CPC925 Upgrade Stage 1 - Visual

[DeanB]

I'm researching into upgrading the stock 1.25" visual train on the 925, in stages, with a view to AP in the near future. Stage one will be visual only, so far I'm thinking:

CPC >

Baader SCT 2" Clicklock Adaptor (Vis Back)

Baader ClickLock Diagonal

< EYEPIECE

Any 2" recommendations for DSO/Planet?

A future upgrade would be either a Feathertouch or Baader ST focuser, though I believe the Baader one attaches directly to the SCT - which negates the need for the Baader SCT 2" adaptor!?

Regarding AP, would the focuser be of use when attaining back focus on a (Full Frame) DSLR? I'll be looking to OAG it at some point, I realise that's a whole new ball game :-) and separate post.

Dean

[brantuk]

This is what I'm saving for for my 9.25:

http://www.firstlightoptics.com/starlight-instruments-feathertouch/microfocuser-for-celestron-925-sct.html

For AP you'll also need a reducer and a heavy duty wedge - the current Celestron wedge is very nice, it provides a solid base for the scope, and is easily tuned in alt/az. A 2" back will enable you to use 2" diagonals for observing - they come with a 1.25" adaptor so you can use both sizes of eyepiece as well as attach most accessories (cameras, focus wheels, oag's, etc).

You won't need to worry about back focus - the Sct has a huge range of focus cos, when you turn the knob, you're moving the whole primary mirror up/down the tube. You'll have no problem focusing a dslr - it can be used at prime focus or afocally with a diagonal and eyepiece adaptor. Hope that helps.

[Tinker1947]

There are many options, but take into account the space from the visual back to the sensor with all the bits joined together, i have just brought the Celestron OAG and when used with the 6.3f FR there isn't enough space for the FR to get get down to the required (recommended) 105mm using the supplied SCT Adapter there is a 48mm female Adapter in the box and i had this altered to a SCT thread it now has a distance of 103mm'ish distance, the Feathertouch makes it a whole new scope as far as focusing goes well worth the money....couple of pictures may help....

Focuser and Click-Lock Visual back 

OAG and FR this has a Moonlite 2" extender to go in to the Visual Back

FLO supplied all the bits and Adapter alterations.... John @ JTechDesign

[Tinker1947]

Well the sun has been out so i opened up the Obby and put the DSLR and AOG in place.....

DSLR - OAG - FR - Visual back

[DeanB]

Thanks both, in conversation with FLO to get this sorted. That’s one chunky OAG! I was thinking along the lines of the TS-OAG at 15mm.

Still working out if I can get the IDAS D1 LP filter into a Baader Protective T-Ring. How/Do you add filters?

I take it the ClickLock between the diagonal and the FR is an extra purchase.

Originally I was thinking of the microfocuser that fits on the back, but I can see the weight saving in replacing the existing!

The wedge is on the horizon as a purchase, once i can get the observing side of things cracked. Is a Baader Hyperzoom too much (8mm-24mm) too much for a CPC? I’m of the understanding that at f10, it’s best to keep at about 10mm - but then I suppose the FR will help on that one... hmmm...

Dean

[Tinker1947]

The adapter that fits the OAG to the T-Ring in the supplied adapters is a 48mm male this would take the filter and then where i have a small spacer put a 48-42mm reducers, this would them suppress LP from the DSLR only, the Click-lock between the diagonal and FR  is a extra that was introduced before the OAG arrived so will be redundant unless i buy a 2nd FR to alter the FL while viewing as the FR  - OAG - DSLR will remain joined together 24/7. I don't have or used a Hyperzoom, but the Baader lens are really nice in these scopes and won't break the bank collecting them or buy the set and save some money....

http://www.firstlightoptics.com/baader-planetarium/baader-hyperion-68-degree-eyepiece.html

The Celestron OAG is a sturdy piece of kit, larger prism and silky smooth guide camera focuser, well worth considering it also has 5 adapters in the box....

http://www.firstlightoptics.com/off-axis-guiders-oag/celestron-off-axis-guider-sct.html

[ollypenrice]

Be aware that the scope won't get anywhere near covering a full frame chip even with the flattener. This needn't be too big a downer because you can crop, but don't expect to get a workable image across full frame.

For DS imaging are you fully aware of the need for a good wedge? A bad one would drive you to distraction.

Imaging at long focal lengths is a tricky business.

Olly

[DeanB]

Hi Olly, I wasn't aware of the vignetting, that's a shame. Although at least it'll get me some AP experience, then if it becomes a bug, I suppose I'll have to invest in an APO :-)

Aware of the need of a wedgie :-) initially this is just a visual upgrade, taking into account AP in the future so I don't go too far the wrong way with bits and bobs on the back. Then it'll be mostly planetary, edging into DSO when experience, budget and cloudless skies permit.

Dean

[ollypenrice]

Hi Olly, I wasn't aware of the vignetting, that's a shame. Although at least it'll get me some AP experience, then if it becomes a bug, I suppose I'll have to invest in an APO :-)

Aware of the need of a wedgie :-) initially this is just a visual upgrade, taking into account AP in the future so I don't go too far the wrong way with bits and bobs on the back. Then it'll be mostly planetary, edging into DSO when experience, budget and cloudless skies permit.

Dean

Not many scopes can cover full frame format, really very few, and most are expensive. It isn't just vignetting, it's coma that can get you. But in astro terms full frame is enormous and most people image with far less chip real estate. 

Olly

[Mr Spock]

For 2" eyepieces get yourself a 22mm T4 Nagler. It's one purchase you'll never regret

[DeanB]

^

I was looking into the Baader Hyperzoom to get an overall view (no pun intended) of what prime eyepieces to purr-chase in the not too distant. Would the 22mm Nagler be your first eyepiece purchase? :-)

I have noticed the rarity of actual 2" eyepieces, many having 1.25 and 2" stems(?). They seem to be more towards the upper end of the mm range - no doubt for good reason.

Olly:

Yes, I can imagine the pixel area off a 5D mkiii having much more real estate than a webcam/most reasonable budget CCDs, which is why I thought it best to hit the floor running with a chip I already invested in. Certainly looking forward to seeing what this is capable of, even if i do need to crop. As a retoucher, I end up cropping peoples arms and stuff all the time :-) I was (obvioulsy falsely) under the impression that coma was more of a Newtonian(?) problem, maybe just more-so than an SCT.

Danke!

Dean

[DeanB]

I got some of the visual train up and working - reducer and Baader zoom - (awaiting the last adapters from FLO for the diagonal) and got out last night for half hour before the clouds set in. Got my first view of M82 too. Did I really view the Supernova through averted vision!? Stunning - yes it was a grey wisp, but what a wisp!

Got the diagonal on this morning, so looking forward to more gaps in the clouds.

D