Dual imaging setup - would this be a possibility?

[h0ughy]

well i have been thinking - yes i know thats dangerous. I am toying with the idea of getting another gliman special (127ED) to mount side by side with my existing scope. the theory or idea is to align the second scope to the exact location of the first, have the 2 cooled 40D's setup in exactly the same way, orientation and guided by one scope (ed80 that i have now) leaving room to mount the 60mm lunt on the new scope. That way i could in theory get double the exposure times for the same amount of time imaging. With the weather the way it is photon time is at a premium. My question is to modify a losmandy SBS bar or make up a new one? or is there a SBS bar out there already that would allow for this type of thinking. I do not wish to use rings? Also with the capacity of the G11 being 27kg, would this payload push the mount past its limits?

Am i nuts?

[multiweb]

:lol: I reckon that's a great idea. :thumbsup:

[gbeal]

He he, I reckon both are dangerous mate, you thinking, and the side by side idea, LOL.
Seriously though, two at. Once is a great concept, and one I have even considered, but I would be using two differing focal lengths, or cameras to be honest. ED127 and a real long sucker, or really short sucker, or the old RS200 Vixen or similar. Not two exact scopes and cameras.
Mind you, that is just me.
Gary

[h0ughy]

am i nuts Marc? so you think this is a real possibility?

[h0ughy]

same focal length, same cameras, same scopes? the vixen has passsed on to a better land Gary ;)

[multiweb]

Well yeah, the concept is sound. You double your exposure time. The only problem is the mechanics. Handling the weight. You're giving me ideas about getting a mono and shooting highres luminance on one scope while getting colour on the other and vice versa.

[gbeal]

Oh dang Huffy, now look what you have started.
I still favor the different camera and or focal length, but agree, the idea is sound, as long as you can handle the what ifs.
Gary

[g__day]

David,

If you could ensure enough rigidity to eliminate differential flexure, and guide off say a OAG on the longer focal length scope - you could reasonable expect to take two shots at once. Given the differing scopes would have differing magnification and fields of view - doubt you could readily stack the shots across different OTAs though.

Also aligning the scope perfectly might be challenging if one is a SCT - their mirrors tend to sag slightly as you point them across the night sky.

Maybe borrow some gear and give it a go - or ask someone else to try it for you?

[Octane]

There's no reason why you can't stack different focal length images.

I think Tom Davis does the same thing; captures high resolution luminance data with one scope on a large instrument, and, then the widerfields are captured with an FSQ astrograph. Typically, the larger instrument would be honed in on areas that you wish to provide exquisite detail in, such, as fine detail structure of nebulae, while the widefield instrument captures the surrounding starfield. Blend the two as required in post and you have the best of both worlds.

It would be an awesome thing to do. If only I could!

H

[Omaroo]

Been there, done that David. It works a treat. I mixed and matched cameras and scopes for a while - using Registar to align the disparate images for subsequent stacking. I had the FS-102 and Sky-90 imaging at one stage with the FS60-C guiding, and then a C8 and Megrez 80 being guided by the FS60. I had CCDs and DSLRs hooked up in all manner of combinations. The nice thing about using scopes of slightly different focal lengths is that you can also use the narrower FOV to mask over the core of the wider FOV to give it more detail.

[h0ughy]

thanks for the feedback - i am talking about exact same setup of scopes - dsame focal length (identical scopes) not different sizes thoug hi appreciate the responses. matthew that would be my only concern, but rigedly mounting both otas would help reduce "movement - but i dont mind if they are afew pixels out - helps to reduce noise ;)

[Omaroo]

While you're at it David - pick up a pair of amici prisms and construct yourself a rather decent pair of binoculars... :)

[strongmanmike]

The way I see it a 5" scope plus a 5" scope = still less image brightness and thus SNR on extended objects and less depth on point sources than a single 8" scope..let alone a 10" or 12"...?

Given you are talking one shot colour it may be a waste of effort and more expensive in the end :shrug: ie just get an 8" or 10" scope instead.

If you were talking doing LRGB where one scope did the Lum and the other the RGB, maybe you would be on to something :thumbsup:

Mike

[ballaratdragons]

It sounds like a good idea to save time and get more exposures in a given night.

But don't fall into a perfectionist trap of spending two hours exactly aligning both camera orientations. That's where Registar comes to the rescue.
Your cameras can be on totally different orientations, or even at different focal lengths, FOV, whatever. Registar fixes it all.

[[1ponders]]

Nah nah nah Dave. Send one up here (you'll have to throw in another G11 to mount it on though). With that sort of baseline you might be able to get some sort of stereo imaging happenin' ;)


:D

[gregbradley]

Robin Cassady makes a tandem bar and a saddle with adjustments on one so you can do that.

I may still have a Cassady tandem bar (not sure) if you are interested.

Considering how much time it takes to frame an object just right I wonder how good that would be. Perhaps a better setup and one I have seen used a lot is where a widerfield scope is used for colour which is less demanding for detail and a longer focal length for luminance and detail. Aligning them then with no waste of FOV is easier.

If your two scopes weren't accurately aligned you would lose FOV of your camera which could degrade the final image.

In fact this what I was planning to do with my 2 setups. The TEC180 for colour and the CDK for detail. As you say getting double the exposure time is valuable given weather vagaries.

Greg.

[h0ughy]

i am interested - whats it look like - is it all losmandy D plate compatible?

[gregbradley]

Yes it is. I'll have a look for it and see if I can find it.

Greg.

[Peter Ward]

Leading question? :)

A single 8" aperture will gather more light than your 2x setup......

[h0ughy]

thanks for confirming my temporary insanity Dr Ward:D

just sounded a good idea:shrug:

[Paul Haese]

I'm with Mike. If you are gonna do it use two mono camera's You could also do narrow band and RGB at the same time. Using two 40D is a waste of money. Yes they are good but you will get more out of two mono's in the end.

[strongmanmike]

Hey! I was the first to point out that you are a blithering idiot :shrug:

[rally]

Sounds like a good idea in theory - but . . .

2 different sets of Master Darks and the complete Darks library to go with it
2 different sets of Flats to take each night
2 sets of equipment to manage focus between frames

So thats a lot of extra data, processes and potential problems to juggle with and more time taken per night getting the calibration data you need.
More problems on pier flips managing your image data orientations.
If you have your processing down pat and never ever get mixed up - Maybe, just maybe - if not, I wouldn't.

There is always going to be flexure and misalignment - no big deal, but when the two cameras are rotated its another misalignment step to deal with.
Guiding with three scopes to manage now - double the flexure problems on longer exposures.

At the end of the day it sounds like you are trying to get better results by having more data but in reality you are not improving the quality of any particular system - guiding, tracking, acquisition, image quality, focussing.
Potentially even reducing some of those.
Given the extra time doing flats etc you aren't necessarily going to get double the exposure time anyway.

As Peter says
. . . just get the CDK17

Rally

[h0ughy]

thanks for your support Mike;):thumbsup:

well if we cant dream we are dead - Eh?

I might trial the idea with the 127 and the ED80 (larger field of view) and see how that works - no money spent LOL

[Barrykgerdes]

Yes two identical telescopes on the same mount could be interesting as long as they are separated by a couple of feet. Get the video in phase and process it the right way and get the resolution of a two foot aperture.
For those who don't understand feet substitute 30 CM for each foot of separation.;);):D

Barry

[Peter Ward]

..... it is cool however to have different focal length scopes hanging off the same mount.

Side by side plates keep the centre of gravity low, reducing the need for extra counterweights.

[multiweb]

Well, while it's true that one scope of larger aperture will do a better job than two scopes of smaller aperture I still don't think it's a bad idea. You have two scopes, whether they are the same FL or not and two cameras that can do two different things. RGB on one NB on the other or Lum, etc... So yes you double your production. There are multiple softwares now doing good registration between pictures with different image scale and orientations so processing is not an issue anymore. That is no different than mixing old data with newer subs.

[gregbradley]

When the weather is stable and there are a reasonable number of clear nights all that extra work may not be that valuable.

But when you hit a patch of wettish, cloudy weather like Sydney has had for nearly a year now then 2 scopes to double production makes a lot of sense.

Tom Davis has been doing that for ages with his ASA12N for luminance and a Televue NP127 for colour (one shot STL11) with fabulous results.

I am planning to do the same except in my case I am using 2 setups rather than a tandem bar on one. Main problem there is orienting the 2nd scope. That's where the Cassady adjustable saddle setup is the go.

Greg.

[loc46south]

Dual imaging is feasible and it does work - but it is a real pain. I tried it to beat the weather - tried imaging mono & colour at the same time. Biggest problem is flexure and with 2 DSLR's I don't think you will overcome it. My setup - http://www.pbase.com/loc46south/image/120564600

It used a ED120 Equinox and a SW100EDPro on a Losmandy double saddle Plate. I used internal guidence for mono Luminance and external guide head for narrowband. The ED100 shot continuous colour and I ended up using an AO8 to get rid of flexure issues between the two scopes.

The biggest problem comes when you want to automate it and use off star auto focusing - fun fun fun :D:D:D. In the end I gave up and bought a M250.

Geof

[h0ughy]

do you still have that bar Greg?