Originally posted by Capslock118 I did notice how difficult it was to keep even a tiny area of the photo focused.
Welcome to the macro world.
Quote: Question: what is 'Catch-in focus' aka 'trap focus'?
Most of our modern Pentax dSLRs have a Custom Menu option to Enable Catch-In Focus. When the AF switch is at AF-S and the right lens (see below) is used, you point at something and hold the shutter down. When you bring the subject into focus, or the subject moves into focus, the shutter snaps. You've caught or trapped the subject in focus; the poor-person's autofocus.
A good use: set drive mode to Continuous, set camera on tripod, insert wired remote with latch, aim and focus somewhere you expect something to happen, and latch the remote. Whenever something comes into focus there, the trigger fires. This is commonly used when shooting wildlife, birds, burglars, nudists, etc.
There's an advantage over plain manual focus: Often, we aim at something, slowly bring it into focus, get the green-hex confirmation, then shoot. There's a brief interval in which we or the subject may have moved. Blur. Oops. Trap-focus / CIF responds much quicker.
And there's a disadvantage: at small apertures, CIF might not kick in. It needs enough light and contrast to trigger the green-hex confirmation. Another problem: if we don't focus slowly enough, we might swing past the optimal focus point. Blur. Oops. But within its limitations, it's great.
What's the right lens? A manual lens with a shiny mount that (safely) shorts-out the lens mount contacts. A black mount might need paint scraped away, or metal tape added -- thin metal adhesive tape used for furnace repair, sold at most hardware stores. The alternative is a bit of tinfoil, but that blows away easily. Some M42 and M39 lenses have very narrow bases that won't hold metal tape in place, so tinfoil might be needed. Also, AF lenses CAN be used, with tinfoil to short those contacts.
Another alternative for M42: a cheap safe flanged no-infinity-focus M42-PK adapter, which also shorts out those contacts. I use this for close-up and portrait shooting where I don't WANT infinity focus.
Quote: Most of my lenses are completely manual outside of one zoom lens which has the A setting but focus is still manual.
Then with a bit of metal tape, and setting the menu option and AF-S switch, you're all set for trap-focus.
Quote: also: not sure what that black spot is on the top left of each photo is. I seen them in many, but not all, of the pictures i have taken thus far. I originally thought it was dust on one of the lenses but for the photos linked I used a 50mm lens I have not used yet; i guess it must be dust on the ccd?
Look in your manual for Sensor Cleaning, and follow the procedure for Dust Alert.
Last edited by RioRico; 04-14-2010 at 06:50 PM.