Celestron CPC1100 Xlt 11"

[newtyng5]

Evening all, quick post and to the point 

I am intending to part ex my 9.25AVX (SCT) for a Celestron CPC 1100 XLT 11". I realise the aperture increase is small. But I am visual only, and decided this is probably the biggest aperture with portability I can go for.

(I did think about the 12" meade, or 14" Celestron or Meade, but they cost loads, and portability goes down)

So the question is, anyone recommend this change, and used the cpc 1100 ?

I tend to spend the first hour or so aligning my AVX, I am only visual, so an EQ mount does not really matter. I have been into astronomy since 1981, my 1st scope was a 40mm tasco (what a scope!)

Cheers and Clear skies !

[alanjgreen]

As a previous owner of a CPC1100, I thought I would pass on my opinions...

Firstly and most importantly, the CPC1100 is a GREAT SCOPE, I had mine for 4 years and we had 100s of sessions together The scope is a great performer for sure but like all scopes there are positives & negatives, which I shall run through here and you are welcome to message me if you have any deeper questions...

Positives.

1. Viewing position - I am not a fan of EQ mounts for visual as I like the eyepiece at the back and pointing straight up. AZ has always been my choice as a visual observer. The biggest positive of a CPC is the MOUNT. Its fantastic, solid as a rock with no wobbles at the eyepiece. Its a winner You wont spend an hour setting this up!

2. Goto & tracking. Nexstar+. Again, these are great and simple to use. Auto 2 star is the alignment to use and is pretty accurate from my experience. I upgraded to starsense in the end as I could do other setup things while the mount was sorting itself out. Starsense works well with the CPC1100

3. Aperture. 11" is a decent aperture and allows access to a large number of objects.

4. Tripod. Solid as a rock.

5. Collimation - My CPC1100 held its collimation very well. I added Bobs Knobs to make it easier to do in the dark.

 

Negatives.

1. focuser. The 11" is a large heavy mirror and having been a previous owner of a CPC800 where the focuser was easy to use and accurate. I quickly had to upgrade the stock focuser to a feathertouch microfocuser (more on focusers later). The standard single speed focuser is just not accurate enough for the large 11" mirror. Celestron should be shipping two speed focusers on £3000 scopes!

https://www.firstlightoptics.com/starlight-instruments-feather-touch-sct-microfocusers/microfocuser-for-celestron-c11-sct-edge-hd.html

2. 1.25" visual back and diagonal not fit for purpose. You should budget for a 3.25" visual back and a 2" diagonal. The stock celestron stuff is so feeble that I dont know why they bother To get the best from this scope then a low power 2" eyepiece is needed and this means that you need to buy a new visual back and diagonal (more later), I had a Baader clicklock 3.25" inch visual back and it was brilliant. Cant beat a clicklock when you have cold hands and are wearing gloves! Again, for £3000 Celestron should supply better standard accessories or just not supply this cheap crap and knock some money off! This is not a "beginner" scope afterall!

https://www.firstlightoptics.com/adapters/baader-planetarium-2-clicklock-adapter-for-large-325-sct-thread.html

3. Balance - The weak point of the CPC is the fact that the tube cannot be moved forward/back on the mount which means you WILL end up with balance issues at some point. The 11" mirror is HEAVY so the scope is delivered back heavy to begin with. Once you get a 2" diagonal on the back and a big heavy 2" widefield EP then it only gets worse. Adding an ADM balance bar and weights underneath gets around all these issues. Don't buy a rear mounted crayford focuser as these will lead to terrible rear balance issues (feathertouch microfocuser is the way to go) due to the weight of the crayford PLUS the extra weight of your eyepieces due to them hanging further away off the back.

https://www.firstlightoptics.com/adm-counterweight-kits/adm-mini-dovetail-counterweight-celestron-11-kit.html

4. Dew - As an SCT owner you will know that they love to DEW UP! you WILL need a dew shield and it will give you 2-3 hours at most on the 11". You WILL need to add a dew heater tape and run it on FULL power if you want to stay outside longer than 2-3 hours. Either get the dew shield with built in heater tape that FLO supply or budget for separate tape. You will therefore need a dew heater controller (simple straight through one will do unless you also go for an 2" eyepiece heater tape (as I did) then a 2-channel controller is needed). This means that you then need multiple cigarette lighter power sockets. In conclusion, if you intend to USE THE SCOPE then budget £100+ for a heating setup or you wont be using it for long on a cold night

https://www.firstlightoptics.com/dew-prevention/astrozap-flexi-heat-dew-shields.html

https://www.firstlightoptics.com/dew-prevention/hitecastro-single-channel-dual-port-dew-controller.html

5. Weight - this scope is VERY HEAVY. Lifting it up off the floor (to take outside) requires you to have a back that is in "A1 condition". It was killing mine so I ended up buying a 2nd CPC tripod that I left in the garage with the scope on. This meant that I never had to lift it off the ground. Go see a CPC1100 in the flesh if you can - its a BIG BEAST of a scope!

 

Other thoughts.

The most important accessory for a CPC is a CHAIR. You get to sit at the back (where the eyepiece will be!) and enjoy a beatiful tracked view. If you are relaxed and comfortable you will see MORE...

1. If you go to see a second hand scope. Release the azimuth clutch and spin the tube. It should rotate up to 360 degree rotation smoothly and without much effort. When I bought my scope this test resulted in a 90 degree spin and then stop. Why was I doing this test? My tracking was drifting away (objects not staying centered). The chinese workers like to overtighten a clutch bolt inside the scope (instructions found on the web), I had to strip my scope down and loosen this bolt a quarter turn, restick with thread glue and all was well. If you get tracking drifting issues (but goto is fine) then this is the first thing to check.

2. On a regular basis, every couple of months, you need to spin the scope in one direction through several full rotations - this redistributes the azimuth bearing balls and helps to prevent unever wear on them increasing their life expectancy.

3. Focusers - budget for a two speed feathertouch microfocuser. The scope is a joy to use with one of these onboard.

4. Make sure you get a fastar version with removable secondary mirror. This allows you to (1) take it out to blow it with an air blower to remove dust and (2) means you can easily remove the secondary when it comes time to clean the corrector...

5. The corrector plate will need cleaning at some point (mine lasted 3 years). Its an easy job that just needs patience. You need to remove the corrector from the scope to do it properly. Get the instructions off the internet just make sure you take note of how loose the little screws on the front are and put them back in the same loose state to avoid pinched optics!

6. BUY a dessicant cap to put in the back of the scope when not in use. It will keep the insides dry and look after the mirrors.

https://www.firstlightoptics.com/offers/flo-125-2-inch-desiccant-cap.html

 

Eyepieces.

With my CPC1100, I used a 41mm panoptic (excellent), a 22mm Nagler (Brilliant and hits the sweet spot), 17.3, 14, 12 Delos (great EPs). You will not need anything below 12mm as it will be too much power.

 

Conclusion

Its a great scope and will deliver great views, but be aware of the negatives and comfortable with them before you jump in. I think you will enjoy the CPC over an AVX mount for sure. 

Make sure you dont overpay for second hand! Celestron have really increased the price of the CPC1100 over the last couple of years. Find out how old the scope is and find out what the seller actually paid for it (ask to see the invoice). Pay a price up to 70% of what the new price was when it was new. Then add on money to cover the extras that are being supplied with the scope.

Have you discounted a 12" DOB? I moved to a DOB after the CPC and while the lack of tracking is a pain, its a much cheaper road to larger aperture. I would not have got mine if its wasn't for Nexus push-to system (from astrosystems) though. I dont go outside to spend all my time searching, I go outside to spend my time observing! - with the CPC you will get plenty of observing.

HTH,

Alan

 

[cfpendock]

I have had a CPC 1100 Edge which is pretty similar to the XLT, for around 6 years, and I concur with everything Alan said above.  It is certainly a stunner when it comes to visual observing.  I bought the Edge because I wanted to move into photography, and the Edge system gives a flat field which you need for photography.

However, there were one or two other differences - the standard eyepiece is an 82 degree 23mm Luminos which is superb.  The other difference is that the Edge has a 3" visual back with a 2" diagonal.

I never experienced bearing wear - although they are in fact easy to replace.  Naively, I also bought a wedge for photography but it was never very successful, so eventually I "de-forked" the OTA and now use it on an Eq mount.

Although heavy at nearly 30 Kg, I found the design of the lifting handles very good and made mounting the scope very easy.  I also found it relatively portable.

As Alan has indicated, dew (certainly in the UK) can be a problem.  I sorted that with a dew shield made from a £5 camping mat and a homemade dew strap.

If you do go down the CPC route, I did learn that for storage it is better to have the OTA horizontal.  If you store the CPC with the OTA vertical and pointing down, if the weather is very hot then grease from the focussing mechanism can drip onto the corrector plate.  Not good.

Chris

[newtyng5]

Thank you so much for your replies. Especially Alan, that's a lot of info, must have took a while, and I appreciate that!

Not sure if my signature appears, but I have a TV Panoptic 41mm, and a TV Nagler 22mm.

Also, as you say I would recommend astrozap heated dew shields (I have one for my 9.25).

And definitely the FLO dessicant cap. (I have one of those and it's a necessity for SCT's in my opinion).

I really appreciate the replies, really nice of you both to take the time!

As for Dob's, I love Dobs, I had a beacon hill 10" years ago. Thing is 9 out of 10 times, I observe (travel to a dark sight), with a friend, and he has a 14" skywatcher goto dob. We have been observing together since we was young, so it didn't make much sense to get another dob, and comparing views from our scopes is always interesting. (surprising my 9.25 had comparable views of certain objects to his 14", faint fuzzies the dob always wins).

Thanks so much again, I will let you know how I get on.

 

Edit, and going forward I intend to replace the luminous eyepiece with an ES 14mm 100°( so I have all 2"), and the myriad is a great eyepiece, but at 9mm (like Alan suggests) I hardly use it, my friend uses it more on his dob, but its good on the moon, and planetary nebulae (and planets if they was not so poorly positions for us northerly folk).

Clear skies

[newtyng5]

Cheers again. Got the cpc 1100 (and its not that heavy at all).

Gonna do a first light tomorrow hopefully (looking favourable). If so will post my thoughts.

I now have a 9.25avx for sale with extras, but cannot post it here (not enough posts). So I posted it to some friends on EMS first, and will post it in a few days on ABS .

Thanks again for the advice. Also managed to get a fastar version, which isn't that important, but makes cleaning easier as you say Alan, cheers m8.

[newtyng5]

Had a quick shakedown , viewing session, very pleased. But wow, the cables get all tangled with the rotation. So I bought a bumbag from ebay for 2 quid, cut a hole in it and put the dew controller inside it, and Velcro strapped it to one side. Ordered 2 more to Velcro strap the tracer power supply to the other side. Jobs a good 'in. Should be ready set go, for next time.

As for observing, it was really misty, even after driving to a darkish sky, but m82 looked great with quite a bit of detail. The scope needs a good clean really, it's not terrible, so will clean the corrector (got the solution and some pec pads), just waiting for the rocket blower. As for the primary, I will leave that and get it professionally cleaned at some point in the future, probably in a year or two (it's not that bad).

Will post a proper first light later.

 

Clear skies!

[alanjgreen]

Yep, Velcro is the way to go. I had all cabling running over to one side and Velcro'd to one of the arms of the scope. I tried to work my way across the sky so this just needed the occasional lift and move of the power pack which I had in a protective box on the floor.

i like the sound of the bum bag solution, I never thought of that.

if you make sure "cord wrap" is on (in the telescope settings) then you won't get tangled, just the occasional slew in the wrong direction as the scope will refuse to pass the "set point" in the same direction.

[Sunshine]

Had the CPC1100, my biggest pet peeve was keeping that huge corrector free of dew, you'll need some good heat with that beast, loved it though but its size and weight were too much as i had to carry the monster down flights of stairs every time i wanted to get out with it, it was a chore.