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Thread: Help Required On Use Of Fast Standard Zoom Lens

  1. #1

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    Help Required On Use Of Fast Standard Zoom Lens

    Hi, I have recently upgraded from my kit lens and bought the Sigma 17-50mm F2.8 EX DC OS HSM, I have the Canon 450d.

    I describe my photographic knowledge as minimum and tend to shoot images more on the feel of the moment than technical awareness, clearly an area I am hoping to improve...anyway what rudimentary knowledge I have gained relates to aperture size and how that's best applied to depth-of-field. I take a lot of nature-type shots, so landscapes need to be as sharp as possible, this has me using larger apertures..but here's the thing...am I right in thinking that my new lens capacity to allow lots of light restricts its prime use to low light situations?

    However if that's so would not low f numbers, under those conditions, be unsuitable for landscape photography?

    That being so I'm now wondering what situations exactly this f2.8 lens is best applied to?

    Meanwhile in playing around on my local beach late afternoon, here's how it performed at f20 around 1/8th

    https://www.flickr.com/photos/sliabh...n/photostream/

    As a dedicated bungler of photography I would welcome any advice, thoughts on this.


    Erainn
    Last edited by erainn; 21st January 2015 at 12:19 PM.

  2. #2
    dubaiphil's Avatar
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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Hi Erainn

    First up, there's a welcome thread to introduce yourself to the forum.

    Secondly, your questions. Having an f2.8 zoom does not limit you to low light situations at all. f2.8 zooms are generally better optically corrected and resolve better than their variable aperture cheaper cousins. Diffraction affects all lenses though, so shooting at very high f numbers may compromise your image quality for the sake of Depth of Field. Low apertures can be suitable to landscapes, as long as there are not elements of the frame in the foreground which you want particularly sharp in your image.

    You will be able to isolate your subject more from backgrounds, particularly at the longer focal lengths of the lens.

    Generally lenses are performing at their peak 1 stop from wide open to around 1-2 stops from fully closed down. So your f2.8 should show an increase in performance if you're peeking from f4 to f11-13. However you've got that extra stop to play with if you need it to maintain a shutter speed that you want and or keep your ISO to levels that are workable for you and your gear.

    I'd recommend setting up on a tripod towards the end of the day and trialling your lens at different apertures for a like to like comparison.

    One of the big advantage of a fixed aperture lens is just that - it's fixed as you change focal length. None of that "am I going to be shooting at f4 or f5.6 or somewhere between". Another advantage, not for your focal length but more for the telephoto zooms, is that when you add a teleconvertor you will lose a stop or two of speed but your body will still be able to autofocus (allbeit more slowly as a rule). Consumer telephoto zooms are variable aperture and don't work with teleconvertors.

  3. #3
    Mark von Kanel's Avatar
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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Hi Erainn,

    Welcome to CIC! if you could add your approximate location to your profile it will help us give you better advice also yiour first name would be good because we are a friendly bunch here!

    If you want greater depth of field (DOF) you need a smaller aperture (hole that lets the light through the lens) its confusing because the smaller the hole, the larger the number its represented by.... so F14 would give a smaller hole and more DOF (things in focus) than F2.8.

    your larger apertures (F2.8) are to allow you to take pictures in lower light levels or to throw backgrounds out of focus for creative use.

    Although using you lens at F20 may give you better DOF you should remember that it may not give the best quality images, most lens's perform best between F8 & F11 outside of those settings you may get diffraction / edge softness ect. so you need to play and see how your lens behaves at these settings.

    If you look in the tutorials section youll find stuff on this subject, have a read and come back with you questions.

    Mark

  4. #4
    dubaiphil's Avatar
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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Try shooting your lenses back to back if you have the kit lens too. Try high contrast scenes (leaves against a bright sky for example) and see how the lens cope at the same aperture and focal length. With better glass, coatings and corrections against CA you should notice a big difference in what you're paying for. When I moved from an 18-105mm kit zoom to a 24-70 f2.8 Nikkor there was a massive jump in IQ, before you even get to the creamy backgrounds at 70mm and f2.8

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Thank you very much for kindly replying with that advice.

    Erainn is my first name

  6. #6
    Moderator Dave Humphries's Avatar
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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Hi Erainn,

    A warm welcome to the CiC forums from me too.

    As Mark and Phil have mentioned, discussing apertures can get very confusing, so it helps if you are also clear when you say "low apertures", whether you mean "lower f number" (= larger physical aperture hole, giving narrower DoF), or the converse.

    e.g. phrases like "low (or high) f number" and "wide (or narrow) aperture" are less likely to cause confusion.

    Don't worry, I went through the same thing when I started, we all did - and there's lots to learn, just take things one topic at a time and keep asking questions until you understand fully, then move on. You'll never stop learning.

    You may find these threads helpful:
    HELP THREAD: How can I post images here?
    How to Get Effective Feedback for your Posted Images


    Could you do us a favour please?
    Could you click Settings (right at the top),
    then Edit Profile (on left)
    and put "Erainn" in the Real Name field
    and where you are (roughly) in the Location field?
    this helps everyone give you more personal and relevant answers and remains both obvious and visible in all your future posts - thanks in advance.

    All the best, Dave

  7. #7

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Hi Dave, yes that's good advice, precise terminology is helpful, I'll attend shortly also to my profile.

  8. #8
    Moderator Manfred M's Avatar
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    Re: Help Required On Use Of Fast Standard Zoom Lens

    First of all, landscape photography is much more than taking a shot of a scene that stretches from your feet to the horizon. It also includes shots in urban environments (often referred to as urban landscapes) and other more detailed elements in the natural environment (closeups, with blurred backgrounds).

    Let's make sure we are on the same page so far as definitions go; low aperture numbers (f/2.8) means that the lens iris is (relatively) wide open and lets in lots of light and has a shallow depth of field (DoF). A large aperture number (f/22) means that the lens iris opening is quite small, lets in relatively little light and has a large DoF.

    The other two variables associated with getting the proper exposure are shutter speed and the camera's sensitivity to light; ISO. Let's look at how these affect your image.

    Your camera's base ISO (the lowest numerical setting) gives the highest quality; meaning the highest colour depth, dynamic range and sensor noise. A landscape shooter will generally set this value as low as is practical for the given light conditions.

    Shutter speed is another important compositional tool. If you set your shutter speed quite low, there is a risk of motion blur, and if you set it high, you can freeze any action. You might think that as a landscape photographer, you will want a high shutter speed because you want to have a sharp image; but if the scene has flowing water in it (for instance a waterfall or wave action on a shoreline), you might be tempted to go for a lower shutter speed to soften the look of water.

    Most landscape photographers will shoot when the sun is close to or even just below the horizon, because the light is more pleasing just around evening or morning twilight (often referred to as "magic hour" or "golden hour", even though it may be much longer or shorter, depending on the time of year and your latitude). Low light, low ISO setting means a slow shutter speed, so most landscape photographers shoot from a tripod.

    Phil, in his response it quite correct; lens performance improves as you reduce the maximum aperture by a stop or two, but there is a limit to this improvement as when the aperture opening gets very small, an effect called diffraction sets in (f/16 and smaller openings), and this deterioration in quality is about the same level as shooting the lens wide open or stopping down one stop from wide open. These effects are all more noticeable when the image gets enlarged (i.e. I tend not to worry about these if the images are posted on the web, as the impact is unlikely to be noticeable).

    You are doing the right thing; get out there and shoot and figure out how the various settings affect your results. Study other photographer's works and see what they are doing and try to emulate their shots that you like in your own work.
    Last edited by Manfred M; 21st January 2015 at 12:26 PM.

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    grumpy, I apologize if my ignorance and lack of precision has proved irksome, not intended. I am very grateful for your helpful advice and insights

  10. #10
    Moderator Manfred M's Avatar
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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Quote Originally Posted by erainn View Post
    grumpy, I apologize if my ignorance and lack of precision has proved irksome, not intended. I am very grateful for your helpful advice and insights
    Not irksome at all; I certainly hope you did not interpret my thoughts that way. We were all beginners at some point and moved forward from that position.

    I was just trying to point out the variables and tradeoffs a photographer needs to know about and consider when taking a picture. There is no simple cookbook solution to photography, so developing a understanding as to how everything fits together is critical to becoming successful. The way I look at it; there are three stages in the development of a photographer.

    Stage 1 - Novice photographer - It's all about learning the mechanics of taking a picture; your camera, lenses and other equipment and how to use them. Overlay basic compositional skills these establish one as a "good" photographer.

    Stage 2- Intermediate photographer - having mastered the basics, one starts to understand one's subject and how to get good images out of that subject. The subtilties of compostional and technical skills allow you to explore you subjects, regardless of whether it is landscape, insects, architecture or people. Nicely said, it's all about learning your photographic environment.

    Stage 3 - Advanced photographer - having mastered the technical and compositional aspects of photography, and having in-depth knowledge of your subject matter, as it pertains to photographing it, you now get to discover yourself. This is the point in photography where you develop "your own style" and look as you are now photographing subjects in a way that is meaningful to you.

    All of this takes time; usually a long time. While I don't agree with Malcom Gladwell that it takes 10,000 hours to become skilled at some task (it takes less time for some tasks and much longer for others), I do believe the underlying premise is correct. Becoming a good photographer takes a long time.

  11. #11
    Tringa's Avatar
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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Hello Earinn and another welcome to CiC. I cannot add to the excellent advice already in this thread except to reiterate Mark's suggestion to look at the Photography Tutorials section on this site - it has lots of very good information.

    Dave

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Hi, Erainn. Others have already answered your questions. I will re-emphasize the advantage of the fixed aperture lens mentioned by Phil. Another advantage of the f2.8 is that even if you only shoot landscape and never use the widest aperture, it provides the advantage of more accurate autofocus and more light for your eye when looking through the viewfinder. When doing so you are always looking through the lens "wide open" at maximum aperture(lowest f-stop). So when looking through the viewfinder with an f2.8 lens, you have twice as much light as looking at exactly the same scene with a lens of f4 max aperture.

    I had a copy of that lens. It is really an excellent bit of glass. Unfortunately the OS didn't play well with my Nikon camera so I got rid of it. Wishing I hadn't now. Really a sharp lens.

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    IzzieK's Avatar
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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Erainn...strange name...I will second most of what other members here are saying. 'Will have to add that if you do not understand some terminologies used in photography, google is your friend who can have choices of answers in the level you would understand it. It takes time for anything, short of long, it still takes time.

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Quote Originally Posted by IzzieK View Post
    Erainn...strange name...
    Sounds Gaelic to me?

    Welcome, Erainn: by co-incidence, I've just bought the older Sigma EX DC, 18-50mm, constant f/2.8.

  15. #15

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Hi Ted, hope you are enjoying the lens, I'm still trying to work its best settings for certain conditions. All part of the fun.

  16. #16

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Izzie, yes indeed, time and a willingness to explore the options I'll get there.

  17. #17

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Dan, cheers for that, I'm trying to learn about its best qualities out in the field

  18. #18

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Dave I shall sure take a peek at the tutorials, and hopefully the proverbial penny will drop

  19. #19

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    Re: Help Required On Use Of Fast Standard Zoom Lens

    A big thanks to all who have so kindly advised me on this ongoing challenge I really appreciate your suggestions and encouragement.

    With time my knowledge may equal that of my present enthusiasm..

    today during late afternoon I was down on the shingle beach, with a strong wind and big waves. The sun was sinking slowly behind cloud and I thought it a chance to try the lens...

    Now before I continue here's a cringe-warning to anyone who may be driven to drink by the innocent foolishness of my thinking..

    Looking at the sky, cloudy, with a fair amount of light and surrounded by a surface of pebbles I wanted to see how photos came out taking a shot seawards....I noticed that when getting the sky right the beach foreground would be underexposed....so I chose a number of different aperture sizes at 1/125 at f5.6 seemed ok..... Are those lighting/location circumstances difficult as far as getting both foreground and sky at the right exposure? In my lack of technical expertise it seems a tough call..that said it was a wonderful excuse to get out in the elements

  20. #20
    rpcrowe's Avatar
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    Re: Help Required On Use Of Fast Standard Zoom Lens

    Erainn...

    Lovely name with, I expect, a Celtic background...

    There are two great ways to get practiced in the use of f/stop and shutter speed...

    First is to select programmed (P) exposure and use this mode to shift through all the shutter speeds and f/stops which will give you the same exposure but with different shutter speeds and f/stops. This will show you the imagery difference when using different shutter speeds and different f/stops. All of the images will be the same exposure but will look different. As an example 1/100 second @ f/16 is equal in exposure to 1/2,000 second @ f/4 but the f/16 will give you a greater depth of focus (AKA: depth of field) than the f/4 image and the 1/2,000 second exposure will freeze action better than the 1/100 second exposure...

    A second training method is to select either aperture priority (Av) or shutter speed priority (Tv) and then select auto exposure bracketing (use one stop bracketing). Select burst mode and the camera will shoot one exposure at the meter reading, one exposure at one-stop less than the meter reads and one exposure at one-stop greater than the meter reads. You can go into the menu (see your manual) and select the sequence of these three exposures. For training purposes I suggest that you select the minus exposure, as meter reads exposure and plus exposure in that order. Your camera will shoot three different exposures and stop shooting until the next time you trip the shutter.

    You will the be able to view your exposures in whatever editing program you use and you will be able to see which is the best exposure. If you shoot a great variety of subjects in a variety of lighting situations, you can learn to adjust your exposure and not depend entirely on the meter reading.

    As an example when shooting a very bright scene like snow, you will see that the plus exposure will give you a better image and when shooting the proverbial black cat in a coal bin, the minus exposure will be best. That is because your meter is set up to provide an 18% gray image and will underexpose the snow scene and overexpose the cat in the coal bin in order to make the image gray. Of course, you don't want gray snow or a gray black cat and that is why you need to adjust your exposure instead of blindly following your meter reading...

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