Odd artifact on Vega: what caused it?

[MikeOram]

I was playing with a simple compact camera last night, taking shots of Vega. The first of a series of 50 shots shows a weird 'plume' out of Vega (see image). I know there's terrible lighting - it was only 11 at night and it was more twilight than night: in my defence, I was just playing, thinking that if I can't get something out of a 1" compact camera,  AP isn't for me. 

I'm a complete newbie at this but (1) None of the other stars have it, so not vibration? (2) It's not on dark frames, so not a sensor artefact? (3) It's one the .RW2 file as well as the .JPG, so not JPG processing artefact?

Anyone got ideas as to what caused it? 

[tooth_dr]

Looks like the camera moved during the exposure.   Because Vega is the brightest, its most noticeable, but it's also evident on the star to the left of the image, and to a lesser extent on the other stars in the image.

 

[MarkAR]

Yup, there's some movement. Best way to reduce this is to set it to timer or use a remote trigger. If you can lock up the mirror that could help as well.

[Corncrake]

51 minutes ago, MikeOram said:

but (1) None of the other stars have it, so not vibration?

Anyone got ideas as to what caused it?

I was going to suggest the same as the others, but they beat me to it cos I was still playing with it in GIMP and was going to ask if you meant :

other stars in this image or

other images of other bright stars ( not that there are many at this time of the year, but you know what I mean, brighter than than the double-double ! )

 clutching at reflections for example, but it doesnt look like that shape anyway.

So, there I am rabbiting on hence why I'm way behind 🤣

[MikeOram]

I though at first it was vibration, but I'm not so sure: I use the camera's timelapse and the next frame shows similar 'trails' in the more peripheral stars but nothing on Vega. And, forgive my ignorance, but wouldn't movement of the size of the 'plume' do at least something to the image of other stars? [when I subtract the two frames all that's left is the plume]

[Tenor Viol]

Vega is significantly brighter than anything else there - by  factors of dozens (5 magnitudes is a difference of 100 fold). I suspect in the second photo the stars all look to be slightly distorted in the same direction, so it's probably some trailing. 

You haven't provided much info: what's the focal length and aperture of the lens, how long was the exposure, what was the ISO, was it guided? These all help towards eliminating issues. 

Edited July 7, 2020 by Tenor Viol

[Corncrake]

No exif data in the jpg. Dont know the camera ! What is it doing mechanically after it has timed-out ? Doing that just removes your finger vibration ???

as the shape has changed it suggests perhaps not a lens defect, I still put money on vibration/movement.

Vega is not known for eruptions !

Edited July 7, 2020 by Corncrake

[MikeOram]

Many thanks for everyone's input: as I say, I'm testing the AP waters (without investing in new equipment). A bit more information:  the camera (DMC-TZ100 compact: 1" 20MP sensor) was on a solid tripod (Manfrotto  475B, Benro S6 head: more than capable of holding the camera steady). No tracking let alone guided (I think this is where the trailing comes from). Used the built in time-lapse, so not touching the camera as it shoots. 5 second exposure [10 second exposures produce noticeable trailing]. ISO-400 (twilight conditions). Focal length 27mm (73mm as 35mm equivalent) .

Consensus seems to be a movement/vibration artefact. I must say I'm surprised at how much difference the brightness makes - lots of trail/plume on vega but no change to the other stars. I would have wrongly expected them to become less bright if the camera moved as the light would have been 'smeared' to a similar extent. I live and learn.

 

[Corncrake]

ah ! I am not intimate with that camera, is it mirror or mirrorless? If the former can it be locked up to avoid, eliminate possibility of,  vibration from that.

Does it do RAW ? jpg artefacts and processing can hide diagnosis.

Now I'm shooting in the dark

 

Edited July 7, 2020 by Corncrake

[MikeOram]

Hi Corncrake,

Thanks for your interest and help. Its a mirror-less camera and not at all suited to AP (slow lens, small sensor...). I just wanted to see if a simple set-up - for which read not getting anything new -  could get results that would compare/reflect  what I see in my bins. I have to say, it's exceeded expectations with much fainter stars coming out with a bit of post-processing (mag 7 easy to see, mag 8 evident even in the poor conditions for the shots of vega last night with only 49 frames).

I save both RAW and JPG (raw - Panasonic call them RW2 - for stacking, jpg to quickly filter out duff frames like the one above). The artefact is also in the RW2 file, so its not jpeg artefacts. 

The camera has a built in time-lapse option (intervalometer with delay before starting shooting)  but I guess I must have somehow knocked the tripod some seconds after setting it going). Just for my peace of mind, I'm going to try and replicate the effect: its does gives a dynamic sense to the frame. 

[Corncrake]

1 hour ago, MikeOram said:

going to try and replicate the effect 

dynamic sense to the frame. 

Hi again,
yes sorry, my bad., I missed your earlier ref to RW2, (poorexcuse = evening meal prep at same time !) my Panasonic calls raws RAW would you believe

So, yes the assembled collective seems to have worried it to death and its back to experimenting again, good luck, it will be interesting to see how you get on, these newfangled mirrorless sound tempting for various reasons !

 

[Tenor Viol]

Might worth hanging a weight off the tripod column

[MikeOram]

Thanks for the idea Tenor: my tripod weighs in at a hefty 4.5kg by itself and and can easily take another 10kg which would make it absolutely rock solid. I'll lug something heavy out next time  .