Atik 383L+ Is a reducer necessary?

[joelshort]

I am anticipating getting an Atik 383L+ mono camera in the next few weeks, and I was hoping some of you Europeans who have this camera could give me a bit of advice (I'm in the USA).

1. I will be using an 80mm APO (f/6.25) and 200mm Astro-Tech RC (f/8), along with 1.25 inch (31mm) filters. Atik says 31mm filters are OK down to about f/5, but will I experience vignetting with my setup?

2. Is a focal reducer and/or flattener necessary with this camera?

Thanks in advance for any advice.

joel

[ollypenrice]

Hi,

I have no experience of your setup but I don't think you'll have any vignetting that flats won't cure.

Whether or not your apo needs a flattener depends on what it is, I would say. Have you imaged with it before? If you have a standard DSLR you could try a quick astro shot to see how the stars look in the corners.

Olly

[joelshort]

Thanks for the reply, Olly. I currently have a QHY8 camera, which has a larger chip than the 383L+, and have used my 80mm apo many times with it. I also have a field flattener (not reducer) and even with the flattener I do get a bit of vignetting with the APO and QHY8, but nothing that flats can't take care of. I suspect with the smaller chip of the 383L+, even using 1.25" filters will not produce more vignetting than I am currently getting with the QHY8.

However, if I use a combination REDUCER/flattener, that will take the f ratio of the APO down to f/4.7, will the flattener part of that offset the lower f ratio, in terms of how much vignetting I get?

As you can tell, I'm really just trying to bide my time until the new camera arrives in a few weeks (hopefully), at which time I can actually test everything out.

joel

[ollypenrice]

Well, according to Atik f4.7 might be a bit margnal, perhaps? You'll have to give it a whizz unless someone out there knows how to calculate it all out. I think you'll love the camera though. One thing to think about with it is flats. You need a dim light box becasue the shutter precludes exposures below a certain time. Is it 0.2 sec? I can't remember. You might kill a bit of waiting time by looking into that!

Olly

[NickH]

200ms is correct. Flats I have raun for a few seconds to be honest. I also noticed vignetting on my TMB setup.. and I think others here have noticed similar...