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Upgrade to what?

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#1 m00nless

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Posted 25 January 2013 - 05:18 PM

I am considering upgrading from an 8" CAT and after reading lots of posts I concluded that such an upgrade would probably not have much meaning (I would not see much more) if I go to a 10" CAT or reflector. So I am now considering either an 11" CAT or a 12" Newtonian. A 12" Newtonian would probably not be easy to handle on my own and a 11" CAT seems a little expensive taking into consideration that I would also need a mount (with tracking and goto capabilities). Any suggestions are welcome.

#2 CJK

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Posted 25 January 2013 - 05:19 PM

What's your goal in upgrading?

-- Chris

#3 Aquarist

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Posted 25 January 2013 - 05:56 PM

Also, do you have a dark observing site? Is portability a requirement?

#4 csrlice12

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Posted 25 January 2013 - 06:38 PM

A 12" Truss Dob wouldn't be too hard to handle, or a Portaball like GeneT's would be great if the funding permits.

#5 JimMo

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Posted 25 January 2013 - 06:41 PM

I switched from an 8" SCT to a 10" Orion dob and thought the image was much brighter and had a much wider true FOV to boot. I sold it when my larger dob was finished but regret it to this day. That 10" was easy to transport and set up and a joy to use. SCT's are great but there was more fuss factor involved compared to a simple dob.

#6 Eddgie

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Posted 25 January 2013 - 06:55 PM

In general, I think that to see really worthwhile improvement, one needs to increase the aperture by about 40% to 50%.

If you are not married to the SCT design, my recommendation would be one of the new Orion 12" Go-To dobs, especially if you have a garage or covered outdoor area to store it. Wheelbarrow handles make it easy to move a dob.

The Go-To dob will give you a huge improvement over what you are using today. You will get both a much wider and much brighter true field. The coma won't be any worse than what you have now, and you can use a Paracorr if you want to, and the field will still be much wider than you can get with a C11, and with the Paracorr, much sharper at the edge of the field.

If you want to turn it into a screamingly good planetary scope, when you get it, send the mirror to someone to have it refigured up to a high level of correction. It will likley be better on planets out of the box than your current scope, but a professionally re-finished mirror will convert it into a fantastic planetary telescope.

The Orion 12" Go-to in a solid tube goes for about $1750. Less than the price of a new C11 OTA package.

My next telescope will be a go-to dob. I just can't decide if I want to do a 12 or 14 inch.

#7 m00nless

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Posted 25 January 2013 - 10:34 PM

This could be a major upgrade after years and the goal is to enjoy the benefits of a larger telescope. I live in a relatively dark site, but portability is important. I can not get an Orion 12" GOTO (they won't ship here), so any more ideas?

#8 Gray

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Posted 26 January 2013 - 12:00 AM

You'll definitely see brighter images with a 12" reflector over an 8" CAT. I'd go for the 12" Meade Light-Bridge if they will ship?

#9 Raginar

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Posted 26 January 2013 - 12:44 AM

Get a 12-14" dob... can you drive somewhere they will deliver? :)

#10 Starman1

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Posted 26 January 2013 - 12:47 AM

Yes, 12" Meade LightBridge with Digital Setting Circles from JMI (you can buy the whole scope already set up from him directly).
Or, if that's not a possibility, any brand of 12 to 12.5" truss dob with a Sky Commander DSC added.(over 16,000 DSOs in the memory)
You really don't need tracking when the field of view is so much larger than an SCT at the same power.
[Example: 8" SCT at 200X with 82 degree eyepiece: 0.4 degree field of view.
12" f/5 dob at 200X with 82 degree eyepiece: 0.8 degree field, or 4X the area of the field in the SCT.

#11 Mike B

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Posted 27 January 2013 - 04:44 PM

[Example: 8" SCT at 200X with 82 degree eyepiece: 0.4 degree field of view.
12" f/5 dob at 200X with 82 degree eyepiece: 0.8 degree field, or 4X the area of the field in the SCT.



Don, i think you must mean a 10mm EP in the SCT @ 82* = 0.40* TFoV, whereas the same EP in the Dob yields only ~150x, and 33% more TFoV.

The same magnification in the same AFoV eyepiece will yield the same true field, regardless of the scope driving said magnification... IOW, the net system FL would be the same if the same mag resulted.

or something like that?

#12 Starman1

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Posted 27 January 2013 - 06:24 PM

[Example: 8" SCT at 200X with 82 degree eyepiece: 0.4 degree field of view.
12" f/5 dob at 200X with 82 degree eyepiece: 0.8 degree field, or 4X the area of the field in the SCT.



Don, i think you must mean a 10mm EP in the SCT @ 82* = 0.40* TFoV, whereas the same EP in the Dob yields only ~150x, and 33% more TFoV.

The same magnification in the same AFoV eyepiece will yield the same true field, regardless of the scope driving said magnification... IOW, the net system FL would be the same if the same mag resulted.

or something like that?

Doh! Exactly.
I should have made the scope the same size, with different f/ratios and the same eyepiece.
Example: 8" f/10 with 10mm eyepiece versus 8" f/5 with 10mm eyepiece.
Your math is correct for the two scopes in question.
The 8" f/10 SCT, with a 10mm eyepiece yields a 0.40 degree true field.
The 12" f/5, same eyepiece, yields 152X and a true field of 0.54 degrees, a 35% increase in field width and am 82% increase in area of field.
Still significant, but my previous post was in error.
Thanks for catching that.
Sheesh, mumble, mumble. :foreheadslap:






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