Wednesday, 29 April 2009

Photos at Night

I love low light and night time photography. The photos have an atmosphere that you just can't get during the day.

To get the best from your low light shots, there are a few "rules" to follow that you would not typically follow during a daytime shot.

So how (and when) should you take a night time photo?

I follow some guidelines.

1) TRIPOD - ALWAYS use a tripod or some kind of support. No hand holding. No excuses, full stop. End of story. Close the book and go to sleep.

If you must take that shot and you don't have a fully extensible tripod in your back pocket then use some kind of support. No, don't go and call the Samaritans because you don't have your tripod. Rest your camera on something. A bin, a wall, a railing. Even prop it against something like a lamp post or a tree. Watch out for those grey squirrels and pigeons, nasty critters!

2) ISO - Keep your ISO at 100 (or the lowest setting on your camera).

Due to the amount of low signal light (shadows and black areas) the image will start to show colour noise. And, due to the long shutter speed, it will get worse. That's enough of that.

3) APERTURE/SHARPNESS - Stop down the aperture.

Even slightly. You want decent sharpness especially at night and if you understand how sharpness is interpreted in a digital image, then you want the best next neighbour contrast at the pixel level that you can get. A wide aperture is blurry and has a shallow DOF.

I aim for a range between F/8 and F/11 for the best performance of the lens and decent DOF.

Most of the light from objects at night is low level reflective due to lack of large/strong incident light so get the best from your lens.

4) TIME OF DAY - Never shoot at night!

What!? Yeah, you read it right. DO NOT shoot at night time! ;-)

Shoot at "low light". This should be your "bingo moment" coming up :-)

When the sun just sinks below the horizon, there is about a 30 - 45 minute timeline where the light in the sky is changing quite quickly (getting darker). You may be lucky and get some colour as the light rays from the sun bounces around in the atmosphere and hits warmed gases and dust particles that scatter the light and create that sunset colour.

But there will be that moment when the sky starts to turn a very deep blue going to black. This always happens, guaranteed. It's nature, or is that physics? The street lights have just come on and they haven't had enough time to warm up to their sickly orange glow! That is it! That is the moment you are waiting for. Shoot like crazy because it won't last for long.

5) EXPOSURE - Have a "go to" exposure memorised.

This is a personal taste and is down to your experience.

What I have is a number of aperture and shutter speed settings, for a specific sunset period. My ISO is always at 100. These two numbers are what I know will get very close when the sun has set, the sky is getting dark blue but not black. From there, I can adjust quickly if it is a little brighter or darker.

Try to have your own set from your own experience. To get you started, try F/8 for 10 seconds and then adjust the shutter speed for the correct exposure.

6) Shoot at night.

There are times when you do want to, or need to, shoot at full night. When? Well, shooting stars, the moon, star trails. When people aren't on the street. Although you could shoot very early in the morning when the sun is just about to come over the horizon.

This post is worthless without pictures...

Transition Set One - Tower Bridge (Single shot, OCF - Off Camera Flash).

Any easy one to start off with. The camera is tripod mounted with my 580EX off camera (in my hand). No remote trigger for the flash, I am doing some light painting. No, I'm not flashing the bridge!

The sun has just hit the horizon to the right of the frame and is setting.
A few minutes later, the lights on the bridge are turned on.
The sky is now turning darker and this I think is the best time and my favourite shot. See the moon in the background?
It is that dark blue to black I was talking about. I think this one is a little too late. See how much detail you can see in the previous image compared to this one.

Transition Set Two - London City Panorama (multiple stitched shots)

A little more complex, doing a multi shot pano at the same time as low light. It is possible for the light to change slightly from the first to last shot, especially with moving clouds, so be very FAST!
The sun has set and the sky is turning black. There is still some interest left in the sky so you can still get away with taking the shot. A few minutes later, that shot was gone. Time to go home.
A rule breaker. Does this one work? No? why not? Yes, why so?
Don't forget to try some creativity and have fun.
The most difficult exposure I have attempted so far.



Saturday, 18 April 2009

Panorama Pictures


The immediate benefit of taking a multi-shot panorama is the FOV (Field Of View) and also size and ultimately image quality. Lets say for example you use a 6 megapickle camera, it's one of those organcic green ones. Well if you crop say 10% off the top and bottom to make it "look like" a panorama shot then it becomes a 4.8 megapickle image which restricts the size you can print to maintain the best resolution.

By taking multiple images and blending them, you get a much larger image and thus better resolution (clarity and sharpness) when printed at say A0 size. Plus, they can look pretty cool.

When I first started taking these they would kind of work sometimes and other times I had quite a few problems that I would then spend hours in processing to fix. Over time, experience (and frustration) taught me how to ensure a higher success rate at the time of capture.

(If there are any terms which are unfamiliar to you then please spend a little time with google to read up about the details. It will benefit you in the long run.)

(My) Most common mistakes:

1) White balance
2) Exposure
3) Lens Focus
4) Speed of capture
5) Camera rotation (overlapping and parallax errors)

With regards to point 5) you can shoot a panorama with the camera on a tripod and also hand held. I now prefer hand held (if the shutter speed is fast enough) as I can control the rotation near enough to the lens nodal point. If you are doing commercial work then it is a priority to get yourself a dedicated panorama head for your tripod. For us amateurs, some simple techniques will work most of the time.

Ok, so let's start with the first point.

White Balance.
I used to have the camera set to Auto White Balance (AWB on the camera). This would cause each shot to be metered by the camera and it changing the colour temperature depending on the type of colour cast it thinks it was "calculating".

The result would be that each joined shot would have different colour casts to them which you would see across sections of the pano image.

Therefore, if shooting in daylight (indoors or outdoors) then set the white balance to the type of day it is. Sunny, cloudy etc If shooting at night with street lights or indoors with lights on then set the white balance to the type of lighting in use. Tungsten etc.

Exposure.
If you shoot in AV, TV or whatever other mode you prefer then sorry but you are going to have to learn to shoot in "M" mode. There is unfortunately no work around. This is probably one of the most important rules in taking successful panoramic pictures.

What would happen if you use one of the auto modes is you take a shot (camera decides exposure - Aperture and Shutter Speed), move slightly and then the shutter speed or aperture changes because the in-camera meter is trying to maintain 18% gray. When you come to stitch the images together, you may have darker and lighter shots to merge together as the camera is trying its best to maintain the same exposure across the scene.

But I hear you thinking, gears whirring, smoke out of the ears: "If I am looking at a scene in front of me, say 160 degree FOV (field of view), then the sky may be quite light near the sun and it is getting darker further away from the sun."

Eureka!

What the camera will try and do is balance the whole scene to 18%. Making some parts lighter (dark areas) and some parts darker (the light bits) by adjusting the shutter speed or aperture.

Here is an example of a panorama shot with the camera automatically exposing for the scene. See the banding that happens. This is why manual exposure is a must.


You want it to capture the lighter parts and darker parts as you see them. Because this is how the brightness in the scene graduates and so you want to recreate it in the shot. This will then guarantee a decent tonal graduation from light to dark, dark to light etc.

First of all meter the whole scene: Preset your aperture, you want this at F/8-F/11 for the best DOF - depth of field and sharpness compromise due to lens diffraction. Check your shutter speed and up the ISO if you need to. If you are on a tripod then leave your ISO set to the lowest value. Now scan the scene (looking through the viewfinder) from left to right and watch the light meter. If the light meter moves an equal + and - amount across the whole scene then you are virtually spot on. If not then change your shutter speed to get this result.

Take a test shot in the lightest and darkest part. Check the histogram on each shot. For the lightest part, does it clip the highlights? On the darkest part, does it block the shadows? If so then adjust the shutter speed either up or down a 1/3 of a stop and try again. You want to get to a situation where you are not clipping the highlights or the shadows. If you are unable to manage it, sometimes you can't, then set the shutter speed as close to mid exposure so you DO NOT clip the highlights on the brightest part.

Lens Focus.
Before you continue, swot up on Hyperfocal distance and Depth of Field. Then, find out the hyperfocal distance for the camera AND lens you are using. Why camera, because you need the CoC (circle of confusion) for the sensor. You basically want the objects nearest in the scene and furthest away from you to be in focus and sharp. There is a point where you cannot get objects really close to you in focus whilst getting a sharp background. Get to know what this distance is and then back up a bit.

Right, back from google?

Set your lens to MF (manual focus) and dial in the hyperfocal distance on the focus ring then leave it.

Sorry I have not gone into detail on this but there are sites out there that can explain hyperfocal and give you calculators that will do a lot of the brainwork for you.

THIS is a good site.

As a general rule of thumb, you can focus a third of the way into the scene. To do this, set the lens to AF, choose the focal length you want to use and then focus on an object a third of the way into the scene. Set the lens to MF, which will preset the focus so it won't change. Then recompose and leave the settings on the lens.

Third rule; Preset the focus on the lens.

If you made it this far then well done!! I got bored and had a quick play on GT5.

Anyway!! This is "all" you need to do on-camera.

Speed of Capture.
If you are shooting at Golden Light or on a day where there are clouds in the sky then you need to be pretty quick when you take your shots. This is due to the light changing across the scene you just averaged due to the setting sun and/or clouds moving. If you are taking shots of any moving parts like water, people, cars, boats etc then you will get some ghosting or disjointed parts. You will have to post process these manually.

Aim to get across the scene in about 5 seconds. Anything under 10 seconds would be great.

Fourth rule; Be quick.

Camera Rotation.
You need to know about parallax errors and lens nodal points for this section. Google is now your friend :-)

Hold up your index finger in front of you. Check what is directly behind your index finger, lets say in this case it is a tree in line with the finger. Focus on your finger and then close just your left eye and then your right eye. See how your finger shifts depending on which eye you close. This is the parallax errors. Because your eyes are slightly apart, hopefully not Uma Thurman distance (sorry Uma), then that slight shift in distance means you are looking at your finger and the scene behind it at a slightly different angle.

If shooting handheld, when you rotate around the scene, anything in the foreground will appear to shift because the angle at which the lens is viewing the scene and thus the foreground to background object is slightly different. When you come to stitch your picture together a rock, for example, in one scene will have shifted slightly in the second scene and thus not on the same alignment.

Here is an example. See how the rails on this scene are not aligned.


So you don't rotate! You basically shuffle your feet around the camera.

This is the pivot point. If you rotate, then you are spinning within the pivot point under your body and the camera is on the outside rotating around the pivot point. If you keep your camera steady and use the point directly under the camera, then the camera spins around the pivot point and you move around the outside.

You want the pivot point at the camera to be around a third of the way from where the lens connects to the camera to the end of the lens. This is my general rule of thumb. You can use a monopod held under the lens to rotate around. Be careful not to shift the focus ring.

If you want to be precise then you need to find out the nodal point for your lens depending on the focal length and use a pano head for your tripod.

If you are using a tripod then just rotate. You will have some parallax errors but hopefully they will be slight and your stitching software can cope with it.

Overlap your images by about 30-50% Use an object as a reference point and line it up in your next scene.

Fifth rule; Shuffle yourself around the camera/lens if hand held.

Camera Orientation.
This isn't a rule, it is a preference.

I try and shoot most of my scenes in portrait mode. It gives a better pano in my opinion as it gives the final image more height.

It's up to you, try both and see which you like.

Multi-row Panorama.
This is where you take multiple rows, as well as columns, resulting in a much higher resolution. Some stitching software can cope well with this format and so if you are thinking of printing a very large image then go for a multi-row format.

You start from the top left of the scene work across, move down and back to the left and move across again. Continue for as many rows as you like and ensure that you overlap by 30-50% across the horizontal as well as the vertical.

I find that a standard or longer focal length lens works well with multi-row as it reduces the wide angle distortion for each shot.
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Quick Notes.

White balance
Preset to a manual setting such as Sunny, Cloudy, Tungsten

Exposure

Set camera to "M" mode and preset the ISO, shutter speed and aperture. Meter for the average area of the scene and leave it.

Lens Focus

Set the lens to MF - Manual Focus. Focus a third of the way into the scene.

Speed of capture

Take the shots quickly; within 10-15 seconds.

Camera rotation

Turn around the centre of the camera and overlap from around 30-50%
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Some applications that you can use to stitch your images together:

Autostitch (free), PTGui, Pano Tools, PT Assembler, Photoshop's Photomerge.

British Library Reading Room. Here I am slightly tilted up to capture the skylight into the picture. I used a lens that had IS (image stabilisation) on it otherwise the shutter speed would have been too low to get a sharp image. This is a 14 shot image.

London City at Sunset. An example why being quick is paramount. The right side of the scene is getting dark as the sun sets. The left side, where the sun is setting, is still light but it is constantly changing.




Monday, 13 April 2009

Stereo Images

There is a trick to it. Either you can do it or you can't.

Ok so put your face about 2 feet away from the monitor and keep the image centered in your view. (Click on the pic for the larger version). Then cross your eyes slowly (not too much) and you will start to see three blurry images. Concentrate on the one in the middle.

The one on the left is your right eyes image shifted to the left and the one on the right is your left eyes image shifted to the right. The one in the middle is being created in your mind by merging the two images together as they pass each other. Concentrate on the "merged" image in the middle and after a few seconds your mind will focus the image.

This was done hand held to see if it worked, it did, kind of.

Click on the pic for the larger image, This one is too small...

INFO: Take a shot. Then move your whole upper body about a couple of inches to the right and keep the focal plane parallel to the scene. Then take the second shot.

Don't twist your body to the right, you want to physically shift the whole of the camera to the right, directly parallel to the scene.




Friday, 10 April 2009

Macro Time Lapse Gardening

To combine photography with gardening, buy a propagator, compost and seeds. Sow the seeds and then take a macro photo over the duration of the growing season and record the growth.

So, here is the propagator with the sown seeds.

A day later, any growth? Hmmm, I'm too impatient!

Pick a grid, which one will be first to sprout forth a growth?




Saturday, 4 April 2009

Flash Gels

I ordered a swatch book of lighting gels which are very useful as flash gels for speedlights, and cheap! The one I received had around 200 different colours and cost £10! They are supposed to be free so go and visit your local studio or stage lighting supplier and pick one up yourself.

OK, so how do I hold the gels against the speedlights without using chewing gum? (we're not kids you know). Well, I could have used a rubber band or Velcro but wanted something that would not bend the gels and did not need any permanent attachment "device" on the speedlights.

Well, I went all Blue Peter and broke out the cardboard and glue!

Here are my home made gel holders, neat eh?


So what do they look like?

Here you go. Using basic colour theory:



Primary and complementary colours.

INFO: Bare flash with gels, triggered with Skyports. The closet one is on 1/4 power and the furthest away on 1/8th power.

Get your mitts on a colour wheel so you don't marry up gels that make your eyes bleed or the image look like an explosion after curry night!


My Website: www.ramyadphotography.com