Understanding the Circle of Confusion?? (image sharpness vs. background/foreground)

KadynClare

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Hello; I am new to the Forum and while I've been using my camera (a cannon rebel xsi) for about three years I'm just starting to realize how LITTLE I actually understand about how it functions; I'm hoping to improve my photography skills so that when I take shots I can get consistently better images as opposed to what I get now; where sometimes I get stuff that's amazing that I love and other times I can shoot 500 images and get complete crap.



I've spent most of the morning reading (and writing notes! lol) on aperture, iso and ss, and I think I have a better understanding of how ISO is contributing to a lot of my outdoor shots not coming out well, and learn that even though my camera says it can shoot at an ISO of 1600 that for my model/type of camera those images usually come out with so much noise they're crap. Good to know.



I'm having a lot of trouble understanding how to calculate where I should stand/how much to zoom for the appropriate depth of field/circle of confusion/image sharpness.

I'm most often shooting horses and riders outdoors using a telephoto lens (50 - 250mm) And I'm generally at least 100 to 150 ft away from the subjects.

I'm finding a lot of difficulty keeping my subject crisp and sharp and I've tried using the calculator located in the tutorial but just ended up even more confused as it's telling me I need a 444mm lens to shoot? If this is the case I suppose I should just give up now as I certainly cant afford one of those super fancy telephoto lens's the pros use.


Is there a way to get better shots using the equipment I do have or is the best I can hope for sometimes getting good shots by the grace of god and pure dumb luck?



More specifically a friend has asked me to photographer her competing over the next three days at a horse show; unfortunately indoors. I hate indoors. It always comes out complete crap.

What can I do to make it better? I'm going to be in the stands for her dressage tests, flash will not be allowed (and it would be useless anyways at that distance)

I'll probably need a shutter speed of at LEAST 1/250 to keep the horse from blurring; possibly 1/400 would be much better. Unfortunately light in the local indoor isn't the best and now knowing that I should only open my camera ISO to 800 max; how do I not produce under-exposed images??? while maintain a SS fast enough to not get motion blur?? Is there a way?

Should I shoot with my 35-50mm lens and then massively crop images later so it doesn't look like I was shooting from a football field away? or leave my telephoto lens 'zoomed out' so that I don't make the images darker?

Her horse is also completely black so shooting him always presents a bit of an exposure issue. Help??!!
 
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Gary_A

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Are you using a tripod for you long distance shots?

At the inside event, what distances will you be shooting? Do you know what lighting you will have to work with?
 
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KadynClare

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I do not own a tripod I usually hold my breath when shooting, I also usually shoot action in continuous mode so I'll shoot for about 4-5 seconds rapid fire (or as rapid fire as my camera gets) then breath let the camera catch up with putting the images on the SD card and shoot again.

The indoor is the Raleigh Hunt complex so it has overhead lights that seems adequate to the naked eye, I believe they are florescent I have shot there before and all of my images came out very disappointing. I opened my aperture up the first time I was there to 1600 (big mistake images had so much noise it was ridiculous I scrapped all of them), last time I was there to shoot a carriage horse show I shot at 800 ISO about 65 feet up in the stands, The horses only do walk and trot though so many of the images could be done at a slower shutter speed then is required for capturing crisp/sharp dressage horse movements.

I will be in the stands again for the indoor event. I'll be trying to photograph from the end of the arena with the opening to my back (so I don't get terrible backlighting in my shots) or from the center of the grandstand shooting straight onward; unfortunately many of these shots will be tilted down as I'll be at least 15-25 feet above the arena from this position. I usually zoom in with my lens, though I'm not sure to exactly what length(distance??) How would I see that information when shooting? I have never noticed/considered it before as I did not really understand (and obviously still don't) the relationship between aperture/focal distance etc.
 

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I have no idea what your problem is because I gave up trying to read the solid block of text when I was less than one quarter of the way into it.

Try using a few breaks to split it up and make it readable and then you may get a more replies.
 
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KadynClare

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I'm sorry, I do not know why my spaces did not show up in the original post, It is fixed now.
 

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I think you will need to find something to brace yourself against.

Setting your elbow on a fence rail, resting your shoulder on a post, really anything that plants any part of your upper body against something solid is going to help.

You're going to want to shoot pretty open, around f/4.0 through f/8.0 perhaps, and at the longest focal length your zoom allows.

Then work on getting the focus right. Some cameras have focus modes that are designed specifically to track a moving object, if yours has that, read up on that specifically and try it out. You can test it on cars passing by on the street. An alternative it to pre-focus on some object where the horse will be doing something interesting (a fence to jump, a turning mark, something like that) and wait until the horse arrives there to shoot. You might experiment with burst shooting here, and start shooting slightly before the horse arrives.

You're going to get a lot of shots that are not keepers, especially at first.

Good luck!
 

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A properly exposed image at high iso is better than an underexposed image with a lower iso brought up in pp. I would try to shoot at 1/400 with maxed out iso. If they are still underexposed lower the ss, not going lower than 1/250. I am assuming you have a kit lens with varied apertures. So I would probably keep it pretty wide (f4), but it will change as you zoom in/out. No reason to hold your breath as 1/400 would be fast enough to freeze camera shake!

as far as your location. Shooting with the open area behind you is good...this means the light will be falling onto your subject and you need all the light you can get! Bottom line. You are going to have a hard time producing quality images with your current gear :(
 

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Hello; I am new to the Forum and while I've been using my camera (a cannon rebel xsi) for about three years I'm just starting to realize how LITTLE I actually understand about how it functions;
Hi. How are you standing now with your understanding ? For calculation of DoF you can use this:
Online Depth of Field Calculator
 
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KadynClare

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I feel like I'm staring at binary code.

I keep reading about f-stop value, that the opening in the camera increases as the f-stop number dec4reases, and according to the chart/example in the tutorial at f/4.0 my SS needs to be 1/2 second, but to shoot fast enough to reduce motion blur on moving horses I need to shoot at least 1/250...

I have a pretty cheap zoom lens, I had no idea what it was when I bought it; I've been using it for almost 2 years now. It says 1:4-5.6 IS on it; does this mean that at 55mm 4.0 is the minimum f-stop and at 250mm 5.6 is the max?

If my camera lets me select an f-stop of F4 to F22 on it's current setting (Av) does this mean I'm still only shooting at 4 or 5.6 because the lens is incapable of changing??
 

KmH

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I'm most often shooting horses and riders outdoors using a telephoto lens (50 - 250mm) And I'm generally at least 100 to 150 ft away from the subjects.

I'm finding a lot of difficulty keeping my subject crisp and sharp and I've tried using the calculator located in the tutorial but just ended up even more confused as it's telling me I need a 444mm lens to shoot? If this is the case I suppose I should just give up now as I certainly cant afford one of those super fancy telephoto lens's the pros use.
You don't need to spend $11,000 on a pro grade 400 mm f/2.8 lens.
Canon EF 400mm f/2.8L IS USM II Super Telephoto Lens for Canon EOS SLR Cameras but pros use that lens for several reasons.

You might consider getting a used consumer grade - [/url=http://www.amazon.com/gp/product/B0007Y794O/ref=as_li_tf_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B0007Y794O&linkCode=as2&tag=hdiumds-20]Canon EF 70-300mm f/4-5.6 IS USM Lens for Canon EOS SLR Cameras[/url]

Or if you can afford it a used - Sigma 150-500mm f/5-6.3 AF APO DG OS HSM Telephoto Zoom Lens for Canon Digital SLR Cameras


Should I shoot with my 35-50mm lens and then massively crop images later so it doesn't look like I was shooting from a football field away? or leave my telephoto lens 'zoomed out' so that I don't make the images darker?
No, because when you massively crop you lose resolution.

The best solution is to have sufficient 'reach', or focal length, to do the job.

Shooting action sports requires using gear that because of it's capabilities is a bit more expensive.

Some of the info in this tutorial may be helpful - Understanding Camera Autofocus
 

o hey tyler

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I feel like I'm staring at binary code.

I keep reading about f-stop value, that the opening in the camera increases as the f-stop number dec4reases, and according to the chart/example in the tutorial at f/4.0 my SS needs to be 1/2 second, but to shoot fast enough to reduce motion blur on moving horses I need to shoot at least 1/250...

I have a pretty cheap zoom lens, I had no idea what it was when I bought it; I've been using it for almost 2 years now. It says 1:4-5.6 IS on it; does this mean that at 55mm 4.0 is the minimum f-stop and at 250mm 5.6 is the max?

If my camera lets me select an f-stop of F4 to F22 on it's current setting (Av) does this mean I'm still only shooting at 4 or 5.6 because the lens is incapable of changing??

No, your lens stops down when the aperture is set to anything smaller than your maximum aperture when you hit the shutter and only when you hit the shutter (or use the DoF preview button). If you're talking about this lens: Amazon.com: Canon EF 35-80mm f/4-5.6 III Lens: Camera & Photo

Your max aperture at the widest focal length is f/4, and it's f/5.6 when all the way zoomed in.
 

KmH

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It says 1:4-5.6 IS on it; does this mean that at 55mm 4.0 is the minimum f-stop and at 250mm 5.6 is the max?
Yes, or actually the widest lens aperture (f/stop) or maximum, rather than minimum, aperture.

F/4 is a fraction and is a bigger number (and larger lens opening) than f/5.6 is at the same focal length.

If my camera lets me select an f-stop of F4 to F22 on it's current setting (Av) does this mean I'm still only shooting at 4 or 5.6 because the lens is incapable of changing??
Yes. When your lens is zoomed to 250 mm it cannot be at f/4. F/5.6 is the largest lens opening it can have because of mechanical limitations.

Understanding Camera Lenses
 

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. (answered)
 
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KadynClare

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So, I've been reading aperture and f-stop and depth of field articles/tutorials all day now; and it seems unless I can spend the big $$$ for a lens capable of an aperture setting of 2.8 and then be spot on with my timing/focus I'm not going to get good indoor shots. the f4 f8 settings require too long of an exposure; so the photos will come out under-exposed.

So the next three days indoor will be a wash. :(

however when I shoot outdoor sports shots my lens seems to do ok. Since indoor sports stuff seems to be way outside my price range; if I wanted to get those really zoomed in views. Lets since say in an outdoors cross-country horse competition setting; I'm usually at least 100meters from the subject.

Would buying something like a 500mm/1000mm manual focus lens be okay; I'd obviously use a tripod and only focus on one set area or fence since moving the camera/adjusting the manual focus would probably take way too much time with a horse moving at 30 mph to re-focus between shots; at least not without a crap load of practice; and even then that's probably unrealistic.

Or would you save up and purchase an auto-focus lens that's only capable of 500mm?
 

KmH

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Yes, indoors makes it hard because the camera needs a lot more light than our eyes do, and the camera gear (cameras and lenses) that can do that is not inexpensive.

A monopod is often preferrable to a tripod when using long lenses for action sports shooting.

Before auto focus was routinely available, we shot action sports with manual focus lenses. Today's auto focus cameras no longer include some of the manual focusing aids we had in the 1980's.
 
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