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11" sct of cg5 - would I regret it?

Demonperformer

By Demonperformer
in Discussions - Mounts

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Demonperformer

Demonperformer

Posted
Posted

I am in the throes of upgrading, and had more or less settled on an 8SE to replace my 6SE.

Until ....

I have just found that for an extra £400 (which in truth would be stretching me to the limit) I could get an 11" sct on a cg5. Now an equatorial mount of some sort is on the cards for the future, and that £400 extra is half what I would pay for an EQ6+EQMOD, and it would include a decent finder that could be adapted for autoguiding, so on the face of it that would appear to be a good deal.

But ...

I am wondering if I would find the cg5 mount not good enough for an 11" scope, particularly as my long-term aim is to get into some serious narrowband imaging (because of all my local friendly streetlights) which involves some pretty long exposures and therefore the need to track the scope accurately for relatively long periods of time. I wonder if I would end up wanting to replace the mount with an EQ6 anyway. If that is what is going to happen, I would rather stick with the 8SE, as I am used to the SE mount and could just get on with using the increased aperture rather than messing around with an EQ mount until later.

So, thoughts anyone, on whether the cg5 is a suitable mount for imaging with an 11" scope?

Thanks.

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Demonperformer

Demonperformer

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@mall ... yes, that's where i saw it

@peter&michael ... thanks, you have more or less confirmed what i thought. I guess what I really needed was someone to tell me I was not making a great mistake by passing it by, which is what you have done. Thanks.

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Adrian

Adrian

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I would point out that it should be ok for visual (I have a 10" meade on a cg5 and that is about the same weight at 15kg), and if you are planning on moving to an EQ6 anyway, it will be easier to sell on the CG5GT than the SE mount in order to help fund the switch.

Whether the C11 would be ok on an EQ6? I'll leave that to someone else...

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perfrej

perfrej

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I find the NEQ6 not quite up to the job with a EdgeHD 9.25, and Orion Shorttube guider and an SBIG ST8300M with Starlight-Xpress filter wheel. It weighs in at 17 kg and it is likely near the limit for the NEQ6, even though I have changed all the bearings for real ones.

/p

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htj

htj

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I've got a CG5, and would not even consider putting a C11 on it. It might be able to handle a C9.25 okaish, but I'd say the sensible limit for imaging would be a C8.

I have mixed tracking experiences, but I think a large part of it is the operator :-). I find I can get to track fairly well at 1270 mm and a webcam for planetary imaging, but things become VERY difficult when I barlow 2x. In fact I haven't managed to get a proper imaging session with that. But the operator might be the fault here.

/H

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rfdesigner

rfdesigner

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not really applicable.. but my 12" newt has a fl of 1500mm, and it was getting blown about quite a bit on my fullerscope MkIV mount the other night (thumping beast of a mount), so much so I had to up the guide rate to 0.2 sec intervals just to hang on in there.

The bit on the C11 that I'd worry about isn't the 11, it's the focal length.

Derek

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Demonperformer

Demonperformer

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Well, that is pretty unanimous. Seems that, if I were to go for the C11 option, I would need to fork out an extra £800 for the EQ6 now to make it a viable option, and that is simply way outside of my budget.

Thank you all for your advice, and I am now reverting to plan A [8SE now, save up for EQ6].

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si@nite

si@nite

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I regularly use the C11 at f10 on the NEQ6pro for spectroscopy....no issues.

Guiding using a beamsplitter and a 25 micron slit. Works well.

I to agree there should be no issues using a C11 on an NEQ6 mount even with guide scope.

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x6gas

x6gas

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Agree with all of the above.

I have a CG5-GT which images and guides well with my C6N but I wouldn't even consider putting the 11" SCT on there. It will just about handle my 10" newt for visual but it's not even worth thinking about for imaging - even with quite short subs...

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Revs

Revs

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I've just mounted a C11 on my HEQ5. It's just good enough for visual and with the f6.3 FR it's just steady enough for imaging... just. I would think a CG5 might be tolerable for visual but nothing like for imaging.

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billhinge

billhinge

Posted
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I am in the throes of upgrading, and had more or less settled on an 8SE to replace my 6SE.

Until ....

I have just found that for an extra £400 (which in truth would be stretching me to the limit) I could get an 11" sct on a cg5. Now an equatorial mount of some sort is on the cards for the future, and that £400 extra is half what I would pay for an EQ6+EQMOD, and it would include a decent finder that could be adapted for autoguiding, so on the face of it that would appear to be a good deal.

But ...

I am wondering if I would find the cg5 mount not good enough for an 11" scope, particularly as my long-term aim is to get into some serious narrowband imaging (because of all my local friendly streetlights) which involves some pretty long exposures and therefore the need to track the scope accurately for relatively long periods of time. I wonder if I would end up wanting to replace the mount with an EQ6 anyway. If that is what is going to happen, I would rather stick with the 8SE, as I am used to the SE mount and could just get on with using the increased aperture rather than messing around with an EQ mount until later.

So, thoughts anyone, on whether the cg5 is a suitable mount for imaging with an 11" scope?

Thanks.

Just my 2 pence worth

I bought one of the FLO C11/CG-5 packages realising that it was possibly on the 'heavy' side - well it's not nearly as heavy as my first 8.5" homemade scope in the 70's (made out of thick plastic sewer pipe and car axles !)

Any way I figured that for the price I was just paying for the C11 and the mount was free. (I was building my own Stevick Paul and pillow block mount but was tempted by the C11)

So I bought a Berlebach UNI to replace the standard tripod and so far I have found the C11 to be acceptable for visual use (what little I've managed thanks to weather). I did try some DSLR short duration snapshots and I reckon it's OK for that too with a bit more practise.

In future I may upgrade to a slightly beefier commercial mount or continue with my DIY project (2" stainless steel bars on 2" pillow blocks) but I'll still have my C11 to put on it eventually

The current CG-5 doesn't seem noisy to my ears and no one has complained so may be they upgraded it recently? I opened the Dec axis to see what was inside and mine was fairly smooth without the nasty grease other people mentioned. (worm has a white grease similar to very soft vaseline)

I've ordered the replacement ADM saddle and and Losmandy dovetail to replace the stock dovetail as this is where the main source of vibration is.

Just a tip, being also once into DIY HIFI which also has a vibration fetish I ordered some sorbathane pads off ebay and stuffed them between the balance weights which helps reduce some vibration there, may get some more to stuff into various cavities :(

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ollypenrice

ollypenrice

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I'd say the CG5 would be totally useless for DS imaging with a C11. The weight says no and the tracking accuracy says no which makes no x no = no squared! In this thread weight, as ever, seems to dominate everyone's thnking. My thinking is dominated by tracking accuracy at long focal lengths. In NB you need long subs, too, compounding the problem.

Clearly I don't have Ken's level of competence when it comes to autoguiding with mounts because Ken can make an LX200 work (not many people can do that!) and he says 'no issues' using an EQ6 with his SCT. My EQ sixes don't track that well under autoguiding and I'd have plenty of issues if I tried it at long FL, which I don't. I don't know what I'm doing wrong but I stick to about a metre of FL with an EQ6. I'd risk another 500mm but no more.

Anyway, for NB imaging would you really want a whacking great FL? The NB objects are often huge and bigger in NB than RGB. What I mean is that in RGB you have the Cone and you have the Rosette, for instance. In NB you realize that they are part of the same structure.

Olly

PS Right now I'm imaging at 2.4 metres of FL on Yves' Mesu 2 mount and that is quite simply plug and play. I walked out, I switched it on, and it is knocking out the round stars. An EQ6 is like that - at short focal lengths.

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Demonperformer

Demonperformer

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Thanks for everyone's continued input on this. I have now got the 8SE arriving today. In fact, the point became a little academic when I saw that the C11CG5 combo had gone from FLO's clearance page!

@Olly - I do see your point about FL. Really my primary purpose is an improved general-purpose instrument. For when I get into NB, I have been wondering if, instead of a finder-guider, I might get something like the Ikharous ED80 with 0.8x reducer. Then, I could use either scope to actually image and use the other one to guide, depending on which is the more suitable scope for the subject. More expensive, but may be more useful in the long run.

I have been following your Mesu mount thread with interest. At 4500 euros, it is a significant leap from the EQ6 and well outside my budget for the foreseeable future. Of course, if the euro keeps performing as well as it has been, but the time I reach the stage of actually purchasing a mount, 4500 euros might not be that much more expensive ...

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ollypenrice

ollypenrice

Posted
Posted
Thanks for everyone's continued input on this. I have now got the 8SE arriving today. In fact, the point became a little academic when I saw that the C11CG5 combo had gone from FLO's clearance page!

@Olly - I do see your point about FL. Really my primary purpose is an improved general-purpose instrument. For when I get into NB, I have been wondering if, instead of a finder-guider, I might get something like the Ikharous ED80 with 0.8x reducer. Then, I could use either scope to actually image and use the other one to guide, depending on which is the more suitable scope for the subject. More expensive, but may be more useful in the long run.

I have been following your Mesu mount thread with interest. At 4500 euros, it is a significant leap from the EQ6 and well outside my budget for the foreseeable future. Of course, if the euro keeps performing as well as it has been, but the time I reach the stage of actually purchasing a mount, 4500 euros might not be that much more expensive ...

If you do go down the long FL route I suspect that you'll be wanting an OAG. I'm using one for the first time and find it pretty fiddly compared with a guidesscope, so at short FL I'd opt for the latter. myself. Even OAGs need anti flexure measures, it seems! I'm still not persuaded by the OAG and can't help thinking that if someone made a proper guidescope - 80mm F5 with full length tube and no focusser, just a fixed back with spacers and focus by moving the camera before locking, it would be fine.

Olly

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Demonperformer

Demonperformer

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8SE has now arrived ... in the throes of unpacking ... sorry about the UK cloud for the next fortnight ...

Mmm ... hadn't really considered OAG seriously - I seemed to have absorbed a somewhat 'negative' overall view, of something that was fiddly to setup and temperamental once you had achieved that - not based on active looking at them, just a general sense from what I had read casually.

Anyway, after a bit of internet rummaging, it would appear that OAGs are something you either love or hate - which I always find makes getting an objective comparison difficult! However, I did find Guide Scope versus Off-Axis Guider analysis to be an interesting article, which seems to make a pretty good case for the OAG - even I could tell the difference between the stars in the videos, and that is saying something.

Pricewise, I reckon a finder-guider (with the mount and adaptor) would cost me between £100-£130. The Ikharous option would be about £350 (but would give me the option of imaging with two different systems) with the OAG coming in at about £160 (the celestron one at FLO). I think that would definitely make it a choice between the OAG or Ikharous options.

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