Monday, May 24, 2010

ISO and Noise

ISO in a nutshell is how sensitive your sensor is. In days gone by it was a measure of how sensitive your film was. ISO 100 was for shooting in bright light and ISO 800 or 1600 was for shooting in darker conditions. Point-and-shoot cameras often don't let you play with this and the camera chooses for you but it is an integral part of DSLR settings.

The main purpose for increasing ISO is usually to do with camera-shake. If conditions are getting darker then increasing the ISO makes the film (or sensor) more sensitive and therefore it picks up more light at a faster rate and therefore the shutter speed can be reduced - which helps prevent camera-shake.

Sounds great? Well yes, but there is a trade off as always and that's "noise".

Noise is something people don't really notice until it's pointed out to them... certainly, I didn't. After reading this go and have a look at some pics you've taken in low light conditions and you'll see it when you zoom in. In some cases it can be quite obvious.

Here is an example. These pictures were taken in a restaurant under relatively low light without a flash. The first picture was taken at ISO 200 with f3.5 and a resultant shutter speed of 1/10th of a second. The picture below that was shot at ISO 3200 and f3.5 and allowed a shutter speed of 1/250th of a second.

Obviously the shutter speed of the second picture in much faster and so it's less likely to show camera shake as the chances of you moving the camera much in 1/250th of a second is highly unlikely. However if you compare the 2 close-ups of each picture you will see a grainy artifact on the ISO 3200 picture. That is noise.

Personally, I try to shoot in the lowest ISO possible. Normally, I have the camera locked at ISO 100 or 200 but I never let it go above 800 as the noise on the D90 is quite noticeable above this. There is software to remove noise but the results vary. Therefore my advice would be use as low an ISO as you can and add a flashgun if need be.

Or carry a tripod/monopod with you everywhere to prevent camera shake!!!

Thursday, May 20, 2010

35mm f1.8 vs 50mm f1.8

So I love my 50mm lens. I've told you before why it's a great purchase but essentially here are the reasons in a nutshell...

1. Cheap
2. Wide aperture and great bokeh
3. Good in low light
4. Weighs nothing
5. Superb for portraits

However, the problem with the crop sensor is that it magnifies the 50mm to 75mm which really is quite zoomed in and I found that at parties and nights out (where this lens should come into it's own) the pictures were too close and I was having to stand miles away which can be an issues in a busy restaurant etc. Also, in properly low light the lens would struggle unless the ISO was boosted - sometimes to unusable levels e.g. 3200.

What were the choices (aside from buying a flashgun)?

Well I decided that the 50mm f1.4 was prohibitive from a cost point of view (>£300) and it still didn't solve the problem of being too close. So I had a rethink and decided to go for the Nikon 35mm f1.8 for about £160.

This didn't solve the low light problem as the aperture was still only f1.8 max (or so I thought) but it did mean I would have a wider amount included in each picture. With the cropped sensor it still equated to 52.5mm but that was greatly improved on the adjusted focal length of the original 50mm.

That was reason enough but I'd also read some reviews saying that it had better colour and contrast than the 50mm so after it arrived (today) I decided to put it to the test.

Here is a series of pictures taken at different apertures in low light. I fixed the ISO at 200 and let the camera choose the speed (not much of a difference there).

I think the most immediate thing that stands out is in fact the contrast and the colour like that review said (and how consistent the 35mm is). At f4 there isn't much of a difference but at either extremes there is huge differences. Although the shutter speed is much the same for both lenses and probably won't help much in low light conditions there is a massive difference in how "usable" the pictures are.

I also noted (although it's hard to see on this blog) that the bokeh with the 35mm (especially at f1.8) is far superior and much more aesthetically pleasing. The 50mm blur is super soft at that aperture and, blown up, looks terrible.

A final point is that the 50mm needed a 35cm minimum distance from the subject to take the picture whereas I could still focus at 20cm with the 35mm which just gives a bit more flexibility.

So all in all I think it was a good purchase and I don't think I'll be using the 50mm again. Having said that, the 35mm is for DX sensors and the 50mm can be used with both a cropped and full-frame sensor so if I ever get round to buying a Nikon D3x or something insane like that then at least I'll have one lens I can use!

Sunday, May 16, 2010

Circular Polariser

I'll not go into the optics of these and telling you how they work is a bit pointless - except that they work best at 90 degrees to the sun and reduce the light coming into your camera by about 2 stops.

What you need is to actually see the difference between a picture taken with the filter and one without. Both of the following pictures have been taken as JPEGs in camera with no post processing.

This is the original without the filter. It's OK but the sky is boring and the sea has a lot of glare.

This is with the polariser on. You can immediately see that the sky has changed to a more contrasty blue and the clouds are more interesting. The sea has lost it's glare and again becomes a deeper blue. The overall image is more pleasing and it's one of the very few effects that Photoshop has trouble replicating. If you are ever going to buy a filter this is the one.

One thing I would say is not to buy a cheap one as they don't work that well and it's a total waste.

Saturday, May 15, 2010

Crop Factor

It's taken me a while to figure out what the difference between a full frame sensor and a cropped sensor is. There is loads of detail on line about these 2 types of sensor but I think what mattered most to me was to do with wide angle shots and zoom lenses.

A few months ago I bought the Sigma 70-200mm f2.8 and a mate of mine stated that actually it was 105-300mm on my camera. It took me ages to understand what he was going on about and it wasn't until I stumbled onto a picture like the one below that it finally made sense.

This piture was taken in Puerto Banus in Spain and shows the famous "La Concha" mountain. If you imagine that the full picture is what a 35mm film camera would take. It's also what a full frame sensor would take. Cropped sensors are smaller so the area of light falling on the sensor is less. The red rectangle is the 1.5 crop of Nikon's cropped DX sensors and the green rectangle demonstrates the 1.6 crop factor of Canons smaller sensors. As I said before the 200mm becomes 300mm on the Nikon DX sensors (this would be 320mm on the Canon - since 1.6 x 200 = 320).

You can now see how a cropped sensor artificially increases your zoom since if you were to print all three pictures at 6 x 4 inches they would all contain slighty different amounts of the view. This is great from a zoom point of view but at the other end of the spectrum it can be a problem.

When you have a wide angle lens you like the Tokina 11-16mm f2.8 and you are using it on a cropped sensor it actually becomes 16-24mm which means you don't get as much width as you would on a full frame. It can be frustrating but I guess it's something you have to put up with.

Comments and critisisms always welcome.

Sunday, May 9, 2010


Filters are a useful aid to photographers. They come in many forms and essentially sit infront of your lens to either colour, darken or enhance your photograph.

The ND10 is a bit of a speciality filter and really takes a while to master - which I'm nowhere near yet. ND stands for Neutral Density and it blocks light without changing the colour that comes through the lens onto the sensor. The ND10 blocks ten stops of light which there for only lets in 0.1% of the light.

What's the point of this? Well it means that in broad day light you can keep the shutter open for ages. Normally this would make your shot completely white but with the filter in front you can easily do a 30 second shot without this happening. This has two significant effects.

First, clouds will move in that space of time creating some interesting skies. Secondly, water smooths out to give surreal textures. If you compare this shot with the first one you will see how different they are. This one was taken WITHOUT the ND10 filter and its more of a snapshot in time where as the upper picture really demonstrates the crazy effects you can pull off with this filter.

It's a nifty bit of kit but there are a few issues you should be aware of. It is so black that almost no light goes through and the camera really struggles to focus in autofocus mode. Sometimes, if it's bright enough and your camera has it, you can use Live View mode to focus but realistically you have to compose your shot first then put the filter on and take the shot. REMEMBER to turn off you auto focus after setting up the shot or else the camera will start trying to focus which you press the shutter and most likely it won't take the shot.

Another problem is that due to the super-dark nature of this filter it can't really be used long after sunset without having to leave the shutter open for minutes or longer. That presents another issue as you may then require a remote to lock the shutter open for more than 30 seconds - the tech and gadgetry of photography never ends I'm afraid. There are weaker filters that you can use, but alas I don't have any of those yet, but as soon as I do I'll post the results.

PS - A circular polariser can block 1 - 2 stops of light and can come in useful when the light is getting too low for the ND10 if you don't have any other filters.

Thursday, May 6, 2010


This term is used a lot in photography and it refers to out of focus background of blur. It's tied quite closely to depth of field but is more interested in the quality of the blur. In fact, some people would say that you get "good" bokeh and "bad" bokeh. I've never been to good at telling the difference as it really comes down to personal preference.

The easiest way to see an example of bokeh is to take a shot of someone at night time with street lights in the back ground as bokeh appears really easily from blurred highlights and distant lights. You'll see it all the time on TV as movie
cameras seem to be excellent at producing this.

The ideal bokeh should be perfect circles but this is very difficult with lower end lenses. Often the blades of the aperture cause pentagons and hexagons - you can see how my 50mm f1.8 has created decent blur but on closer inspection the would-be circles are actually heptagons by the seven blades of the lens.

It's also worth noting that too small or too large an aperture will cause bad bokeh. I'm not going to tell you why quite yet. Try experimenting with f4, f10 and f22 and see the difference for yourself. Remember, you are aiming for as perfect a circle as possible.

Wednesday, May 5, 2010

Depth of Field (DOF)

Depth if field is a bit of camera jargon that crops up all the time. Essentially it means the distance from the lens that is in focus. You control this using the aperture - a wide aperture e.g. f2.8 gives a very narrow DOF (I prefer to use "shallow") and a small aperture e.g. f20 gives a wide DOF (again I think "deep" makes more sense). It's confusing but the smaller the "f-number" the larger the aperture i.e. the hole through which the light passes into the lens.

This is much easier to demonstrate with some shots I've taken. Here for example I've used f2.8 and you can see that only the first dice is in focus.

This shot has been taken at f8.0 and already you can see that more of the dice are now in focus (please no comments about my incorrect use of die and dice!!)

This final shot has been taken with an aperture of f20 (or f22 - I can't remember) and it's pretty obvious that much more of the shot has come into focus.

Once you stop using auto mode, aperture priority is probably the next mode to get to know on your camera. There are a few basics to remember though. Larger f-numbers let in less light and your camera will normally compensate by decreasing the shutter speed. Unless the available light is bright your shutter speed will be very low and the camera shake will be noticeable.

Conversely, too large an aperture may cause abberations and fringing of ojects so your maximum aperture should normally be avoided in all but top end lenses. I'll talk more about these problems in another post.

Tuesday, May 4, 2010


This is a very simple post.

I have a small rickety tripod and while it's good enough for the odd picture it's pretty bad if there is even the slightest bit of a breeze. Pictures are soft and shaky and now that I've started to experiment with long exposure work the tripod is proving to be truely dreadful.

So a word of advice - you've got a DSLR with more mega-pixels than you can shake a stick at and probably several lenses and a bunch of other kit which you've paid a pretty penny for. So don't buy a cheap tripod. I'm now taking most of my pictures on the tripod so what's the point in having one that ruins every picture?

With tripods you definitely get what you pay for but there is an element of name brand price hikes e.g. Manfrotto and Giottos. However they do make bullet-proof stuff but if you're going to pay less than £60-70 you're going to be looking for a new one in a few months time. Once you're in the £150 range you should be safe for a while - remember you might need the head to go with it.

One other thing to note is that tripods are designed for a certain weight maximums and once you start buying top end cameras and large lenses the weight piles on. Keep that in mind if you've got ambitions of being more than a casual clicker.

Monday, May 3, 2010

Macro Extension Tubes

There is some amazing macro photography out there. For the lay person, macro is that super-close photography that people normally associate with insects and flowers.

However, macro lenses can be confusing because lots and lots of lenses say "macro" on them and when you use them the picture isn't as close as you thought it was going to be. That's because when it comes to the lens itself macro simply means that it will focus at a distance of less than 100cm. So if you want to do proper zoomed-in ultra close-ups then you have to invest in a decent lens that might cost several hundred to several thousand pounds.

Or do you???

There is, infact, a way to cheat. Ok, so the results aren't quite as sharp and the kit is a bit more fidgity than a dedicated macro lens but you can take super-close-ups for the grand total of £5!!!

I managed to find a set of these macro extension tubes online for £5 (although you can pay upto £150 for name brand ones). The ones I got really are "no frills" but they do allow for from decent pics. The way they work is that they fit inbetween your camera and whatever lens you are using (a 50mm works well). This moves the lens slightly further away from the sensor and thus vastly increases the macro ability of the lens.

It works in the same way that a magnifying glass does - get someone to hold the magnifying glass infront for their eye and slowly move it away from their face and you'll see the size of their eye increases dramatically. The same thing happens with the lens - the further it moves away from the camera the more the magnification.

They do have the disadvantage that you have to be very very close to get your subject in order to get it in focus AND the depth of field is super narrow.

So if you are thinking of doing any macro work I suggest using these first. At least that way you'll not have wasted much cash and once you've got to grips with the techniques you can invest in some proper kit. I took this picture when I first got them last year and while it's not a great photo it does give you an idea as how close you can get - and this was with just one of the tubes as opposed to all three that came with it!

Bordering Photos

A lot of people don't like the look of borders round photographs. I tend to use them and to those folk that don't like them I would say - at least you should know how to do them! Anyway, enough folk have asked me how to do them so here's some chat on the subject.

There are several ways to create a border including several free programs on line. I tend to use one of photoshop's methods and I'll explain that techique here. You can also do this on Elements. Here are the steps for a 15 x 10in pic with border...

1. Open your pic
2. Decide what size you want - I tend to make all my pics 3:2 ratio (i.e. 6 x 4in or 15 x 10in etc)
3. Crop your pic slightly smaller than this e.g. 14 x 9in
4. Ctrl + A to select the remaining pic once you've cropped it
5. Ctrl + C to copy the pic
6. Choose the colour you want the border to be - on the bottom left of your screen there is a white square on top of a back square. The background one is the colour the border will be. Click it to change the colour BEFORE going any further as you can't change it later.
7. Then goto File --> New
8. In the new window that opens put 15 inches width and 10 inches height then click OK
9. Ctrl + V to paste the pic into the canvas
10. Goto Layer --> flatten image then save your pic.

You can also write in the border using the text tool etc.

Hope that helps.

Saturday, May 1, 2010

50mm f1.8

After buying a DSLR and playing about with the kit lens for a while people begin to ask the question "What should I buy next?" - at least I did.

Digital photography really is a gadget-fiend's paradise and if you are a bit geeky like me then you are in trouble. There is so many toys out there that you could go mental with choice. Camera bodies aside there are lenses, filters, remotes, tripods, monopods, SD cards, software, backpacks, flashguns and reflectors to name but a few of those toys.

My kit includes...

Nikon D90
Pansonic Lumix TZ5
Nikon 18-105mm VR f3.5-5.6
Nikon 50mm f1.8
Sigma 70-200 f2.8
Tokina 11-16mm f2.8DX
B+W ND10 filter
Hoya Circular Polariser

...and through these posts I'll tell you what I've bought and why. What I've bought might not suit you but hopefully some of my rantings might be of some use in helping you decide what to spend your pennies on. BEWARE - photography is very very addictive and can become very very expensive so try and put a great deal of thought into purchases before you spend anything. Most shops will let you try lenses etc before you buy them but you should also do some on-line research first.

Anyway, regardless of whether you use Canon, Nikon, Pentax or Sony (or any of the many other DSLR camera manufactures) most folk would probably agree that the first thing you should buy (after the camera itself) is a fixed 50mm lens. These are brilliant lenses for several reasons.

Firstly they are one of the cheapest lenses you can buy. This is of course dependant on the maximum aperture which can push the price right up e.g.

50mm f1.8 = £90
50mm f1.4 = £230
50mm f1.0 = £3000

Secondly, this is what's called a "fixed" or "prime" lens. That means it has no zoom function and keeps a constant focal length of 50mm. Your feet become the zoom and you have to move in close or walk far away to get the shot you want and that really teaches you composition. It's worth sticking this lens on for a couple of weeks and using nothing else.

Thirdly, because it has a wide aperture it lets in loads of light which means it performs well in low-light conditions. Also there is very little glass for the light to travel through which again helps make best use of the available light.

Forthly, because of the huge aperture you can get fantastic bokeh (background blur).

And finally, 50mm is equivalent to what they human eye sees and if you look through the view finder and then open the other eye you will see that objects are about the same size with both eyes. This means that shots with this lens look very "real". This is often referred to as a portrait lens probably because the results you get with it a aesthetically pleasing - perhaps on a subconscious level.

I'm sure there are several other reasons to buy this but I think most photographers will tell you that this is a great puchase and should be one of first.

PS - I also like it because it's tiny and there's always space for it in the bag!

Rule of Thirds

So this is a basic composition "Rule". I say rule but it's not really a rule, just some guidance. If you are stuck with the components of a picture then applying this guide can improve the composition - or so the folks in the know would say.

Here is a picture of the Lady's Tower in Elie in Fife. It's a reasonable example of this rule. Essentially you draw a grid in the viewfinder to create 2 vertical lines and 2 horizontal lines. You end up with 4 intersecting points and over one of those points you should position your main subject. Most cameras have grid that can be switched on and off in the view finder so that you don't have to guess.

Here's what the picture would look like with the grid switched on. You can see that the Tower is positioned over one of the intersections and some would say this makes for a better composition. These "rules" though, always come with the caveat that they are "meant to be broken". What you think looks best is really all that matters but keep an eye out for these tips and tricks as they can sometimes come in handy.

Hand Held HDR

Mostly HDR needs to be done on a tripod. That way the pictures perfectly align. Photomatix does, however, have the ability to be a bit forgiving and will do some aligning for you if the pictures don't overlap 100%.

So you see a great HDR opportunity but you don't have your tripod with you. What do you do? You can always balance the camera on something to keep it stead but sometimes that's not practical. However, if you have a relatively steady hand most DSLRs will let you do without a tripod.

They way to do this is to first set up the brackets - on the Nikon D90 there is a small button on the front left of the camera that says "BKT". You press and hold this and roll the dials to set the number of shots and how over or under exposed they are. I use 3 shots at +2, +0 and -0 which seems to serve me well.

Next you put your camera onto high speed repeat shooting. Make sure you have a flick through the menu section about this as the factory setting might be lower than the camera's maximum. Mine was set on 3 frames per second (fps) and I increased the value to 4fps. The object of this is to take all 3 pics in rapid succession. You are NOT a tripod and although you can brace yourself for the shots there will still be a small amount of movement between them. Using the fastest fps minimises this.

Next gently squeeze the button and click, click, click. You should have all three shots reasonably aligned. Stick them in Photomatix and you have your HDR result - hand held and not a tripod in sight.

On final point - sometime it's worth focusing first and then switching the auto-focus off before taking the shots. I've noticed that under certain conditions the camera will try and re-focus between shots and by the time it does you will have moved slightly and the shot's ruined.

Comments and chat as always appreciated.

HDR - High Dynamic Range

I am a total sucker for HDR - Here's some of my attempts.

Since I started taking pics this has been the technique that most of my mates have asked me about. There are several tutorials on line about how to do this and most of them probably make more sense than this post but this is my take on it and hopefully you'll understand my ramblings.

So why do HDR? Well it's all to do with "Stops of Light" Here's a great tutorial on light stops and what they mean. So you see from that tutorial that a stop of light is just an arbitary phrase that indicates the amount of light you are allowing the camera's sensor to see. Increase your aperture by one stop doubles the light available to the sensor and decreasing the aperture by one stop halves the light available. You can also alter this using shutter speeds and ISO settings - but that's a topic for another day.

Anyway the human eye can make out good detail over about 20 stops of light - that's why on a bright day you can see the detail in the grass and the trees but still see the detail in the sky and the clouds. A camera sensor is a bit rubbish in comparison to the eye - your average point-and-shoot sees about 7 - 8 stops of light and a high end DSLR sensor sees about 10 - 12 stops of light.

If you go outside just now and take a quick snap of anything on auto mode and include about 30% sky you'll see that the sky goes completely white (or at least loses a fair amount of detail). You can compensate for this by using your camera's "exposure lock" function which should be in your manual - although the foreground may go dark. Also you can use a ND Graduated filter to darken the sky slightly which works really well. Here's some of Graham Stirling's work using Lee ND Grad filters (ND stands for neutral density incidently which means they block out some of the light without changing the colour).

There is normally about 2 stops of light difference between the sky and the ground and this might be even more e.g. on a bright day when you are standing in the shade. Your camera will try it's best to capture the middle ground and therefore dark bits might become silhouettes (also known as shadow clipping) and the lighter bits may become over bright (also known as blown highlights). These situatations can be a disaster and mean that you miss out some valuable parts of the whole shot. You can rescue some foreground detail and highlights but not if they are too black or over blown respectively - at least not without the end result looking weird.

So it appears that I've gone off-topic there but there was a reason - HDR!

As the name suggests High Dynamic Range is a technique that allows you to cover a high range of exposures or stops of light. This can increase that 10 - 12 stops I mentioned earlier to perhaps 16 or so. The concept is quite simple - you take several shots (usually 3) of the same scene - these are sometimes known as "bracketed" shots. Each shot takes a slightly different exposure - I normally take a +2 exposure shot which is over-exposed, a normal (or +0) shot, and a -2 exposure shot which is under-exposed.

This is the +2 shot. You can see that a lot of detail has been blown out in the sky. However, there is a lot more detail available in the darker parts like the water, the hull of the boat and the trees.

This is the normal shot or +0. This is the kind of shot that a point-and-shoot camera would take and what my DSLR took without and filters or exposure lock. You can see it's tried to make the best of the situation and keep come some of the highlights and provide some detail in the dark parts. This basically makes the best work with the mid-exposure range.

This is the -2 shot which is under exposed. The darker pasts of the picture as now almost black and clipped in some ares. This picture would normally be unusable but you can see that there is excellent detail in the sky and the brighter parts of the land.

This is where HDR comes in. You can use several programs e.g. Photomatix to then put all three pictures together. It'll take the useable parts from the three shots and create a final picture which looks like this...

Ok, so the purists out there will say that this is cheating and not a "real" photograph. To some extent I agree. It's a cheap way to give a mediocre shot a WOW factor that it wouldn't have otherwise. I certainly failed to work on composition etc when I started doing HDR. It's worth getting good at the basics first before taking this technique because it'll make an OK shot good but never great. All the other elements of photography have to be in use first to create that ultimate HDR shot.

Hope that helps you lot understand how to do this. Comments and critisisms welcome as always.

White Balance

So white balance is something you hear about and to be honest most of us ignore in the beginning. Most cameras have an "auto-WB" mode and for the most part that's pretty accurate and works. However, in extreme conditions e.g. indoors or night-shots the camera can get confused... badly.

So white balance? What is it?

Well my understanding is that different light sources (the Sun, street lights, indoor blubs) have different "temperatures". In other words, they emit a slightly different colour. Depending what colour the light source is you should set your camera to that. Alternatively, you can, and should, shoot in RAW and fix it later (but we'll cover that in another post). The point being that white bits should then still look white and not oranage for example.

However, that can be quite tiresome and so people often just leave it on Auto. But even with a decent DSLR your camera may still have a hard time decerning the white balance in auto-mode.

I took this shot last night near Glencourse Reservoir. As you can see there is a dreadful orange colour cast in the clouds - something I would have never have noticed a year ago. This light is coming from the street lights of Edinburgh - this is "light pollution" - something you can clearly see in the sky when you are driving into most cities/towns at night if there are some clouds in the sky.

Here you can see that I've corrected the white balance in Adobe Camera Raw and immediately there is an obvious different. You can see that the clouds are now the correct colour and also the sky has become a dark blue colour. Although the actual sight may have looked like the first image, your brain (or at least mine) seems to sieve out all the abnormal colours and what you're looking at just seems normal. It's not till you correct the white balance that you see the difference.

I should point out though that although you can do this after the event using a RAW file (instead of JPEG) by fixing it in post production, that's not a efficient use of your work flow and you should set your camera's white balance for each shoot. This saves a lot of time afterwards. Just don't forget to change it back afterwards! So hope that explains something that took me months to figure out.

Comments and critisicms welcome.