Troubles with Nikon D70s SLR

[Gooly001]

Here are some of my macros shot with f/2.8. Note the limited Depth of Field and some unsharpness as most were shot hand held. Another thing to notice is that with the shallow depth of field, the background is now pitch black because of the faster shutter speed, there is not enough time for the camera to get full exposure on the background therefore rendering it black.


















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[Gooly001]

Delphinus,

If you have white crushed coral and it is relatively clean, then you can use that as your reference for the White Balance.

If are using Photoshop and needing a reference for "white" you can use the color picker in the Levels Adjustment and select the gravel as your point of reference for white. This will set all the other colors in place as well.
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[Delphinus]

Hehe, the whole problem with sand and gravel is that it IS hard to keep relatively clean A lot of people will have BB too. I was thinking a small white piece of white acrylic might work, but wasn't sure if it might be too reflective or something like that.

[Jason McK]

Originally Posted by R.A.D.

Here are some of my macros shot with f/2.8. Note the limited Depth of Field and some unsharpness as most were shot hand held.

Marco Lenses by nature have very narrow depth of field. it's the physics of the Lens elements. The only way to increase depth of field is to decrease magnification.

Cool shots BTW
J

[Gooly001]

It's not the magnification but rather the ability of the macro lens to focus down to a few inches. Most conventional lenses have a minimum focus distance of 2-4 feet. A true macro lens will allow the user to focus within inches sometimes mm to the object. Although this may seem like an increase in magnification because you are focusing so close it is rather the macro lenses nature to focus down so tight and that is why they cost so much. If I selected a higher aperture on the lens ie f/16-f/22 and had enough lighting, the result would be a much sharper image that is focused front to back. Most photographers use f/2.8 as a setting when shooting close up is because they want their subject to be sharp but the background to be blurred so that it will not distract the viewer.

True magnification is dependent on the size of the lens that you buy. ie 50mm, 100 mm, 200mm etc..

If I had a 60mm macro and wanted to take a macro shot, I might have to be as close as 1 inch away from my subject. However, if I had a 105mm macro I can now shoot the same image but be further back. Both shots I can select f/2.8 and still get the same blurred and sharpness effect. The only difference is that one lens is magnifying almost twice the other and I can stand further back.
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[Gooly001]

Delphinus,

Try using a clean piece of white PVC piping. If you find that your image is darker then it seems, set your exposure compensation to +1 EV (exposure value). If this is still too dark then +2 etc....make sure that you don't blow out the rest of the image. In other words, keep an eye on areas with highlights so that they don't appear too bright and compete with the subject that you are photographing.
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[Jason McK]

Originally Posted by R.A.D.

It's not the magnification but rather the ability of the macro lens to focus down to a few inches. Most conventional lenses have a minimum focus distance of 2-4 feet. A true macro lens will allow the user to focus within inches sometimes mm to the object. Although this may seem like an increase in magnification because you are focusing so close it is rather the macro lenses nature to focus down so tight and that is why they cost so much. If I selected a higher aperture on the lens ie f/16-f/22 and had enough lighting, the result would be a much sharper image that is focused front to back. Most photographers use f/2.8 as a setting when shooting close up is because they want their subject to be sharp but the background to be blurred so that it will not distract the viewer.

True magnification is dependent on the size of the lens that you buy. ie 50mm, 100 mm, 200mm etc..

If I had a 60mm macro and wanted to take a macro shot, I might have to be as close as 1 inch away from my subject. However, if I had a 105mm macro I can now shoot the same image but be further back. Both shots I can select f/2.8 and still get the same blurred and sharpness effect. The only difference is that one lens is magnifying almost twice the other and I can stand further back.

I have to disagree the lens elements in the marco lens completely change the rules of normal lenses. Depth of field is dependent on the positioning of the lens elements and not f-stop. stopping down to f22 from f2.8 will gain you millimetres of depth of field where as minor decreases of magnification will gain you centimetres.

Anyway. This is usually not a problem with Tank photography as you are never mm from you subject.

Depth of Field Information

J

[Gooly001]

Jason,

This was extracted from the web link that you posted:

"Effect of f-number

For a given subject framing, the DOF is controlled by the lens f-number. Increasing the f-number (reducing the aperture diameter) increases the DOF; however, it also reduces the amount of light transmitted, and increases diffraction, placing a practical limit on the extent to which the aperture size may be reduced. Motion pictures make only limited use of this control; to produce a consistent image quality from shot to shot, cinematographers usually choose a single aperture setting for interiors and another for exteriors, and adjust exposure through the use of camera filters or light levels. Aperture settings are adjusted more frequently in still photography, where variations in depth of field are used to produce a variety of special effects."


Here is another link to close up photography, please read halfway down the article re: DOF

http://www.tcinternet.net/users/nmol...hotography.htm

http://www.shutterfreaks.com/Tips/ControllingDOF.html
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[Gooly001]

Here is a link on photog glossery terms:

http://www.floccinaucinihilipilifica...raphy:Glossary

I think that there may be some confusion regarding f-stop verses focal length or maybe focal plane?

Depth of Field
Depth of Field refers to range of distances such that elements are in focus. An image with a narrow depth of field has a very small amount in focus. An image with a large depth of field has a lot in focus.

f-stop
The f-stop is the unit of measure for the aperture. The f-stop is the the size of the aperture expressed as a fraction of the focal length of the lens. This is why some zoom lenses have different minimum f-stops based on the amount zoom. An f-stop of f/16 (f being the focal length), means that a 200mm lens has an aperture openning of 200/16 = 12.5mm. A 18mm lens has an aperture openning of 18/16 = 1.125mm. For a given f-stop any lens, regardless of focal length, transits the same amount of light to the sensor or film.

Focal Length
The focal length is the distance from the front element of a lens to the sensor (or negative). The focal length can be used to describe the effect that the lens has on the produced image. A long focal length (say, 50mm and up) make objects look closer (like a telescope). Short focal lengths (24mm and smaller) capture a wider view, making object smaller. Lenses with short focal lengths are sometimes refered to as wide angle.

As you can see the focal length does have an effect on magnifying the object , however a macro lens will still allow the lens to be positioned closer to the object.

I still stand my ground on that DOF is greatly controlled by the f-stop or aperature setting. Try shooting with your DSLR on Aperature Priority and set it to f/2.8. Focus on a subject 4 ft away from you with some background objects. Take a the shot. Next, set your aperature to f/22 and focus again on the same subject. Take a shot. Compare the 2 shots and I can gaurantee you that your DOF difference will be huge, not just cm but in ft. At f/2.8 your focus will only be for the first few feet. At f/22 the focus should be from the subject to infinity. Therefore DOF is largely controlled on by the f-stop.

Jason, I'm trying to understand your point. Is there another way of explaining what you are talking about?
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[Jason McK]

I think we have gotten way off topic and I feel bad for highjacking Kyle's thread
But we are talking about 2 different situation. A True Marco photo taken so that the image is 1/2 the oringonal size or greater relys far less on f-stop then magnification as discribed by this equation

DOF~2NC[(M+1)/M2]

Sorry hard to write in text it should be M squared

J