ED80 + pollution filter + reducer/field flattener

[luka]

Hi

I am trying to reduce light pollution in my images (live very close to city) and I was thinking of getting something like Baader UHC-S for my ED80 + DSLR (Nikon D90 ATM). I am also thinking of getting a reducer/field flattener at some later stage.

I am confused about sizes and how things get mounted:
1. The pollution filter comes in 1.25" and 2" which obviously is supposed to match the eyepiece (does it screw into eyepiece?). What size do I need for imaging with a DSLR? How does it get mounted?

2. What about the reducer/field flattener? For example Skywatcher ED80 0.8x. How does this get mounted? It seems to be 2" - do I need 2" light pollution filter to match it? Does the light pollution filter gets mounted on it?


Also what would be the recommended reducer/field flattener for ED80 (Skywatcher)? There are lots of reviews on the Internet but most seem to be several years old and the mostly recommend William Optics 0.8X II FR has been discontinued.

Thanks in advance
Luka

[Atmos]

The Sky Watcher flattener MAY be screwed onto the back of the focusing unit, someone can correct me there.

As for the filter, you'll need a 2" and that will screw onto the nose piece for the DSLR t-thread.

[acropolite]

IMO the SW flattener is the best option for the ED80. There are specific models for each ED so make sure you get the correct one. Mounting is by threading on to the stock SW drawtube on either the single or dual speed focuser. There's also a wide adapter available for Canon to allow full frame coverage, not sure whether there is a Nikon equivalent. Adapters are now made to allow fitting of the SW reducer to alternate focusers, this one also allows fitting of filters.
http://www.firstlightoptics.com/adapters/flo-adapter-for-skywatcher-focal-reducers.html

Some info and photos of setui in this post http://www.iceinspace.com.au/forum/showpost.php?p=992467&postcount=8

[traveller]

Hi Luka,
I image with an ED80 and a DSLR.
I have T ring on the camera body, then attached an Orion field flattener on it (it will screw into the T ring) http://www.bintel.com.au/Astrophotography/Reducers--Correctors--Flatteners/Orion-Field--br-Flattener/679/productview.aspx
The other end has a 2" filter thread (which I screwed on a Baader UHC-S filter http://reviews.agenaastro.com/review/OFIL-BP-FUHC/Baader-UHCS-Nebula-Filter)
The whole kit then slides into the ED80 focuser unit (I upgraded to a Baader Click Lock like this http://agenaastro.com/baader-2-click-lock-eyepiece-clamp-celestron-skywatcher-m56-2956256.html)
Hope that helps.
Bo

[JimsShed]

I bought the Hotech field flattener for my Skywatcher ED80. Sharp to the edge. It's not a reducer as I didn't want objects to be smaller than they already are. The ED80 already has a wide field of view.
I don't use any filters for my photography as I found little or negative benefit when using my Sony a6000. Instead the image processing using Deepskystacker and Photoshop does a much better job of removing the effects of light pollution.

Jim

[luka]

Thanks to everybody for replies!!!
Things are much clearer now. I was not even aware that the piece in the drawtube unscrews :-)

Now the only thing I am not sure about is the t-ring size. The thread on my t-ring has 42mm diameter. I have seen some which are sold as M48, for example this one (http://www.astroshop.com.au/products/details.asp?id=MAS-053E5). I am just not sure if this is what I need as 48mm is still few mm short of the mentioned 2" (51mm).

Can someone please put a ruler across the middle of the thread on the reducer or the field flattener and let me know a rough measurement. Or alternatively measure the diameter of the thread on the t-ring that fits the reducer/field flattener.

Thanks again for great help
Luka

edit:
Don't worry about my post above, M48 seems to be the right size.
I have also found M42-M48 adapter here (http://www.bintel.com.au/Astrophotography/Camera-Adapters---T-Rings/Bintel-M48-to-M42-Adapter-Ring/1982/productview.aspx). Half price compared to a new M48 t-ring.

Will get it together with the Orion field flattener.

Thanks again

[traveller]

The Orion flattener will screw directly into the t ring of your DSLR.