View Full Version here: : Focal reducer for astrophotography with a dob?
13-04-2012, 11:39 AM
I was planning on doing some astophotography with my sdm this weekend. Is it possible to use a focal reducer to get a wider field on my f4.8 scope? I want to attempt taking a series of images using my SLR (40D) and de-rotate them through software. I had Peter make me a set of shorter truss poles to bring the SLR to focus.
I want to attempt imaging a few DSO with the SDM, see how it goes. I have Servocat installed to assist with tracking.
Would appreciate any tips, thanks :D
13-04-2012, 12:17 PM
I'd see if you could borrow a FR and find out if it suits before investing your hard earned dough. :)
You should be able to go for at least 20 seconds before any trailing is visible and you will be surprised at just how much detail you will be able to capture in that short time.
Set your camera to raw and keep shooting until you fill your card, try for at least 70 or 80 images. You might consider turning on the In Camera Noise Reduction. That will save you having to to darks later.
I wouldn't be worried about Flats atm. Focus on capturing your Light frames for now, learning your camera and how it works with your scope. Enjoy this first stage of the learning curve.
13-04-2012, 12:59 PM
The only reducer / corrector for newts I can recall was made in Germany by Keller and was very expensive and only covered a CCD chip like an ST10 or ST8 but would make your scope work at ( I think ) F3
The main thing you will need is a coma corrector , the televue on slows the scope by 15% but the Baader will keep it at F4.8 and should work well.
Note that they both need some "in focus " room.
It would be good to here how you go , I have a Servo Cat on the 24" but have never tried imaging with it.
14-04-2012, 01:44 PM
Cheers thanks for that. I'll give it a try and post up how it goes.
Wow I didn't realise just how expensive these things are:eyepop: .I'll definitely try to borrow one from somewhere if I can first. You should be able to take some nice dso images with the 24" using short exposures. I'd love to read your experiences if you try it :)
Hi you can use a sct 6.3 reducer flattener on your Newt and it works quite well but you must find the correct spacing. The field is not as flat as a high end ASA but the image is quite nice.
Clear skies Ken.
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