A long night with the Elephant Trunk

[Gareth88]

Hi all, I decided to be a dedicated person for once in my life and stay up till now ha, I give you the elephant Trunk nebula, taken with my Esprit 80, with a 1600mm-Pro and a 120mm-mini for guiding. 600 x 6 and 4 x 1200 in Ha, 600 x 6 and 2 x 900 in SII and 600 x 6 in OIII ( a lot of ands.. sorry! ) Flats only, no darks, cooled down to -20, All stacked and processed in AstroArt 7. 

Let me know what you think! 

[Adreneline]

Good start on a target that is not favourably positioned right now.

I have just started imaging with an ASI1600 (in fact my first two targets were the Heart and the Elephant's Trunk!) having spent the last two years imaging with an Atik428ex CCD. One thing that is immediatley apparent is that in the Bortle 5 skies in this location long exposures with the CMOS 1600 don't seem to yield the same results as long exposures with the CCD 428 CCD. I tried Ha and OIII at 120s, 180s and 240s at both 139 gain/offset 21 and 200 gain/offset 50; I think the 200 gain had the edge on 139. In both cases the stars were not saturated so I don't think I overcooked the exposure times.

I used the advice given in the tables at the beginning of this CN thread to provide me with a starting point.

Might be worth you trying shorter exposures. Even at 240s individual lights appear to be very 'weak' but calibrating and stacking reveals more detail than I was achieving with the 428ex at 600, 900 and 1200s.

Good luck!

Adrian

[Gareth88]

1 hour ago, Adreneline said:

Good start on a target that is not favourably positioned right now.

I have just started imaging with an ASI1600 (in fact my first two targets were the Heart and the Elephant's Trunk!) having spent the last two years imaging with an Atik428ex CCD. One thing that is immediatley apparent is that in the Bortle 5 skies in this location long exposures with the CMOS 1600 don't seem to yield the same results as long exposures with the CCD 428 CCD. I tried Ha and OIII at 120s, 180s and 240s at both 139 gain/offset 21 and 200 gain/offset 50; I think the 200 gain had the edge on 139. In both cases the stars were not saturated so I don't think I overcooked the exposure times.

I used the advice given in the tables at the beginning of this CN thread to provide me with a starting point.

Might be worth you trying shorter exposures. Even at 240s individual lights appear to be very 'weak' but calibrating and stacking reveals more detail than I was achieving with the 428ex at 600, 900 and 1200s.

Good luck!

Adrian

Hi adrian,

thank you! It was puzzling me ( I didnt grasp what was being said in the CN post when I read it but now you made it clearer. ) 

I’m under class 6, so not ideal ha but I do Go up to a farm where it’s class 4, I haven’t gone higher than 139/50, I wasn’t brave enough, I’ve jumped from a dslr after a few years to a cmos, so it’s all abit alien but a very fun and reward learning curve ? . Even after watching a lot of videos ( easier for my brain to process ) things do sink in after the 5th time of watching it.

Gareth

[Adreneline]

17 minutes ago, Gareth88 said:

I didnt grasp what was being said in the CN post

To be honest I had to read it all a bunch of times before I figured it out and there is still much of the thread that confuses me even now. I may well be wrong but I interpret the tables as giving maximum exposure times so for my ~f4.5 system with gain 139 it implies not to exceed 1.9 mins. The skies here are >19 mags/arcsec^2; I'm pretty sure the relationship is not linear between 18 and 21 (more likely exponential) so I played safe and went for 2, 3 and 4 mins just to see what happened.

The trouble is all this experimentation needs clear nights - preferably a whole string of them - one after the other!

Praise be we have cloudy nights so we have lots and lots of time to process - and make Darks!

Oh joy!

 

[Gareth88]

I’m just on the fence with my mag skies being 19.24, but they have just installed led lights now all around so hopefully it might go up ( or not ha ) 

on my next night when ever that might be ( joy of our weather eh ) il have a play with it all, try gain 200 / 50 and probably go for a exposure of 2 minutes  and work from there  I presume this is why it looks also slightly out of focus aswel ? Even tho my focusing is bang on ? 

Gareth