Steve's Digicams Forums

Steve's Digicams Forums (
-   What Camera Should I Buy? (
-   -   how do dSLRs do this.. (

digraph Dec 15, 2006 7:14 AM

I have three general questions...

1. Do AF zoom lenses have an aperture ring, focus ring, and zoom ring? I can't seem to distinguish them in lens diagrams.

2. Is it true that you can't compose your picture on the LCD on the back of a dSLR?

3. If you put an older non motorized lens on a dSLR, and you select the shutter speed, does it tell you what F-stop to choose and dial to for each image you want to capture?

peripatetic Dec 15, 2006 7:38 AM

1. Generally the modern lenses only have a focus ring and a zoom ring. Most do not have an aperture ring, it is controlled electronically.

2. Yes. (With one exception - one of the Olympus cameras has an additional sensor which is used for a preview. But it's not exactly live because it comes from a different sensor to the one used to capture the picture.)

3. I think it depends somewhat on the camera. But in general I think you are then best switching to Aperture priority mode. You need to manually set your aperture (on the lens and also on the camera at the same setting) and the camera will automatically select the correct shutter speed for you, according to the meter.

mtngal Dec 15, 2006 8:06 AM

1. Depends on the lens - I have AF lenses both with and without aperture rings.

2. LCDs only show what you've taken, except for the Olympus. I've always preferred viewfinders anyway.

3. It depends on the lens/camera. I have Pentax and I have two different types of manual focus lenses. My older ones are completely manual - I have to set the aperture on the lens ring, then the camera can meter and set the shutter speed. If I set a specific shutter speed on the camera, it won't tell me what aperture to use (it will take the picture regardless of the exposure). I also have newer lenses that will let the camera set both aperture and shutter speed (in the Pentax world, these lenses have an "A" on the aperture ring). Exposure works the same as any modern lens - you can specify the shutter speed and the camera will set the aperture.

All times are GMT -5. The time now is 6:26 AM.