Saturday, June 23, 2012

Spot the Difference!

I was recently looking through some pictures from last year and I wondered what some of them would look like if I re-processed them from scratch without the previous final image for comparison. I So this is the original final image of Kilchurn Castle up in the North West of Scotland on the banks of Loch Awe. It's a lovely site but I actually found it quite hard to negotiate a good shot of the castle. The spit of land that the castle is on is very narrow so doesn't really afford you a good angle. Also it was locked so I couldn't get inside to try something from there. Ended up on the opposite bank wading through about 500m of marsh land to get to where I took this picture from. Anyway, it was evening and the colours of the light and the surrounding countryside were quite orange and brown. This cast onto the castle and confused the white balance and actually it was quite difficult to make the castle stand out so there was a fair amount of over-processing done and a lot of dodge/burn (a very valuable tool which I should post about some day). The final shot is not bad but now looking back at it I think that it's a bit false-looking and quite surreal. The trick is to be either super-processed where it's obvious that your going for a stylized look OR to be subtle so that the viewer doesn't really notice it. I think that this shot falls somewhere in the middle and on retrospect doesn't do the scene justice.

So with a fresh pair of eyes and a few months more experience it's interesting how the result has evolved. There's not a great deal of difference but I think it has a more natural feel to it. The castle certainly is less harsh looking and stands out more from the surrounding water and hillside. There is also a smoother overall finish to the whole shot. Interestingly, I removed the house to the right of the castle which I left in on the first shot but conversely left in the pylons which I did consider cloning out but felt they are a part of the Scottish countryside nowadays so left them in. The blacks in the hills are a bit blacker and the whites of the clouds (especially in the water) are a bit whiter and the blues in the sky/water are richer. I like it. Yes, I think I like it quite a bit more than the original so all in all a worth while experiment. At this point I would like to say again - YOU MUST SHOOT IN RAW!!! There is so much information hidden away in a RAW file that you can go back to it over and over again and reprocess it a million different ways to a level that a JPEG just can't compete with. It's also worth saying that the software for this moves on at almost a monthly rate so when I first processed this I was using Adobe Lightroom 3.0 (which then became 3.1 then 3.2) and now I'm using Lightroom 4 (well actually 4.1) and with each upgrade the possibilities increase and the quality of the result improves. Therefore it's always good to go back and have another look at older shots. This also gives you something to do when you're having a summer like we are right now - rain rain rain.

Panning

Panning is something that a lot of sports shots incorporate. It's a way of taking a shot that lends motion to the picture. This shot shows an Aston Martin racing round Knockhill Race Track. I say "racing" but actually my Dad was driving and it was more like he was driving Miss Daisy. Anyway, even though he was driving really slowly there is still some motion blur in the background. It's quite easy to achieve the blur but the real trick is keeping the car in focus. So how is it done? Well much like the wildlife shots, I use servo / continuous focus so that the car stays in focus. Then you have to slow your shutter speed down to about 1/50th second. Next you have to have steady hands and keep a point of focus like the grill or the wheel. Your camera should be on continuous fire and as the car goes past try and keep the view finder on the same point of the car then press the shutter. Keep the button pressed until the car has gone past and you will have taken 7 or 8 shots in a row and hopefully one of them is in focus enough to use. This technique takes a lot of practice as it's really hard to get the car sharp so you might have to have several attempts. Dad went round the track several times and of the 50 or so shots I took only one or two were of any use. Of course, he'll say that it was because he was driving so fast. Well thanks to this technique it looks like he was!

Tuesday, June 5, 2012

Shooting the Wild


So I don't really know much about shooting wild life. A good place to start is at your local zoo, however, most of the animals are artificially tame and sedate so it's easy to get the shot you are after with a bit of zoom and some patience.

But what happens if you are on location? Well this shot shows what you don't want to happen...

You can imagine how upset I was when I got home to find this out-of-focus useless shot on the card. To get the wee ground squirrel standing on it's hind legs so close to the camera and not get the shot was frankly gutting. What went wrong? Well in this case it was simple - I had left the focus on manual for a previous shot and so it didn't focus on the animal but just some arbitrary point in the distance. Horrible.

None the less, it is quite a funny shot but would have been one of those "once in a life time" shots if I'd only remembered a few basics about shooting animals.

Recently a few friends of mine have posted some shots of animals on facebook and this reminded me that I wanted to go through some pointers for what to do when shooting this genre. As I hope I have already have demonstrated fully, I don't always remember what to do so this is also an aide memoir for me. But hey, that's one of the main reasons for this blog!

So here's the list...

  • I shoot in aperture mode and that allows all of the following tweaks...


  • Use a large aperture - this allows a fast shutter speed. However, don't have it too wide as this will cause aberrations and also you will lose some sharpness. Instead, stop down the lens a bit - so if you are shooting with an f1.8 lens then stop down to f2.5 or if you are shooting with an f2.8 lens (common in long lenses) stop down to f4.


  • Increase your ISO. Get it up to 1600 and if you are shooting in full frame go to 3200 if you have to. This will create noise but Lightroom 4 is incredible at removing this so I don't tend to bother about noise anymore. In fairness I shoot with a Nikon D700 and it's noise performance is incredible so I've got quite a bit of wiggle room. The reason for increasing the ISO is that is increases your sensor sensitivity and therefore increases your shutter speed. The result being that you have a better chance of "freezing" the image instead of having movement blur. This is a real problem with wildlife shots - those bugger move!!!


  • Under expose slightly. This will again increase your shutter speed a bit. I tend to shoot at -0.7EV which allows protection of the highlights in the shot also. Sometimes the bright parts of a shot will be overly white and when you try and recover the highlights there is nothing to recover. Under exposing slightly gives you a chance of getting back detail in those bright areas of the shot.


  • CONTINUOUS FOCUS. This is perhaps the most important thing. You can fix most things in post processing, however, one thing that you have no possibility of fixing if focus. So if you focus is off (like in the above photo) then you might as well ditch the shot. In Nikon cameras this is called "continuous focus" but in Canon it's referred to as "Servo Mode". This means that the camera continues to focus on the object in the middle of the view finder. Therefore, if the animal move towards or away from you then the camera will adjust the focus automatically. This really increases your change of getting the creature in focus.


  • Anyway, I hope that you can see my point with this entry to the blog because if I'd paid attention to these "rules" then perhaps I would have got a shot like this...


    Tuesday, April 17, 2012

    Portrait Post Processing

    A friend of mine has been getting quite into his photography recently. It's really nice at that stage to compare yourself to others and see how people do things differently from you and what various techniques people employ. Of course the best way to learn is by doing and soon it all starts to make sense. Anyway, this chappy took a portrait shot of his other half and we used the RAW file to see how each of us process our shots. This is by no means exclusive and I'm sure plenty of the photographers that I look up to would shun what I've done here and do things completely different. Oh well, I only spent 10 mins on it so tough, this is all you're getting. So this is the original. It's not a bad wee shot. It's ambient light only from camera right but that is introducing some shadow on the the right side of Sam's face. The background is quite plain which is ok but it therefore doesn't really lend itself to depth of field. It's also a bit similar in colour to her top and eyes and skin tone so this makes everything a bit bland. As with every single person I've ever photographed, there are routine skin blemishes but those are easily dealt with.
    This is my friend's version of the shot after processing. I'm not sure of his setting but there are a few things that are worth saying about it - from a personal view point of course. First the colour. It's a bit too warm. Not that that's a bad thing but the issues here is all the colours involved in the picture are from the same palate and this makes every aspect of the picture quite samey. Also there is the issue that warming up a whole picture also warms up the blues to orange and I've got a feeling that in real life Sam's eyes are blue but here they have gone grey due to the warm white balance used. There is that lock of hair at the top of the shot which is quite distracting and should probably be cloned out. I also think that the tone makes her look a bit flushed and although some of the blemishes have been removed, overall I think that there is a loss of contrast in the face. I think also there is some fill light that's been used on her right side and that helps with the shadows but that again reduces the contrast and there is a lack of "pop" in the result.
    Ok, so this is my version. I realise that it's a bit overdone but this helps illustrate the points I was making above. So what have I done here. Well I opened the original in lightroom. I've used the following settings.
    White Balance
    temp - 4793K tint +14
    Tone
    Dropped the exposure by -0.25 Recovery 15 fill light 40 blacks 5 brightness +53 contrast +36
    Presence
    Clarity +23 Vibrance +13 Saturation -4
    Tone Curve
    Highlights +11 Lights +24 Darks -1 Shadows -5 The only other thing I did in light room was to introduce a post crop vignette of -14 to separate the subject from the background a bit. Then I opened the newly saved JPEG in Photoshop and cloned out the hair strand at the top. I used the heal tool to remove a some of the skin blemishes next. Finally I then saved the shot and then opened it again in Portrait Professional to even the skin tone and play with the eyes. One thing I would say about this kind of software is that it is very VERY easy to overdo is and with only a small amount of tweaking this shot already is beginning to look quite fake so be subtle. Now, if you don't have this program there is still things that you can do. You can either use the brush in Lightroom and change the contrast and saturation of the eyes. Or you can use the magic lasso tool in Photoshop and highlight the eyes and then play about with the levels and the saturation to achieve a similar effect. Also the dodge and burn tool helps to locally increase highlights or shadow to create some local contrast. It's also worth noting that if you use the Lightroom brush you can put the sharpness slider right down and that actually introduces some subtle softness to skin too. Anyway, I hope you get the drift. There are millions of possibilities and eventually you'll find a way to make a shot work in Post Processing that didn't necessarily work in-camera. Good luck. Z

    Monday, April 9, 2012

    HDR Panoramas

    So I was staying up in Perth last night and this morning after breakfast we headed out for a walk and that took us up to Kinnoull Hill. On top of the hill over looking the Tay Valley is a Victorian folly. I'd seen this the day before and wondered what the view would be like from up there. A folley, I was later to learn, is a fake or decorative building that the Victorians would erect to give the area a bit more style and kudos. They usually served no other purpose other than to raise the profile of the resident gentry so that they could boast about castles on their land etc. Anyway, the issue today was that I didn't have my wide angle lens with me. This presented a problem - how was I going to get everything in shot? Also my wide angle has a 77mm filter and these don't fit my other lenses to I was a bit screwed if the sky was going to be very bright. Yes there are other ways round this but I decided to employ some other techniques and see if I could get something decent. Firstly, I decided I wanted a panorama. That meant taking a series of shots from the left hand side of the view through to the right and then stitching them together in photoshop afterwards. But as I said, I didn't have any filters that would fit the lens that I was using so I decided to employ that old love/hate technique of HDR. So here are the first set of shots. 4 portrait orientation shots each of which were made up with 5 different exposures. The dark shots catch the highlights and the bright ones pick up the detail in the dark areas. Merge these together and you get a shot that has detail every where. Below are the 4 shots before the merger.
    So that bit above is called tonemapping and I use Photomatix to do this normally. Once in photoshop, I went to "new" and then opened a "photomerge" file. You then take the shots you want and add them to the open window then merge the files. I just used the auto settings and it turned ou quite well. So below is the result of this.
    Ok, so the above shot is ok but there is a few things that don't look right. Mainly the colour and the contrast are a bit off so there are plenty of things that can be tinkered with in photoshop. I tend to boost the colour a wee bit and then use a lot of dodge and burn manually to pick out some more detail. Also a bit of vignette helps at this point too. This is a bit of a rush job as I'm back at "real" work tomorrow but I wanted to get this post up.
    So the next thing I noticed about the above picture is that when you look at it closely there are some real issues. These mainly come from the fact that each of the shots in the pre-photomerge are a series of several shots. Therefore to take these the camera fires off 3 or 5 or 7 or 9 snaps (depending on how it's set up) in a row at different exposures. During the time it takes to take these shots things move! This is all well and good if you are taking an HDR shot of a building or something static. However, these pictures had moving cars and branches etc in them. This means that each of the 5 shots that I used to build each of the HDRs for the above panorama has slight "ghosting" effects. Up close the branches look a bit blurry or there are trails of cars (usually grey) along the road. Photomatix does a decent job of removing these but it can't deal with all of them. So is there an option to fix this? Yes. Some people spend hours and hours cloning out all the problem bits which essentially erases them from the picture. But as I said this can take a long time. It does give a good result and if you have a lot of time then this is a decent way to go. However, there is another way round this and it's by doing what's called a "pseudo-HDR". The difference with this technique is that you only take one shot instead of a whole series of shots. You then use the RAW file to create an underexposed jpeg, a normally exposed jpeg and an overexposed jpeg - hence three different exposures from a single photograph. This means that these are all identical shots so there are no waving branches and moving cars etc. I did this with three different shots the same way I did the panoramas above (but from a slightly different location) and then dealt with them the same way as the "proper" HDR shots. This is the result and you can see that it's not that different from the second shot in this post. Decent result from only 3 photographs in comparison from the 20 that were used to create the first panorama.
    Don't worry, this post is almost at an end. After a few tweaks in Photoshop here is the final result and I think that this might be the way forward for HDR when there are moving objects are involved. I know there are some real masters out there that don't need this in their trick bag but I think I do mainly because it takes me so long to do a normal HDR. Anyway, hope this jibberish all makes sense and if you've got any question then please leave a comment and I'll do my best to answer it.
    Who needs a wide angle lens??? Get snappin! Z

    Kinnoull Hill

    So today I'm going to do this walk... Kinnoull Hill in Perth. Unfortunately, I didn't pack the wide angle lens which is going to cause a problem as the filters etc are 77mm and they don't fit the lenses that I've got with me. So what are my options? 1. Well I have a 24 - 85mm with me so I can shoot at 24mm and hope that it's wide enough and then try to bring in a filter in Light Room to darken the sky. 2. I can shoot in HDR 3. I can try a series of portrait orientation pics and do a panorama 4. As above but bracket them all and put together an HDR panorama So I'm going to try them all and then post the results later today. Fingers crossed that I get something good as the weather look pretty dreary just now and there is no signs of it brightening up. There is an old Victorian Folly up there and that should provide some decent foreground interest although I'll not be on my own so I'm sure the non-photographer walkers are going to get pissed off with my photo antics on the hillside. Watch this space...

    Sunday, March 18, 2012

    Photo editing software

    Ok so a lot of folk are asking what they should buy as their first bit of photo editing software. To be honest, unless you are going to be spending mega bucks then I suppose it doesn't really matters. Personally, I use Light Room for my RAW editing which is the most amazing program on the planet for this, but for finishing touches, I just use Photoshop Elements which is one of the cheapest programs on the market.

    In fact, if I didn't have light room then PSE would do me just fine for the basics and a couple of years ago this is all I was using.

    Anyway, here are two shots taken this morning and I've only made a few basic adjustments to them, but I wanted to show you what a difference a bit of post processing can make.

    This is the original shot from the Bass Rock this morning, taken from Dunbar. It's ok but there are a few things I don't like about it. First, it's a bit flat which is due to low contrast. In other words, the dark bits are a bit too light and the light bits are a bit too dark. This is easily fixed by raising the contrast level slightly.

    Also it's not exactly straight and also something that annoyed me is that the cloud bank to the right is sloping up the way and I wanted that to be a straight line which would make the "layers" of the sea, land and sky look a bit more pleasing. Rotating and skewing the shot fixed this.

    I also think that the colour is a bit bland so a boost in either saturation or vibrancy makes the shot a bit richer.

    Finally, I didn't like the composition. The Rock wasn't in quite the right place to make the shot jump out of the screen so I cropped it slightly to improve this.

    I'll not bore you with further details, suffice it to say that playing around with even the most basic settings in any post processing program can make all the difference in the final result...

    More Long Exposure Chat

    I get quite a lot of questions about long exposure shots. These are the shots where the sea goes all smooth or the clouds flatten out and end up looking like a water colour painting. Essentially, the longer the shutter is open moving subjects like water and clouds will be "smeared" across the photo.

    However, the problem with this is the longer the shutter is open the more light gets in and if too much light gets in then the picture will become over exposed and possibly completely white.

    I've talked about filters before but some of these are expensive yet you don't always need these to achieve a similar effect. You can just take your shots at night or before the sun has fully come up and that immediately means that the camera will keep the shutter open to allow enough light in which may buy you a couple of seconds.

    Please bear in mind that you MUST have a tripod to do these kind of shots

    Next reduce the aperture to a very small hole eg f18 or above. This again lets in even less light and increases the exposure time thus allowing even more time for moving subjects to smooth out.

    Finally you can drop your ISO as low as it will go eg 100. This reduces the sensitivity of the sensor and therefore increases the shutter time. It's really worth learning about your ISO as it can help you out in many situations --> high ISO e.g 1600 = more sensitive sensor and therefore faster shutter speed (good for low light conditions e.g. night time or indoor shots), low ISO e.g. 200 = less sensitive therefore slower shutter speeds but good for bright conditions e.g.. sunlight.

    So here are three shots using the above principles and no filters.

    This shot was take at ISO 100 with an aperture of f8 and resulted in an exposure time of 0.6 sec. You can see that there isn't much movement in the cloud and it really just looks like a "snap shot".






    This shot was take at ISO 100 with an aperture of f22 and resulted in an exposure time of 5 sec. Now you can see that the clouds and the smoke from the chimney has begun to smooth out due to the longer exposure time of 5 seconds.





    This shot was take at ISO 100 with an aperture of f45 and resulted in an exposure time of 15 sec. The very narrow aperture allows hardly any light in so the time has to be increased in order to let enough light in and so the camera increases the exposure time appropriately - 15 seconds in this case. As you can see the clouds and the smoke have had a much longer time to smear across the shot and so it gives that smoothed out effect that everyone keeps asking about.

    It's actually quite a simple technique but the results can be quite startling. You can try this yourself using these techniques and hopefully you'll get something similar. Also try it with running/moving water as you really can get some beautiful effects with rivers and the like.

    Good luck.

    Z

    Friday, February 17, 2012

    Star Trails

    I've been meaning to try this for ages but wasn't really sure how to go about it. There is a program called startrails.de which is a PC based only and that was frustrating as I spend more time on my Mac. However, I found another program called Starstax which works on the Mac.

    So to take a photo like this you need to set everything up in the cold and the dark first. This shot entailed using a wide angle lens (at about 20mm) and set to a wide aperture of f5.6 and an ISO of 200. The main focus was on the light house but with the wide aperture it made the stars slightly blurry which makes softer trails once processed.

    Then I took about 40 shots in a row - each one a minute long (hence frozen fingers and toes due to the 40mins that it took to do).

    Once you've got all your shots you stick them into lightroom and process the first one to get it bright enough and plenty of stars exposed. Then "sync" all the shots so they are processed the same way. Export them into a new folder of JPEGs.

    Then open up Starstax and simple add all the photos and merge them. That'll create the final image that should look like this one (or hopefully a bit better even!).

    Good luck.

    Sunday, January 22, 2012

    More White Balance

    So I've mentioned white balance before. It took me a while to really understand what it means but now that I know what this is I find it difficult to look at older shots without getting frustrated. Primarily the issues show themselves up in a wedding I shot a few years ago where the brides dress is yellow/orange inside the church. At the time I didn't even notice but now that I know what I'm looking at I would suggest that you all learn about this sooner rather than later.

    White balance is easiest thought about as temperature - where 2000 kelvin is very blue and 10000 kelvin is very orange i.e. the "temperature" of the picture determines the overall colour of the picture. White balance is a way to make the "whites" white. The higher the white balance temperature the more yellow/orange the picture and lower the temperature the bluer the picture.

    The most important rule in all of this is - if you have the ability to shoot in RAW as opposed to a JPEG then you MUST!!! RAW files can be fixed afterwards with software and it doesn't matter how it looks in camera however JPEGS are much harder to fix afterwards.

    And now for another example. If you look at this first shot of Buachaille Etive Mor you perhaps don't notice anything wrong with it. However, if you really have a close look at the snow on the mountain and the water in the foreground you can see that it's not quite the right colour. It actually looks a bit yellow/orange. That's because I processed this with a higher temperature - 6411 Kelvin actually.

    After looking at this for a while I decided that the shot was too warm and that it didn't look right. Afterall snow is cold and this actually makes the shot look too warm. So I went back into Light Room and reprocessed this too make it slighter cooler (not that it isn't already a cool shot! Lol).







    So with a bit of tinkering I moved the white balance temperature slider down a few notches to 5350 Kelvin and the result was this shot. You can see that it's a bit colder looking and that the whites are now white and not yellow. It I'd moved the slider further down to , say, 4000 Kelvin the water would have turned blue so it's important to get it just right.

    Having said that. Some shots benefit from a bit of warmth especially portraits so sometime is worth notching a shot up a few Kelvin. Anyway, as always, you should experiment as much as you can and I hope you find this post useful.

    Good luck.

    Thursday, September 15, 2011

    Focal Point

    Was mucking about in St Cuthbert's grave yard today with the camera and thought I would post a bit about the focal point of a picture. I guess there are some rules like "always focus on the eyes" etc.

    So with most cameras, half depressing the shutter "locks" the focus on whatever was in the center of the view finder. You then keep the shutter half pressed and re-compose the shot to your liking. Then press the shutter fully and snap your picture.

    Why do this? Well you don't always want the subject in the center of the shot to be the focal point. The shots below show how the picture can change depending upon what you're focusing on. Give it a shot and see how you can create some unique images that you previously might have over-looked. (Click on it to see a larger image)

    Wednesday, August 24, 2011

    Toycolor Analogcolor

    So there's a real growing love of the old fashioned looking hipstamatic-type pictures going around at the moment. Have a look at the following Flickr series to get the idea...

    Hipstamatic Examples

    I have a Mac and while there is an app for the iPhone there isn't a Mac plug-in for Photoshop Elements. You can achieve the same effect in about 5 - 10 mins with photoshop but it's a bit fiddly and requires a good knowledge of the layers palate.

    So I went searching on the net for a free program that would do the same effects in a simplified way. Didn't take too long to find the Toycamera Analogcolor program which is great. A few clicks and you can give your pictures that 1970's feel with ease. See the comparison below...



    Enjoy!

    Wednesday, August 10, 2011

    3Run Triptych


    This is something that you might like to try. Creating a triptych is quite straight forward but you have to bear in mind that the 3 pictures are quite slim and so make sure the subject isn't occupying too much of each frame. When you come to cropping them you will lose a lot from the sides which would be a bit pointless.

    This was done using a canvas of 30x20in and 3 crops of 8x17in to place on the canvas. "Stroke" is used to create the white outlines. Then place your text and bingo!

    Thursday, May 5, 2011

    Sigma 70-200mm f2.8 - Revisited

    So as you know, I've not been a fan of this lens. Was almost at the point of putting it on eBay when a mate of mine asked if he could have a play around with it.

    "Knock yourself out. And if you smash the lens in the process, I'll not be that bothered."

    Well after 10mins and some initial difficulties of a Canon user using a Nikon user's kit he'd come up with some very impressive pictures and notes to go with them. Essentially he was looking for the "Sweet Spot". This is the focal length and aperture that gives you the best picture. I know that the sweet spot on my Nikon 85mm f1.8 is about f4. However that lens has no zoom so f4 is always going to be the sweet spot.

    The Sigma, however, has a focal length of 70mm to 200mm and so the sweet spot (or sweet "aperture") will vary depending on the focal length. He discovered the following ,very usable, results...

  • 70mm max aperture for sharp focus - f4
  • 105mm max aperture for sharp focus - f2.8
  • 200mm max aperture for sharp focus - f6.3


  • So while I was right that this lens is not useable at f2.8 most of the time I was amazed to see that at 105mm it gave really great results wide open at f2.8.

    I now intent to keep the lens (at least for the time being) and to some extent it feels like I've been given a new lens. Just goes to show how far a bit of time, patience and experience goes.

    Wednesday, February 23, 2011

    Sigma 70-200mm f2.8

    So I've got the Sigma 70-200mm f2.8 lens which I've had for over a year. I've often said I hated it and I've had lots of folk arguing about it on Flickr etc. Seems it has quite a following but I really dislike it.

    Don't get me wrong, it's brilliant at certain settings but at the larger apertures it's total pump. I mean the reason that you buy a large aperture lens eg f2.8 or wider is because you want 2 things...

    1. Narrow depth of field

    2. Ability to take pictures in low light.

    With this lens you get neither! That's correct and I'll show you why.



    This first picture is taken at f2.8. That's means that the lens aperture is open as wide as possible. That allows lots of light into the sensor and so should allow you to take pictures in low light. However, you can see from the insert that even though this was focused accurately, the picture is soft and the text is blurry.

    If you imagine that you were taking a picture of someone and were focusing on their eyes then no matter how still you were and how well you focused, you would never get a sharp picture. This picture was taken using a tripod and still it's not sharp.



    This shot is take at f8.0 and you can see immediately the difference. This picture is super sharp and a huge difference from the initial picture. The text is sharp (as far a the bleed from the ink allows!) and there is still a really usable depth of field.

    This comes with a real issue and that is that f8.0, while sharp, doesn't let in all that much light. So if you were in a dark church shooting a wedding this aperture would not be wide enough - unless you have a flashgun like the AWESOME Nikon SB-900.

    So you see there is a bit of a conflict of interests with this lens. The bokeh (background blur) at f2.8 is not very pleasing and the bit in focus is soft and not really usable. To rectify this you need to close down the aperture to about f8.0 and at that point low light becomes a problem. Don't get me wrong, this lens is brilliant from about f8.0 onwards but you really need lots of light to get the best from this lens.

    Lenses that have large apertures are typically called "fast lenses" but in this case the Sigma 70-200mm f2.8 is definitely not a fast lens so I probably wouldn't recommend it.

    Get something else.