Photography Newbie in need of advice.

[Inkanyezi]

I hope that this thread is not spinning off at a tangent.

We have outlined at least two possible or even probable causes for missing sharpness according to the original question. One is that the lenses might have an AR coating issue, the other that the viewfinder screen might be unsuitable.

As these are Nikon lenses, and the camera is full frame, I would like to believe that the lens sharpness should be sufficient, if we can exclude the fogging caused by insufficient anti-reflection coating.

So for the OP, Spartacus, I suggest to follow advice here. Check by using Live View, that the lenses can indeed provide a sharp image, and also check their AR coating, by photographing a dark object on a white background at different F-stops to see whether there is any softening, particularly when stopped down.

If deciding to change the viewfinder screen to one that is better for manual focusing, be sure to have it calibrated. The "slice of yellow" mentioned with <P7> in the instruction at http://www.focusingscreen.com/work/d700en.htm not only needs not be taken out, but should not be removed in the ideal case, because it is a shim that should put the screen in the correct position. If the new focusing screen does not sit in the correct position, it will not give correct focus, but might give back or front focus, and such "slices of yellow" are used to put the screen closer to or farther from the lens. That is the calibration of the focusing screen. Ideally, this shim is correct from the manufacture of the camera and should remain in place.

So please do try the lenses out by focusing in LV and checking contrast with a dark object in the image center, surrounded by white. If the AR coating is OK with your lenses, they should be sharp enough.

[Manfred M]

Urban / John - some interesting material from both of you. I'm not 100% sure about the sensor reflectance issue. The AA array does include anti-reflective coatings and the whole sensor array is designed to allow as much light through to the photodetectors as possible. Most of the scattering and resultant ghosting issues are as a result of light not hitting the sensor perpendicularly. The relatively matte surface of the film emulsion did reflect and scatter light as well.

I would also agree that a piece of polished glass would in theory have to be flatter than film, but film guides and pressure plates, especially in 35mm cameras do a reasonable job of keeping deformations to a minimum.

I think the other advantage of more modern lenses is related to new glass chemistry, thin-film technology and materials and lens element manufacturing technology:

1. Improved thin-film coatings - as you have mentioned, this technology has improved significantly over the past decade or so;

2. Glass chemistry improvements - high index of refraction and low dispersion glasses have historically been very expensive or hard to use; for instance traditional fluorite glass has excellent optical qualities but is very brittle. Breakthroughs in glass chemistry means that the price has come down so much that these formerly expensive glass types are now commodity items that they are even used in low end lenses; and

3, Mass production of aspherical elements - traditionally lenses were made up of elements that were ground traditionally and were spherical in nature. Aspheric elements showed up in a few high end, speciality lenses. These were hand ground and had extremely high reject rates. With the development of glass (and plastic) moulding techniques these elements are now relatively inexpensive and commonly used even in low end lenses. The low end lenses use new plastic to glass bonding techniques in their production.

[Inkanyezi]

Urban / John - some interesting material from both of you. I'm not 100% sure about the sensor reflectance issue. The AA array does include anti-reflective coatings and the whole sensor array is designed to allow as much light through to the photodetectors as possible. Most of the scattering and resultant ghosting issues are as a result of light not hitting the sensor perpendicularly. The relatively matte surface of the film emulsion did reflect and scatter light as well. /.../

Maybe you are misunderstanding my points, and you are certainly wrong on one count.

The AA filter is highly reflective, and it does not scatter light. It is more like a mirror, so it is essential that the camera lens would not bounce any light reflected from the AA filter back toward the sensor. In the other case, film, light that bounces off the film surface is scattered, as it is a matte surface, and very little of it will come back after a second reflection from the lens, and moreover, such light will not primarily fall in the center of the image, but be distributed over the entire frame. Thus its impact is very small.

This is a major problem when using old lenses on digital cameras. Some lenses behave better, some worse, but essentially, any lens that does not have sufficient AR coating on its rear elements will suffer from center spot fogging. The lens may work beautifully with film, but with digital it would create a soft spot in the center whenever there are bright areas surrounding. The soft spot is there also when those surrounding areas are not particularly bright, but it might be less noticeable.

So have a look at your AA filter. Usually it is an orange tinge, and very much like a mirror. That is the surface that bounces light back toward the lens.

The lens may have several reflective layers, the closest one the back side of the rear component, then the front of the same, and then even the very diaphragm blades sometimes are highly reflective on their backside. The latter is one of reasons why the problem is getting worse when stopping down. The curvature of the surfaces of rear lens components may throw this fogging light more or less into the very center of the image.

So "anti-reflective" coating of the AA filter is more a wild guess than reality. When you remove it, substantially more light will hit the sensor.

[pnodrog]

In our high humidity climate the first thing I would check is that they do not have any fungus on any of the elements in the lens. I have had some cleaned and given other lens away to students to play with while they are learning about perspective and composition and can live for awhile with a soft lens.

I have a Sigma 70-300 lens I got for a Nikon 801 film camera about 20 years ago. After taking it around Thailand and India it went soft and needed dissembling and a good clean. Have been using it on my Nikon D200 until earlier this year and it was still reasonably sharp. The Sigma was auto focus but I would expect your Nikon lenses to be basically better but maybe not until you close down a few stops.