Adam J

How would you both rate the sharpness / color correction of the 80 vs the 100? I note that the FOV is not that different between the two 400mm vs 550mm focal length what made you decide to own both and which did you own first? Which do feel you use more? The main thing putting me off the larger scope is weight on my HEQ5 pro. But to be honest the 80 is not an issue for me so long as its optically as good as the 100. Adam

If you want to do HaRGB then get a Ha filter and a Lpro. The Duel band filter is for making bi-color images in narrowband. So with HaRGB you are using the Ha as a luminance layer and then getting color from the L-pro. With the Duel channel filter you will be able to split the channels, assign the Green and Blue channels back to Blue only and Keep the red seperate. Then re-combine to get a Blue + Red image, lastly you generate a synthetic green channel. In essence that will give you something that looks like all the veil nebula bi-color images that you see taken by mono cameras. Adam

No the 55mm distance will only be correct for a DSLR as you have a dedicated camera you will need to make up 55mm of space between the rear flat of the corrector and the sensor. The Flange Distance for your camera is: 17.5mm from front face to sensor. As such you need to make up 55mm - 17.5mm Hence you need another 37.5mm of T2 extenders between the flattner and the camera. Without that spacing in place your so far out that this clearly explains your issues. Adam

yes, but to be honest i dont see why you would want to do that, just separate the channels and process separately to gain a bi-color image from the STC for emission nebula and for galaxies or reflection nebula use the Lpro, I would not use the L-pro for nebula unless its just to add some RGB stars only.

Thanks, just hard to get a real feel without using one.

300 is not so bad when you think my AD 5nm set cost me £900 Also over 300 for seperate baader oiii and ha 2 inch.

yes but altairs filter is 32nm wide at oiii and thats the most important band for light pollution. STC filter is 10nm i believe. Thats a massive three fold advantage to STC.

I think that the quad band is pointless as you cant separate out the SII from the Ha using the red pixels and the difference between the placement of SII and Ha in most cases are not pronounced. I.e for the most part SII looks like dimmer Ha signal. In the same way Hb is dimmer Ha signal so only really adds color balance at the expense of contrast. So in essence: get Duel band (OIII + HA), if thats not possible get tri-band (Ha+Hb+OIII), if thats not possible get quad band (Ha +Hb + OIII + SII)... I would not be using separate filters with OSC following the advent of these new designs, at least not unless i was trying to image from central London...then I would be using AD 3nm filters. Adam

Are there any experienced Esprit 80 users who would be willing to share their experience of the scope. I am strongly considering one and I see a large amount of variability in the quality of the images I see on astrobin. If anyone is using a ASI1600mm pro with the scope then that would be even better. Also nice to see some images. One of my worries is that the Ha stars are not as tight as I have seen on some other scopes, but again it could be the user / processing. So hard to tell. Adam

Thats not colimation, you need more spacing between the flattner and the camera.

No dont send it to the tools in the camera shop. Have you tried using a rocket blower yet?

That's exactly what I said. ""What you do get by using a focal reducer is more photons per pixel as you changed your image scale."" Image scale being directly related to FOV for the same camera...

I think your setup has to be very sloppy before you will get flexure at over 2 arc seconds per pixel image scale with a 10min exposure. I certainly am not doing anything special with my guide scope and I have never encountered this problem.

Oh I understand and yes you are right, but I tend to think there is no Myth just people not understanding it correctly in the first place. As you say what you do get by using a focal reducer is more photons per pixel as you changed your image scale. As for binning...yes but you dont gain any field of view that way. Personally I would not recommend a RASA for a beginner for multiple reasons. Adam

Not so, the number of photons arriving per pixel is purely determined by the f-ratio of the scope. A larger aperture at the same f-ratio will only give you more photons per arc-second^2 it will not give you more per pixel and that is what matters for signal to noise ratio. That happens because at fixed F-ratio as you increase aperture you increase focal length and as a result you reduce the image scale in terms of less arc seconds per pixel and so everything remains equal but you have less field of view and more ""magnification"" although the idea of magnification in terms of imaging is a false concept in itself. Adam

There is a RGB matrix in front of your Canon (RGGB) its giving you less resolution than you think because of that, while as the mono will resolve more detail because it lacks the RGB filters even in comparison to a color camera of equal pixel size. So I promise you that a 460EX will outperform your canon in terms of resolved detail with ease you wont want to drizzle! The key thing to understand in this is that on a color camera only 25% of pixels are Red, 50% green and 25% are Blue. Not to mention the fact that the amount of noise reduction you need to use with a DSLR is much higher and all noise reduction techniques in effect exchange resolution for signal to noise in any case. SO using less noise reduction gives you more resolved detail.

It wont not work but you will likely loose some optical efficiency hence you will not have the full benefits of F2, which is not to say you wont still have a very fast system.

Do not 100% quote me on this one but I strongly suspect that its all the same flattner with the 0.85x. I know that the 72mm 0.85x flattener and the 80mm 0.85x flattner are no different at all, I assume that the 120ED one is also no different.

You can get a 31cm dove tail bar from skywatcher, The weight of the bar itself moves the centre of gravity backwards as the tube ring moves to the end of the scope.

Not sure that its a good idea to use something like the SW Equinox (which is a doublet) with a 0.8 reducer, I think that would be pushing the optics a little hard and you will see some some chromatic abberation. Lots of 80/480 triplets such as the Altair Starwave 80EDT or the WOGT81-III etc and go down to 384mm with a 0.8 reducer and a little under F5. ASI1600mm pro or Atik460EX was the decision i struggled to make, I dont think there is a correct answer in fact. What I can say is that wither one is capable of producing stunning images and so your not going to experience any disappointment or regret in either case. 2.34"/pix vs 2.18"/pix is insignificant you will not notice any difference. So that leaves just a few factors on which you make a choice. 1) How do you feel about the micro lens diffraction effect on a ASI1600mm pro? Ill be honest with you I have found myself actively avoiding some targets due to it. The Ghost of Gamma Cas being one example that I considered imaging then decided not to because I knew I would end up with unsightly reflections and diffraction effects from the ASI1600mm pro and would never be happy with the image. Two more are the Horse head and the Butterfly nebula, serious targets that I dont want to image because i know ill get a big boxed shaped refraction effect around them. 2) The ASI1600mm pro is larger than the 460EX so is the extra size worth it to you in exchange for the diffraction effects and reflections. 3) I dont think i would personally buy a new 460EX vs a new ASI1600mm pro because that is a huge difference in price, but they come up often second hand and hence cheaper than a ASI, they are well built so buying used is low risk. 4) Despite what some here will argue I have had some issues taking good flats with a ASI1600mm pro, you end us with multiple dark flats because each channel needs a flat and they are all different exposures. Its a pain to me at least. 5) I think that the file size thing is overblown but using APP it can mean that when using things like dynamic distortion correction the stacking time will be very significant (24 hours in one case for me). 6) You need to dither a ASI1600mm pro to get the best results and that can lose you between 30seconds and 60 seconds per frame if you are dithering for every frame at 300s exposures that not an insignificant hit to efficiency. 7) I think that the ASI1600mm pro is slightly more sensitive than the 460EX but for my friends results vs my camera on similar setups I dont think its so significant such as to be the driving factor behind your choice. Also in many situations the ability to fully hardware bin 2x2 for OIII and SII is not an insignificant advantage as it results in a large increase in sensitivity for the 460EX. 8 ) With a ASI1600mm pro you will be doing 5 mins subs for narrow band vs 10min subs for the 460EX. Personally I think that if you can guide for 5 mins you can guide for 10 mins so I dont see that as a significant issue, also note that this does not mean that the ASI1600mm pro is twice as fast as the 460EX that is not how it works. So bottom line, if you take all the above into account I think it boils down to: slightly less effort, smaller FOV and hardware binning for the 460EX Vs Slightly more effort, larger FOV, situational but nasty diffraction effects and slightly more sensitivity for the ASI1600mm pro. Armed with that information its down to individual preference. Hope that helps you make your choice. For me, I picked the ASI1600mm pro because of the FOV of my 130PDS at 650mm demanding a larger sensor. But if i was working at around 400mm I would have picked the 460EX. Others will disagree for sure, but as I say there is not correct answer only personal choice both are great cameras. Adam

Yes that is how I would it. I use unity gain although I have seen some still using gain 200 at that exposure length.

No faith, 5/7 = 0.71 56/77 = 0.72 0.72 * 0.71 = 0.516 At the same image scale (as pixel size is also a factor) and accepting that read noise is dominant in narrow-band imaging. OR 77/5 = 15.4 56/7 = 8 1 / (15.4 / 8 ) = 0.519 Rounding errors hey. So what does that actually mean for you? Well it means that if you want to achieve about 2 arc seconds per pixel (a good starting point) at a reasonable FOV the two following combinations will work. 1) The KAF8300 with the SW ED 80DS-Pro will give 2.18 arcsec / pixel at 2.04 x 1.52 degrees. You can go with the KAF8300 and the 65Q becuase that will leave you at 3.12 arc-seconds per pixel...maybe a little more than what I would consider optimal. 2) The 65Q with the Atik460EX will give 2.62 arc-seconds / pixel and will give you 2 degrees / 1.6 degrees so virtually identical or actually a little larger FOV than case 1) above. But it will be almost exactly twice as fast as the above option image scales are very close. Cant use it with the ED80 because the FOV is too small. But the really interesting stuff happens if you go a little faster with a scope, perhaps something like a WO ZS73 at F6 or even a GT71 at F4.7. In both cases the pixel size of the ATIK460EX will still work at those focal lengths but the KAF8300 is increasingly sub optimal. Maintaining FOV an Esprit 80 will give you F5 and so will be something like 4 x faster than the KAF8300 and SW ED80DS-Pro combination. Adam

Theory suggests the 460EX is twice as fast as the KAF8300, but with only half the area. Thats fine when you have a large subject and you can either do a two panel with the KAF8300 or 4 with the Sony in approximately the same time the Heart like you say is a good example but more planning required. But if its a smaller fainter target (soap bubble for example) or anything that fits the Sony FOV in a single frame it will just be faster and higher resolution than the KAF8300 and on an identical scope the KAF8300 has no come back to that. Also worth noting that the gap in sensitivity is even larger for SII than for Ha due to the fall off in QE of the KAF8300 at longer wavelengths. Finally you can afford to bin 2x2 the Sony for faint OIII and SII where as the larger pixels of the KAF8300 will result in a large pixel scale if you bin them 2x2. Adam

Well I suspect that there is only one theory but multiple interpretations of what people regard to be an acceptable signal to noise ratio.

I would go 130PDS not 150PDS as its not much less aperture for visual but much lighter for Imaging.