My astrophotography 2021

CCD vs Film? Lots of time vs no patience? Alright, this is your place to discuss all the astrophotography what's and what's not. You can discuss about techniques, accessories, cameras, whatever....just make sure you also post some nice photos here too!
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celeron787
Posts: 73
Joined: Sun Jan 12, 2020 2:30 pm

Re: My astrophotography 2021

Post by celeron787 »

hhzhang wrote: Tue Mar 16, 2021 5:42 pm
Is the trailing (with autoguiding on) in the DEC or RA? I guess it is DEC. From what you describe, you have already achieved a very low alignment error (suppose the unit is arcmin).

The visibility of a given DEC/RA error is determined by your pixel scale. If my total drift error RMS is 2.x'' per minute (not difficult), I would then start shooting 1-min subs with ~200mm FL + 3.76micro pixel size (~4"/px). This can be relaxed a little bit in my practices.

Sometimes I feel the alignment may not hold position once you slew to different positions. And the trialing effect would different for the same error but at different positions. So sometimes I just point the scope/cam to the target object and do a quick PHD2 drift alignment there to ensure the error is controlled.

I think the alignment work for the above target performance should not exceed 10 minutes.
The trailing is in RA but only very very slight. When you do the phd2 drift alignment on target, do you adjust the azimuth or altitude?
I intend to only take 30s subs.
hhzhang
Posts: 345
Joined: Sun May 10, 2020 4:11 pm
Favourite scope: 115mm APO

Re: My astrophotography 2021

Post by hhzhang »

celeron787 wrote: Tue Mar 16, 2021 7:30 pm
The trailing is in RA but only very very slight. When you do the phd2 drift alignment on target, do you adjust the azimuth or altitude?
I intend to only take 30s subs.
The precision in RA on the star tracker even with autoguiding may be questionable. I guess your scope FL is 250mm or shorter, and then the RA trailing would not be acceptable for 30s subs. Have you tried a slightly east-heavy balance?

One problem with my star tracker is that in some range of positions, the RA speed looks a bit off -- far from smooth. So I always try to avoid running it in those positions -- so I just take off the scope and the bracket and flip the position.
Last edited by hhzhang on Tue Mar 16, 2021 11:11 pm, edited 1 time in total.
hhzhang
Posts: 345
Joined: Sun May 10, 2020 4:11 pm
Favourite scope: 115mm APO

Re: My astrophotography 2021

Post by hhzhang »

hhzhang wrote: Tue Mar 16, 2021 11:01 pm
celeron787 wrote: Tue Mar 16, 2021 7:30 pm
The trailing is in RA but only very very slight. When you do the phd2 drift alignment on target, do you adjust the azimuth or altitude?
I intend to only take 30s subs.
celeron787
Posts: 73
Joined: Sun Jan 12, 2020 2:30 pm

Re: My astrophotography 2021

Post by celeron787 »

hhzhang wrote: Tue Mar 16, 2021 11:01 pm
celeron787 wrote: Tue Mar 16, 2021 7:30 pm
The trailing is in RA but only very very slight. When you do the phd2 drift alignment on target, do you adjust the azimuth or altitude?
I intend to only take 30s subs.
The precision in RA on the star tracker even with autoguiding may be questionable. I guess your scope FL is 250mm or shorter, and then the RA trailing would not be acceptable for 30s subs. Have you tried a slightly east-heavy balance?

One problem with my star tracker is that in some range of positions, the RA speed looks a bit off -- far from smooth. So I always try to avoid running it in those positions -- so I just take off the scope and the bracket and flip the position.
Yea I'll try a little east heavy and see how it goes. I think the setup should be able to handle it fine as others I've seen have more load and have no problems unguided.

When you do the phd2 drift alignment on target, do you adjust the azimuth or altitude?
hhzhang
Posts: 345
Joined: Sun May 10, 2020 4:11 pm
Favourite scope: 115mm APO

Re: My astrophotography 2021

Post by hhzhang »

celeron787 wrote: Wed Mar 17, 2021 10:44 pm Yea I'll try a little east heavy and see how it goes. I think the setup should be able to handle it fine as others I've seen have more load and have no problems unguided.

When you do the phd2 drift alignment on target, do you adjust the azimuth or altitude?

I do azimuth adjustment first and usually, the result suffices.
hhzhang
Posts: 345
Joined: Sun May 10, 2020 4:11 pm
Favourite scope: 115mm APO

Re: My astrophotography 2021

Post by hhzhang »

2021-3-18

Went down to ECP and TMCR and spent a few pre-dawn hours there, but only managed to collect several minutes of subs that are nearly clouds-free.

Image
hhzhang
Posts: 345
Joined: Sun May 10, 2020 4:11 pm
Favourite scope: 115mm APO

Re: My astrophotography 2021

Post by hhzhang »

Anybody went out to capture the Moon encounters Mars on its path in between Hyades and Plaides?

I went out a bit late when the targets were at a low altitude already. Since Plaides was lower, it got affected by the light pollution and the clouds badly.

The biggest factor is of course the brightly shining moon -- not even half illuminated.

Image

Allow me to do a little bit of editing using earlier-date (Mar-2) shots of the same field.

Image
Last edited by hhzhang on Sun Mar 21, 2021 4:10 pm, edited 1 time in total.
hhzhang
Posts: 345
Joined: Sun May 10, 2020 4:11 pm
Favourite scope: 115mm APO

Re: My astrophotography 2021

Post by hhzhang »

Went down to ECP/TMCR to capture some milky way target (Antares and its neighbors) -- too bad the high clouds never went away. Collected many subs but hardly of any use.

But the three planets saved the trip -- a little. Jupiter and Saturn are steadily transiting the Capriconous, while Mercury steps closer to the Sun.

Image
hhzhang
Posts: 345
Joined: Sun May 10, 2020 4:11 pm
Favourite scope: 115mm APO

Re: My astrophotography 2021

Post by hhzhang »

2021-3-31

Last night of March. Finally came a clear night.

Spent a few cozy hours at Upper Seletar.

Was too late to catch the sunset. But the serene twilight scenery alone is fully worth the trip.

The stars emerge from the sky glow in the twilight.

Image
hhzhang
Posts: 345
Joined: Sun May 10, 2020 4:11 pm
Favourite scope: 115mm APO

Re: My astrophotography 2021

Post by hhzhang »

How I wish the skies are clear of hight clouds.

Image

See bye-bye to the winter stars
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