Newbie Questions - Filters & Metering!

Discussion in 'Photography Forums' started by kelvin, Sep 13, 2007.

  1. kelvin

    kelvin
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    Long time lurker of the photography forum here!

    Apologies for the "newbie" question, but can someone explain to me the basics of filters, and perhaps while you're at it, metering!?!

    I recently purchased a 400D (& Kit Lens) having wanted to take the plunge into "proper" photography for quite some time. I had previously read up on a lot of the theory on exposure/apertures/shutter speeds etc, but am quickly finding that real world experience is far more valuable and am enjoying playing around with various settings to achieve different results.

    One thing I haven't the foggiest on, is filters, and the results that can be achieved through using them. I was advised to purchase one to protect my lens, but am aware that not only are their several types, but also sizes. Which one do I need, and where do I start when it comes to looking at others?! I'd also appreciate some tips on metering - both an explanation on what it is, and what can be done with the various types of metering available on the 400D.

    Any advice gratefully received! I look forward to reading your replies, and to being able to play a more active part in here now i've "joined the club"!

    Kelvin.
     
  2. py6km

    py6km
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    Hi kelvin - to protect your lens you should get a basic filter such as a "Skylight" filter. They are fairly cheap (should be tons on eBay). In terms of the size of filter you need, you need to check the thread size of your lens - I'm sure someone will be along in a minute to tell you what that is. It should also be stated either on the end of the lens, or on the lens cap somewhere.

    In terms of metering, I would suggest getting "Understanding Exposure" by Brian Peterson. Just finished it myself, and would say it is invaluable for a true understanding and appreciation of the subject.
     
  3. py6km

    py6km
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    If I may, could I point you to this

    Basically giving my thoughts on where my emphasis needed to be placed when starting out 'properly' in photography - you may (or may not) find something of interest :smashin:

    We also had an interesting discussion about exposure last night (thread entitled "Exposure question - confused !").

    :thumbsup:
     
  4. Geordie Jester

    Geordie Jester
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    Someone will come and tell you what size filter you need. But check the front of your lens. Screw on filters are avail that fit onto the front.

    The other option with filters is to go down the route of Cokin type filters. These are square in shape and slide into a holder that is fitted to your lens and holds them infront of the glass.

    Typically a UV filter is used to protect to the lens. It has a slight effect on image in that it cuts out the glare that you can get in bright UV. You might see benefit at the coast in particular.

    Polarising filters only let certain directions of light into the lens. The direction is chosen by rotating it. It has two parts, the outer rotates. This means you can achieve saturated colours in particular by removing glare and also see different effects in glass and water. For a lake for example you can rotate the filter to make surface like a mirror, or transparent to see the rocks below.

    Coloured filters can be used to add a change in tone/warmth.

    ND (Neutral density filters) block out some of the light. Think of them as just being a tinted window with no colour. This means that if you have one on the front you need a longer exposure to get the same photo as not having it attached. This allows you to blur waterfalls as an example. If you NEED a longer shot to get correct exposure then the water will be blurred and smoke-like. A GRADUATED ND filter is one that is clear at one end and gets less clear at the other. This means you can use one to darken down a sky, but leave foreground untouched. It is to get around the problem of exposing for a field and finding out that the sky has just bleached away any detail. A grad can "hold off" the burn and give you a shot that looks more balanced.

    Metering......... Your camera doesnt know what you are photographing so has a stab at what it thinks. If you change to spot meter in your camera and experiment you will see what it is doing. Change to app priortity and point at something. You have chosen the aperture and the camera will choose the shutter speed. The shutter speed it chooses will be the one that if you take the shot, the thing you meter off will come out equivalent to mid grey. Half press the shutter and it will meter off the target. Continue to press and the photo will be taken. With this in mind, you will hear of people metering off something else, recomposing and taking the shot. Try taking a meter reading off the sky with a half press. Keep half pressed (or press exposure lock) and move camera to the subject you are photographing. Fully press and take shot. The photo you have taken is "right" for the sky. This may or may not be right for the photo. If you meter off something really bright then the camera will try and turn that to mid grey so the rest of the photo will come out quite dark. You are basically setting the mid point of the brightness in the scene. Once you get your head around this........then it will become obvious why when you photograph a snowy scene it comes out too dark. The camera sees the snow and tries to turn it mid grey. It means you have to exposure compensate two stops or so up to get the snow back to white as you would want.

    The various types of metering you have in your camera give options for taking shots. The matrix type approach is when the camera looks at lots of different points in the shot and bases it's decision on all the information in the scene. Very good for point and shoot approach or if you hand the camera to someone to take a shot for you. Usually this sort of mode automatically gets selected in "fully auto" modes. You then get "centre weighted" approaches where the metering gives more weight to the centre of the scene when it is deciding on exposure. Spot metering is literally basing the decision on a very small spot. For me this is my favoured mode as I feel like I have more control on what the camera is doing. I use Manual mode with spot meter and take readings of different areas in a scene before I choose the best rather than let the camera. That said, the camera is v good !!

    hope some of this makes sense !!

    pick up "Understanding Exposure" by Bryan Peterson. Lots of people seem to like that book. It made me move to Manual mode and be in control.
     
  5. kelvin

    kelvin
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    Thanks for the replies thus far - very interesting reading :)

    py6km,

    I read your thread yesterday and will pick up a copy of "Understanding Exposure" (although Amazon.co.uk are quoting a 3-4 week lead time at the moment :(). I will track doen the exposure thread and have a look at that in a moment...

    Geordie Jester,

    Wow - lots of info to take in, thankyou!

    Another question if I may...

    My understanding of your metering explanation (please correct me if i'm wrong, and bear in mind that this is massively over-simplified!), is that it is effectively the method that the camera uses to determine how the shot should be exposed? With this in mind, how does it differ from the exposure compensation dial that I have on the 400D? Does it simply take the reading, then up/reduce it depending on the compensation I set?

    Thanks again guys :)

    Kelvin.
     
  6. Geordie Jester

    Geordie Jester
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    Yep, thats what it does. If you meter off something and you know that the decision the camera will make is going to be "wrong" for your shot you can compensate by adding or subtracting stops of exposure. Usually in fractions of stop intervals.

    But what will the camera DO to achieve that? It depends on the mode. If you are in aperture priority you are giving the camera the control of the shutter. So if you use the compensation dial, the camera will have to increase/decrease shutter speed.

    Things to remember though. Sometimes there is no where for the camera to go. If you are shooting as fast as its capable then there is no way you can compensate any higher/lower.

    Another thing I find irritating with the compensation is that I forget to turn it back to zero (another vote for Manual mode where you just move the shutter/aperture yourself if you want to compensate)

    Just remember that sometimes there is something in the scene that is "better" to meter off than a main subject. But it depends on what you are trying to achieve. You might meter off the sky and end up with a sillouhette of a castle. Or if you meter off the castle then you might be able to see the detail in the stonework, but all the detail in the sky is lost. Obviously on a tripod you could take two shots, exposing one shot for sky and one for castle and then re-combine them later in photoshop ;) taking the best bits of each photo to make a new composite.
     
  7. Member 79251

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    Ok, I understand the above.....I am currently reading the book. I have an issue but its a bridge camera and not a dslr.

    I have used Manual on my older camera without any issues, I was using it before I worked out what it was. Now my problem, when I use it now I have issues.....What I mean is that the half press will show 2 images, the camera has a view finder and a lcd on both it will very quickly show a perfect image and then flick to my settings.!!!

    But if I change to aperture priority I can see the camera work, the shutter speed changes and so on. Depending on what I point at.

    Anyone help ? Is it just another get yourself an 'proper' camera reason. :confused: Can you even meter in manual ?
     
  8. Geordie Jester

    Geordie Jester
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    Not sure I totally understand.......but....

    I have a bridge camera too....

    In manual mode on mine...... I do get a sort of preview when I half press (ie get the impression of how it might come out). A meter bar comes up that indicates whether it is under/over exposed at the spot. If I release the shutter my meter stays on and I can move the view around and see the exposure bar go up and down as I pick different subjects. If I choose something I want to meter off, you have to point at the wall (say) and then move the shutter/aperture until the meter reading hits zero.

    Do you not think you have a meter at all that comes up ?

    I get this sort of bar.

    underexposed
    |----I----0-------|


    overexposed
    |---------0-----I-|


    "correct"
    |---------I-------|
     
  9. Member 79251

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    I wish I had those features.....!!!!! My camera seems very basic to yours. I have looked at the manual various times and also some bloke has even done a white paper on it. http://www.aakatz.com/whitepaper/part3.htm he has screens also on the website !! :confused:
     
  10. Geordie Jester

    Geordie Jester
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    What is the camera you have ? Even SLRs from the 1960s had metering. It would be odd if you have a manual mode and then don't have a light meter ! They can't expect you to carry a one around !!

    Hang on.......just had a read.......from your white paper it looks like you do have a meter (see lower).........



    EV - Calibrating Your Exposure


    EV (Exposure Value) is the baseline used to calibrate your meter. Normally, the default EV (EV = 0) on all the H-Series cameras is pretty accurate. But you may wish to shoot a little darker or lighter than normal. I tend to shoot most of my shots a little dark (-.3 to -.7 EV) to prevent blown-out skies and to preserve shadow and color detail. In my experience, there's nothing worse than an overexposed, washed-out picture with blown highlights. Very hard to recover from in post-processing. But, if you elect to work darker or lighter than normal, be prepared to post-process most of your pictures.

    In all automatic modes, setting EV changes the formula
    the camera uses to calculate the proper aperture, shutter speed or ISO. It is how you tell the camera to set all subsequent photos a little darker or a little lighter. It is your exposure preference setting.


    EDIT:

    *****************************************
    Built-In Light Meter

    In Manual mode, EV undergoes a wondrous metamorphosis. Since you don't need EV in Manual mode (you're making all the decisions yourself), the EV display becomes your light meter. Instead of setting your exposure preference, it reports the result of the settings you selected. It tells you if you've exposed too bright (+.3, for example) or too dim (-.7, for example).

    Of course, the response of the EV meter is based on the camera's built-in defaults and, most unfortunately, the H-Series cameras do not allow you to calibrate the EV meter in Manual mode (my Nikon DSLR does).

    So to adjust to your own preferences, you have to adjust your decision process instead of the camera. For example, I generally don't shoot when the EV meter shows "0". I wait until it shows -.3. Simple!
    ****************************************************
     
  11. Member 79251

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    Looks like I need to learn to read :suicide:
     
  12. Geordie Jester

    Geordie Jester
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    hehe! post back if you get it sorted and find the meter
     

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