Question about DOF preview on Nikons

[epp_b]

So, as I understand it, there are two DOF preview systems for Nikon SLRs.

There's the old mechanical system, which was simply a lever that stopped down the lens by adjusting the aperture prong, which had a mechanical linkage to the aperture ring. This system does not work well with G lenses because older film bodies do not "know" how to set the aperture from the camera controls and the mechanical stopping point doesn't exist because G lenses have no aperture ring. As a result, use the DOF preview simply stops down the aperture to it's smallest setting, even if the camera body is saying that it will use a wider aperture when it takes the shot (the n8008, for example, can use G lenses in P and S modes, where the aperture value for an exposure is calculated by the camera, not user controls). OK, that's acceptable: there's no electronic linkage between the mechanical DOF preview button and the cameras metering system because it wasn't necessary at the time the body was made as G lenses didn't yet exist.

The modern DOF preview system is an electronic button that tells that camera to stop down the aperture by reading the aperture setting electronically. This works on G lenses because the camera body "knows" how to set the aperture from the controls.

Now, I was reading KR's review of the N75, in which he states that "The depth-of-field preview doesn't work with manual lenses.".

If the mechanical DOF preview system simply adjusts the aperture prong to stop down until the mechanical hard stop set by the aperture ring, I don't see why the electronic system can't do the same.

eg.:

if (isCpuLens) {
readApertureValue();
stopDownToApertureValue();
}

else {
stopDownAsFarAsItCanGo();
}

Forgive my nerdiness

Is this a limitation only on this particular camera body or do current Nikon DSLRs have the same limitation?

EDIT: just found this on Nikon's site for the D700...

Depth-of-field Preview: when CPU lens is attached, lens aperture can be stopped down to value

(emphasis mine)

So, it seems that it is more "planned obsolescence" from Nikon. Too bad, there are tons of fantastic old used Nikkor lenses all over the place for cheap.

 

[JerryPH]

How important is the DOF preview? How often do people REALLY use it? Instead of seeing a darkened area that represents the blurred areas of the pic, I just take a picture and look on the back LCD and *see* the result as it really is.

Actually, I've reassigned the DOF preview button to other more valuable functions for my needs.

 

[Mike_E]

I used to and would again if it were a better system.

For me the LCD is difficult to get a real feel for the impact of a shot because it's so small. Don't get me wrong, it's great for technical information it's just that the view screen is already set up to fill your vision comfortably so why limit yourself needlessly.

 

[JerryPH]

He mentioned the D700... it has a huge 3" 920,000+ pixel screen. It is *more* than adequate to judge DOF. If you need a touch of magnification, that is possible and just zoom around the picture, though it really is not needed.

I'd not base WP or colour info on the LCD, but DOF, composition and to *some* extent, exposure (along with the histograms)... but nothing more. It does the job.

 

[epp_b]

How important is the DOF preview? How often do people REALLY use it? Instead of seeing a darkened area that represents the blurred areas of the pic, I just take a picture and look on the back LCD and *see* the result as it really is.

I'll concede that, on a digital camera, it's a convenience. And, yes, on my D40, which doesn't have DOF preview, I can take a shot, look at the LCD, then adjust and retake if necessary. But, why waste your time and finite number of shutter actuations on throw-away shots? I prefer to get the shot right first time anyway.

On a film camera, I'd consider DOF preview a absolute necessity because you can't do the same sort of immediate experimentation as you can on digital.

For me the LCD is difficult to get a real feel for the impact of a shot because it's so small. Don't get me wrong, it's great for technical information it's just that the view screen is already set up to fill your vision comfortably so why limit yourself needlessly.

Agreed, I was about to make that point as well.

 

[Pure]

Not sure, but I know the D90 has the DOF function

 

[jlykins]

How important is the DOF preview? How often do people REALLY use it? Instead of seeing a darkened area that represents the blurred areas of the pic, I just take a picture and look on the back LCD and *see* the result as it really is.

Actually, I've reassigned the DOF preview button to other more valuable functions for my needs.

Agreed, I reassigned my button too. The lcd on my D300 is plenty big to judge the DOF.