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cameramonkey

Digital Rebel. extremely shallow depth of field?

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Ok, I have noticed this on mine, not sure if anyone else has seen this. I dont use this body for freefall, but I know alot of you do and might have some answers.

I notice that the depth of field is extremely shallow on mine. At first, I thought there was a malfunction. it seemed like all my photos were out of focus. then after looking at the pictures carefully, I could always find one spot that WAS in focus. but everything else wasnt. and I mean its REALLY shallow. from 10 feet, somebody sitting on the couch would have thier knees in focus, but the face isnt. we are talking a depth of field in the order of 6 inches in that scenario.

It could all be my lens. I am shooting using the original EF 28-75 lens that came with my Rebel 2000. I just havent had the cash to pony up for a new lens to test this theory.


So anyone else notice this, or is it just me?
Two wrongs don't make a right, however three lefts DO!

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What exposure is it set to?If on auto and a fast shutter speed is selected,then a low f-stop will be used to let in more light if needed.A low f-stop means a small depth of field and the opposite with a high f-stop number
God gave men 2 brains,but only enough blood to fill one at a time....I can live with that.

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I am just using the full auto setting.

I am aware of the impact of the aperture on the depth of field. Based on the amount of light needed for proper exposure for the CCD, it seems like the lens just isnt "fast" enough to handle what the body needs. just flying by the seat of my pants, if feels like the digital version requires alot more light than the film body. That particular lens was barely fast enough before, and now it seems worse.
Two wrongs don't make a right, however three lefts DO!

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the digital version requires alot more light than the film body.



There is the 1.6 conversion factor when dealing with Canon digital. The focal length of the lens will be increased by 1.6x due to the sensor being snaller then a 35mm frame.

Maybe this is having an effect on the performance somehow? Aren't there some newer EOS lenses that will only work on the digital bodies? Is you lens to crappy for the digital to work properly?

Just some guesses. Also, check the info on your oics to see what settings the camera is selecting. Oh yeah, what about the focusing? Are you on auto focus, and if so, does the camera have selectable focus zones, and what zone is it set for?

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I haven't noticed a difference in the amount of light required to properly expose an image between my Digital Rebel and Rebel 2000.

Are you sure you've got your ISO "film speed" set properly? If you've got that set eronously low, the effect would be that your aperature would be wider than required, which shortens your depth of field. While shooting indoors or in low light, you may want to use ISO 200 or higher.

_Am
__

You put the fun in "funnel" - craichead.

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What's the speed of the lens?

Also, what's the aperature and shutterspeed of the images you don't like? Filmspeed, shutterspeed, and aperature are all stored in the files themselves, and you can view these settings through Photoshop, Picasa, or in Windows by right clicking on the image, selecting "Properties", then the "Summar" tab, and hit the 'Advanced" button.

_Am
__

You put the fun in "funnel" - craichead.

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Depth of field is a function of subject distance, focal length, aperture, and media size (1.6x CMOS or CCD, 35mm film, or 6x6 medium format film).

Going to a faster lens (ie: f/2.8 or f/1.8) is not going to help anything. A larger aperture (smaller number on the f/scale) will only make the DOF smaller. For daylight skydiving pictures, you will need to be around f/8 or f/11 to get good depth of field, and this range is covered adequately by the lens you have now. I would imagine you are using the wide end of the lens (28mm), which will help somewhat.

In bright sunlight, at f/8 and 100 ISO, you should be getting a shutter speed around 1/250. Bump the ISO to 200 and you should get around 1/500.

Try setting your camera to Av, set the aperture at f/8, and let it adjust the shutter speed as needed.

Google "depth of field calculator" and "exposure calculator" and play around with those a bit...

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How does media size affect depth of field?

_Am



Just taking the lens and surface area into account, in "theory" it doesn't affect DoF at all.

In reality however, the smaller the imager the greater DoF you will have because of other factors such as pixel density vs. projected image size. This is why standard definition television has a greater depth of field than say 35mm film and is a major contibuting factor in getting the "film look" that many people try to achieve when doing something shot on video.

HD changes this a bit and so does the newer "full size" chips on digital cameras compared to the "conversion factor" chips from jsut a few years ago.

That said, this ISN'T his problem.

My "guess" is that he's trying to take photos in the wrong "auto" mode. If he simply went to aperture priority and selected, for instance, f11, he'd have MUCH more depth of field. Of course, the exposure times would probably also be longer as well.
quade -
The World's Most Boring Skydiver

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I haven't had too much trouble with depth of field.

there are a number of factors that come into play (although, primarily the F-stop, and the focal distance are most important...)

This was taken w/f/8.0, shutter 1/13 (thus the movement), and ISO of 1600 (so it might be a bit grainy.

I also shot it in the Rebel XT's A-DEP mode that adjusts the Depth of field to help ensure the entire group is in focus.

As you can see both my aunt and my cousin are in focus even though they are seperated by 8 ft or so... unfortunately, and fortunately, a digital SLR is not entirely a fire and forget type camera... it does require some expertise to use...

Scott
Livin' on the Edge... sleeping with my rigger's wife...

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Ok, I have noticed this on mine, not sure if anyone else has seen this. I dont use this body for freefall, but I know alot of you do and might have some answers.

I notice that the depth of field is extremely shallow on mine. At first, I thought there was a malfunction. it seemed like all my photos were out of focus. then after looking at the pictures carefully, I could always find one spot that WAS in focus. but everything else wasnt. and I mean its REALLY shallow. from 10 feet, somebody sitting on the couch would have thier knees in focus, but the face isnt. we are talking a depth of field in the order of 6 inches in that scenario.

It could all be my lens. I am shooting using the original EF 28-75 lens that came with my Rebel 2000. I just havent had the cash to pony up for a new lens to test this theory.


So anyone else notice this, or is it just me?



Hmm - I think it's in the setting that you use -

here is one that shows a "little" depth . . .
I'm not usually into the whole 3-way thing, but you got me a little excited with that. - Skymama
BTR #1 / OTB^5 Official #2 / Hellfish #408 / VSCR #108/Tortuga/Orfun

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As you can see both my aunt and my cousin are in focus even though they are seperated by 8 ft or so... unfortunately, and fortunately, a digital SLR is not entirely a fire and forget type camera... it does require some expertise to use...



Thank you for your explination but we need more information. Please post more shots of your cousin... :)

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Aren't there some newer EOS lenses that will only work on the digital bodies? Is you lens to crappy for the digital to work properly?



There are EOS mountable lens on the market that are designed specifically for the smaller APS sized image window. But basically they are just designed that way to reduce the size of the lense. i.e. the Sigma 30mm f/1.4 is much smaller because it doesn't need to have as large a final field of view. It still performs at the equalivant of a 50mm because of the difference in the sensor sizes.

I have a good example of a closer up picture of my dog that has a smaller depth of field and subsiquently some of the near field is out of focus.

I'll post it when I get home.

Scott
Livin' on the Edge... sleeping with my rigger's wife...

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Here is the picture I promised... notice that the depth of field is much smaller but the points of focus (i've marked them in the picture) are close to the camera and the depth of field is much less...
Livin' on the Edge... sleeping with my rigger's wife...

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Use a smaller aperture (bigger number) if you want more DOF. That picture looks exactly lilke I would expect it to at f/3.5. Also, there is no contrast for the focus point on the nose to grab on to, so that one is really not being used by the camera. The ear is determining the actual plane of focus.

----------------------------------
www.jumpelvis.com

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I wasn't trying to imply that the DOF should be more then it is... I was trying to provide an example where there was a shallow depth of field.

In fact I wouldn't want the background to be in focus because I would generally Crop the image such that most of it wouldn't be there and it only detracts from the portriat of Karma.

Scott

edited to add: that FWIW I just tested the Passive AF and the the camera appears to be able to get enough contrast from Karma's Face to be able to focus also from examining closeups of the image It appears to me that the Focal point is somewhere between her nose and her ear.

I also only marked the center of the box...
Livin' on the Edge... sleeping with my rigger's wife...

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I am just using the full auto setting.



problem located....

find a way to get a smaller aperature (as everyone else has said)

aperature priority, higher iso (allows smaller ap, due to increased light sensitivity) more light.etc..

maybe do a bit of research on how and why camera components interact, and the results to be expected....

there are way to many posts like this...:|


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Yes, if it's the same sound as what is on my camera it appears to be the little metal brackets on the flash.

on my camera at least it doesn't make any noise with the flash up.

See attached photo.
Livin' on the Edge... sleeping with my rigger's wife...

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