Wait a minute...I never used a focal reducer!!

[emadmoussa]

I really never saw why I would use a focal reducer. I mainly use refractors which they have wide FOV anyway. Now with C11 SCT..I'm thinking, would it be really necessary if I'm not using it for DSO imaging? Or Visual?

[Naemeth]

Focal reducers are really mainly used for cutting exposure times, a side effect is getting a wider FOV (to be honest, you can see it whichever way around you want ).

I can't see the point of a focal reducer in an SCT unless you are doing DS imaging - the whole point in getting an SCT is for the massive focal length making it an ideal planetary scope, reducing the focal length just makes this more difficult.

[emadmoussa]

Focal reducers are really mainly used for cutting exposure times, a side effect is getting a wider FOV (to be honest, you can see it whichever way around you want ).

I can't see the point of a focal reducer in an SCT unless you are doing DS imaging - the whole point in getting an SCT is for the massive focal length making it an ideal planetary scope, reducing the focal length just makes this more difficult.

Absolutely, I was thinking the same. I posted the question here simply because I thought I was missing something.

[matsey]

Hmm...

I bought one when I just had the 6SE, but only really because I wanted to use my webcam to take a mosaic of the moon and the magnification was too great without it. I now use it on the 925, but only when I'm imaging. For visual, I've only found a few objects that I'd maybe want to use it for - Pleiades being a notable one. But when I want to look at that, I tend to just grab the binos instead rather than faff around putting on the focal reducer then removing it again afterwards. Other large objects, like Andromeda, get washed out with light pollution anyway, so I can fit what's visible in the FOV of my scope without the reducer.

So, if it's visual only, I'd say you probably won't need one, particularly if you've got other scopes with a wide FOV you can use instead.

Matsey

[matsey]

Lol, too slow !!! :)

[emadmoussa]

Hmm...

I bought one when I just had the 6SE, but only really because I wanted to use my webcam to take a mosaic of the moon and the magnification was too great without it. I now use it on the 925, but only when I'm imaging. For visual, I've only found a few objects that I'd maybe want to use it for - Pleiades being a notable one. But when I want to look at that, I tend to just grab the binos instead rather than faff around putting on the focal reducer then removing it again afterwards. Other large objects, like Andromeda, get washed out with light pollution anyway, so I can fit what's visible in the FOV of my scope without the reducer.

So, if it's visual only, I'd say you probably won't need one, particularly if you've got other scopes with a wide FOV you can use instead.

Matsey

Yes, the C11 is meant primarily for planetary and lunar visual and imaging. Refractors give me wide field of view anyway.

[faulksy]

Hmm...

I bought one when I just had the 6SE, but only really because I wanted to use my webcam to take a mosaic of the moon and the magnification was too great without it. I now use it on the 925, but only when I'm imaging. For visual, I've only found a few objects that I'd maybe want to use it for - Pleiades being a notable one. But when I want to look at that, I tend to just grab the binos instead rather than faff around putting on the focal reducer then removing it again afterwards. Other large objects, like Andromeda, get washed out with light pollution anyway, so I can fit what's visible in the FOV of my scope without the reducer.

So, if it's visual only, I'd say you probably won't need one, particularly if you've got other scopes with a wide FOV you can use instead.

Matsey

so with a focal length reducer how much of the plaids can you see, or better whats your tfov ?

[matsey]

so with a focal length reducer how much of the plaids can you see, or better whats your tfov ?

To be honest I don't know..... All I know is that when I look at it without the reducer I can see the central area, but not all seven main stars - so it's always at that point that I grab the bins rather than swapping in the reducer. I suspect though that it would be able to fit it all in... just about.

[Macavity]

Visually, reducers work as calculated, but never *extend* anything much. In practice, with your longest focal length e.p., the typical result with a MCT / SCT is vignetting, secondary shadow etc. Imaging is where the reducer comes to the fore. Particularly with a small "chip", you can achieve great results. A well-collimated, stable, f/10: 8", 9"... 11" scope running at f/5... f/3.3 - What's not to love? Of course, push it too hard and you get all manner of distortion and may not have enough in-focus available, but...

The Pleiades have a nominal diameter of 2 Deg. But (as I found in practice) you need a fair bit to "frame the dipper". Otherwise, they just look like a fairly ordinary bunch of stars! As noted above, you really need a short focal length refractor to do the job. Of course most DSOs are only 10-20 arc minutes in extent, so there are maybe fewer limitations re. these "planetary" scopes than some suggest...

[ollypenrice]

I see no point in using a FR visually in an SCT. The FOV is limited by the baffle tube so a 2 inch widefield EP will reach that limit without reducer and give you higher magnification, less scatter and better contrast. If you don't intend to move to 2 inch EPs then the reducer can widen the FOV.

Olly

PS, Macavity, there IS something not to love about the 3.3 reducer; it is only useful on very tiny chips like the old webcam ones. If all we needed for F3.3 DS imaging was a 3.3 reducer and an SCT you would see no other scopes in use but, alas, it's not like that! The good dealers provide this warning with the 3.3, the bad ones don't.

[emadmoussa]

As a matter of fact I gave up on the idea of focal reducer. I don't see the point especially when half of my EPs are 2 inch.

[Macavity]

PS, Macavity, there IS something not to love about the 3.3 reducer; it is only useful on very tiny chips like the old webcam ones. If all we needed for F3.3 DS imaging was a 3.3 reducer and an SCT you would see no other scopes in use but, alas, it's not like that! The good dealers provide this warning with the 3.3, the bad ones don't.

Hmm... I was fairly careful in implying "small chips"?

But, in my quest for a little levity, a tad ambiguous?

[ollypenrice]

Hmm... I was fairly careful in implying "small chips"?

But, in my quest fo

r a little levity, a tad ambiguous?

I'm wasn't criticizing but just being sure that anyone reading the thread be aware of the limitations of the reducer since I know a number of people who splashed out only to find that it didn't do what they'd hoped it would do. It's a shame, though. If someone could make a Celestron priced F3.3 astrograph they'd take the world by storm! If you use a webcam sized chip the 3.3 is a useful accessory.

Olly

Olly

[Macavity]

I'm wasn't criticizing...

Oh, I (really) do know that...

So much has been SAID on various forums re. focal reducers, severity / origin of vignetting in SCTs (2" and 1.25"), small chips, large chips... Even experimental evidence is insufficient for some! LOL. And, as you say, pursuing the latter can indeed be expensive too.

Perhaps the most satisfactory result for anyone offering "user support"...

Questioner chose not to pursue idea? Result! [teasing]

P.S. I lament the demise of the "focal reducer calculator" - by that Finnish chap.

Just numbers? But if someone / anyone wants to do something really useful...