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Finding the focus point

post #1 of 18
Thread Starter 

I really want to start using my camera to its potential, so I thought I'd start asking questions and see what comes of it. 

Camera is a Canon EOS Rebel T1i

The lens I use most is a Canon 18-200 with stabilizer.  I tend to keep a polarizing filter on it because I use the camera a lot in the outdoors in bright light. 

I also like having a filter because it has proven to be good protection  for the lens when the camera was dropped. biggrin.gif

 

First question: 

I (sometimes) have a difficult time finding  the right focus point when I line up a shot. 

 

I've uploaded 12 Photos  of some morning glories I have on my patio as an example. 

 

These shots were taken while they were in the morning sun with the house beginning to shade them  just a touch. 

 

Whole plant: 

 

 

So the question is, how do I focus on something in the distance without changing the frame of the photo. 

Shot with focus on the back blooms but had to adjust the frame of the photo. 

 

Shot with blooms centered but focus changes to front bloom

 

 

Side view to give perspective of depth. 

post #2 of 18

What mode were you on in shooting these pics?

 

(ie something like "program auto exposure (ae)",  aperture mode, shutter mode, full auto?)

 

 

google on "depth of field" 

 you will get results from very techy to very illustrated.

 

I think that will help

post #3 of 18

Well, asking for photo advice on a ski forum is always risky.  You should see how bad the skiing advice is on photo.net!

 

It sounds like your camera is set "too automatic".  What works for me is to lock the auto-focus system to the center point.  Then, I use "focus and recompose", ignoring all the nay-sayers.

 

http://dptnt.com/2007/08/focus-and-recompose-2/

 

By the way, if you're looking for a filter to leave on always, try a UV or skylight filter.  The polarizer has differing effects depending on your orientation to the sun and the rotation of the filter.  It also eats a lot of light, which could be an issue at night.

post #4 of 18
Thread Starter 

For the top photo, it was set on Full Automatic,

 

The next two were set on close up

 

The last one was set on Landscape, while I was fiddling with settings. 

 

 

Xela, we have some amazing photographers on this site.  I'm confident that I'll get some solid advice. 

 

I actually hope to go out on a photo trip with Splitter some time and learn more about using the equipment I have, and perhaps find out of there is something more I need. 

post #5 of 18

I think it may be helpful to turn off much of the automation in the camera.  If you're the type of person who has a specific idea of how you want a picture to come out, you probably don't want to give too much control to the camera.  Frankly, this is why most people buy DSLRs and I find it funny that DSLRs have so many auto modes.

 

So, I'd start by ditching modes like Closeup and Landscape.  Instead, stick to these parts of the dial: P, Tv, Av and M.  Most old-schoolers will tell you that you'll learn the most using M (manual mode).  Personally, I think you can learn in the others as well if you pay attention to the aperture and shutter settings that the camera is picking.  You can play in P mode by spinning the main dial before pressing the shutter button all the way.  I second docbrad66's suggestion to learn about depth of field.

 

As for focus, I think the default is "all AF points active", but I think you can press the AF point selection button (top right of the back) and move some controls to select a specific AF point.  I'd suggest the center one; it's usually the most accurate.  With luck, this setting will be persistent.

 

Your camera has a depth-of-field (DoF) preview button on the front below the lens release button.  You can use this to see what's in focus, although it's hard to see due to the small, dark image in the viewfinder.

 

Keep in mind, also, that your lens has a minimum focus distance of about 1.5 feet.  This can be a limitation when shooting flowers.

 

If you're the self-study type, you might want to take a look at this:

 

http://photo.net/learn/making-photographs/

post #6 of 18

Focus and recompose using center focus point is the answer. 

 

It shouldn't matter which exposure mode you use (AV, TV, M... even P/green square, unless those last two limit your focus choices). AV is probably the workhorse exposure mode for most of us professionals shooting for print, btw. 

 

The way AF works though requires some contrast in the area of the scene you want to focus on. That's why solid colors/textures can be difficult to get AF to lock onto.

post #7 of 18

Work on manipulating your depth of field using manual then transpose that to your different auto modes. There is so much to learn by letting  go with some of the technology .  Shutter speed, aperture and film speed all affect film quality or individual options to get the shots you need.

 

Read  Joy of Photography for good basic understandings of film capture

post #8 of 18

Did you take another run at it Trish. For starters, why not look at your old shots on the computer and see what aperture your camera was using for those shots.Do you understand the relationship between aperture and depth of field? The more open the aperture (smaller number) the shorter your depth of field will be. So try it in Aperture priority mode. Set your aperture smaller like f22 and see what happens. You may find that you get blurring from camera shake as your shutter will have to be slower, so turn up your ISO and or use a tripod (even the wind blowing on the flowers will blur them if your shutter is too slow). Your lens is only physically capable of so much, you may find that you just can't get it all in focus, but if you can, that's how you will do it.

post #9 of 18

All the above advice is good but to summarize:

1) Most DSLR cameras have a manual or "M" focus setting, so consider using that when there is this kind of issue. 

2) Most DSLR cameras have at least three default focusing settings.  One is the typical point it and shoot and the camera will do the rest.  Another pinpoints (center focusing) for focusing and the third allows you to frame your shot yet move the focusing point.  This is great for those tripod shots.

3) Most cameras allow you to point it at your subject and hold the focus by pressing down lightly on the button, and then (after you move the camera to frame the shot) press all the way down to take the shot.

4) Rarely a prime lens needs "tuning", and I don't think that is your issue.  Some modern DSLR cameras allow you to adjust for front or back focusing lenses, but again this is rare.

5) Depth of field is a biggie when taking good photos, and articles on this subject and DoF charts can be found all over the Internet.  A quality lens may cost more because it allows for a greater out of focus blur (bokeh) and is still sharp wide open.  Sometimes you want everthing sharp, and sometimes you want the background blurred.  That is why newpaper and sports photograpy is often times subject sharp and background blurred.

 

Below are two handheld shots, both using the "center focus" option. On the first shot I simply pushed the shutter release button half way down until I heard a beep (meaning it was in focus), framed the shot holding the button half way down, and then took the photo.  In the first photo the background is an ugly chicken wire fence so it was shot wide open to blur the background.  If I had a longer lens with me you wouldn't see the chiken wire, but that wasn't the case.  The second shot needed two subjects in focus, while trying to blur the background so it was shot two stops from wide open (by my son for a scouting merit badge).  Neither of these are "money" shots, but they are examples of the above and suitable for our purposes.

 

 

 

Last idea: Go to www.500px.com and "search" for the type of photo you are trying to take (e.g., "stars streaking"  or "fireworks" or "flowers", etc.  Then find some photos you are crazy about and see what shutter speed and aperature the photographer used.  500px is a great learning tool for me.


Edited by quant2325 - 8/28/12 at 10:09am
post #10 of 18
Thread Starter 
Quote:
Originally Posted by epic View Post

Did you take another run at it Trish. For starters, why not look at your old shots on the computer and see what aperture your camera was using for those shots.Do you understand the relationship between aperture and depth of field? The more open the aperture (smaller number) the shorter your depth of field will be. So try it in Aperture priority mode. Set your aperture smaller like f22 and see what happens. You may find that you get blurring from camera shake as your shutter will have to be slower, so turn up your ISO and or use a tripod (even the wind blowing on the flowers will blur them if your shutter is too slow). Your lens is only physically capable of so much, you may find that you just can't get it all in focus, but if you can, that's how you will do it.

Funny you should post that. 

One thing I found out about my camera/lens, is that if you hold the button down half way, then let it up, you can select where it focuses depending on where the little red lights light up.   Its not fool proof, but it does help choose a different focus point. 

I have done some more experimenting with some different areas, settings and light.  I have also done some photos of the same plant life at the same time of day. 

Its a work in progress, especially since I picked a plant that isn't the same every day because the blooms only last a few hours then make way for new blooms. 

 

Here are two shots in Linda's garden

This one is on auto

 

Same place, AV setting, This is the best shot I got using AV. 

 

post #11 of 18

without yanking the EXIF data, I'm guessing your aperture was open pretty wide and the ISO is set high.

 

Take your ISO down to the lowest "normal" setting (your camera might go down to 100 with "low" settings below that.  ISO 100 is a very reasonable place to start.

 

The other thing you could do is close up your aperture and shoot (Higher f/ number).

 

The best plan of attack would be to take the ISO down and shoot a few shots at different f-stops (apertures) and see how DOF and shutter speed changes.

post #12 of 18

TC,

 

Last post (gotta get out of town).  See the chart below.

 

Once you have a good exposure (look at the histogram on your camera's LCD for starters) you can use a chart like this for an idea of relative exposures.  Looking at "9", f/22 at 1 sec. lets in as much light as 1/250 at f/1.4.  Same exposure, but a huge difference in depth of field.  Using the Av function of your camera shouldn't over expose the photo (your post above) if the shutter speed was fast enough (or, as suggested above, the ISO is too high).  In fact, your camera will automatically adjust either the shutter speed or aperture (depending upon what setting you use) for you.  There are good books written about every popular camera sold that have a wealth of information in them.

post #13 of 18
Thread Starter 
Quote:
Originally Posted by splitter View Post

without yanking the EXIF data, I'm guessing your aperture was open pretty wide and the ISO is set high.

 

Take your ISO down to the lowest "normal" setting (your camera might go down to 100 with "low" settings below that.  ISO 100 is a very reasonable place to start.

 

The other thing you could do is close up your aperture and shoot (Higher f/ number).

 

The best plan of attack would be to take the ISO down and shoot a few shots at different f-stops (apertures) and see how DOF and shutter speed changes.

I just checked. ISO was set at 3200.  

 

I'm going up to Northstar today to have dinner with friends.  I'll play around with it and report back. 

post #14 of 18

The choice of ISO is pretty important.  For outdoor, daylight shots, I aim for 100-400.  As the numbers start getting above 1600, there's usually a trade-off of image noise in order to get the shot in a low-light situation.  Cameras differ, of course.  If you're in bright light with a high ISO by accident, the camera will try to accomodate by stopping down the aperture and shortening the shutter speed, but there are limits and you appear to have hit one.

post #15 of 18

IS0 3200 is quite high. (My Lumix FZ47 ("pro-sumer" line) stops at 1600.  And i stop it before that most all the time..

 

 i think of ISO as "light sensitivity", so higher is good for low light. 

but of course it may pick up grains of dust as well.

"only as high as you need it" is probably a good heuristic

 

My suggestion: take the same shot ONLY changing you f stop, either in full manual mode or

whatever mode lets you change aperture, camera decides exposure time ("A" or aperture mode)

 

this will have a lot to do with "depth of field"  

 

The focus is part of it but I would suggest f stop is the larger part of what you are asking about.

 

http://digital-photography-school.com/aperture-and-shutter-priority-modes

post #16 of 18
Thread Starter 

After playing around with the settings, using AV, 100ISO and adjusting the aperture 

Again, I'm trying to use the same flower shot area to get a consistent idea of where I'm going. 

IMHO This is a huge improvement over the original photo. 

 

 

 

Same location, photo from Original post. 

post #17 of 18

It's helpful to understand how autofocus works in order to understand how (and why) it behaves a certain way ...

 

Depending on your camera, there are a number of auto focus sensors used to detect an object in focus.  On the consumer/prosumer DSLR's it ranges from 9 sensors anywhere up to 50 or so. The sensors are arranged in a pattern covering the view you see in the viewfinder.  The image below is the autofocus sensor array from a Nikon D7000 ..

 

 

 

If you don't do anything to change it usually ALL sensor points are active.  This is referred to as area mode or zone mode depending on your camera.  Usually, by default, the camera will pick the sensor point (or points) that covers the closest object in the viewfinder in order to focus the frame.

 

In your first shot, the closest object was the flower on the right.  In the second shot it's the flower in the center of the frame.

 

If you want the camera to focus on an object further back in the frame - a great technique for showing depth in your photos - you'll either need to focus-and-recompose or to select a different focus mode that let's you choose the focus point.

 

The beauty of Auto mode is that the camera makes all the choices for you.  The downside is that it rarely makes the right choice! rolleyes.gif

 

I'm a Nikon shooter, so I'm not familiar with the Canon settings, but I would recommend digging through your manual to see how to change the focus modes and/or focus point.


Edited by OldEasternSkier - 9/17/12 at 2:02pm
post #18 of 18
Thread Starter 
Quote:
Originally Posted by splitter View Post

without yanking the EXIF data, I'm guessing your aperture was open pretty wide and the ISO is set high.

 

Take your ISO down to the lowest "normal" setting (your camera might go down to 100 with "low" settings below that.  ISO 100 is a very reasonable place to start.

 

The other thing you could do is close up your aperture and shoot (Higher f/ number).

 

The best plan of attack would be to take the ISO down and shoot a few shots at different f-stops (apertures) and see how DOF and shutter speed changes.

 

Quote:
Originally Posted by quant2325 View Post

TC,

 

Last post (gotta get out of town).  See the chart below.

 

Once you have a good exposure (look at the histogram on your camera's LCD for starters) you can use a chart like this for an idea of relative exposures.  Looking at "9", f/22 at 1 sec. lets in as much light as 1/250 at f/1.4.  Same exposure, but a huge difference in depth of field.  Using the Av function of your camera shouldn't over expose the photo (your post above) if the shutter speed was fast enough (or, as suggested above, the ISO is too high).  In fact, your camera will automatically adjust either the shutter speed or aperture (depending upon what setting you use) for you.  There are good books written about every popular camera sold that have a wealth of information in them.

I haven't really been using the camera much over the past year, but I've got the bug to pick it up again and started playing with these tips after some trial and error getting shots of the Super Moon

I took the results to a friend of mine who is a photographer who gave me a ton advice on reducing "noise" which I'm going to implement on my next outing.

One thing he suggested was that I shoot in RAW instead of JPEG to take out some of the noise. 

 

Here are some results and setting  choices.  All photos taken at same vantage point in a short amount of time. 

 

M - ISO 3200, 70mm, 1/5.6, 1/15

 

AppleMark

 

A-Dep - ISO3200, 90mm, 1/5.6, 1/60

 

 

TV ISO 3200, 70mm 1/5, 1/125

 

P ISO 3200, 70mm 1/5 1/60

 

 

CA ISO400 60mm 1/5 1/60

 

Full Auto ISO400 60mm, 1/5, 1/60

 

AV - ISO 3200, 70mm 1/14, 2.5  For sure need a TriPod to do this sort of thing.

 

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