Rebel XT 100mm Macro Help

[Roger]

Well I have shot two rounds of pictures with my new lens and I have to say it takes good tele pictures, however I get alot of out of focus shots up close. I have used tirpod and without and flash and without.

I am thinking it is because I am in Program mode and letting it select the Aperture. * a guess , I hope that is the reason*

Here are links to my webpage with both days samples.

http://r0ger.homedns.org:10000/10/2006_10_25/index.html

http://r0ger.homedns.org:10000/10/2006_10_26/index.html

I could use some sugestions on what I am doing wrong, I thought it was to much movement at first, ( could be the case) but it seems that some of the sharp pictures are just half out of focus when close.

Thanks

[gluwater]

Your Aperture is too large. You should be shooting at f/8 or smaller. When takeing close up images your DOF is very limited. Most of your shots were between f/2.8 and f/3.5, when they should have been between f/8 and f/22.

Take this image for instance, it was shot at f/8. Notice how small teh DOF is.
http://gluwater.smugmug.com/photos/99390675-M.jpg

[gluwater]

I should have also mentioned that the closer you get the smaller your DOF will be. If you use your extension tubes with the macro lens you will get greater than 1:1 and your DOF will be extremely small. If you are using a flash a good place to start is using Manual. Set you aperture to f/11 and shutter speed from 1/160th - 1/250th. You will be using the flash as your main source of light. It is also a good idea to use a flash bracket and diffuser.

[Rudi]

Your aperture is too wide, Lundrog!

When shooting Macro, the DOF will be extremely shallow. You really have to stop the aperture down to regain some of that DOF, to make your entire subject appear in focus.

Most of your shots in the gallery that I visited are shot at f/2.8 or f/3.5, very wide apertures. This will not do for macro work. Try shooting at f/8 and f/11 for a start, maybe even f/16 or smaller. You will see a great improvement.


P.S. Beaten to the punch by gluwater. :)

[Roger]

So if I remember I need to change it to f11 or somthing then hit the dof butten?

Does that change what I see?


Me is new to this....

[gluwater]

Personally I have never understood the DOF button. I have tried it and I haven't noticed a very big difference visually. You really just have to practice and try different apertures until you can visualize what DOF each will give you at different distances.

[Roger]

Got somthing to turn out in Macro on 2nd link last image. Page is updating now, give it 15min.

I will try to shoot Macro Monday or Tuesday, I hope that Helps.

Thanks all.

[Rudi]

Yes, and even in that image you can see the effect of shallow DOF - it really is VERY shallow when you shoot Macro.

Good luck, let us know how you get on when you try with a smaller aperture.

[Paul S]

Program mode is good for one thing only: shooting with a "normal" (i.e., close to 50mm) lens, handheld. If that's not what you're doing, don't use it. Program mode does whatever it can to keep the shutter speed above 1/60, and doesn't really care about anything else.

You should be in Av or M mode most of the time, so you can have complete control over your shots. (There are also times when Tv mode is appropriate.) It may take a little time and effort to get the best results, but with practice, you can get much better results than with any of the Auto modes. In macro, you normally want more DOF. But in some cases, you actually want less. The only way you can control this is by making sure that YOU, and not the camera, determine what the aperture should be. Let the meter tell you what the shutter speed should be after you select an aperture (but be ready to correct it based on the histogram after taking a shot).

-Paul

[Roger]

Program mode is good for one thing only: shooting with a "normal" (i.e., close to 50mm) lens, handheld. If that's not what you're doing, don't use it. Program mode does whatever it can to keep the shutter speed above 1/60, and doesn't really care about anything else.

You should be in Av or M mode most of the time, so you can have complete control over your shots. (There are also times when Tv mode is appropriate.) It may take a little time and effort to get the best results, but with practice, you can get much better results than with any of the Auto modes. In macro, you normally want more DOF. But in some cases, you actually want less. The only way you can control this is by making sure that YOU, and not the camera, determine what the aperture should be. Let the meter tell you what the shutter speed should be after you select an aperture (but be ready to correct it based on the histogram after taking a shot).

-Paul

Do you know any guides or metering and reading Histograms?

[Paul S]

Do you know any guides or metering and reading Histograms?

I don't have anything specific to recommend. Really, I find the Canon meters to be pretty good. But the key is the histogram. I have my camera set to display the histogram along with the image immediately after every shot. I know that means the picture is tiny (Canon has a real problem here--I don't now why they haven't made a better combined histogram/image display yet), but it's important. Every image will have a different histogram shape, but the key points are:

1. If the histogram touches the right hand side, then there are pixels which are blown (the blinking highlights feature makes this even more obvious).
2. If the histogram touches the left hand side, then there are pixels which are essentially black.

If you have both, you're going to have to choose which is worse! Or deal with other it in other ways (NDG filters, multiple exposures for blending or HDR, flash, etc.).

If the histogram touches neither side, then you can get a good expsoure in post processing, whether or not it's perfect in camera. (You do shoot RAW, I hope!) However, if you use your RAW converter to increase the effective exposure, you will increase noise. So the "standard" recommendation is to shoot with the histogram as far to the right as possible without actually hitting the right side. If, in post processing, you then choose to decrease the effective exposure, you'll actually be decreasing noise.

This, of course, assumes you're willing to do some post-processing. ;) Otherwise, shoot as the meter says, look at the image, and decide if you want to increase or decrease exposure, and then shoot again (if necessary). But be aware that the LCDs on the camera aren't always a good way of judging exposure--and their apparent brightness can depend greatly on the ambient light.

-Paul

[Roger]

I don't have anything specific to recommend. Really, I find the Canon meters to be pretty good. But the key is the histogram. I have my camera set to display the histogram along with the image immediately after every shot. I know that means the picture is tiny (Canon has a real problem here--I don't now why they haven't made a better combined histogram/image display yet), but it's important. Every image will have a different histogram shape, but the key points are:

1. If the histogram touches the right hand side, then there are pixels which are blown (the blinking highlights feature makes this even more obvious).
2. If the histogram touches the left hand side, then there are pixels which are essentially black.

If you have both, you're going to have to choose which is worse! Or deal with other it in other ways (NDG filters, multiple exposures for blending or HDR, flash, etc.).

If the histogram touches neither side, then you can get a good expsoure in post processing, whether or not it's perfect in camera. (You do shoot RAW, I hope!) However, if you use your RAW converter to increase the effective exposure, you will increase noise. So the "standard" recommendation is to shoot with the histogram as far to the right as possible without actually hitting the right side. If, in post processing, you then choose to decrease the effective exposure, you'll actually be decreasing noise.

This, of course, assumes you're willing to do some post-processing. ;) Otherwise, shoot as the meter says, look at the image, and decide if you want to increase or decrease exposure, and then shoot again (if necessary). But be aware that the LCDs on the camera aren't always a good way of judging exposure--and their apparent brightness can depend greatly on the ambient light.

-Paul

So in Manual, meter using the light, then use Bracketing and take a picture + 1 0 - 1 exposure? at least until I can learn a little more...

:)

[Paul S]

So in Manual, meter using the light, then use Bracketing and take a picture + 1 0 - 1 exposure? at least until I can learn a little more...

Well, if the scene doesn't have any weirdness (like sunsets which include the sun, bright lights, silhouettes, etc.), that'll do the trick. Disk space is cheap!

But learn to use the histogram--it's your most valuable tool in digital.

Try this article: http://www.naturescapes.net/092004/gd0904.htm

-Paul

[Roger]

Well, if the scene doesn't have any weirdness (like sunsets which include the sun, bright lights, silhouettes, etc.), that'll do the trick. Disk space is cheap!

But learn to use the histogram--it's your most valuable tool in digital.

Try this article: http://www.naturescapes.net/092004/gd0904.htm

-Paul

Thanks, I will check out that page.

[Jeff JTPhoto]

Have to agree with the others Roger... Its all about DOF. You also need a fast enough shutter speed to stop any movement...

[Roger]

Understood, I have to clean my lens then I can try some more.

[E.B. West]

Personally I have never understood the DOF button. I have tried it and I haven't noticed a very big difference visually. You really just have to practice and try different apertures until you can visualize what DOF each will give you at different distances.

If I understand what you don't understand:nah: , the DOF button just closes the lens down to the aperture that you have set so that you can see, through the view finder, what the sensor will see. If you're not seeing too much difference, then there is little or no difference between wide open and what you have it set at.