Monday, 31 March 2014

A bit about lenses.

Hello again, I was asked over the weekend for some advice on which lenses to buy and if I would review a few. So I will share with you a bit of what I personally think would be good starting lenses.
I use Canon cameras and always have and so can only give my advice on these lenses but I am sure other manufacturers have very similar lenses.
First off I would say that in my humble opinion the lens is more important than the camera it is attached to. Always buy the most expensive lens you can afford.  
 Now I am aware not everybody can justify throwing loads of money at lenses and your camera probably came with a kit lens. The best thing you can do is to trade that kit lens in straight away for something better.
Here are a few choices that I would certainly consider in the mid price range.
The nifty fifty 50mm f1.8, This is pretty much a given for anybody really. About £90.00 new £50.00 -£60.00 this is a fast lens, by fast I am referring to the f-stop of 1.8 meaning you can take photographs in difficult low light levels and you can get quite creative with very shallow depth of field it can achieve. With the crop factor of none pro camera bodies this lens is actually around a 75mm lens in old money making it a perfect lens for portraits. 

For a general purpose zoom lens I use a 17-85mm f4-5.6 macro lens. Weighing in at around £340.00 it is not cheap but it is Image stabilised and the macro function works well. The f-stops are the smallest at either end of the zoom range so you can achieve f4 at the widest point and f5.6 on full zoom. Obviously you can use bigger f-stops. This lens pretty much lives on my camera and really is a lovely piece of glass covering a zoom range that I feel is more than enough for most general photography from landscapes to portraits and for getting that bit closer on distant subjects.
If you are wanting to get that bit closer then a larger zoom lens is going to be on the shopping list. I use a 100-400 IS L at £1200.00+ but really for most people this kind of expenditure isn’t necessary,
A 70-300mm f4-5.6 is probably going to be more than adequate for most needs and the £390.00 price tag is a bit more user friendly.
Whilst some of the lenses mentioned above are probably around the same price as a prosumer body I feel that they really are worth the money. You really do get what you pay for with lenses.
I hope this little guide has been of help Lou, lol :)

Wednesday, 19 March 2014

Shutter Speed.

Shutter speed.
Sorry for the delay in writing this bit up, been sidetracked lol. Ok so how does shutter speed affect your photography.
In photography, shutter speed or exposure time is the length of time a camera's shutter is open when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time.
Sometimes people have asked me why their photographs are never quite sharp or are always a little blurry.
Sometimes this is due to incorrect shutter speed, using a shutter speed that is too slow.
As a general rule of thumb you should use a shutter speed that is equal to the focal length of the lens, E.G. 100mm lens would require a shutter speed of 1/100th of a second minimum,  whilst a 400mm lens would require 1/400th minimum to prevent blurry pictures.
Image stabilised lenses allow for lower speeds to be used but this is just a general rule of thumb.
Shutter speed works in conjunction with aperture and iso to give you your exposure value or EV. As I explained in the previous posts about the aperture and iso they effect one another in a linear manner, as one value goes up or down then the other values also change to give the correct EV.
Changing your shutter speed can be useful for things like sports photography or photographs of fast moving objects, using a fast shutter speed to freeze the motion.

 Other times a slow shutter speed can be used (as well as a tripod) to capture flowing water in a motion blur etc.

 Usually a shutter speed of around 1 or 2 seconds is needed and a good sturdy tripod for this type of shot.
Well that's the three basics of exposure covered, any questions please feel free to drop me a message or on the blog. 
Happy snapping :)

Tuesday, 4 March 2014

Understanding ISO/ASA

What is this ISO and ASA stuff that I can see on camera’s and film boxes etc and how does it affect my photography?
Well quite simply ASA stands for American Standards Association and ISO stands for International Standards Organisation.
It is a method of standardising film speed or digital sensor reactivity to light.
The method of measuring them is different but from our point of view they are effectively the same. 100 ASA is the film equivalent of 100 ISO.
What it all boils down to is the sensitivity to light of film or your camera sensor.
If you are taking photographs in very light daylight settings with few shadows you will be able to use a low ISO/ASA setting whilst maintaining a relatively high shutter speed so that you do not need to use a tripod.
If you are taking photographs in dark situation, dim light shadows night time etc, to maintain a shutter speed that does not require long exposures on tripods etc you will need a high ISO/ASA rating.
Seems simple enough but there is a trade off for using the higher settings. The higher ISO/ASA settings introduce what is called noise in digital images or grain if you are using film.
This can be used in a creative manner at times but for the most part it is an unwanted necessity.
There is software that can help reduce the effect on digital images post processing but I find it better to keep it as clean as possible in camera.
Modern DSLR camera sensors are getting very good at handling noise and I have personally seen a big difference in the years I have been using digital cameras.
Below are a few 100% crops taken at different ISO levels using a mid range DSLR camera the Canon EOS 7D.

The top image was taken at 100 ISO next 800 ISO and the bottom image was taken at 12800

ISO/ASA is the second part of learning about exposure and if we look back to the previous post about aperture we can see how they can effect each other.
If you up the ISO/ASA then it makes the sensor/film more sensitive, therefore we can lower the aperture size (select a bigger fstop) to maintain a larger depth of field at any given shutter speed.
If you are struggling to grasp this re read the sentence and go back to read how apertures work. The most confusing thing is the way the bigger the fstop the smaller the hole in the lens but eventually you will remember this automatically ;)
The next installment we will deal with the final part of the exposure triangle so we can put it all together and hopefully I will have written it all in a manner everybody understands instead of how many books and articles write. lol
Cheers Happy Shooting

Saturday, 1 March 2014

Understanding depth of field DOF.(Aperture)

Understanding depth of field.
Ok, so what exactly is depth of field and how do we use it and manipulate it to get better photographic results.
depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.
Below are three images taken using different aperture settings on the camera.
The aperture is the size of the hole that the light travels through in the lens to hit the film/sensor. These holes are measured in f-stops.

From left to right the aperture settings were
 f5.6 at 1/20th of a second
f11  at  ¼ of a second
f22  at 1 second.
The camera was focused on the rock behind the shell. As you can see as the f stop number increases the DOF also increases but here’s the catch.
If we look at the numbers again the smaller the f stop the shorter the exposure time. This is because the smaller the f stop the larger the hole or aperture is that lets the light in. This is the offset between shutter speed and aperture.
So a large fstop number is actually a smaller hole but you will get a greater DOF.
Now when you set your aperture on your camera you will not see the DOF change as for large fstop numbers the hole would be so small you would hardly be able to see the image. The camera stops the lens down to the required aperture a fraction of a second before the photograph is taken.
Some old film cameras had a DOF preview button which would stop the lens down without taking a photograph but I don’t think many digital cameras have this facility.
 The following is an example of a photograph taken with a shallow depth of field, f5.6