HyperStar Mono Camera

[Wayne76]

Hi Everyone, 

Currently I am using Hyper Star system on the 1100HD CPC unit to take photos, 

I am thinking of change to mono camera,

I am thinking of buying the QHY183M with Baader high speed filter,

Or does any one has any suggestion for which other mono camera I should go for Hyper Star system ?

 

This is one of the pic I took with my QHY 10 with Hyper Star

Or is it really necessary to change to mono camera just to use H, Oiii and Sii filters, 

[vlaiv]

I think it is a good choice - It is smaller sized chip compared to QHY10, but from looking at this image it looks like your system is suffering at corners - so smaller sized chip - that will be less noticeable.

You can image NB with OSC camera, but you need "special" processing to make it "regular" mono image. With normal imaging you have debayer / demosaic stage at some point. With NB you don't want to do that - if you calibrate with flats - just treat your image like mono after calibration. If you don't apply flats you need to divide each bayer matrix component with it's relative QE (dividing with flats does exactly that for you as each pixel of the flat will gather photons in proportion to its QE in that wavelength).

While it is possible to do NB with OSC camera, much better results come from use of Mono cameras for NB (Better in terms of SNR, not in terms of resolution like for LRGB, for NB both have the same resolution).

Only thing that I would advise you to do before deciding for that particular combination is to see online if anyone else reported problems with reflection or diffraction patterns. Some people experienced strange diffraction patterns with a different camera model and NB filters - and I think it is both related to type of filters, their distance to sensor and "speed" of light beam from scope. You will be shooting at very demanding speed (you already know that and hence special high speed filters from Baader) - so just see if anyone else reported problem for this combination.

[Wayne76]

Hi Viaiv,

Thanks that sound very complex......?

I will go study OSC camera,

Does any one, have try Hyper Star with Mono camera, which one is the better one to go for,

 

 

Thanks, 

[ollypenrice]

21 hours ago, vlaiv said:

 

While it is possible to do NB with OSC camera, much better results come from use of Mono cameras for NB (Better in terms of SNR, not in terms of resolution like for LRGB, for NB both have the same resolution).

 

Sorry, I don't follow this. Surely if you use use an Ha filter in an OSC camera light will only be recorded on one pixel in four. Wouldn't this equate to a loss of resolution?

Olly

[vlaiv]

3 minutes ago, ollypenrice said:

Sorry, I don't follow this. Surely if you use use an Ha filter in an OSC camera light will only be recorded on one pixel in four. Wouldn't this equate to a loss of resolution?

Olly

It depends on particular Bayer matrix used on OSC camera, but most recent Bayer matrix response curves that I've seen don't actually cut off light completely in different parts of spectrum - I guess that manufacturers do that so they can recover some resolution even in RGB mode. Have a look:

This is response graph for recent OSC camera - at 656nm for example QE of Red is decent - around 80% (this is probably not absolute QE, but relative), Green has QE around 9%, while Blue has very low QE of around 3-4% (? maybe).

This means that for Ha signal every pixel will record some light, while G and B will suffer poor SNR because low QE - they will still be able to record signal and resolution is kept. This is why you need to "normalize" response - divide each pixel with its QE to get "uniform" - here uniform is in signal level, not in associated noise. Dithering is important with this kind of imaging to allow noisy pixels to be mixed with less noisy ones (final pixel will have some high SNR reds, some low SNR greens, and some very low SNR blues). One also benefits from some sort of algorithm that weighs contributions depending on sensitivity of particular pixel or respective SNR.

BTW using flats automatically normalizes pixel values and you get regular mono image if you don't debayer it.

This particular sensor will probably have better results in OIII than in Ha, but each sensor has slightly different curves. You can even shoot with OSC that has blue practically at 0 - but you need to dither, and only use R and G pixels (3/4 of pixels in each sub) - this is called bayer drizzle.

[ollypenrice]

5 minutes ago, vlaiv said:

It depends on particular Bayer matrix used on OSC camera, but most recent Bayer matrix response curves that I've seen don't actually cut off light completely in different parts of spectrum - I guess that manufacturers do that so they can recover some resolution even in RGB mode. Have a look:

This is response graph for recent OSC camera - at 656nm for example QE of Red is decent - around 80% (this is probably not absolute QE, but relative), Green has QE around 9%, while Blue has very low QE of around 3-4% (? maybe).

This means that for Ha signal every pixel will record some light, while G and B will suffer poor SNR because low QE - they will still be able to record signal and resolution is kept. This is why you need to "normalize" response - divide each pixel with its QE to get "uniform" - here uniform is in signal level, not in associated noise. Dithering is important with this kind of imaging to allow noisy pixels to be mixed with less noisy ones (final pixel will have some high SNR reds, some low SNR greens, and some very low SNR blues). One also benefits from some sort of algorithm that weighs contributions depending on sensitivity of particular pixel or respective SNR.

BTW using flats automatically normalizes pixel values and you get regular mono image if you don't debayer it.

This particular sensor will probably have better results in OIII than in Ha, but each sensor has slightly different curves. You can even shoot with OSC that has blue practically at 0 - but you need to dither, and only use R and G pixels (3/4 of pixels in each sub) - this is called bayer drizzle.

Thanks, that's interesting. I'd be keen to see some subs taken this way and compared with those from a mono equivalent. You know how sceptical I am about theory's ability to predict practice in imaging! I mean there is sooo little Ha signal passed by green and blue.

Olly

[vlaiv]

1 minute ago, ollypenrice said:

Thanks, that's interesting. I'd be keen to see some subs taken this way and compared with those from a mono equivalent. You know how sceptical I am about theory's ability to predict practice in imaging!

Olly

It will be much lower SNR compared to respective mono equivalent, or one should use more imaging time to get to same result.

I personally would never choose that route, but if I needed to take NB image for some reason and I did not have access to mono sensor (or for purely scientific reasons - like to help you restore your faith in theoretical side of imaging - for those theories that are sound and properly applied ) - I would know it works and how to do it

[ollypenrice]

^^ ?

Olly

[HunterHarling]

The problem with a mono camera is that you have to use a filter slider. Each time a filter is exchanged, new dust will collect and new flats will be needed.

However, it may not be such a problem, and I'm certainly going to try it with my ASI1600mm.

15 hours ago, ollypenrice said:

I'd be keen to see some subs taken this way and compared with those from a mono equivalent.

I may do just this in the next couple of weeks.

[Wayne76]

15 hours ago, HunterHarling said:

The problem with a mono camera is that you have to use a filter slider. Each time a filter is exchanged, new dust will collect and new flats will be needed.

However, it may not be such a problem, and I'm certainly going to try it with my ASI1600mm.

I may do just this in the next couple of weeks.

 

ZWO 1600 seems to be a good camera, also being introduce by Dean from Starizona

If you are also using HyperStar, pixel size will be 1.4/pixel, with field of view of 108.6 X 82.1

https://starizona.com/tutorial/pixel-resolution-and-field-of-view-calculator/

After checking, 

With QHY168, will be 1.77/pixel, with field of view of 144.9 X 96.4

With QHY183, will be 0.88/pixel, with field of view of 81.6 X 54.6, that will be too small......

My current QHY10 which is 2.23/pixel, with field of view of 144.9 X 96.4, same is QHY168

 

To combine OSC images with narrow band filter, seems very difficult, if any one got a web site with information pls let me know, 

 

I think I will give get the QHY168, since I am more familiar with the QHY system...

When it come to small object, just use the normal NB filter with Celestron focal reducer at back of the telescope...

 

But, there is one problem, Badder seems to be out of stock on the high speed filter for over 6 month now......

 

 

 

 

 

[Adam J]

On 03/06/2018 at 00:44, Wayne76 said:

 

ZWO 1600 seems to be a good camera, also being introduce by Dean from Starizona

If you are also using HyperStar, pixel size will be 1.4/pixel, with field of view of 108.6 X 82.1

https://starizona.com/tutorial/pixel-resolution-and-field-of-view-calculator/

After checking, 

With QHY168, will be 1.77/pixel, with field of view of 144.9 X 96.4

With QHY183, will be 0.88/pixel, with field of view of 81.6 X 54.6, that will be too small......

My current QHY10 which is 2.23/pixel, with field of view of 144.9 X 96.4, same is QHY168

 

To combine OSC images with narrow band filter, seems very difficult, if any one got a web site with information pls let me know, 

 

I think I will give get the QHY168, since I am more familiar with the QHY system...

When it come to small object, just use the normal NB filter with Celestron focal reducer at back of the telescope...

 

But, there is one problem, Badder seems to be out of stock on the high speed filter for over 6 month now......

 

 

 

 

 

Be aware that you will need high speed filters for imaging with a hyper-star. The ASI1600mm pro has a diffraction pattern around bright stars...not sure if it gets better or worse with faster optics but the speed of the optics is clearly a active factor.

You could also consider the 460EX for mono imaging. 

However....I have often heard that OSC is in fact preferential for hyper-star due to the filter handling issues and the need to use filters that can operate at F2.  The QHY10 is an older OSC design, I would personally be tempted by the ASI294mc pro if I was looking for a modern camera to use with hyperstar. 

Also take a look at the Duo-Narrow band filters. Not sure what there max F-ratio is though. 

Adam