Adam J

Its not something you could possibly see with the eye by inspecting the mirror. your talking about an error in the 100's of nm range. The only thing that you can do to confirm it is to make a mask ( a ring of card) to block the outer 1cm of the primary mirror, if you then have a sharp edge on the star test then you have your answer. Would not effect DSO viewing or imaging too much but will impact performance for planetary imaging and viewing. Adam

The outser border being hazy can be that the scope has not cooled down sufficiently, but it can also indicate a rolled adge on the primary mirror. Adam

Oh yeah loads of things wrong with that tool, I really dont like it. 1) Seems to suggest that anything outside of 1-2arc seconds per pixel is a bad idea and its just not the case. 2) Vastly overestimates average seeing conditions. 3) Takes no account of the fact that spot size vs pixel size determines how sampled a star is and not arcseconds per pixel, I work at 4.2arcseconds per pixel on a regular basis and don't experiance square stars. 4) Takes no account of apperture size in the calculation and so often leads to the 183mm pro 2.4um pixels being seen as the most suitable sensor for wide feild refractos when infact resolution would be diffraction limited to the Daws limit in these cases. 5) Makes no attempt to balance resolution against Signal to Noise advantages of using larger pixel cameras. Or indeed acknowledge that smaller pixels have the same effect are slower optics and vice versa. 6) Doent really try and ask what the user is trying to image, different requirements for faint emission nebula imaging vs galaxy imaging. 7) Gives absolutely no consideration to the effect of a OSC bayer matrix vs Mono camera on effective resolution. Could probably go on. Just dont use it guys. Its missleading. Oh and while i am at it I am not sure on the maths behind the filter size calculator either. I would write my own online tool but I have three kids and a job so if I did stuff like that I would have no time left for the hobby itself. Adam

Its difficult to quantify as your image scale comes into play, but it is around 1/3rd more sensitive. Has some less desirable qualities too though in terms of calibration. (As does the 1600 in terms of micro-lens / diffraction reflections) It has larger pixels which is better for speed, but not detail. All in all the 294 is better in most situations, but you are correct the difference between a DSLR and a cooled mono camera dwarfs the difference between the 1600 and 294. It would be difficult to pick a mono camera that would leave you disappointed with your purchased in comparison to a DSLR the jump is just that big. Adam

It depends, the 294mm pro is more sensitive. but is more expensive and is not available in a package deal like the 1600mm pro. The 294 will also require 31mm filters as opposed to 1.25 inch (Similar price, but to be honest I have a preference for mounted filters). There is also the 533mm pro about to be released and I would consider it the better sensor sensor of the three although with a smaller field of view at a given wavelength. However, all things said any of these three will work just great. Adam

Depends on the chip, some perform internal calibration for short exposures and have difference noise characteristics in short exposures. Or just don't take consistent length exposures below 2 seconds.

I don't think that serious AP is the correct term to be honest. You can do some serious work at 200mm focal length with a lesser mount. So for example my ~200mm AP kit totals up to over £3000 worth of equipment, that is AD filters, mono cameras, autofocusers etc. Its serious equipment for serious AP, all mounted on an AZGTI mount. I say this having had a HEQ5pro as my first mount and having subsequently split that to a AZEQ6GT for heavy weight imaging and the AZ GTI for mobile imaging. Note: The AZ GTI while great for the price often needs hands on tuning to perform and so it would not be something so a none technically proficient user. I think that its more accurate to say that is you want to use a 80mm+ refactor and image at under 2 arcseconds per pixel then you are going to need a HEQ5 Pro or better. SO I would say that it all depends on focal length and if you are wanting to image at a focal length of 450mm+ you probably want a HEQ5 pro as a minimum. If you are imaging at less than that you can probably use a lesser mount with no degradation in image quality. Interestingly at the time the HEQ5 pro was such a popular mount that when I sold it on I sold it for more than what I purchased the used AZEQ6 GT for, everything has gone up in price quite a bit since then though. So I don't know how much group think this happening with the HEQ5 pro especially when you have options at the same new price in the form of the CEM26 and GEM28 that are arguably superior mounts in a number of areas. Adam

Both charts are relative values not absolute. The 462 is the better camera for Jupiter particularly as you can use a 850nm filter to better effect.

I suspect you mean quantum efficiency which is only one thing of lots of things to consider when choosing a camera. It being nearly impossible to take the conversation further without knowing what the rest of your setup will be, your budget and what. You intend to image.

Well if you keep it outside in an obsy it's always ambient, if you don't then your crazy.

I would say the 127 Mac with the AZGTI but mainly because of the AZGTI as opposed to the scope. Not the the 127 Mac is a bad scope by any means. But you can always pick up something with a shorter focal length to complement it and the have a good mount to put it on.

Thanks was thinking about how it would fair as a airline portable (hold) mount.

Of your obsy is damp it will kill your optics long before it will kill the mini pc.

Don't see how that would help, can you show me what you mean?

Could you stick something like a coke can next to the mount head for me please? Was looking at one of these but can't get a feel for how big it is.

In theory the mirror could be tested as perfect. In reality the in use value is lower due to diffraction from the central obstruction and so it would never reach 0.98 in use.

No it won't be Polly or you would have a strehl Vs wavelength chart. It will be green light almost certainly. Nothing has a Polly of 0.98 over the visible range lol.

That is a very nice lens you got a good one if that report is accurate about 1/8th wave. You should be very happy.

Ok for an achromatic refractor you will 100% want a UV/IR cut filter. I would actually go a little further and recommend a Baader Fringe Killer. https://www.firstlightoptics.com/achromat-semi-apo-filters/baader-fringe-killer-filter.html Will leave things slightly yellow but more contrasty. Other alternatives are the baader semi-apo filter - darker image but leaves a better colour balance. Astronomik L3 - is going to leave purple fringes all over the place but better than no filter. Adam

What optics are you using?

Only if I see a change in HFR or I change a filter. Or I don't like the focus curve I got.

Probably so long as it's not too hard to get the filter in.

I 3d printed one. Might still have the file not sure.

Ok well i have seen a TS115 on their web site before. Assumed they had gotten it as a special for someone. Adam

https://www.firstlightoptics.com/ts-telescopes.html So these are imported with TS branding from the eastern manufacturer? Assume to get around the customs fee. Adam