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Focal reducer... Benefit?

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#1 dgerow


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Posted 28 December 2012 - 09:42 PM

Just wondering? I am the proud owner of an 8SE with no immediate plans to delve into imaging. Are there any advantages for me to obtain a focal reducer? Those darn things really have me confused. :confused:

#2 WarmWeatherGuy


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Posted 29 December 2012 - 12:52 AM

For imaging you want to avoid using eyepieces. To change the magnification (field of view) you would use a Barlow lens or reducer lens.

For visual use you can get a wide range of powers by simply using a wide selection of eyepieces. For any power you can get with the f/6.3 focal reducer you can get the same power with a different eyepiece and not using the reducer. It is better to have less glass between you and the thing you are looking at so it is better to not use the reducer for visual use.

As far as the "flattening" aspect of the focal reducer that also won't mean much for visual use. Your eye can change focus as it looks across the field of view.

#3 barbarosa


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Posted 29 December 2012 - 02:47 AM

Borrow an f/6.3 FR and try it. You might like it for visual. You might even like it better than using a longer f/l EP.

I don't say that there are not some who can detect degradation from the extra glass, but I cannot. A reducer can be less expensive than adding additional EPs. But in the end it is a matter of what works best for each of us I think.

#4 Peter9



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Posted 29 December 2012 - 05:32 AM

I find my 0.6 focal reducer very useful with my 8se on eyepiece down to 25mm. It gives me a pleasing wider F O V of the heavens with, as far as my eyes are concerned, no degradation of the view.
I normally keep mine permanently attached to my spare 24mm x 8mm zoom eyepiece.

Regards. Peter.

#5 Bob Griffiths

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Posted 29 December 2012 - 08:43 AM

I run a 2 inch Denk S1 Power switch diagonal..on both my 8i and CPC1100...

I use the built in focal reducer of the Denk the VAST MAJORITY of the time while I am observing... almost never use the barlow

Could not live without a focal reducer and I am a 110 percent Visual guy

Bob G.

#6 Midnight Dan

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Posted 29 December 2012 - 10:34 AM

Just wondering? I am the proud owner of an 8SE with no immediate plans to delve into imaging. Are there any advantages for me to obtain a focal reducer? Those darn things really have me confused. :confused:

Think of it as the opposite of a barlow. A barlow increases the magnifiation, while a focal reducer reduces it. If you want to see wider views of the sky, you have two options. You can buy a longer focal length, wide AFOV eyepiece, or you can use a focal reducer.

The big downside of an SCT focal reducer, is that it's a pain to put on and off. It has fine threads and it takes lots of turns to remove your diagonal or visual back, put the focal reducer in place, and then replace the the diagonal or visual back. That's why some people, like Bob, use a Power Switch instead. Switching from barlow to focal reducer to nothing is extremely quick. Other people tend to view with the focal reducer in place all the time. This is not a bad option with a long focal length instrument with an SCT. You can still get to the high mags with the right eyepieces or a barlow.

I have a focal reducer but I rarely use it. I have a 36mm, 72° AFOV eyepiece that I use for most of my wide field viewing. Switching eyepieces is MUCH faster than putting a focal reducer on/off. Every once in a while, I go for the absolute widest view I can get which is using the 36mm along with the focal reducer. But again, not very often.


#7 Starman81



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Posted 29 December 2012 - 08:39 PM

These f/6.3 focal reducers (Meade, Celestron, Hirsch, etc) are also marketed as field flatteners. Those of you who use focal reducers, can you see this benefit at the eyepiece??

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