13 replies to this topic

[Hrothgar]

Anyone on here with experience using an IMX678 mono sensor for EAA of Galaxies and Globulars on a 150/1200 Newtonian? I’d be particularly interested in hearing about the settings you use. Anything else as well, as long as it relates to above.

[TelescopeBah]

Hello there,

I have not used the camera you are talking about, however, using the Field of view calculator, shows that your FOV with that camera would be pretty small. Also the scope with the parameters you say, is fairly slow for EAA, at F/8. It's not impossible, you would just need good tracking and longer exposure times.

[scanner97]

I'm just an AP guy who's interested in trying EAA at some point, so love to hear other responses.

 

These thoughts are coming from an AP perspective ...

 

Seems like the fov would be okay for most galaxies and globs.  M31/33 or the largest globs would not fit.  Most galaxy groups wouldn't, and very few nebulae other than planetaries.  If you want more fov for DSO on a budget, a 585 camera is not a bad option.

 

What I don't know is how long an exposure you'd need for your galaxies to get a good EAA result at f/8.  If you need longer exposures, your mount becomes a question.  And the long f.l. is a challenge, especially if you needed to guide.  With that plate scale, guiding would mean an OAG, which is one more thing in your imaging train, hanging off the focuser.  And then you start needing an AP capable focuser along with a more capable mount.  (Maybe you already have a solid mount and a focuser that can handle the weight...)

 

Anyway, how long is long enough for really dim objects in EAA at f/8 is a question someone with more experience will be able to answer.

 

Good luck!

[Udi]

I am using the IMX 678 with C11" - Wonderful details of M51, M82 etc. Yes; I don't see much of M31 and M33 - but the rest of galaxies - amazing.

[scanner97]

Hi Udi, Are you using the C11 at native focal?  What's your typical exposure length with galaxies for EAA?  Tx!

[Hrothgar]

Thank you Viking. 

 

I agree that FOV is not really an issue for what I was trying to use the combo for.

 

Nebulae don't hold the same interest for me - all those garish colours .

 

I have an NEQ6 Pro so guiding is not an issue, or at least not that I have noticed. 

 

I use Sharpcap mostly. Plate solving can sometimes be a issue, but I have work-arounds:

 

-  a quick stack plus slight adjustments to centre (the go-to function on my mount is very, very good when everything is properly aligned to begin with)

- a quick swop in/out with the IMX 585 OSC sensor and plate solving using Sharpcap if the previous fails

 

The focuser on my particular 150/1200 is indeed less than perfect.

 

I saw monochrome shots by someone a while back (on Astrobin I think) which I liked a lot - none of that garish colour . That person used a combination of an IMX678, a luminance filter and a C9.25 at native if memory serves. I haven't been able to find that back, which is annoying since an IMX 678MM plus an 150/1200 Newtonian fell into my hands separately short while back for very little.

 

Apart from the expected sluggishness, I've had no issues using the 150/1200 Newtonian with the IMX585 OSC sensor I own. The IMX678MM combo is more tricky I find.

 

I was just wondering had anyone tried this combination for EAA (or even for AP). I tend to prefer longer EAA exposures - 40-60 mins per subject - to short hop-abouts, a sort of hybrid EAA / AP maybe, neither fish nor fowl. So far (early days), I can't seem to find ideal gain/exposure settings for what I want to do, especially where galaxies and this combo are concerned. As F8 is sluggish and me a combination of luddite / lazy / getting on, I was trying to save time by enquiring here.  

 

PS The inexpensive 150/1200 Newtonian is surprisingly good when used visually as well.  

[Hrothgar]

I'll second Viking's query Udi. What kind of exposure and gain settings do you use with the C11? There's one of them lying around here as well. 

[scanner97]

Nebulae don't hold the same interest for me - all those garish colours .

The colors don't have to be garish.  It's all in the processing.     But some folks prefer grayscale and there's nothing wrong with that.  Even some advantages.  Everything is a trade-off.

 

 

Apart from the expected sluggishness, I've had no issues using the 150/1200 Newtonian with the IMX585 OSC sensor I own. The IMX678MM combo is more tricky I find.

 

I have a 678 I use as a guide cam.  The 2 um pixels are great for that, but would be rough at 1200 I imagine.

 

On exposures, I was thinking about subs.  I assume your 40-60 minutes is the total integration time.  What sub-exposure lengths are you shooting when you do that?   

 

It sounds like you have gear and experience; looking forward to hearing how it goes!  I will dip my toe into EAA at some point, probably with the 678 for planetary and the 571 for DSO.  In the meantime, I'm just trying to collect data on how folks do what they do.  

Edited by scanner97, 25 March 2025 - 03:09 PM.

[Udi]

Hi Viking and Lift Off,
There are two configurations for EAA, and another one for Planetary stacking:
1- With the Celestron 0.63 focal reducer, I am able to use for most DSO, the Sharpcap plate solving. I also use it for two stars alignment in alt-az mode that U like to use for quick EAA. But polar alignment won't work on such small field and Eq. mode is problematic. The solution is:
2- For Eq mode as well as for AltAz without a reducer, I am using the original finder scope of the C11, converted to a 200 wide scope which uses a Mead LPI-G advanced camera, and mounted and aligned well on the C11 using a rings I purchased in AliExpress. I input both to Sharpcap, first using the wide scope wit plate solving to get to te object' then switching to the 678 camera, adjusting  a bit to center' and starting the EAA.
3 - For Planetray stacking', I am using a similar configuration, but after locating on the planet, I turned of sharpcap and thurn-on Fire Capture with 678 for capturing 10,000-20,000 frames, and then process the result using AstroSurface.
Attached are few examples.
 

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[Hrothgar]

You are correct Viking. I should have used 'integration time, or maybe 'stacking time' when talking about EAA. How I used 'exposure' in that context was careless.

 

Ditto with my use of 'monochrome' and 'grayscale'.

 

I have only been out 4-5 nights with the 678 and apart from some views of Globulars, I have been less than happy. Last night I tried  it on M104 and M51 and the results were unimpressive. So I switched back to the 585.

 

With the 585 I do something like 10-30 sec subs at around 200-300 gain. It depends on the telescope I'm using and what I'm looking at, whether I'm on my own or people are around, the ambient conditions. By and large, I have a feel for that camera at this stage for EAA, but it took time. 

 

The 678 is proving to be more tricky. I'm not very technical minded.

 

I have not used the 678 for planetary EAA though the 585 has produced images in Sharpcap that pleased me a lot.

[Hrothgar]

Thank you Udi. Any recollection of the gain/sub exposure settings you used on those Galaxies?

[Udi]

Apologize, I forgot to detail it before:

- In alt-az without a focal reducer I an using 5 seconds per frame and a gain of 350. With a focal reducer the gain is 300.
- In Eq. mode without a focal reducer I an using 30 seconds and a gain of 300. With a focal reducer the gain is 250. As I am not using guiding I am not going beyond 30 seconds per frame.
- For planets I am using the Sharpcap  curves to adjust the gain, also targeting few milliseconds exposure.

For DSO's, I am also using darks, and flats with dark-flats

My mount is AZ-EQ5.

Edited by Udi, 26 March 2025 - 04:30 AM.

[Hrothgar]

Many thanks for the info Udi.

 

I will try these settings when I get out again, maybe even tonight.

[Udi]

Good luck Lift Off,
looking forward to see the (hopefully good) results!