Widefield Triple Imaging Rig

[Gina]

Hi Gina...how's the vibration when focussing the lenses. ..will you set up all the focus in one go at the start of capture or can you start capture on no1 then 2 ect without vibration affecting capture images.Davy

So far there doesn't seem to be any problem but time will tell when I get into imaging proper without binning. The weather is not very conducive to that ATM Might get the odd hour of clear nigt sky.

[Gina]

I now have the adapters fitted tightly into the plates with the two outer plates able to slide in two directions about a millimetre or so. I could do with devising some method of moving the plates orthogonally with finer control than could be had by grabbing the protruding bit with pliers and tugging/pushing

[Chris]

Well done on getting some test shots under your belt Gina, the allignments looking good! Great progress on the 'contraption' also

[Gina]

Thank you Chris

[Gina]

I'm thinking of swapping the RGB filters for NB and if the sky stays clear long enough, have a go at NB on the Cygnus Loop tonight. Ha on the 460, OIII on the gold 314 and SII on the red one. I'll tackle the framing adjustment system tomorrow. Getting too tired for awkward mechanics tonight. Now where did I put the filter slide?.....

[Gina]

I swapped the filters for NB and set up for an imaging run on the Cygnus Loop but by the time it got dark the clouds had rolled in, so that was that! No DSO imaging tonight

I decided to take some images of the security lights on the garage on the far hill so that I could see how far out the framing alignment was. I was also able to get some idea of how the focus was after adding 1.5mm of padding to reduce the lens to sensor distance and with the thicker Astrodon filters. One of the 105mm lenses wouldn't focus. The other was fine and so was the 135mm. I was surprised how different the focussing distance was between the two 105mm lenses but on thinking about it I've realised that one is with the OIII filter and the other with the SII filter and it's a known fact that ordinary lenses have a different focus this far into the red compared with green/blue. I think this would be an easier test subject for adjusting the alignment than a daytime view.

Here are samples from each set of subs showing the framing alignment. This was with the lenses roughly set in their middle positions. The light was centred in the 460 frame as reference. Images are 460 (reference) with Ha filter, 314-1 Red with SII filter and 314-2 Gold with OIII filter.

[jonnopfc]

Gina,

Just a quick thought, surely with your rig you are possibly producing a psuedo 3D image?

Jon

[Gina]

Yes, with the views across the valley with trees and hedges in the foreground this would be the case. With very distant objects the image shift due to spacing of the cameras would be negligible. The security lights on the garage in the above tests are somewhere between half a mile and a mile away and the outer cameras are about 7" apart. If we estimate the distances as 1Km and 170mm that's a subtended angle of 0.6 arc seconds. The resolution with the 314L+ and 105mm is 12 arc seconds per pixel so the shift is negligible.

[jonnopfc]

Gina, I appreciate that with the distances involved then yes it wouldn't be noticeable certainly where DSO's are concerned and even the planets but it might be noticeable with the moon. We certainly see the moon as a three dimensional object with our eyes so a zoomed in image?

[jonnopfc]

I know that might be asking a bit much with your rig but if images were taken with say two camera's set the right distance apart then there might be a possibility.Or am i talking complete nonsense lol

[Gina]

You would need to be imaging to a small fraction of an arc second per pixel to make it work. The atmosphere in the UK wouldn't allow that.

[Gina]

I've at least temporarily, given up on screw adjustment of the lens alignment and just gone for friction on the lens mounting plates ATM. I might sort out something better later. Meanwhile, using a lot of patience I think I have got the alignment reasonable and I'm hoping to do an imaging run tonight as the forecast is good. Here's the three images across the valley with Ha (460), OIII (Gold 314) and SII (Red 314) filters. Focussing was manual. I used a tree on the horizon for reference.

[Gina]

Managed a couple of hours of imaging time last night 20 x 5m Ha, 24 x 5m OIII and 15 x 5m SII all unguided. Have to sort out the guiding - PHD wouldn't move the guide star enough to calibrate despite all I tried! I increased FL from 55mm to 135mm on the guide camera but still no joy. I'd prefer not to go any longer because of the weight of the longer FL telephoto lenses. Tried the SX Lodestar software but couldn't see how to connect to ASCOM telescope. May try AA5.

Here's the uncropped processed image (Hubble pallette) showing the alignment. I must have inadvertently turned the 460 (used for Ha) as that is at a different angle from the others. Still covering all the 314L+ frames though.

[Chris]

NIce one GIna, You're getting loads of signal even without the guiding, 6 hours work condensed into just 2 hours is amazing, you have certainly worked for it

[Gina]

Thank you Chris

[Epicycle]

Just read the thread, I'm triply impressed! Too complex for me though.Here is alternative although a lot less fun than your project: 3 people at SGL agree to share subs. The three agree the same target, exposure times etc and each one takes ha, oiii and sii. Upload stacks in drop box and voila. After all there are lots people with the combo 460/small refractor or similar...

cheers

E.

[sloz1664]

Hi Gina,

That's a cracking first image on YOUR triple rig. You must be very pleased with the outcome, considering the problems you had with guiding. I am really impressed.

Cheers

Steve

Sent from my GT-I9300 using Tapatalk 2

[Gina]

Thank you Steve Yes, I'm very pleased with the result. This is the first time I've captured SII with this object. Also pleased with how much data I've got in just a couple of hours (only just over one for SII due to bad focussing for the first hour). I was also pleased to get round stars with 5m subs - made the time and effort on PA worth it The rig still has some work to do on it but initial results have made it worthwhile

[ncjunk]

Excellent results well done Gina!

I love that target as well.

Sent from my GT-I9003 using Tapatalk 2

[jonnopfc]

Gina,

That is an amazing picture hopefully one day finances and wife permitting i might be able to produce something that good.

Jon

[Naemeth]

Gina, really nice image. Having a triple imaging rig certainly speeds things up (of course, set-up is complicated as you've proved )

[Andrew*]

Great project and superb first result. Just tiny tweaks to make and you'll be rolling in the data 3 times as fast.

Well done!

[Gina]

Thank you very much everyone

I'm working on it today and hope to get more data tonight - we have a few hours of clear sky forecast

[Gina]

Several hours of clear sky last night but I spent a couple setting up and sorting out. The framing had shifted and the movement I allowed for with the gold camera system (OIII) was insufficient to get alignment. I had fixed the red (SII) imager as I had set that up in the middle of the 460 frame (Ha) and as long as one of the 314s is somewhere near the middle of the 460 it's fine and it's only the 314 to 314 alignment that is critical. BUT unknown to me the red 314 lens mounting had moved between the previous imaging and getting the rig on the table indoors

Fortunately, with the lenses used, the Cygnus Loop is a bit smaller than the frame and I was able to get just sufficient overlap between the 314 frames to cover it.

Here's the result of combining and applying Hubble pallette :-

1. Uncropped - just resized for upload.
   
2. Cropped to cover the Cygnus Loop and resized.
   

[Quatermass]

Very nice Gina, quick question what method are you using to sharpen your images? off topic my be so pm if you like Cheers QM