UKH

Fancy a photo challenge/project tonight?

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 The Lemming 11 Apr 2020

Seems like it will be a clear sky tonight, and maybe one or two of us are not going anywhere tonight. Can't think why .

I've never done any star trails and tonight seems as good as any time to have a play. Anybody fancy a Star-trail/time-lapse challenge?

Rules are simple, its got to be shot through a window at home or in your back garden.

And most important, stay safe and wash your hands.

Post edited at 18:55
 Tom Valentine 11 Apr 2020
In reply to The Lemming:

I've been fancying this for a bit but have discovered that the B setting on Lumix cameras  doesn't seem to be what it says. 

It cuts off after 4 mins on both cameras I've got which makes the star trail a very small line on a wide angle lens which is what most people use. 

Obviously on a long lens you will get a significant arc of light after 4 mins but in a very confined area of sky.

Keen to see what other users have to report back: Panasonic forums I've looked it up on claim its a safety device to stop the build up of heat.

 The Lemming 11 Apr 2020
In reply to Tom Valentine:

Going to play with my GH5 tonight. The first plan is use my 12-35 lens at 2.8.

Take a shit load of images at one minute intervals with a shutter delay of 50 seconds. I'm hoping for an hour and a half of images which I will then stack together in some software. Don't know what yet but I'll find something.

This is all guess work where I am going off the 450 rule as a guide and roughly doubling the exposure time for a trail in each shot. The delay will give the camera 10 seconds to get ready for the next shot.

This is all trial and error as I live next to a fekin bright street light, which is directly below the North Star.

 Tom Valentine 11 Apr 2020
In reply to The Lemming:

Ah! Stacking. I thought you were just taking photos....   

I think I might get the old Yashica out........

Post edited at 21:19
 The Lemming 11 Apr 2020
In reply to Tom Valentine:

Just started my shots. All seems well so far and in an hour and a half I shall pop back out and see the results. And then I'll point the camera in the opposite direction with as little light pollution as I can muster in the garden.

 The Lemming 11 Apr 2020
In reply to The Lemming:

New thing to learn. Go outside and clean the lens every now and then. I've had to ditch half my images but I've got 37

to play with in the morning.

Post edited at 23:34
 The Lemming 11 Apr 2020
In reply to The Lemming:

And here's my first ever attempt

https://www.flickr.com/photos/the1lemming/49762483446/in/dateposted-public/

I'm quite pleased

In reply to The Lemming:

> New thing to learn. Go outside and clean the lens every now and then.

...or wait for the dew to come down before you start shooting .  I think you can actually buy camera / lens warmers to prevent condensation too. However, you want a cold sensor to reduce shot noise.

 Jonathan Bean 13 Apr 2020
In reply to The Lemming:

Great idea. Did this on Tues, as opposed to Saturday but the days are just merging into one anyway!

https://jonathanbean.photography/star-trails-over-my-house

129 images stack for the sky, merged with a single foreground image. 30 second exposures, 4 seconds apart. ISO 640. F4.

J

 Tom Valentine 13 Apr 2020
In reply to The Lemming:

Excellent.

Scopes have an extension tube called a dew guard on them. Something similar could probably work on your camera, probably a deepish lens hood.

So is each line on your image the result of a 50 second exposure and 30 seconds on Jonathan's??

Post edited at 10:12
In reply to Jonathan Bean:

That’s really lovely!

 The Lemming 13 Apr 2020
In reply to Jonathan Bean:

Now that is impressive.

May I ask what software you used in post?

 Jonathan Bean 13 Apr 2020
In reply to Tom Valentine:

Not sure I follow Tom.

The sky trails are a merge of 129 thirty second images, with a four second pause between end of one exposure and start of the next. Does that clarify?

 The Lemming 13 Apr 2020
In reply to Jonathan Bean:

Mine were 50 second exposures with a 10 second gap in between each exposure.

My next project will have a shorter gap, say 2 seconds or 4cseconds. Hopefully this will give the sensor a chance to cool down and reduce gaps between the moving stars.

 Jonathan Bean 13 Apr 2020
In reply to The Lemming:

Thanks. 

Batch edited the raw files with Photoshop. This tutorial was very helpful.

youtube.com/watch?v=6BshOrLNySg&

Then in Photoshop, imported all of the batched images into one single file onto layers. Then you can set the blending mode on the layers to 'lighten' which essentially merges them all in to one. 

Did a single edit of the house and merged with my sky. 

J

 The Lemming 13 Apr 2020
In reply to Tom Valentine:

>  So is each line on your image the result of a 50 second exposure and 30 seconds on Jonathan's??

No. Each of my images produces a tiny star dot like normal. The exposure is 50 seconds because my iso is 200 and this allows a slight capture of movement just enough to blur the star from pinpoint to a smudge.

I then used software, starstax, to compose the 37 images into one image that gave the illusion of long startrails.

Post edited at 10:41
 Tom Valentine 13 Apr 2020
In reply to The Lemming:

So each line is approx 35x 50 seconds worth of captured light, or the star's movement over29 mins with time added for the intervals?

 The Lemming 13 Apr 2020
In reply to Tom Valentine:

Nope, each line is just a dot. 37 images stacked together are just those dots placed next to eachother by using software.

If I wanted a single exposure/image, and not the 37 that I took, then I would have needed to have a single exposure of 30 minutes to get the same effect of the startrail at the length they are.

 Tom Valentine 13 Apr 2020
In reply to The Lemming:

I think we mean the same thing: each line is  37 dots stacked together, each dot worth 50 seconds of light collection.

Can you stack them in camera?

 The Lemming 13 Apr 2020
In reply to Tom Valentine:

> I think we mean the same thing: each line is  37 dots stacked together, each dot worth 50 seconds of light collection.

Ahh, break down in communication.

> Can you stack them in camera?

No idea if a camera can do that. Maybe there is an app for apple or android though?

 The Lemming 13 Apr 2020
In reply to The Lemming:

Going to have another go tonight. I'm even going to have a stab at a timelapse as well.

This time I'll reduce the exposure length and reduce the rest time between each exposure. I'm going to go with 30 second exposures with a 2 second gap between each shot. This is for a 12mm lens and the 450 rule.

Just remembered, my camera has an inbuilt Timelapse feature. It can take a shed load of images with the inbuilt intervalomiter and at the end of the capture it can convert those individual RAW or JPEGS into an MP4 movie.

The camera does not have a feature to stack the images but a 4K timelapse is cool.

Post edited at 16:42
In reply to The Lemming:

Good work sir!

In reply to The Lemming:

Hi,

Why are you trying to eliminate star trailing in your individual exposures by limiting their duration, then adding them all together after to bring out the trails?

The point of your 450 rule is to keep the stars as points which seems counter productive here when i think you are trying to make trails. Why not just stop down your lens and do fewer longer exposures from the outset? You can increase the exposure time up to the point that either your camera stops you or your images are overexposed.

I accept that by taking lots of shorter exposures you can increase the dynamic range with stacking, but that's not really relevant for star trail shots.

 The Lemming 14 Apr 2020
In reply to richard_hopkins:

>  Why are you trying to eliminate star trailing in your individual exposures by limiting their duration, then adding them all together after to bring out the trails?

Probably because this is my second ever attempt at star trails and I am learning by experimentation. Last night's attempt was nowhere near as good as my first attempt. Last night I followed the 450 rule to keep the stars pin-point to stack. It did not go to plan and I just created a dot-to-dot image.

>  The point of your 450 rule is to keep the stars as points which seems counter productive here when i think you are trying to make trails. Why not just stop down your lens and do fewer longer exposures from the outset?

Yep, however I would have not come to this conclusion without experimentation and seeing for myself.

>  I accept that by taking lots of shorter exposures you can increase the dynamic range with stacking, but that's not really relevant for star trail shots.

Here's my second attempt. Composition wise I like considering the limits of my location and subject matter.

https://www.flickr.com/photos/the1lemming/49772236893/in/dateposted-public/

 Tom Valentine 14 Apr 2020
In reply to The Lemming:

Very good. I too was puzzled by your referring to the 450 rule ( I call it the 5000) but if that's what you were aiming for fair enough. I always assumed the whole point was to create a trail by leaving the shutter open for a considerable length of time, which is why I was disappointed to find the 4 minute limit for the B setting on both my Lumix cameras. I haven't tried it yet but assume that on my 12-32 lens (24-64 real ) it will hardly register as a line. I think your images give a good indication that at least 30 mins is needed. I have a manual remote but I'm not sure if I can lock it open for longer than the 4 mins.

 Tom Valentine 14 Apr 2020
In reply to Tom Valentine:

I meant 500!

 Tom Valentine 15 Apr 2020
In reply to The Lemming:

Confused now!

Decide to set mine up for single shot 4 mins . Plug lockable remote in,  B setting, all works ok. 

set it up on tripod with just a few treetops in and no other light- switch won't operate.

tilt camera to include house window lights- switch works.

Repeat to confirm. Scratch head a few times.

Any suggestions? Or explanations, at least.?

 Tom Valentine 15 Apr 2020
In reply to Tom Valentine:

Forums suggest it cant focus so set to manual

In reply to The Lemming:

This topic got me thinking, so here's my attempt https://adobe.ly/2VIXmkX

 Tom Valentine 19 Apr 2020
In reply to LucaC:

Nice one. They look like half hour lines to me.  How did you do it?

Regardless of stacking, I've realised that the four minutes my camera allows me on B is equivalent to 1 degree of arc, which on a 12 mm (24 adjusted) lens is just a small smudged dot.

 james mann 19 Apr 2020
 Tom Valentine 19 Apr 2020
In reply to james mann:

Great effort. I was interested in the other shot in your gallery which is titled "Bosigran .Long exposure"  because that's what my Non stacked images look like.

Post edited at 18:59
In reply to Tom Valentine:

This was a Sony A7 shot at 30s, f4, ISO 200. Set with a wifi trigger for 120 shots with a 3 second gap in between, so about an hours worth of shooting. In the end I used 102 of the photos as some of the early ones were still a little light, and the final ones had some blur from dewing up. RAW files batch edited in LR CC, exported as TIF and stacked with Starstax and exported as TIF for a final touch up. The camera is out again this evening on the same settings to see if I can do any better!  

 The Lemming 21 Apr 2020
In reply to The Lemming:

I had another go last night and got a meteor as well in the stack, but the single event is quite tricky to spot.

https://www.flickr.com/photos/the1lemming/49801596256/in/dateposted-public/


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