Adam J

APP cant separate Ha from SII, thats not possible and to be honest due to the overlap between Green and Blue pixels at the OIII wavelength you cant correctly separate Hb from OIII either. The only channels that APP can fully separate out are Ha and OIII....well unless someone makes a Hb / SII duel band filter at any rate. The main advantage of a duel narrow band filter (Ha and OIII only) is that it allows you to image the two wavelength at the same time with an OSC and hence increases the efficiency of OSC narrow band imaging which is normally well behind that of a mono camera. Problem is that the OIII wavelength tends to be much wider band pass than on a dedicated OIII filter and so it still suffers more from LP than individual filters and as the peak of the green filter pass does not match the OIII centre wavelength you also lose efficiency due to lower QE too. But its better for OSC in terms of overall efficiency. But like I say there really is not point in trying to include SII and Hb into the mix as all you are doing is harming signal to noise while also not being able to process them as separate channels. Adam

Well Ha and SII are both covered by the red pixels and so you will never separate them using an OSC camera as both will appear red. As for the Hb being in the same places as the Ha all its going to do is shift the Ha red towards pink, something that can be done in processing anyway. Adam

Personally I would want to see the narrowest oiii filter and ha filter possible and I think all this talk of Tri / quad filters that include Hb and SII is marketing spin designed to mitigate the fact that not all the manufacturers are able to create duel band pass narrowband filters with sufficiently narrow band pass to isolate oiii from Hb and or Ha from SII and so want to present this as a design feature when really on an OSC Hb and SII are not going to bring much to the party. So my recommendation would to get the a duel band pass filter with the narrowest oiii bandwidth available and forget about Tri and quad. Adam

The others including the likes of ATIK, Orion, QHY, Altair, ASI do define the units being used in their data sheets I'll post example when not on my phone. They all use the same definition of unity gain. But who is technically correct is not the issue. The issue is that unlike myself and you and some others here I am willing to bet most people don't think in dB at all. As such it will likely confuse the majority of their customers sufficiently such that they see one noise level and the other and they just pick the lower value, or as above they wonder if the anti-amp glow is increasing read noise, that would be a real shame for a good company such as SX. Prior to the response from SX it even confused everyone in this thread full of people who understand dB myself included. Sometimes you should just go with the flow 🙂

Actually that explains everything. They are defining unity gain as 0 dB gain. All the other manufacturers define unity gain as the gain at which 1e is encoded to 1-bit of information on the 12-bit a/d and that happens at 11 dB of gain for the IMX290 not 0 dB which the other manufacturers simply call zero gain. The upshot of that is that the SX figures are vertually identical to the other manufacturers figures once you account for the difference in definition of unity gain. This is very good news. When you look at the zwo graph you will see that the gain scale is not in dB but 0.01dB per gain increment. Unity gain is clearly not defined as zero dB on that graph but as gain 110 (11dB) They would be best advised to use the long established definition as if people don't realise they are using a different definition of unity they will appear to be at a disadvantage when in fact it's identical. For the record I did not think unity means max gain. I now regard the inconsistancy as resolved. Adam

It's certainly worth asking asking SX due to the inconsistancy. With luck they will reply and we will find out. Can you provide a link to where you asked the question?

I said no such thing. I just note it's inconsistent with other manufacturers measurements of the same chip. At any rate the important thing is how it performs in the real world.

The IMX290 is one of Sonys highest sensitivity cameras, it does not have 3e read noise at unity. If it did then at zero gain it would be more like 6e read noise, to put that into perspective that is worse that a Canon 1000D from 2008.

I said it is only an impression, due to its ability to work effectively with shorter exposures. However, I cant quantify that as I have done no like to like comparison. I would not want to give the impression that I think that the ASI1600mm pro or any cameras with that sensor are perfect though. For one it benefits from dithering where as the 460ex or similar camera does not require dithering and with the ASI1600mm pro's short exposures that can actually harm your efficiency. To an extent you cant get away without dark frames with the 460ex due to its high degree of uniformity. The 460ex has a stable bias and so dark frame optimization is possible if you do use dark frames. But probably the biggest advantage of the 460ex is that it does not suffer from the micro lens diffraction effects that the ASI1600mm pro does suffer from. For me there are reasons to chose either camera. But the larger sensor in the ASI1600mm pro is very compelling. Adam

What application do you have in mind for that camera / what scope are you thinking of matching it to? It's potentially a very sensitive camera. A replacement for icx825 based cameras like the atik 414ex, potentially as sensitive with a larger sensor and similar pixel size.

You are not the first person I have heard complain about that exact camera. I would probably go with the ASI224mc if it was me it's a big step up from the QHY.

I understand about ease of use...but simplicity and reliability are not the same thing. Have you considered the ASI air I think it added DSLR support recently maybe not sony mind you. Guess I have just heard lots of stories of frustration with stand alone guiding.

I would not touch stand alone guiders. Too temperamental and insufficient control.

I assume you set the wheel to mono directional rotation? Its not something that I have ever had a big issue with as I keep my filters quite clean. I also dither heavily and so that might be helping. Perhapse there is some way you can modify it. Is the issue with all the filter positions or just one of them? Adam

I think that you might struggle at a £100 budget. Given your scope and mount I think that imaging planets is a starting point although as noted they are not currently well placed for imaging from the UK, which is not to say that you cant try. I think that the ASI120mc is a good choice to start with but it is more that your budget. Adam

Incorrect spacing would not normally result in coma in the centre of the image. Only the rear optical element being tilted in so far as I know.

yes that is horrible.

I think its more to do with if I owned it myself I would know its condition and that it had been well looked after. Sensible especially with kids. Although in that case I would also be concerned that I succeeded in getting across the message that you cant just do that with any telescope etc.

If they were willing to look through it first lol

No I am quite interested in seeing things like the transits or partial eclipses but the sparsity of such events does not justify buying a solar wedge if i had a solar wedge for those events I am sure I would use it more frequently though, I simply prefare DSO imaging and that is expensive, my concerns over safety mean I dont want to use the cheap option in solar foil. I have a masters degree in laser physics and people I know have been involved in laser related accidents resulting in eye damage, that is a very similar type of damage and so I am hyper aware of the consequences and it makes you take great care with your eyes. I dont need multiple things in my life that can potentially blind me even if it is unlikely. Adam

no my main interest by far is DSO imaging anyhow and so I would not want to invest any cash into solar observation just for transits.

For me its not worth the risk even if tiny as the consequences of something going wrong are life changing. Hence I use a camera or project.

Those charts say 1hour for narrow band don't take that literally. 5 to 10 mins max.

Exact Same amp glow pattern on the asi294mc pro so that would have been something he would have needed to deal with anyway. But yes...take darks, flats and dark flats. Don't use bias and don't use dark frame optimization. I recommend 2x2 bin at his focal length so guiding won't be too tough.

Nice detail in the galaxies, just a shame about the background, have you used flats? Or is this just a moon related issue?