Focusing Issues with Nikkor T-ED 360/500/720 lens?

[Pere Casals]

The amount of motion of the circle of coverage is not the same as the motion of the focused image on the groundglass.

This is true, I understand what you point... but IMHO this is not the nasty effect the OP should consider.

Ok, the displaced nodal point (in Tele glass) provocates a parallax shift when tilting, in the shown situation (see drawing) we should lower the tripod head some 50mm to compensate it, wich is irrelevant por distant subjects but it may require a correction for close subjects.

This is somethig that's better compensated with the tripod than by the camera movements, if we want exactly same optic axis than with the non Tele lens.


The nasty effect is another thing: the wild circle displacement and a the change in the focus, both are lower with the tele lens, so a Tele is more suitable, in this regard. While the parallax shift (that can be corrected anyway) is mostly irrelevant in landscape.


Not about Macro... We are talking of a field camera with a Nikon T system with long focals and with a moderate circle, so the Tele can tilt more in the front before exhausting the available rear rise and front drop necessary to keep the coverage circle on our sheet.


With long focals a Tele allows to tilt more in the front because the circle displaces less.


Well... then we also may consider that a Fujinon C 600mm has a 620mm circle so with it we may displace all what we want !


It was nice you pointed that, now I understant all that a bit better.

[Willie]

Have read that the 720 configuration will cover 8x10. Is this correct? Light loss in the corners - or vignetting? Stopped way down or at mid apertures?

[Corran]

Yes it does. No hard vignetting. I usually shoot at f/22 or f/32...of course that's only 1-2 stops from max aperture!

[Pere Casals]

Have read that the 720 configuration will cover 8x10. Is this correct? Light loss in the corners - or vignetting? Stopped way down or at mid apertures?

It depends, if soft corners in the 8x10" negative are no problem... Of course if corners are in the Out Of Focus then there is no problem. YMMV.

The way you consider the illumination beyond the nominal image circle is a personal choice.

[Corran]

Corners are not soft on 8x10, the lens is perfectly usable. My guess is the 360/500/720 uses basically a 1.4x and 2x TC type of design to get the configurations - hence the loss of light. A 2x enlargement of the image circle would naturally cover 8x10 (and some extra). I've used it and have no qualms with it. I'm not going to argue anymore about it though - one can make their own decisions, obviously.

[LFLarry]

Thank you!!

There are a couple tricks you can try. If you are concerned about the distortion caused by rear movements, you can use back tilt to determine the total amount of tilt needed, then re-zero the rear standard and apply the same amount of tilt to the front standard, then adjust the entire camera to re-center the composition.

Another technique is to apply front tilt, then re-center the composition by applying front rise, assuming your lens has enough usable image circle for this. This is the quickest way to get the shot. The Nikon T 360/500/720 has a moderate amount of image circle for this, I don't know if it has any additional wiggle room beyond its rated circle (the 500 and 720 focal lengths may have additional room based on my experience with the Nikon T 600/800/1200).

Fortunately rear movement distortion is usually minimal with longer focal length lenses like the Nikon T, so rear movements are usually fine.

[MAubrey]

Corners are not soft on 8x10, the lens is perfectly usable. My guess is the 360/500/720 uses basically a 1.4x and 2x TC type of design to get the configurations - hence the loss of light. A 2x enlargement of the image circle would naturally cover 8x10 (and some extra). I've used it and have no qualms with it. I'm not going to argue anymore about it though - one can make their own decisions, obviously.

This is my experience with the Nikkor 600/800. I've used the 800mm f/12 for portraits and telephoto landscapes on 11x14.

[Pere Casals]

This is my experience with the Nikkor 600/800. I've used the 800mm f/12 for portraits and telephoto landscapes on 11x14.

If you are to make ULF contact prints then with only 8 lp/mm on the negative you make a perfect job, lack of contrast can be tolerated/loved or somewhat compensated with an expansive development, so no problem. Instead Christopher Burkett (8x10" slides) uses an APO Tele Xenar 800 for his museum size ilfos, for several good reasons. YMMV.

One can say that the T 720 can be used in 8x10" with limitations and drawbacks, but it cannot be recommended for 8x10".

[MAubrey]

If you are to make ULF contact prints then with only 8 lp/mm on the negative you make a perfect job, lack of contrast can be tolerated/loved or somewhat compensated with an expansive development, so no problem. Instead Christopher Burkett (8x10" slides) uses an APO Tele Xenar 800 for his museum size ilfos, for several good reasons. YMMV.

One can say that the T 720 can be used in 8x10" with limitations and drawbacks, but it cannot be recommended for 8x10".

Indeed. There are all sorts of reasons to do all sorts of things.

[Pere Casals]

Indeed. There are all sorts of reasons to do all sorts of things.

Sure. In a recent exhibition Sally Mann crafted the most impressive prints many have seen on a wall, and many times the taking lens was beyond the nominal coverage limits.