Focal point

[Raincheck]

Hi,Maybe a stupid question but where is the focal point when zoomed in all the way with a canon 100-400mm.I believe it's at the front of the lens but not sure.Thanks in advance,Rain

 

[Sonoma]

If you are referring to the point that determines the minimum focus distance, that is the front of the sensor in the camera. There should be a small mark on the top of the camera body about 1/2 an inch from the back. That point is always in the same spot no matter what lens you have on your camera, but the minimum focus distance does very greatly by lens.

Hope that is what you were looking for.

 

[KmH]

Is 'zoomed in all the way' 100 mm or 400 mm?

Do you mean the focus mechanism inside the lens?

According to the specifications the closest focal distance is 5.9 feet, and that would be at 100 mm. Anything closer than 5.9 feet cannot be sharply focused.

 

[clanthar]

Do you mean nodal point?

 

[Raincheck]

Sorry I wasn’t clear enough, yes I mean the nodal point cos I am planning to do a panorama but I haven’t used the 100-400mm for that yet... I am going out for a shoot on Friday evening after work and I have only a small window of opportunity concerning the light. In Dublin, Ireland you have these beautiful dark cobalt blue sky's with amazing reflections in the water but only for 15 to 20 min so I have to get it right. Below the panorama shoot subject an x amount of portraits shots from another bridge downstream (a pedestrian bridge about 400 mtr away) to get a full view. Tips advice is more than welcome….

the subject

Is the nodal point at the front of the lens when I zoom into the bridge with the canon 100-400mm?

location

Thanks,
Rain

 

[Raincheck]

Example of a pano I did first try:
Stormont Castle is a baronial mansion on the Stormont Estate in east Belfast which is used as the main meeting place of the Northern Ireland Executive.
Panorama handshot 11 portrait pictures - full size 580mb 16000x4000 300 dpi

 

[Raincheck]

Hope someone can guide me here before 17.00 local time

Btw I am just replying to my post to keep it alive

 

[ann]

go here,

Panoramic Tripod Heads, Photography Poles and Levelers for Professional & Amateur Photographers

they have a tutorial on finding nodal points.

 

[Raincheck]

Thanx Ann had a look and could find some usefull info. But the calculations are stopping @ 200mm but I am getting closer

 

[rpm]

those look amazing....and holy cow on the size of that thing (file and resolution)...

 

[Raincheck]

RPM,

I am hoping for that one shot (in this case a pano) to print off as big as possible, that's why I keep the file sizes original.
The downside is it takes a while to process even on my iMac 16GB ram... but hey maybe one day I can hang one on my wall!

Rain

 

[rpm]

either one would be wall worthy really...wish you luck on your attempt...post results...

 

[Ron Evers]

Here is the answer you desire, I just Googled it.

 

[Helen B]

You actually want to find the location of the 'entrance pupil', not the front nodal point (the web is responsible for spreading this error!). Most methods of finding the 'nodal point' really find the entrance pupil. The entrance pupil is easy to find - just look into the lens from the front and estimate where the iris appears to be (not the physical location, but the apparent location). Put your finger on the lens barrel where you think the entrance pupil is, then move your eye side-to-side a little. That will tell you if your finger and the entrance pupil are in the same plane. Adjust your finger position as necessary. That is close enough for most purposes, and takes less than a minute.

The entrance pupil is the image of the iris when seen from the front of the lens. It is, and always has been, the correct rotation point for stitched panoramas.

Best,
Helen

 

[tirediron]

You actually want to find the location of the 'entrance pupil', not the front nodal point (the web is responsible for spreading this error!) ...... The entrance pupil is the image of the iris when seen from the front of the lens. It is, and always has been, the correct rotation point for stitched panoramas.

Not meaning to hijack the thread, but could you expand on this Helen? Specifically the difference between the front entrance pupil and the nodal and their functions? I've always been under the impression that it was the nodal point that should serve as the rotation point.