May 28
Focusing technique with wide aperture lenses is important to getting accurate focus.
1. Keep in mind that the square in the middle of your VF is representative of the spot metering point, not the center AF point. The two semi-circles around the spot metering square actually represent the criss-cross center AF point. If you want proof, find a black object in front of a white background and then use center AF to focus, but keep the object out of the semi-circles. AF won’t work. Now move an edge of the object within the semi-circles and you’ll notice AF will work, even if the center square is not “touching” the object. So, even you have the center square dead center on the lemon, the AF can still choose any point within the semi-circles.
So, what do you do? Use the AF point just the right or left of center, the one that is a simple line. Have the line overlap the background and the edge of the lemon and you will get sharp focus since it measures contrast on a straight line only, it has no area to cover like the center AF point.
Happy shooting!
Posted by Munims @ dpreview
Jan 20
This is a great tip. Taken from Canon forum.
Think of the aperture as a circle (or hole) that lets light in to control Depth of field, or DOF, which is basically how much of your view is in focus. F/1.8, for example, means that the circle is pretty large (shallow DOF), which would let a lot of light in, but would only leave objects in the same plane of your subject in sharp focus. Shallow DOF is how people get that sharp subject with a blurred background (a.k.a. bokeh). OTOH, F/11 means that the circle/aperture is smaller, reducing the amount of light getting in, but increasing the DOF. In other words, the more of your view will be in focus. When someone tells you to stop a lens down, they are telling you to decrease the aperture/circle (increase f-stop number) . Full F stops from 1.0 are f/1.0, f/1.4, f/2.0, f/2.8, f/4.0, f/5.6, f/8, f/11 . . . and i don’t know where it goes from there.
So anyway, as an example, if someone tells you to stop down a lens by . . let’s say 2 stops . . . they mean for you to go from f/2.0 to f/4.0 (or f/2.8 to f/5.6 or f/4.0 to f/8.0). it gives you a sharper picture.
Posted by markubig
Jan 19
Q: What is the difference between “full frame” and “crop sensor” (APS-C) lenses?
A: Full frame lenses draw an image large enough to cover a full frame of 135 film (i.e. the common 35mm film most familiar to most consumers). Crop sensors only cover the APS-C frame, i.e. the sensor size in 1.5× crop factor DSLRs. Both Minolta DSLRs and all current Sony DSLRs other than the A900 have the smaller (“crop”) sensor.
In practice, owners of crop sensor cameras (i.e. any Sony DSLR other than the A900) can choose either type lens. There is no disadvantage to using a full frame lens on a crop sensor camera (if the desired type of lens is available as full frame, that is). However, some lenses that cover only the smaller sensor area can be smaller, lighter, and/or cheaper than their full frame equivalents. Wide-angle crop-sensor lenses are also more readily available at very short focal lengths (which are required for ultra-wide fields of view on crop sensor cameras). Full frame lenses may sometimes have better image quality, but one should read tests and reviews of individual lenses to ascertain their suitability in that regard. Continue reading »
Jan 16
If you are not familiar with HDR (High Dynamic Range) Photography, you may want check it out.
Visit : HDR Explained
Visit Terry Ratcliff’s tutorial @ www.stuckincustom.com for a comprehensive guide. He is one of the HDR photgrapher/artist around. One of my favorite.
Click on More for a basic HDR Tutorial
Continue reading »
