal ratio is F4? So isnt there anything in front of the 600d?

Have you checked collimation?

Regardless, that is some nice detail you got with just two subs.
And if the camera is not modded, you don't need an IR block as the camera has it already.

Cheers
Alistair

Edit: i'd suggest using ISO 400 and with the filter wheel, make sure spacing from the camera sensor to the coma corrector is as per spec of the cc.
You could start a thread in the equipments section to ask questions about the different bits and issues you might have.

[rodroger (Rodney)]

Originally Posted by alistairsam

Hi Rodney

You need a coma corrector, field flatteners are used in refractors to fix the curved plane and an EOS camera or ccd camera doesnt change what is required. You have a much larger sensor in the 600d so deficiencies show up more than the dsi.

Is this cropped, I'm surprised at the relatively minor coma if this is without a cc.
Usually an f3.9 reflector would have much more severe coma, but isnt the f3.9 ratio a resultant of the coma corrector that Orion provide? Native focal ratio is F4? So isnt there anything in front of the 600d?

Have you checked collimation?

Regardless, that is some nice detail you got with just two subs.
And if the camera is not modded, you don't need an IR block as the camera has it already.

Cheers
Alistair

Edit: i'd suggest using ISO 400 and with the filter wheel, make sure spacing from the camera sensor to the coma corrector is as per spec of the cc.
You could start a thread in the equipments section to ask questions about the different bits and issues you might have.

Thank you for the advice Alistair
The Orion has an effective length of 1000mm and diameter of 254mm.
No corrector in the optical chain, so 1000/254 = f3.937.
The manual recommends use of corrector with EOS cameras.
The FWHM average in the full image was about 8.00 as by Maxim DL.
This I attribute to the edge aberration, they are very noticeable in the uncropped image. I could get away with out the use of a corrector if the object of interest is small and I can crop the image a lot. The 18 megapixels gives me a lot to play with. And resolution wise, I discovered is better as per pixels per arc minute of sky, than the Meade DSI.
Thanks for the tip on the filter wheel
Not needing an IR filter is a bonus and this one saved me some money as I was going to purchase one
The filters that I waiting on are a 2" LRGB set, HA and Comma Corrector.
I am purchasing them of Sirius Optics at Underwood in Qld, as I have so far purchased nearly everything off him so far I guess he can organise the right attachments for me etc..
This was the first time I used the Direct connection to the mount using the "Astronomy Shoestring adapter", "USB/Com port adapter" with "EQmod", and a joystick, worked very well I tried it out with both "Astroplanner" and "The Sky 6".
The Autofocus makes life easy too, still deciding on which software to used for focusing. I have tried out "FocusMax" but found it will only worked with Maxim DL & CCD Soft, The focus routine in APT (Using a Bahtinov Mask) is extremely good also but must be set manually.
The only alternative is to Focus in Maxim DL and just re-check when the temp changes?
Just need some clear skies but could be some time yet, where I live in Redcliffe Qld, expecting lots of rain soon....
Cheers
Rod

[alistairsam]

Hi Rodney

My suggestion, Please start a thread in the equipments section as there are a few serious issues with what youre getting and best to clarify them before you spend your money.
Specifically the use of lrgb and ha filters with an unmodded osc dslr, coma corrector and spacing considerations...

Cheers
Alistair

[rodroger (Rodney)]

Originally Posted by alistairsam

Hi Rodney

My suggestion, Please start a thread in the equipments section as there are a few serious issues with what youre getting and best to clarify them before you spend your money.
Specifically the use of lrgb and ha filters with an unmodded osc dslr, coma corrector and spacing considerations...

Cheers
Alistair

I will do, Thanks Alistair