Nodal points for DA* 50-135mm

Yesterday I measured Nodal points for 50-135mm. During this test camera was on RRS focusing rail, so the original measurements would not make sense to others. Here are measurements from the tripod mount-socket of body(K10D).

@50mm -> 8.5cm

100mm -> 0.5cm (As you can see this is almost coincides with tripod mount-socket, which means one does not needs focusing rail at all.)

@135 -> -5.0cm (This was a revelation to me, I did not know that the Nodal point could be behind the camera. I could not find NP in front of the camera and then a google search told that telephoto lenses would have their NP behind the camera body. )

--
best~of~luck
Ramesh

http://www.asnowfall.com

Ramesh Kumar said:

@135 -> -5.0cm (This was a revelation to me, I did not know that the
Nodal point could be behind the camera. I could not find NP in front
of the camera and then a google search told that telephoto lenses
would have their NP behind the camera body. )

Click to expand...

That's why using movements with true telephoto lenses (as opposed to long focal lengths of conventional design) on large format cameras is such a headache inspiring endeavor...
--
Chris May
Denver, CO
http://www.pbase.com/copcarss

CopCarSS said:

That's why using movements with true telephoto lenses (as opposed to long > focal lengths of conventional design) on large format cameras is such a headache > inspiring endeavor...

Click to expand...

I do not know the difference b/w 'telephoto lenses' and 'long > focal lengths of conventional design'. Please post a link so that I can get educated

For FA 100mm macro, NP is way in front of the body, to be precise it is around 8.5cm, but for 50-135mm, at 100mm, NP is right on the body.

I will be getting Sigma 180mm macro and curious where it's NP is going to land.

--
best~of~luck
Ramesh
http://www.asnowfall.com

Ramesh Kumar said:

I do not know the difference b/w 'telephoto lenses' and 'long > focal
lengths of conventional design'. Please post a link so that I can get
educated

Click to expand...

In smaller formats "telephoto" tends to mean lenses longer than the standard focal length (so like 50mm for 35mm full frame). In large format, lenses of longer focal length are just lenses of longer focal length.

So in 4x5, 150mm is kind of the standard focal length. You'll need 150mm of bellows draw to focus at infinity (more bellows draw to focus closer). A standard design 300mm is just like the 150mm, but it needs 300mm of bellows to focus at infinity.

Some 4x5 cameras (especially field cameras) don't have the bellows for anything much longer than 300mm. One solution is the use of telephoto lenses. They don't require as much in the way of bellows as a standard design.

However, using telephotos can be frustrating because their nodal points aren't on the same plane as the front standard. So, if you're trying to use tilt to change the plane of focus, it won't work the same as with a standard lens design.

Sorry, I'm not the best at explaining it. You can head over to http://www.largeformatphotography.info , and you should be able to find a better explanation of it all.

--
Chris May
Denver, CO
http://www.pbase.com/copcarss