Step down metering

[Riotbmx]

Got a question. With my Nikon, it has the AI feature on. Apparently it tells your camera the apperture you're on and adjust the meter reading to the f stop. However, if I depress the DOF preview lever, the light meter reading drops. So... Which is the correct reading?


*sorry typo. It should be Stop down metering.

 

[azzurri]

assuming that your lens is ai and newer (or ai'd), the reading without stopping down is the correct one

 

[Riotbmx]

So if I use a Non AI lens and do Stop down metering, the reading I get will be wrong? I'm really confused cos when you stop down, the aperture closes to the point when the photo will be taken.

 

[azzurri]

if it's a non-ai lens, you hold the dof button and meter. for non-ai lenses, you'll need to stop down unless the camera you're using is designed for non-ai lenses (like the older nikkormats, nikon f and some f2)

 

[Riotbmx]

if it's a non-ai lens, you hold the dof button and meter. for non-ai lenses, you'll need to stop down unless the camera you're using is designed for non-ai lenses (like the older nikkormats, nikon f and some f2)

Sorry I think I'm making you confuse.

Ok let's put it this way, if I set both Ai and Non-Ai lens to f16 using a body with the Ai ring. I depress the DOF preview button and both lenses give me the same reading. But when I release the DOF preview button in theory the meter should remains or move only a little, but it goes up.

 

[Kipling88]

I think u r the one confused. The lens can only be of AI or non AI. Stop down metering used for only non AI lenses, hold down dof preview button as u shoot. AI lenses dun need to, holding down dof preview button wont change metering reading.

 

[Riotbmx]

I think u r the one confused. The lens can only be of AI or non AI. Stop down metering used for only non AI lenses, hold down dof preview button as u shoot. AI lenses dun need to, holding down dof preview button wont change metering reading.

Which was what I mentioned, using an Ai lens AND a Non Ai lens. And you don't have to hold down the lever as you shoot. Just hold the lever, adjust the shuter speed, release the DOF preview lever and shoot. There's this lever in the body that pushes the "pin" on the lens that makes the lenses Ai or Non Ai wide open regardless which f stop you're on when mounted on the body, when the you release the shutter that lever pushes the pin and closes the aperture to the selected f stop. And that's what happenes when you depress the DOF preview lever. So regardless if the lens is Ai or Non Ai, the aperture closes to the selected f stop when you depress the DOF preview lever. No confusion here.

So..... Anyone here have looked into this before and found the answer?

 

[PhotoTime]

Hi,

I think you are the one confused. Your camera is able to communicate with the AI Lens through the AI Lever on both the lens and camera. Therefore, it is able to deduce the shutter speed based on the aperture setting on the lens.

When you "closed" down your aperture using the DOF preview lever, the AI lever on the camera is not released. Therefore, the camera will think there is lesser light entering the camera, and hence it will indicate under expose.

With a non-AI lens, there is no AI Lever on the lens. Hence, it is not able to communicate with the camera. Whatever aperture you set on the lens is not communicate with the camera. Therefore, you will need to use the DOF preview lever to do the metering.

Hence, when using your AI Lens, you need not have to "close" down your aperture to do the metering.

Hope this answer your question and explain everything.

 

[Riotbmx]

Hi,

I think you are the one confused. Your camera is able to communicate with the AI Lens through the AI Lever on both the lens and camera. Therefore, it is able to deduce the shutter speed based on the aperture setting on the lens.

When you "closed" down your aperture using the DOF preview lever, the AI lever on the camera is not released. Therefore, the camera will think there is lesser light entering the camera, and hence it will indicate under expose.

With a non-AI lens, there is no AI Lever on the lens. Hence, it is not able to communicate with the camera. Whatever aperture you set on the lens is not communicate with the camera. Therefore, you will need to use the DOF preview lever to do the metering.

Hence, when using your AI Lens, you need not have to "close" down your aperture to do the metering.

Hope this answer your question and explain everything.

Hi! Thanks so much for pin pointing the reason, I found the answer to my question. So it's actually the AI couple that doubles the "light reduction". I did a test by unhooking the Ai coupling and compare it. it's great to finally get this off my head. Thanks again

 

[PhotoTime]

You are welcome.

I noticed this phenomenon long ago, but never thought of the reason; maybe all along, I am using AI Lens, so not much issues to think of. Only when I am trying to answer your query then I think of the reason.

Thanks for your prompting.