Trying to get a certain effect with stacking

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Duncan.F

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Duncan
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Hi,
I have been experimenting with long exposure shots and as a trial took a load of people on an escalator. I stacked about 20 shots but was disappointed with the results. What I am trying to achieve is to end up with a more solid trail of people by stacking the images on top of each other. the composite image wasn't much better than some of the individual ones. Is there a way I can achieve a better result? I am using CS6.
Thanks,
 
I think it would help if you showed us what you've got so far and described what you did and didn't like about it. It's very hard to visualise.
 
I think I know what's going on, but I'm not sure I know how to fix it...

When you take a conventional shot of a moving subject using a fast-ish shutter speed, the subject is 'frozen' in one place, right? But if you use a slow shutter, then the subject looks ghostly. It's probably easiest to see how/why this happens if we play around with some numbers. Suppose your subject is 0.5m across and moves 5m during your long exposure. Then if you look at any particular point in the subject's path, for 90% of the exposure time the subject wasn't actually there (it was somewhere else in its path). So 90% of your exposure is the background, and 10% is the subject, so the result is that the subject appears transparent and ghostly.

If you want to have a lot of 'solid' people on the escalator, I think your best bet would be to take numerous conventional shots and composite them together. A bit like this perhaps... http://m.imgur.com/XEmCJ
 
I’m not sure if I understand what it is you are trying to achieve.
If it were one person many times using the escalator. Then I would time how long it takes a person to travel the length of the escalator, divide that by the amount of person images I want. Asses that against the shutter speed I need to freeze or slightly blur the image and then using the camera on a tripod set it up to take a burst of shots to embrace what I was after.

Probably talking rubbish as usual.

Rhodese.
 
Duncan,

In addition to the previous advice, this should be easy to do in CS6 assuming the camera was kept nice and stable during the shoot and your starting photos are well defined.

Choose which of the photos you like the best to use a base, ie perhaps no other people passing besides those on the escalator?

It is worth bearing in mind that of course you want the overlap between the people to "fall" the right way, ie people furthest up the escalator are at the back.

Open up your first photo of someone you want to add on a new layer, apply a blank (white) layer mask, paint black on the layer mask on top of the person to be added. This will do the opposite of what you want and remove the person so then invert the layer mask to add the person. [Alternatively, fill the layer mask with black, turn the opacity down half way, then paint white to add the person back in, then turn the opacity back up]

I don't know how much overlap you'll have between the people, but it may be that you won't have to be super accurate with your masking if the scenes line up well and the people wear similar colours. I find it easy/quick to use the brush tool because I have a wacom tablet, if you use a mouse making selections with the quick select tool, magnetic lasso etc may be faster, all personal preference and scene dependent.

Repeat for the other ~18 photos, bearing in mind what I mentioned about people appearing in the right order.

There may be a faster method but I am not aware of it.

Good luck and post your results.

Jeff.
 
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Hi
It's not going to be easy then! Loved the composite shot of the airport... Also thank you for the other suggestions!
 
Hi
TBH I am not sure now! It took ages for me to find anything on Youtube that would help and now I can't seem to duplicate it.....I think if I were to describe the effect am looking for in another way? In the shot I have posted, if it were possible to take a picture of the escalator full up in both directions and with a queue on and off at the bottom. Then to reduce opacity of the people and to add a little blur. I should end up with a solid stream or people but unrecognizable..
 
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