TS-E 24mm Metering

[kim yee]

<p>I have just acquired a TS-E 24mm, and I am trying out the shifting ability of the lens with a EOS 5D.<br>

I am wondering how do one get a correct light meterin using this lens?<br>

My current working order is to get a reading first using manual mode. Then once I get the reading (for Aperture about f11), I do the shift.<br>

The image come out underexpose by almost 2 stop.<br>

Please help with a correct working process for this newbie. thank you.</p>

[jeff_conrad]

<p>From what you've described, your technique seems fine—you need to meter before applying tilt or shift, which you've done. What metering pattern are you using?</p>

<p>If you have another lens (the closer to 24 mm, the better), you could take a reading of a typical outdoor scene using the TS-E 24 and another with the other lens; If you get the same readings, especially if both are close to the “sunny 16” rule, the lens is probably working properly.</p>

[gerrymorgan]

<p>I find the best way to work with TS-E lenses is iteratively, both in terms of focus and exposure. I first set the focus and exposure, then apply tilt or shift, then adjust the focus and exposure again, and often repeat both steps once or twice more. With experience, it's often possible to get the exposure compensation approximately right first time, but I don't find it to be entirely predictable. The 24mm TS-E can even require more than two stops of exposure compensation.</p>

<p>Fortunately, it's much easier than it used to be with film cameras where the only solution was bracketing (with no immediately histogram feedback)</p>

[robin_sibson1]

<p>I've been using the TS-E 24 for many years, originally with film (1V), now on both FF (5DII) and 1.6-factor (50D). If you were using a film camera, then using manual mode with the movements centred to set aperture and speed, then applying the movements and shooting with those settings, would work just fine, although you need to remember that if you are using evaluative metering then the meter reading needs to be taken with the scene framed roughly as it will be with movement(s) applied. Trying to meter with movements applied is hopeless, don't even think about it. On a digital body it's a bit more complicated because with shift applied (the effect of tilt is less significant in this respect) the light from the lens is hitting the photosites from an unexpected direction, and (depending on amount of shift and aperture setting, and on the particular sensor in the camera) this may result in some underexposure, for which you may wish to compensate in the light of experience/experiment. If you are not pushing the limits of dynamic range or noise problems, you can often compensate during post-processing as an alternative. Using TS lenses effectively is a much more deliberate and thoughtful business than using conventional lenses, and you just have to accept that as the price to pay for some of the very special results that can be achieved.</p>

[sknowles]

<p>Jeff is right, with any tilt-shift lens, you meter before any lens movement or with a separate meter, and make adjustments for the change of scene as appropriate or bracket. That's been my experience with two of these non-Canon lenses.</p>

[jeff_conrad]

<p>Like Robin, I've hardly ever found the need for exposure compensation using the TS-E 24. Full disclosure: I usually use spot metering, and with the 24 I usually use an external meter to get a small enough spot size to measure what I want. But I meter as I would for any other lens, so again, I don't think it's an issue with the lens. As Robin also mentioned, it's important to meter essentially the same image framing that you will use in the picture, and I'd say this is true with any metering pattern. The only way to do this is to meter with the camera pointed up to approximate the image framing you get with the shift applied.</p>

<p>You will get noticeable vignetting at the corners, just as you would with any ultra-wide-angle lens. At full shift in the long direction, corners are as far from the lens axis as with a 17 mm lens, leading to a 2.9 EV light loss from cos⁴ alone. With the original TS-E 24, you're also at the edge of the image circle, so there may be some additional losses from mechanical vignetting. This should be less of a problem at f/11 that it would be with the lens wide open.</p>

<p>From what you described, it's tough to tell whether what I've just discussed applies. Again, I'd try metering the same scene with another lens and see how that compares with the TS-E 24 just to ensure that there isn't some problem with the information transmitted from the lens to your 5D.</p>

<p>To repeat: though use of full shift, especially in the long direction, results in noticeable darkening in the corners, I've not found that shift per se requires any exposure compensation.</p>

[JDMvW]

<p>I have the old PC-Nikkor 35mm which I have used back to 1971. I know about the common injunction to meter before shifting, but I've just not found it necessary in practice. I've just metered through the lens as I am using it, and color slides have come out fine. It might be that 24mm focal length would make a difference, but certainly the 11mm or less shift on the PC-Nikkor didn't seem to make the metering while shifted off enough to not work. This was originally on a Nikkormat FTn and later on a Nikkormat EL and more recently on a Canon 5D.</p>

[kim yee]

<p>Well, I have tried out again. I found my problem. Apparently if I shift down. The the centre of the iamge is now on the edge of the lens image circle, that's why it is darker, and I need to compensate about 1.5 stop. <br>

Thanks for the info guys.</p>

[jeff_conrad]

<blockquote>

<p>The centre of the iamge is now on the edge of the lens image circle</p>

</blockquote>

<p>I don't think that's the problem—the diameter of the image circle is given as 58.6 mm; its radius is 29.3 mm. The maximum shift is 11 mm, so the center of the image isn't even close to the edge of the circle.</p>