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Comet C/2025 A6 "Lemmon" on Oct 18th
- Thread starter Michael S.
- Start date
nighthiker
Senior Member
The tail of a comet is like a cat and can change completely within hours. I was taking pictures from a dark location (Bortle 2) last weekend and the tail changed from the 'classical' straight lines to a disturbed lift-off as you can see in the attached 15 sec image within a few hours. The over-processed image is for documentary only as I'm just learning how to stack my 150+ 15 sec images of LEMMON. PIxInsigth and little time ...
Yeah, it’s wild how much they change and how fast. I recall the same thing happening with NEOWISE, which I shot a total of five times, two morning sessions and three evening sessions. It looked very different each time. My shots last night of Lemmon show a dust tail as does your image above that was completely absent a few weeks ago when it was further from the sun. But the ion tail was back, spanning about 12+ degrees. Who knows how Lemmon will look two weeks from now? (Full moon then anyway and the comet very low in the sky, so it’s not like we’ll see or photograph the tail easily.)The tail of a comet is like a cat and can change completely within hours. I was taking pictures from a dark location (Bortle 2) last weekend and the tail changed from the 'classical' straight lines to a disturbed lift-off as you can see in the attached 15 sec image within a few hours. The over-processed image is for documentary only as I'm just learning how to stack my 150+ 15 sec images of LEMMON. PIxInsigth and little time ...
nighthiker
Senior Member
Hi!
I captured the long tail only by chance: I have had a 135mm lens with me which I was planning to use, but I've forgotten my insulation jacket. So I got very cold over time (around -3 deg C) as I took also other pictures (aurora!) and when I finally set up the tracker I was too cold to change the lens and simply used the 85mm lens which was already on the camera. Afterwards I went into the car and slept until sunrise. Waking up with a glacier in plain view isn't that bad. :-D
I captured the long tail only by chance: I have had a 135mm lens with me which I was planning to use, but I've forgotten my insulation jacket. So I got very cold over time (around -3 deg C) as I took also other pictures (aurora!) and when I finally set up the tracker I was too cold to change the lens and simply used the 85mm lens which was already on the camera. Afterwards I went into the car and slept until sunrise. Waking up with a glacier in plain view isn't that bad. :-D
Lemmon today 21102025. Olympus 40-150 Pro at 150 mm, f 2.8, ISO 2500, 2 s.
Mark H
"Life is worth photographing"
https://www.flickr.com/photos/139785057@N08
Mark H
"Life is worth photographing"
https://www.flickr.com/photos/139785057@N08
Last edited:
I hope you took more than one of those. Then you could stack them. You could probably stack five minutes or perhaps even 10 minutes worth of such exposures before the comet's motion wrt the stars starts to smear out the details in the tails. I know, that's a crazy 150 to 300 images. Its why there are trackers.Lemmon today 21102025. Olympus 40-150 Pro at 150 mm, f 2.8, ISO 2500, 2 s.
Personally, last evening I took over 30 minutes of 30-second tracked images with a 50mm f/1.4 lens at f/2.8 on an APS-C camera (I don't have a full-frame camera...yet) in order to capture as much of the ion tail as I could. I got it but the resulting signal-to-noise ratio (snr) isn't great even so. Your lens collects 2.7 times as much light for each second of exposure as what I used, but you would still need to do more than 300 2-second exposures to get the same snr.
2sealsonwheels
Well-known member
Oct 20th....the old fashion was, no stacking....just a single exposure....
Nikon D5600 with AF-S DX 16-80mm 2.8-4 VR, settings with each photo
F/4 80.0mm 3.0s ISO-1600...cropped
F/4 80.0mm 3.0s ISO-3200.....uncropped...full of satellites
--
Just having FUN with little old DSLR cameras!
Nikon D3500/D5600 and AF-P DX NIKKOR 70-300mm f/4.5-6.3G ED VR Lens and recently with the AF-S FX 500mm f/5.6 PF VR (Loving this lens!)
https://www.instagram.com/24megapixseal/
Nikon D5600 with AF-S DX 16-80mm 2.8-4 VR, settings with each photo
F/4 80.0mm 3.0s ISO-1600...cropped
F/4 80.0mm 3.0s ISO-3200.....uncropped...full of satellites
--
Just having FUN with little old DSLR cameras!
Nikon D3500/D5600 and AF-P DX NIKKOR 70-300mm f/4.5-6.3G ED VR Lens and recently with the AF-S FX 500mm f/5.6 PF VR (Loving this lens!)
https://www.instagram.com/24megapixseal/
Last edited:
I don't have tracker, so single photos. Here is another single, cropped and hevy proseccing.I hope you took more than one of those. Then you could stack them. You could probably stack five minutes or perhaps even 10 minutes worth of such exposures before the comet's motion wrt the stars starts to smear out the details in the tails. I know, that's a crazy 150 to 300 images. Its why there are trackers.Lemmon today 21102025. Olympus 40-150 Pro at 150 mm, f 2.8, ISO 2500, 2 s.
Personally, last evening I took over 30 minutes of 30-second tracked images with a 50mm f/1.4 lens at f/2.8 on an APS-C camera (I don't have a full-frame camera...yet) in order to capture as much of the ion tail as I could. I got it but the resulting signal-to-noise ratio (snr) isn't great even so. Your lens collects 2.7 times as much light for each second of exposure as what I used, but you would still need to do more than 300 2-second exposures to get the same snr.
Mark H
"Life is worth photographing"
https://www.flickr.com/photos/139785057@N08
Last edited:
nighthiker
Senior Member
You don't need a tracker for stacking. Just take enough short exposures and stack them e.g. with Sequator. For a not-too-long total exposure time you will not see the relative movement of the comet against the stars.
Stacking is your friend! And it's damned powerful!
Stacking is your friend! And it's damned powerful!
Thanks!
Mark H
"Life is worth photographing"
Michael S.
Veteran Member
Good Evening!
I just got that 10mins of clear weather, so I don't have the data to confirm, sadly.
best regards,
Michael S.
Veteran Member
Hui... Bortle 2,I envy you.The tail of a comet is like a cat and can change completely within hours. I was taking pictures from a dark location (Bortle 2) last weekend and the tail changed from the 'classical' straight lines to a disturbed lift-off as you can see in the attached 15 sec image within a few hours. The over-processed image is for documentary only as I'm just learning how to stack my 150+ 15 sec images of LEMMON. PIxInsigth and little time ...
--
Michael S.
EUROPE; dpreview since 2001
(check equipment via profile)
Michael S.
Veteran Member
Haha, got you.
Michael S.
Veteran Member
Lovely...Lemmon today 21102025. Olympus 40-150 Pro at 150 mm, f 2.8, ISO 2500, 2 s.
Mark H
"Life is worth photographing"
https://www.flickr.com/photos/139785057@N08
--
Michael S.
EUROPE; dpreview since 2001
(check equipment via profile)
Michael S.
Veteran Member
Good Evening!I don't have tracker, so single photos. Here is another single, cropped and hevy proseccing.I hope you took more than one of those. Then you could stack them. You could probably stack five minutes or perhaps even 10 minutes worth of such exposures before the comet's motion wrt the stars starts to smear out the details in the tails. I know, that's a crazy 150 to 300 images. Its why there are trackers.Lemmon today 21102025. Olympus 40-150 Pro at 150 mm, f 2.8, ISO 2500, 2 s.
Personally, last evening I took over 30 minutes of 30-second tracked images with a 50mm f/1.4 lens at f/2.8 on an APS-C camera (I don't have a full-frame camera...yet) in order to capture as much of the ion tail as I could. I got it but the resulting signal-to-noise ratio (snr) isn't great even so. Your lens collects 2.7 times as much light for each second of exposure as what I used, but you would still need to do more than 300 2-second exposures to get the same snr.
Mark H
"Life is worth photographing"
https://www.flickr.com/photos/139785057@N08
Did not have time to get my tracker too but you could still stack your images.
--
Michael S.
EUROPE; dpreview since 2001
(check equipment via profile)
Michael S.
Veteran Member
Greetings!Oct 20th....the old fashion was, no stacking....just a single exposure....
Nikon D5600 with AF-S DX 16-80mm 2.8-4 VR, settings with each photo
F/4 80.0mm 3.0s ISO-1600...cropped
F/4 80.0mm 3.0s ISO-3200.....uncropped...full of satellites
--
Just having FUN with little old DSLR cameras!
Nikon D3500/D5600 and AF-P DX NIKKOR 70-300mm f/4.5-6.3G ED VR Lens and recently with the AF-S FX 500mm f/5.6 PF VR (Loving this lens!)
https://www.instagram.com/24megapixseal/
I love DSLRs...
--
Michael S.
EUROPE; dpreview since 2001
(check equipment via profile)
starman1969
Senior Member
Very good Michael.
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