Reducer/flattener confusion.

[dikman (Richard)]

I understand the concept of a reducer/flattener but not the finer operational nuances of them. So, a question for those with more understanding of these things.....I recently bought an SVBony 80mm/f7 refractor, the reducer/flattener they make for it is only available from their Chinese/US stores, not the Oz store. However, they have one here marked for the 102mm refractor, which is sold here, but their advertising says "Designed for use with refractors with focal lengths of 400mm to 660mm and focal ratios of f/5 to f/7.5".

Does that mean it WILL work satisfactorily with my 'scope? If so, why would they market another one that is marked for the 80mm? There is a significant price difference between them too, the 80mm being dearer.

[AdamJL]

It sounds like have a generic reducer/flattener which should work with your 80mm. It's a fairly common thing as well. I had an old reducer/flattener for my 80ED which was made by Orion and covered a wide range of focal lengths and f/ratios.

You'd just have to make sure you are able to connect it to your scope. My one wasn't threaded; it had to be held in place by nylon-tipped locking screws (which I don't like)

When they make dedicated flatteners for your scope, they are always more expensive. My 0.77x and 1x reducer/flatteners for the Esprit were pricier than the Orion one.

[dikman (Richard)]

Thanks Adam, this is the blurb for it, sounds like it should fit.

SV193 0.8X Field Flattener improves the signal-to-noise ratio;meet the needs of sufficient exposure in a short time
Designed for use with refractors with focal lengths of 400mm to 660mm and focal ratios of f/5 to f/7.5
One side is a standard 2-inch socket to connect to the main lens;the other side is M48x0.75 threaded to connect to the camera bayonet
3 elements 2 groups lens structure;Fully multi-layer coating;Blackened lens edges;a superior clear image for you

I'll do a bit more research.

[AdamJL]

yeah that looks good. It's like my old Orion one - it has to be inserted into the telescope tube and clamped in by the three screws at the back of your scope.

https://www.svbony.com/sv503

[AdamJL]

Yep, that's indeed how it works. Here's a video for you

https://www.amazon.com/vdp/03e3906d5...628c546e70d647

[dikman (Richard)]

I've seen that video but what confused me is the one shown is the dedicated 80mm unit whereas the other one (labelled 102mm) has a longer tube so extends further. That's what made me wonder if it would work.
https://www.ebay.com.au/itm/28495908...cAAOSw4hphNb9O

[dikman (Richard)]

For $149 on Amazon I figured I'd take a chance it would be ok with the 80mm. It arrived today and it turns out I had nothing to worry about. It's designed to work with their 70, 80 and 102mm scopes, (it has a 2" extension tube on the front for 102mm scopes) just remove the 2" to 1.25" adapter from the focusser and screw to the reducer (the adapter has a 48mm thread on the inside), and insert into the focusser. Done.
It looks like when the SV305 camera is fitted to the 1.25" end it sits at the focal plane, but I can't confirm it yet as I have the dreaded lurgy ('vid) so won't be doing much for a while.

All very well thought out. As a bonus it should also work with my 102mm Celestron. Now I'm just waiting for the Canon adapter (48mm thread, my current one has 43mm).