Widefield Triple Imaging Rig

[Gina]

Thank you Mark I haven't applied any sharpening to those images but my usual method is Smart Sharpen from the Filter menu in Ps.

[Gina]

Hoping to do some more imaging tonight as the forecast is good. I've adjusted the position of the lens on the SII + red 314L+ imager so I'm hoping I'll have the framing better. I've also included a 2x Barlow with the 135mm lens and hoping PHD will be happy with that. If not I have a 2nd Barl0w I can slip in. Sometime I'll look at other guiding software but I'm used to PHD.

[Gina]

Imaging run proceeding I have the framing/alignment a lot better but still no guiding. Tried a Barlow but couldn't see any stars - fine without. As for software, PHD won't move the guide star enough to calibrate, with the Lodestar software I can't find how to connect to the mount/telescope and with AA5 the telescope connection is clear and working but it's not seeing the camera. The Ha/460 has a bad gradient. the OIII seems fine though rather poor S?N ratio and the SII should be alright now I've set the binning to 1x1 from 3x3

I guess I'm making progress in the minimum size steps A quantum of progress each day!

Update :- Yes, the SII is fine

[Gina]

Here's a quick combined colour image from some of last nights subs 45 x 5m Ha, 28 x 5m OIII and 22 x 5m SIII. Stretched then aligned with RegiStar and finally simply combined in Ps without further processing other than resizing for upload and saving as PNG. This shows a slight improvement in image framing/alignment. That'll do for now - next job is another attempt at guiding. 5m subs are getting boring

[Gina]

Another lens arrived today to add to my collection Jupiter - 9 85mm f2. That will go nicely with my two 55mm f1.8 Super Takumar giving about twice the FOV of the current setup.

[Gina]

Cloud last night prevented any further testing I put a 200mm lens on the guider to see if PHD would work with that. I think the problem with both the Lodestar software and AA5 is drivers.

[Andrew*]

Here's a quick combined colour image from some of last nights subs 45 x 5m Ha, 28 x 5m OIII and 22 x 5m SIII. Stretched then aligned with RegiStar and finally simply combined in Ps without further processing other than resizing for upload and saving as PNG. This shows a slight improvement in image framing/alignment. That'll do for now - next job is another attempt at guiding. 5m subs are getting boring

Fantastic result, Gina. These lenses do well in narrowband, but to me it doesn't look like the optical quality is up to RGB. Are you using them at full aperture? Stopping them down might open up this avenue. I have found these cheap manual lenses to be somewhat variable in quality, but if you pick up old Zeiss or Pentax lenses they can be good.

Andrew

[Gina]

I stop down - mostly by one stop but in some cases half a stop is enough. I tend to get star flaring at full aperture.

[Gina]

If I have any more problems with guiding, I think I'll swap to the 85mm and 2 x 55mm lenses and go for a bigger area of sky - maybe further up Cygnus like the Eagle and friends. These lenses are f2 and f1.8 so I should be able to run at f2.8 so twice as many photons as the current lenses and with twice the FOV I should be able to do 10m subs unguided. I don't think I'm doing any more 5m subs on the Cygnus Loop. I still have the lastest collection to add to the previous data - definiely reached the point of diminishing returns I should thing - approaching 100 subs each colour! I shall conquer the guiding in time and then I'll go back to the Loop and do longer exposures. Meanwhile, I think the shorter FL lenses should be quite interesting (next time we get a few hours of clear night sky).

[Gina]

I decided to swap lenses anyway and took some images across the valley this afternoon to check alignment. The FOV with these lenses is almost perfectly matched so I'll want the alignment to be good. I plan to look further into the alignment issue - I have some new ideas. Here is a sample image from each camera - only rough manual focussing without any aids. I have a plan for a better manual system with timing belts and pulleys with large adjusting knobs. I expect to set up electronic control with stepper motors later.

[michael8554]

Very nice Gina

Once you have the FOV and rotation about right, isn't there stacking software that sorts out FOV and rotation for you?

Cheers

Michael

[Gina]

Thank you Michael

I use RegiStar to align and resize images to fit together - does a great job Doesn't work on landscapes though - only stars.

[michael8554]

Doh ! (extracts foot from mouth.....)

[Gina]

Quite a lot of streaky cloud about last night so little joy with imaging - I was chasing the clear areas around the sky OTOH I did have one breakthrough - got guiding working So simple - just increased the guiding rate in EQMOD from 0.1 to 0.7 in each direction Now have calibration in 12-15 steps per direction. I increase the integration time in PHD to 2s to avoid guiding chasing the seeing and reduced the RA aggression from 70 to 60.

[Gina]

Clear sky tonight - hopefully for several hours With guiding working I am upping the exposures to 20m. I started with 5m for a couple of subs then 10m for 3 subs and now I'm on 20m. Got everything going by 10pm including refocussing and achieving less than FWHM of 2 on all three cameras at 1x1 binning.

I now seem to have guiding set up pretty well - this is a capture of PHD's graph.

[Gina]

Last night we had the best clear sky I've seen for some time. Th Milky Way was clearly visible with the naked eye and seeing and transparency were good. Had the lowest FWHM I've seen yet with under 2 on all 3 cameras. Images were good right up until dawn. I collected 17-18 subs of 20m in each channel plus the 3 10m and 2 5m as I worked up to the final exposure length. As it happens I could probably have gone for longer subs but recent experience has shown that what was good at midnight deteriorarted as mist or cloud came in soon after leaving it to itself. Totals were actually 7 hours on Ha and OIII and 6h 40m on SII so overall a total of 20h 40m for the night How about that then? And in summer - should be good if we get any such great nights in the winter.

Here's the stretched 3 stacks aligned in RegiStar.

And the combined and Hubble palette processed image uncropped.

[JAS]

Very nice Gina, looks like all of your hard work has paid off.

Jason.

Sent from my LT15i using Tapatalk 2

[cfpendock]

That's an amazing image, Gina. I have to say I am very impressed with what you have made of this rig.

chris

[sloz1664]

Hi Gina,

You must be well pleased with last night's results. They are amazing. So many stars.....

I'm really impressed.

It's ssooooo good when a plan comes together.

cheers

Steve

[Gina]

Thank you everyone Getting there

[Gina]

Been doing a bit more to this - improved alignment arrangement and reduction drive focussing (still manual ATM). All set up and ready to go for the forecast clear sky tonight. HAH!! Weather foercast - don't make me laugh - it's totally overcast Even the moon is struggling to make itself seen through the cloud!

[Gina]

Now going on to remote focussing with stepper motors driven from an Arduino Mega. The hardware is built and we now come to the sketch to use with it. Most of this is already written and been used in the twin imaging rig so it only needs minor changes. Experiments with the manual focussing setup show that direct stepper drive with 15 tooth timing pulley driving the focus sleeves on the lenses should give fine enough adjustment. If not I'll sort out micro stepping.

Stepper motor Arduino pins :-

Stepper 1

31 - 1. Blue

33 - 2. Pink

35 - 3. Yellow

37 - 4. Orange

Stepper 2

39 - 1. Blue

41 - 2. Pink

43 - 3. Yellow

45 - 4. Orange

Stepper 3

47 - 1. Blue

49 - 2. Pink

51 - 3. Yellow

53 - 4. Orange

[Gina]

Here is the sketch for the focussing system - not tested yet other than to verify that it will compile.

// Arduino Sketch for triple imaging rig focus control using stepper motors type 28BYJ-48 5v driven by ULN2003 driver modules
// This uses an Arduino Mega 2560.
//
//declare variables for the motor pins
int motorPin1a = 31; // Blue - 28BYJ48 pin 1
int motorPin2a = 33; // Pink - 28BYJ48 pin 2
int motorPin3a = 35; // Yellow - 28BYJ48 pin 3
int motorPin4a = 37; // Orange - 28BYJ48 pin 4
//
int motorPin1b = 39; // Blue - 28BYJ48 pin 1
int motorPin2b = 41; // Pink - 28BYJ48 pin 2
int motorPin3b = 43; // Yellow - 28BYJ48 pin 3
int motorPin4b = 45; // Orange - 28BYJ48 pin 4
//
int motorPin1c = 47; // Blue - 28BYJ48 pin 1
int motorPin2c = 49; // Pink - 28BYJ48 pin 2
int motorPin3c = 51; // Yellow - 28BYJ48 pin 3
int motorPin4c = 53; // Orange - 28BYJ48 pin 4
////////////////////////////
int motorSpeed = 1200; //variable to set stepper speed
int count = 0;		 // count of steps made
int countsperrev = 512; // number of steps per full revolution
int lookup[8] = {B01000, B01100, B00100, B00110, B00010, B00011, B00001, B01001};
//////////////////////////////////
int wfPin = 10; // Widefield focuser select switch
int controlPin = 0; // Input control line pin
int wf =0; // which focuser
int focusCount = 0; // focus count for WF
// int focusCount_b = 0; // focus count for scope
// int focusCountPrev_a = 0;
// int focusCountPrev_b = 0;
int val = 0; // value of control input voltage - function
int wfval = 0; // value of control input voltage for which fucuser
int opCode = 0; // corresponding operation code
int stepSize = 5; // how many motor steps correspond to one focussing step
boolean busy = false; // used to provide single action buttons - wait for "up" before continuing
//////////////////////////////////////////////////////////////////////////////
void setup() {
//declare the motor pins as outputs
pinMode(motorPin1a, OUTPUT);
pinMode(motorPin2a, OUTPUT);
pinMode(motorPin3a, OUTPUT);
pinMode(motorPin4a, OUTPUT);
pinMode(motorPin1b, OUTPUT);
pinMode(motorPin2b, OUTPUT);
pinMode(motorPin3b, OUTPUT);
pinMode(motorPin4b, OUTPUT);
pinMode(motorPin1c, OUTPUT);
pinMode(motorPin2c, OUTPUT);
pinMode(motorPin3c, OUTPUT);
pinMode(motorPin4c, OUTPUT);
Serial.begin(9600);
}
//////////////////////////////////////////////////////////////////////////////
//set pins to ULN2003 high in sequence from 1 to 4
//delay "motorSpeed" between each pin setting (to determine speed)
void serialDisplay()
{
Serial.print ("Focus No."), (wf+1);
Serial.println(focusCount);
}
void moveBackward()
{
for (int s = 0; s < stepSize; s++) {
for(int i = 0; i < 8; i++)
{
	 setOutput(i);
	 delayMicroseconds(motorSpeed);
}
}
focusCount--;
serialDisplay();
}
///////////////////////////
void moveForward()
{
for (int s = 0; s < stepSize; s++) {
for(int i = 7; i >= 0; i--)
{
	 setOutput(i);
	 delayMicroseconds(motorSpeed);
}
}
focusCount++;
serialDisplay();
}
////////////////////////
void setOutput(int out)
{
switch(wf) {
case 0 : {
	 digitalWrite(motorPin1a, bitRead(lookup[out], 0));
	 digitalWrite(motorPin2a, bitRead(lookup[out], 1));
	 digitalWrite(motorPin3a, bitRead(lookup[out], 2));
	 digitalWrite(motorPin4a, bitRead(lookup[out], 3)); }
case 1 : {
	 digitalWrite(motorPin1b, bitRead(lookup[out], 0));
	 digitalWrite(motorPin2b, bitRead(lookup[out], 1));
	 digitalWrite(motorPin3b, bitRead(lookup[out], 2));
	 digitalWrite(motorPin4b, bitRead(lookup[out], 3)); }
case 2 : {
	 digitalWrite(motorPin1c, bitRead(lookup[out], 0));
	 digitalWrite(motorPin2c, bitRead(lookup[out], 1));
	 digitalWrite(motorPin3c, bitRead(lookup[out], 2));
	 digitalWrite(motorPin4c, bitRead(lookup[out], 3)); }
}
}
///////////////////////
void moveB10() {
if (busy == false) { // do it once then wait for button release
for (int i = 9; i >= 0; i--) {
moveBackward(); }
busy = true; }
}
////////////////////////////
void moveB1() {
if (busy == false) {
moveBackward();
busy = true; }
}
//////////////////////////
void moveF1() {
if (busy == false) {
moveForward();
busy = true; }
}
///////////////////////
void loop() {
wfval = analogRead(wfPin); // Select which focuser to control
// Break points 333 and 666
if (val < 333) { // allow for small variations in control line voltage by separating into bands
wf = 0;
} else if (val < 666) {
wf = 1;
} else {
wf = 2;
}
val = analogRead(controlPin);
// Break points 102, 307, 512, 717 and 922
if (val < 102) { // allow for small variations in control line voltage by separating into bands
opCode = 0;
} else if (val < 307) {
opCode = 1;
} else if (val < 512) {
opCode = 2;
} else if (val < 717) {
opCode = 3;
} else if (val < 922) {
opCode = 4;
} else {
opCode = 5;
}
//
switch(opCode) {
case 0 : busy = false; delay(100); break; // clear busy flag and wait for button state to settle (switch bounce)
case 1 : moveBackward(); break;
case 2 : moveB10(); break;
case 3 : moveB1(); break;
case 4 : moveF1(); break;
case 5 : moveForward(); break;
}
}

[Gina]

Been adjusting the framing/alignment. Here are a couple of images using Difference mode in Layers in Ps. The 314s difference and the 460 compared with a 314 - Ha v OIII. Being narrower the 460 is more difficult to get the rotation dead right. Here it is 1 degree out. Unfortunately this comparison method relies on captured images being converted from FITS to TIFF before opening in Ps, so it's not a "live" method

[Gina]

Clear sky tonight so all set up and capturing the Heart Nebula. Had I been ready with camera rotation sorted out I may have been able to get the Soul in the frame as well. I might do a mosaic later with the Soul Nebula in the frame.

After a couple of 5m subs of each to assess the exposures I set up the Ha for 20m and OIII and SII to 30m. Here's a single sub of each, converted from FITS to TIFF and tweaked a bit in Ps.