DSO Imaging: RC or SCT?

[Sp@ce_d]

Bit of a quandary for deciding on a longer FL scope to add to the arsenal.

I had almost settled on an 8"RC but then Sara (swag72) presented her fantastic IC410 with the 9.25 SCT and now I'm leaning towards an SCT!

Budget is probably around 1200 so covers AARC CF & Celestron 9.25 XLT or EdgeHD 800 ( why is the 9.25 Edge more than double an 8" ? )

So, what exactly are the pros and cons of each and what's needed to get imaging at longer FL with the least amount of hassle?

For starters, what I know so far:

Cool down:

RC quicker.. but then I have an Obsy so don't think this matters?

Spikes:

RC - yes

SCT - None

I prefer no spikes ( I can always add them in processing!)

Collimation:

Well, I have fracs so no experience here really

Speed:

I'd want reducer for either.. does either scope have any advantage over the other here?

Focus:

Will they need upgrading?

I've heard about mirror flop with the SCT's. I intend to add motor & focusmax so is there any difference here?

Weight:

Using an EQ6 (at least until I'm happy the EQ8 issues are resolved or I win lottery!)

Your experience/thoughts appreciated

[GuillermoBarrancos]

The edgeHD800 has Mirror Lock for imaging.

Tho the downside of the EdgeHD series seem to be that they require special focal reducers that are quite a bit more expensive than the standard ones used on like the 9.25 XLT.

http://www.firstlightoptics.com/reducersflatteners/celestron-reducer-lens-7x-edgehd-800.html  (tho the reducer for the 8inch HD is still cheap compared to the 600+ bucks for the 900HD and 1100HD  )

There also seems to be something special with 9.25XLT (due to slight different design?), that it has a really good contrast, resolution (and Natural flatter field?). Hence, why it's such a popular scope I guess.

When it comes to focussing and mirrorflop on the regular SCT's.  People tend to install a moonlite/steeltrack/feathertouch focusser like: http://www.firstlightoptics.com/baader-steeltrack-focusers/baader-steeltrack-sct-focuser.html

Teleskop Service sells the 9.25XLT OTA imaging package: http://www.teleskop-express.de/shop/product_info.php/language/de/info/p3657_.html

Last I checked they also sold these OTA's with Farstar/Hyperstar system pre-installed.

[nmoushon]

I started off the same ass you. Thinking a RC would be the best long FL imaging scope but was quickly persuaded to a SCT for several reason.

-No spikes

-completely encolsed mirrors so very little chance of dust getting on them

-With the Edge series you already have a flat field so you dont have to have a reducer/flattener to image with

-The possibility of HyperStar though I will never use one

*You will probably want to upgrade the focuser no matter which one you choose. Though some, more often the RCs, don't even come with a focuser so make sure to check.

*Most RCs are faster than the SCTs and when you add a reducer they become decently fast scopes. Though that only matters depending on your target. If you hunt galaxies then the speed doesnt matter as much but if you hunt nebula then you'll want a faster scope.

*Your EQ6 should have no problem with either 8" scope. I'm pretty sure even the 9.25 will be fine. But if you do get the chance I would upgrade to the EQ8 if you choose the 9.25, it will just make for less fuss.

*You will want to get an OAG to guide with for either scope. This will eliminate any flexure problems that would limit your guiding.

*If you get a SCT I would get the EdgeHD version as they are designed to image with. The only down side is that their reducers are very pricey though there are other reducers out there that are only like $200-300 (instead of $700 for the 11" Edge reducer) that claim to work just as well with the Edge but there are limited reviews on them. Though you dont have to have a reducer because they have a flattener built in so you can image at the full FL and still have a flat field. With the RCs you will need at least a flattener and/or a reducer/flattener.

[Sp@ce_d]

Thanks for the replies. it does sound like the SCT is worth looking at closer then.

It'd probably be an Edge 8 or an 9.25 XLT for the budget as the 9.25 edge is 3 grand with a reducer!, more than double the 8" why is that?

The edge has the flattener built in so I'm not sure how that works if you use a different focusser as you then vary the spacing by fitting a different focuser & reducer?

The reducer for the XLT is 6.3 so a bit faster than the .7 of the Edge. Not sure how to work out what F ratio as the mirror moves to focus so doesn't that change it? From what I've gleamed so far it is possible to lock the mirror on the XLT and use a feahertouch then.

So possibly the 9.25XLT could be the preferred choice for this even though the EdgeHD is marketed for imaging?

Yes OAG guiding.. I have an integrated SXFilterwheel I use now.

[nmoushon]

The FF is built inside the baffle tube so you can put what ever focuser you want on the back and no problem. I don't know the specifics on how it works but i know it works fine lol. You can lock the mirror on the EdgeHD I thought too.

I dont know anything about the XLT so sorry can't help you there.

[Sp@ce_d]

Well, I think I may have committed myself to going down the C9.25XLT route.  A 6.3 reducer & photo back just came up so I took that as "A sign" & bought 'em :grin: :grin:

[swag72]

I'm sure that you won't be disappointed