Pitch Black Skies

On 24/11/2022 at 19:23, Mark Jo said:

were you able to find a solution for the focus?

 

 

I was. I moved the rotator into the back focus.

Hi, I can confirm that they fit fine 🙂 

Peter, that's a great idea. Thank you for your help. 

I need some time to figure out the backspacing but I'm sure this will work.

Alan

@whipdry To use your method I will need an adapter that is m63 female to m42/T2 male.

I don't know if it's just me but I just can't seem to find one.

Hi Peter, well spotted. And yes your right, it does indeed have an m63 male thread there. However it increases the backspacing from 55mm to 63.3mm.

I meet my 55mm with a 10mm and 16.5mm extension. 

I've come up with another solution to incorporate an m48 rotator into the backspacing. 

What do you think?

I should mention that there's an EFW between the camera and the 10mm extension. 

Still facing this unfortunate issue. Really stumped on what I should do. I could remove the rotator but rotating the tube in the rings isn't really ideal, and I don't think I should have to. Surely there's a way.

Anyone?

Can anyone help with this? I really don't know what to do.

After adding a WO camera rotator and the dedicated TS x0.8 reducer into my imaging train, I can't perform an Autofocus routine on my ASIair. There simply isn't enough room. The focus position leaves 5mm of inward focuser travel. The Autofocus closes this gap. I need a few more mm.

Is this normal? Surely I should be able to incorporate a rotator for image framing. I could solve it by removing the WO rotator but that means I will need to rotate the tube in the rings for image framing, plus this will cause an off balance.

I found another possible solution of adding an M48 Artesky rotator into the backspacing, but now I can't find a 15mm m48 extension that is female to female to do this.

The yellow arrow shows the focus position and the 5mm gap left of inward travel. 

Thanks, 5mm does sound like too much for it to be moving.

It's already manually focused at that point so only need minor adjustments. 

I do everything through the ASIair app. I will connect the eaf to my laptop to make sure all internal settings are correct. Maybe there's a driver update.

1 minute ago, knobby said:

How far does the focuser move in ? Surely 5 mm is enough ?

~5mm.

2 minutes ago, Stuart1971 said:

What is the spacer between the reducer and the filter wheel, could that be removed and or a shorter one added…?

No they're needed for the backfocus.

3 minutes ago, knobby said:

If you have 5mm movement available it should work, try using shorter steps in calibration.

Mine only moves about 2mm in and out when focusing, might even be less ?

Nope, tried it. The reducer hits the face of the focuser and I get an error message. 

I've hit an obstacle on my TS 80mm F6. There isn't enough inward focus for my EAF (electronic automatic focuser) to perform an AF (autofocus) routine.

I could solve it by removing the CAA (cameras angle adjuster) but I am then stuck with one fov as everything is threaded together. 

Any suggestions?

Should I swap the .8 reducer for a x1 flattener instead?

Is there a rotator that can thread into the backspacing?

The focus position is a ~5mm gap where the yellow arrow is pointed. 

Excellent work 👏 well done 👏 

I've heard nothing but good things about the Samyang 135.

You will be one to watch out for in the future I think, very impressive. 

I've figured it out. The bin 2 should be 1.98"/pixel.

Not sure why the tool is saying 1.99.

Maybe just a glitch.

Bin 1 0.99"/pixel

Bin 2 1.99"/pixel

pixel^2 x aperture^2

= 0.99^2 × 80^2

= 0.9801 x 6,400

= 6,272.64 bin1

pixel^2 x aperture^2

= 1.99^2 x 80^2

= 3.9601 x 6,400

= 25,344.64 bin2

25,344.64/4 (dividing bin2 by 4)

= 6336.16

 6336.16 - 6,272.64

= 63.53

On 22/08/2022 at 17:20, scotty38 said:

Agreed on all of that although I've not yet used that mode on my 294m but I was only suggesting it based on your desire of sampling though.

I might have been wrong on that. It's probably not as bad as I was making out. The unlocked bin1 mode looks similar to bin1 on both the 1600MM and 183MM.

1 hour ago, vlaiv said:

Not sure what you've noticed, but no - binning just means summing up photons. You can't suddenly get more photons.

Just that bin 1 with my setup is 6,272, and bin 2 is 25,344.

When I divide 25,344 by 4 I get 6,336, so a little more than 6,272. I was thinking that extra 64 was an improved ability to collect more photons.

Perfect, I wasn't using the right words and that was confusing me.

I have noticed that when we bin x2, we are actually getting a fraction more than 4 times the photons per pixel. Does that mean that the QE slightly improves with bin x2 also?

So is there little point to binning in the field, other than reducing file size? Is it a good approach to bin x1 at data capture in the hopes of excellent seeing and if it's oversampled just to bin it in processing?

Thanks, you have explained that very well. I'm getting there. I still feel a small bit stupid though 😅.

The light gathering formula is what's  confusing me. 

My bin 1 figure of 6,272 and bin 2 figure of 25,344.

I'm reading that as bin 2 collects ~4 times more light, thus lets me reduce my total imaging time by a factor of ~4. Albeit with half the resolution.

It has me thinking I could capture an image in bin2 for 1 hour,  and it would be the equivalent of a 4 hour image in bin1. But the bin2 image would be half the size. 

Thanks, apologies but this one isn't sinking in fully yet.

I am under the impression that binning at data capture allows me to collect more photons (super pixel) AND improve SNR, but at the expense of finest detail. 

Where's if I'm to bin in processing, my assumption is that the photons have already been captured, so now I ONLY have the opportunity to improve SNR, but at the expense of finest detail.

Ah perfect. So am I correct in saying that Bin 2 will be faster than the unlocked Bin 1 mode? But Bin 2 and Bin 3 will actually be the same brightness as they are within the same mode? Hope that makes sense. 

Whoops, I must have got the wrong end of the stick somewhere 😅.  I thought by using bin 2 I was making the camera faster.

TS80 with 294MM 

Bin 1 = 0.99"/pixel

Bin 2 = 1.99"/pixel

Using aperture^2 x pixel scale^2 I get

Bin 1 = 6272

Bin 2 = 25,344

I thought by using Bin 2 I was going to make the system 5x faster.

So are you saying that a typical 5min sub will be the same brightness on either Bin?

I have spent the last 3 days crunching numbers trying to find the optimum setup over various scopes and bin factors.. 😬🤣

On 23/08/2022 at 21:08, The Lazy Astronomer said:

2.5"/px will not be an issue at all. My native resolution is 1.7"/px and based on the measured FWHM of the stacked image I usually bin 2x2 during processing, which takes me up to 3.4"/px with no ill effect to the image.

Would it not be better for you to bin at data capture instead? It would reduce your imaging time.