centroid

16 minutes ago, MartinB said:

Sorry Dave, only a bit of flippancy😑

Water under the bridge now Martin, but it came across as a bit of  P*** Take, and that didn't go down well at all.

My apologies if I misread it 🙂.

Onwards and upwards 👍

2 hours ago, MartinB said:

Does that mean that in the real world a Reliant Robin might out accelerate a Porche 911? 🙄

If that is what some folk are foolish enough to believe,  then that is up to them.

If we going from logical discussion to frivolity, then  I'll leave you to it, but in terms of ridulous  exaggeration, I would say that there is a "big difference between scratching your backside, and tearing the skin off". 

For a man whose intelligence, and knowledge, I have much respect for Martin, you surprise, me.

43 minutes ago, vlaiv said:

Thank you.

I have slightly different view on this: If in practice you are not seeing results predicted by theory, then:

- you are applying theory in the wrong way

- you are applying theory outside its domain of validity

- the least likely scenario - theory is wrong and should be corrected or replaced (how often does that happen?)

Theory is devised under controlled lab conditions,  and can only estimate the multitude of variables that could impact on it under "Real World" in use conditions.

Where laboratory testing is involved, unless the test equipment used is calibrated to traceable national standards (UKAS in the UK), the results carry very little standing. Then of course there is Measurement Uncertainty, which usually follows a mathematical distribution, The uncertainties can either be systematic or operator induced, but they are real, and must be taken into account . 

Hey, I been retired for some 19 years, and didn't  think I would be discussing theory v practice, and measurement uncertainties, revolving around an amateur level Chinese CMOS based astro camera, for what is a hobby pass time 🙄

We have probably bored other members to tears. ☹️

If I find out why this 294 camera is giving me poor results, I will let you all know.

2 hours ago, vlaiv said:

Well, let's compare the two with that regard.

Your old CCD:

Peak QE seems to be around 55%

Your new CMOS

this being relative QE graph and peak being estimated at 75%.

(75 - 55) / 55 = 36.4% peak performance improvement.

Ha line is about 30% absolute QE for CCD while it is at (0.9 * 0.75 = 0.675) 67.5% with CMOS

(67.5 - 30) / 30 = 125% Ha performance improvement in sensitivity

I'd say that above statement is correct - it is much more sensitive camera as far as QE goes (mono version probably more).

 

Yep, that is the theoretical result,/prediction,  probably taken under Lab conditions, but to quote an old English saying, "the proof of the pudding is in the eating", and theory doesn't always play out in practice.

I had a 40 year technical career, the last 20 of which were in R&D  (Radio Frequency Engineering, and Electromagnetic Compatibility), and If I had a £ for very time practice didn't align with theory in the real world, I would be a very rich  man.

The only theory that was never wrong, was good old Ohm's Law. 🙂

BTW Vlaiv, your command of the English language never ceases to amaze me 👏.

I can get by with some German and French when away on holiday, but fluent, absolutely not.!!

QUOTE:- Martin B

"Could the issue be that you are comparing OSC with mono Dave?"

Perhaps I should rephrase my question to read "Am I expecting too much from a  OSC CMOS astro camera" Martin.

There has never been any doubt that mono is more sensitive than OSC. Back in the day, I  moved over from OSC to Mono, because I wanted to image in NB, and LRGB. For this purpose I used a 7 position motorised, and usb controllable filter wheel, with L,R,G,B, Ha, Olll, and S11 filters installed. I am not that serious about astro imaging this time around, and see it very much as a sideline to my photography.

After reading user comments on various astro forums that CMOS was so much more sensitive than CCD, I thought I could get acceptable results with a CMOS OSC camera, but I have yet to see this. The image quality I  got with my SX CCD OSC asto cam (H9C), I have yet to see repeated with this 294c camera.

I chose the 294c because of the 4/3rds sensor size, and 4.63x4.63um  pixels, as opposed to the smaller sensor 183, with its very small 2.4x2.4um less sensitive pixel. My SXVR H16 had 7.4x7.4um pixels, and very good sensitivity, but of course that was mono.

I accept that I am now using a relatively budget imaging setup, comprising a £1200 APO Refractor, with a £900 294c based camera (I paid £2000 for my H16 back in 2011), but its not at the real budget end, and as such would expect better than I am getting with a supposedly more sensitive CMOS camera.

However, that is what I have, and I will persist with it, and maybe as I get to better understand its quirks, I will get better results. Time will tell.

I do understand that the IMX294 is old CMOS technology now, and am told that the later generation of CMOS cameras are much improved, and more ccd like, such as the 2600 I believe. However, I am not prepared to invest any more money in what what is very much a secondary interest now.

I really enjoyed the 12 years (2002-2014) that I spent astro imaging, before a medical intervention prompted me to give it up, and move house. This time around it has been one frustration after another, and as yet, little to show for it, and I have come close to walking away from it.

I have nor ordered a 2" Optolong Enhance filter, which will reduce the sensitivity even further. 😅

I have now ordered a 2" Optalong Enhance filter from FLO.

19 minutes ago, Stuart1971 said:

I have asked this same question in a thread in here, since buying my QHY268c, and also made the same comments on not getting the quality images I got with my SX CCD, but am sticking at it, things have got a bit better, but I am not getting the results that other people are with the same camera and much less integration time, its quite disheartening when I see what some people get with say 2 hours of 2 min subs, and if I try the same settings I barley have anything to show for it…☹️
But my SX CCD is now sold, so I have to stick with it….

At least its not just me Stuart.

If I hadn't imaged successfully for 12 years, with a variety of SX CCD cameras, I wouldn't have known any different. But I have experienced what CCD can produce, and I have yet to see it from this CMOS camera, and its re-purposed sensor.

However, its all I have to work with now, and having paid £900 for it, I will persist, and maybe one day it will either impress me, or go in the bin. At which point I will either grab one of  the last remaining SX CCD cameras, or retire again from astro imaging, never to return.

I have seen some good images taken with CMOS astro cams, but I have seen many more that are very 'lack lustre'. Back in the CCD days, it was the other way around.

Reduced brightness for posting here.

If I can get somewhere near this with a CMOS camera, I will be both convinced, and happy.

I this took this image back in January 2012  with a SX  SXVR H16 CCD, (Kodak sensor), with a 110mm f/7 refractor, albeit separate LRGB. All in one evening, and not one night per filter, as someone mentioned on another group, that is how he uses his CMOS camera to get decent results.

Comment:  for some obscure reason it displays excessively bright posted here, but not on my calibrated PC monitor, or on my website.

👍

18 minutes ago, scotty38 said:

FWIW on my 294MC Pro I use gain 121 and leave it there but I'm new to this game really.

121 in what capture package?

As I said, the same gain setting is referenced differently  in different software packages, even by different camera manufacturers.

For example, a gain of 900 in Sharpcap, is the same as a gain setting of 9 under ASCOM control.

Its all done to make life uncomplicated for the end user, 🤣.

Thanks for that input Vlaiv, comprehensive, and informative as always 👍

Are you saying that I should be processing my 14bit captured images at a lower bit setting, say 8bit?

I am learning that CMOS astro imaging, and processing, is a very different 'ball game' to CCD.  I guess that many of today's imagers came into the hobby with CMOS, and no past experience with CCD astro cams.

I would love to have kept one or more of my  SX ccd cameras, so that I could make a direct comparison, using my current setup. But hindsight is a wonderful thing, and when I gave up the hobby in 2014, I had no intention of returning to it.

Out of interest, I will try GIMP, and compare the results. I have always been happy to pay for quality software, and as such, never bothered with the 'freebies'.

13 minutes ago, vlaiv said:

If you want to compare results between CMOS and CCD cameras - then you have to say (or show) what sort of results you were getting with CCDs and in what sort of time / with what gear.

If you want to see if you manged to do the best with your data - or learn how to do it, if that is not the case - it is maybe best to attach raw / linear data and see what others are capable of producing.

If you worry that you did not stack properly - giving access to original data and letting other stack that for you so you can compare is best course of action.

Some of the results can be seen on my photography website. The square format ones were taken with an SC SXVR H16 (Kodak ccd sensor), with a 110mm APO at f/7, and no filter.

I no longer have any of those ccd subs, as I deleted them back in 2014 when I left the hobby, after 12 successful imaging years.

I used to pre-process (debayer, align, stack, and calibrate) in either Astroart 3,4, or 5, or Maxim DL 4. Now it is done in Astroart 8.

I never had any problem in doing this with hundreds of CCD images, or with the sensitivity of the CCD cameras.

There is no doubt the CMOS presents a whole new set of challenges to the CCD imager, now turned CMOS imager.

I guess its very much a case of, as the guy working down a hole in a New York street, said to the lady who asked "can you tell me how I get to Carnegie Hall" to which he replied "you have to practice" 😅

3 minutes ago, vlaiv said:

CCDs also had gain - but you were not able to change it. If you want something like that with CMOS sensors - just pick a gain and stick with it.

 

Indeed they did Vlaiv, but it was preset by the camera manufacturer, and it worked absolutely fine, and no 'faffing' about with settings. I guess it is what happens when the astro camera manufacturers, grab readily available CMOS sensors, that were designed for use in DSLRs, and Smart Phones etc, and re-purposes them them as astro cam sensors.

7 minutes ago, iantaylor2uk said:

What gain are you using? With no filter I usually use 30-60 second subs, and only  go up to 2 mins if I use an L-enhance filter, but I tend to use pretty high gain (200 on my ZWO 071 which has a max gain of 240). Most people with CMOS cameras tend to use shorter subs (as compared to CCDs) and take many of them.

The gain was 9 in Astroart (ASCOM), which is equal to 900 in Sharpcap. I set this based on a sensor analysis, at the best crossover point between read noise, and gain. 

I would be interested to hear what gain settings other folk are using with the IMX 294c sensor. 

Its not easy to quote gain, when different software uses different gain setting numbers to represent the same setting. Ascom is x1, whereas Sharpcap is x100. Never had to play with the gain conundrum with CCD. I think its called progress 😅

I think I will go in the middle, with the 2" L enhance.

Interesting 🤔, 168.76 from Ali Express, and £166 from FLO, plus delivery, which I think is £1.95 1st Class Post = £167.95, so 81p cheaper from FLO.

Amendment:- Just checked on the FLO website, and its £5.95 delivery, not £1.95. So £171.95, thus £3.19 dearer than Ali Express 😉

I am struggling to get images from my 294c CMOS camera, of the quality I used to get with my SX CCD cameras, back in the day (2002-2014).

I can put up with the quirks of CMOS, e.g. green tint, gain and black level setting etc, but as yet the image quality is disappointing. It could be me of course, but I'm not new to astro imaging, a bit rusty maybe, after an 8 year hiatus, but even so.

Here is an image of the Rossette, taken the other evening. 18 x 4 min subs, with a 115mm f/7 Triplet APO + 0.8x flattener reducer, thus f/5.6, and a 294c camera with no filter.

I never had to 'push' the processing as hard as I did with this image, with my SX CCD cameras images.  A combination of Astroart 8, Photoshop CS, and Lightroom, to extract this from what was a very dull, and bland image.

Yep, I know that 18x4 min subs is probably not enough, and I have been told that it needs a good 4 hours of integration. 4 Hours 😮, I never had to get anywhere near that with my CCD cameras.

The resulting image (attached) is way below the quality that I was used to.

I think I just have to decide between the L-Pro and the Enhance, as I guess by town/city dweller standards, my light pollution is low.

I am fortunate to reside 5 miles away from the county town of Ipswich, and thank goodness some 15 miles from the light pollution hell that is the Container Port at Felixstowe. The light pollution there, has to be seen to be believed, and its 24/7, 365 days a year.

2 minutes ago, Stuart1971 said:

You can get this with very fast scopes below around f4 I believe…

I am imaging at f/5.6, so hopefully not a problem 🤞

2 minutes ago, Stuart1971 said:

The L-Xtreme is the best of the three, and works really well with all light pollution and street lights as it has a very narrow band pass in just Ha and Oiii, the L-enhance is a much wider 35nm band pass so not quite as good, and the L-pro is just basically a broadband LP filter….👍🏼

Thanks Stuart.

Just a thought, but thinking back to pre 2014, I saw many reports/complaints of halos around bright stars, from people using LP filters.

Is this still the case I wonder, or have things improved?

Thanks for your input Elp.

In my previous imaging days (pre 2014), I lived in a rural village, without any street lighting,  and never needed any form of LP filter.

Since then, we have moved house, Still in a village, but a much larger one, with street lighting, albeit these go off a 23.30.

However, there is still some residual sky glow from the lighting on the A12 trunk road, which passes close to the village. These lights were replaced some years for a design that projects the light downward, and not outward and upwards. Albeit they still present a degree of light pollution, especially if there is any moisture in the air. 

That said, the light pollution isn't that bad, and certainly nowhere near town or city levels, but I think a filter would be advantageous just to 'clean up' what there is. So maybe the milder of the two filters would be adequate.

Which of the Optolong range of filters is best suited for use with a OSC CMOS camera.

I am thinking the L-Pro?

I do not have the enthusiasm, or the time to go back to Mono, and LRGB imaging, as I used in my previous astro imaging days.

So its OSC now, or not at all.

I have dealt with this company twice this month, as none of the UK astro retailers had the items that I wanted.

Prompt and helpful response to enquiries, and prompt dispatch when order placed.

I'll sort it Malcom, maybe even before the clocks go forward, and the nights shorten 🙂

I don't think its an EQMOD problem, that is just the interface between Cartes du Ciel, and the mount.  Maybe a quirk with the mount (Synscan), and the software.

Or perhaps it just doesn't want me to be imaging objects West of the Meridian 😅

If it was an issue with my photography kit, I would be "chomping at the bit",  but having "been there, and done that'" with astro imaging, its not such a "big deal".

But, thank you for your interest. 👍