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Morning folks,

I'm planning a bit of a change in my imaging setup and after much thought I need some input from others if you can.

I want to upgrade my setup, currently a SW 130pds HEQ5 with a 60mm guide scope imaging with a modded 500D.

I often find my imaging time limited but am planning the build of a mini obsy to make longer sessions more practical.

Would mounting a SW72 ed on top of the 130pds be over kill to get an dual imaging system going and increase the data volume, both with a canon 500d and a simple finder guider, the mount should be ok with this.

Or just keep the status quo and add an auto focuser for longer single scope sessions that can be more automated in keeping good focus with the lighter setup.

The dual version I believe would end up having wider field images as I would probably have to add the higher resolution from the longer FL to the shorter FL images.

Any 2p's worth would be appreciated I just want to achieve more productive sessions.



Edited by sulaco

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What camera are you planning to put into the SW72ED?

If you are planning to buy a new camera, I would recommend getting a mono camera so you can collect luminance on one camera and RGB with the DSLR.

I have been using a dual rig for some years now and it certainly does improve the amount of data I can get. 

I too use a finderguider.

You will need an efficient software for re-scaling and registering the images so that the different data matches.

Getting the scope and cameras actually looking at the same thing and having the same orientation is tricky at first and needs to have no flex.  I set up every time I go to astro camp, so have found the Skywatcher gudescope mount a real boon in doing this.  Especially so as I have realised I have cone error and so each side of the meridian needs a little adjustment.

I am also using an HEQ5 and it works well with my set up.

I've attached a photo for your info. 



Dual Rig cairds July 2018.jpg

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Hi Carole,  

Funny enough I was looking at your blog this morning on my way to work. 

I'm using two DSLR's but do plan on a mono at some point in the future.

The current setup weighs 6kg and I don't imaging the 72 ed would increase it much.

Also I use APP for my processing which would handle it ok I think.



Edited by sulaco

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Newtonian dual rig is possible, but... very very tricky to balance.... Keep in mind, your camera will be on the TOP end of the OTA...

Refractors, are much easier in this case as all the weight is at the bottom and central.

First of all, you will most likely need OAG, I tried to balance my 130PDS with Samyang 135mm+Canon on top and a SW 50ED guider... On NEQ6... No luck...

plus if you will add autofocuser with a direct shaft connection, without the pulley,

you will need to add quite a lot of weight at the bottom of the OTA, otherwise autofocuser will not fit, dovetail will be in the way (check my image carefully).

And lastly,

Even if I have managed to balance mine, - I am not completely happy...

The setup became very, Very sensitive on guiding... I do not have constant guiding results now.. A bit worse seeing conditions and the PHD graph is all other the place... and my mount is NEQ6 not HEQ5...

I do not say it is not possible in your case, - just sharing my experience.

My toys ;)


Edited by RolandKol

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Thanks for the feedback Roland,

I suspected that the Newtonian Dual set up might be a pain to balance as most dual rigs I've seen are all refractor based like Carole 's above. 

I already used the Sky adventurer mini with a Sigma 105mm 2.8 lens at the same time and it works great for getting the most of an evening even if it's on a totally different scale.

I think I'll focus on getting the obsy up and running and work on the auto focusing so it can have longer unattended and just need to close the roof.


  • Like 1

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The 72mm lens gathers less than 2.5 times the light the 130mm mirrored system does, even considering the light loss due reflectivity and central obstruction (I considered 92% mirror reflectivity and 8% light loss due to central obstruction). I would not bother.

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Refractor I believe is the best dual/trial imaging setup. Balance is very important to avoid differential flexture as much as possible. I just finish an All 102mm trial imager, perfectly symmetrical so balancing is not an issue. Each has its own filter to have a very productive night.



Edited by retret66
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