Balancing the scope

[Moonshed]

I emailed FLO explaining the problem and sent them photographs. They have already despatched my order but said that if the bar doesn't fit then just return it for a full refund. They also said they can see no answer to the problem! Can you believe that? What are they expecting me to do, throw away my old Celestron and buy a new one that does take a full length bar? Unbelievable! I replied and asked them about fitting a set of tube rings and I am waiting on their reply. Watch this space!

[CraigT82]

You've probably already tried this but in case you haven't... On your current setup, what if you simply turn the scope around, so that the black clamp knob on the scope and the silver clamp knob on the mount are on opposite sides, would you be able to achieve balance then?

[Moonshed]

CraigT82 well done, what a brilliant and simple idea! Just put the clamps on opposite sides of the bar thus allowing full travel. I removed the bar/clamp from the Celestron, turned it around and screwed it back on the wrong way round. Perfect, I can now travel the full length of the bar and I quickly achieved perfect balance and it is also surprisingly stable. Well done! The simple answers are usually the best. CraigT82 I owe you one!

BTW FLO said it would be difficult to get tube rings to fit as Celestron have made slight changes to the tube circumference over the years. Not that I care!

[Moonshed]

Well that at least explains why Telescope House came up with the solution they did, it was the ONLY solution. I should have known, I have been dealing with them for 25 years and never had a problem. Telescope House, your excellent reputation has been fully restored, how could we have doubted you?

[ollypenrice]

It remains to be seen, though, whether this single rear attachment has much hope for deep sky imaging at high resolution. Until you've tried it you'll find it hard to believe just how stiff the system needs to be, just how little backlash you have to have and just how good the guiding needs to be.

I don't know exaclty which Canon you have but if it were, say, a 1000D you'd be imaging at 0.58 arcsecs per pixel without reducer and still at 0.87 arcsecs per pixel with reducer. These are at the very sharp end of anything I've ever tried even on the very big and very accurate Mesu 200 mount with massive attachments everywhere and an off axis guidier. You are going to need all the help you can get and that single attachment is not going to give you any help on the stiffness issue.

Anyway you're in a postion to give it a go.

Olly

[Moonshed]

Yes, I am sure it will all be very challenging but I have no choice but to give it a go. I will just have to take lots of short subs and hope for the best. If I could find a better way of fitting my scope to the mount I would do it but it would seem there just isn't one. I have to say I am very surprised to discover this, you would think there would be a way in this day and age. If I was an engineer I bet I could find a way! My camera is the Canon EOS 1100D. It will be interesting to see how my foray into digital Astrophotography goes after twenty years of using film.

[Moonshed]

My dovetail bar arrived from FLO this morning, only ordered it yesterday, and guess what, it DOES fit! I was put off because there is only one bolt on the front of the the tube, and it looks very similar to the all others, God knows what they are for, so I was reluctant to unscrew it in case some vital part fell off. As there are two bolts at the other end I had severe doubts that was what the solitary bolt was for. Howevever, when the bar arrived I could see that one fitting had two bolt holes and the other one, so I gave it a go, brilliant! This is such a better set up, way better than that jury rigged thing I had. Photo attached. Looks better doesn't it!

[Waldemar]

I am glad it worked out well, Keith! And yes, it looks a lot better! 

Waldemar

[Moonshed]

14 minutes ago, Waldemar said:

I am glad it worked out well, Keith! And yes, it looks a lot better! 

Waldemar

Thanks for the link to the bar, it proved spot on. Now looking forward to doing some deep sky photography, but with a touch of unimaginable terror as well.? 

[Waldemar]

DSO imaging will not be easy with your set up... so terror it will be ... 
Maybe your best option is off axis guiding ans short exposure imaging. How short?... the proof is in the pudding.
The bigger DSO's won't fit in your f.o.v. Smaller targets like galaxies could be very rewarding.

Succes!!

Waldemar

[Moonshed]

Using my Lumicon off axis guider the field of view takes in the full moon with room to spare, so for example, the Orion Nebula will not be a problem at all. The Telextender combined with a high power eyepiece will of course be reserved for the planets and close up lunar shots.

What is it in particular about my set up that brings you to say that DSO imaging will not be easy? Being new to the digital part of astrophotography I am totally unaware of what it is. Ignorance is NOT bliss!

[Waldemar]

1 hour ago, Moonshed said:

Using my Lumicon off axis guider the field of view takes in the full moon with room to spare, so for example, the Orion Nebula will not be a problem at all. The Telextender combined with a high power eyepiece will of course be reserved for the planets and close up lunar shots.

What is it in particular about my set up that brings you to say that DSO imaging will not be easy? Being new to the digital part of astrophotography I am totally unaware of what it is. Ignorance is NOT bliss!

Hi Keith,

The focal length of your scope in combination with the not so rigid mount with quite a bit of periodic error and the  camera you are using is a challenging combination, but not impossible.
Like is said before: many short subs may do the trick for you. Getting as much information as you can will help too. The many times asvised bestseller:  'make every photon count' will help you a lot. Really good advice in there, a knowledge base you cannot ignore.

Maybe you can think about purchasing a reducer to f 6.3 so you will get a wider field and the whole system will be less critical because it will be faster. There is a reducer to f 3.3 as well, but I never used that. 

A lot of collegues here to help you when neccessary, so ... nothing to worry about!

Waldemar

 

[Moonshed]

Okay, thanks Waldemar. I do understand about it being helpful to fit a reducer for faster imaging and my Easyguider does have such an internal lens fitted, but I would have to dig into my records to find out exactly,  but pretty sure it is around f6. I also understand the problems caused by periodic error but that is something we have to live with. 

What I don't understand is you describing my mount as "not so rigid mount". What is wrong with it, it's just a bog standard EQ5. Or Is that the problem? Should I be using a totally different mount altogether?

Also don't understand why that combination with my standard Canon 1100D is a problem.

I clearly have a lot to learn, but what do other people mount there 8" SCT"s on and what better cameras do they use to create a better combination? It's all so confusing!

And I thought all I had to do was buy a DSLR ?

I will be buying the book for sure.

[physicus]

1 minute ago, Moonshed said:

Okay, thanks Waldemar. I do understand about it being helpful to fit a reducer for faster imaging and my Easyguider does have such an internal lens fitted, but I would have to dig into my records to find out exactly,  but pretty sure it is around f6. I also understand the problems caused by periodic error but that is something we have to live with. 

What I don't understand is you describing my mount as "not so rigid mount". What is wrong with it, it's just a bog standard EQ5. Or Is that the problem? Should I be using a totally different mount altogether?

Also don't understand why that combination with my standard Canon 1100D is a problem.

I clearly have a lot to learn, but what do other people mount there 8" SCT"s on and what better cameras do they use to create a better combination? It's all so confusing!

And I thought all I had to do was buy a DSLR ?

I will be buying the book for sure.

If I were you I'd just have a go and prove everyone wrong  :-).  I did the whole thing backwards starting with a long C9.25 and my 7D and no guiding, and got quite nice pics of the Crab with 1 or 2 min subs - at f10.   And once you're guiding with an OAG, the sky is the limit, as it will probably keep up with the PE.  Secret is to set everything up calmly, step by step, get it all well balanced, focus well; and you'll be punching above your weight in no time !  Then you buy all the other toys.  I got the impression most folks think the EQ5 or equiv is fine for a C8; just balance carefully.

Tim

[Moonshed]

Okay Tom, thanks for that, I will just go ahead and do the best I can and feel sure that with practice I will be able to produce some decent DSO shots. I bought the EQ5 mount from Telescope House, I told them it was for an 8"SCT for tracked long exposure DSO photography and this is what they recommended. I feel pretty sure there are plenty of guys out there with the same set up and producing good results. Looking forward to getting stuck in! 

Thanks

Keith