[John K]

Hi guys,

Well, I envisage that in the next 6 -9 months at most, I would like to move on from my modified Canon DSLR - an ageing Canon 400D, to a mono camera.

Had aspirations initially that perhaps I would go to a cooled OSC camera or a cooled/modified DSLR, but I think if I can address the issues below, a mono could work for me.

Firstly, all my imaging is done with a portable set up with a 12.5" f/5 scope and a focal length of 1600 mm which currently uses a MKIII Baader Coma Corrector, OAG and Loadestar guide camera.

I already do mono work for planetary imaging and have a UK made True Technology filter wheel with 1 1/4 inch LRGB filters.

My criteria as follows:

1. Budget - absolute max $2000k tops, if I have to get a new filter wheel and filters, then max $2,500

2. As my mount is not high end - max exposure levels 5 mins per shot. This means I cannot do like 20 minute expsures, and 10 minutes is pushing ti for me without being in an observatory. This to me means that I need a high efficiency QE chip?? ie. high sensitivity?? and/or that the signal to noise ratio vs sensitivity needs to work in 5 minute increments for stacking.

3. Need to be able to shoot LRGB sequence for an object within one night and ideally 2.5 to 3.0 hours total LRGB exposure time. Most of my DSLR shots have been at this level, and I have been comfortably been able to shoot one object per night. So to me, this says 45 minutes per LRGB channel maximum exposure. HOW REALISTIC IS THIS?

4. Ideally still be able to use my filter wheel and 1 1/4 INCH filters. Optionally upgrade just the internal filter holder and to 2" filters. The True Technology never accepted square filters but I think I can get a 2" filter wheel holder with 5 filters.

5. My current CCD chip on the 400D is 22.2mm x 14.8mm and 3888 x 2592 in pixels. I don't need for the CCD to be bigger than this, but ideally I don't want it to be much smaller as I find it fits most deep sky nebulas perfectly in my 12.5" f/5

6. In terms of image scale, I am guessing that I would like image scale of around 0.7 arc seconds per pixel or thereabouts to allow me to do sharpening and some deconvolution. I could have this wrong. My shooting location (Heathcote, Vic) is not renound for the seeing conditions, but it can be ok.

7. I am not a brand freak - I am not into high end or low end brands. For me it's about value for money, and also about getting the latest technology. I know that QSI?? and Sony?? chips at the moment are being talked about highly. Not fussed - just want something that will be still producing results in 5 years. I have been able to get 8 years out of my DSLR and it's still going strong.

8. Weight. Not discussed very often, but the lighter the better - my scope has a rotating truss and if the camera weighs more than my Canon 400D 510 grams than perhaps I will be pushing it when I add my filter wheel.

9. Ideally needs to be usable with my Baader MKIII coma corrector so I don't have to buy a new one. Only have a spacer designed to be used with a DSLR.

10. Back focus - I currently appear to only have 15mm of back focus left. THIS COULD BE A SHOW STOPPER! But this already includes the OAG, coma corrector and DSLR adaptor and then the 400D. I hope this issue alone is not a show stopper indeerd! Otherwise perhaps the solution is simply a camera with a built in low profile filter wheel??


Am I dreaming here? A lot of things to consider.

Hope the people one IIS that have been on the same journey and moved on from a DSLR, but also with the above complicating parameters, can offer some advice.

Look forward and appreciate your comments.

Clear skies,

John K.