OT: Help me understand something....

Hi All,

 

While this is off topic to Leica, I am confident that I will find my

answer here. So thank you in advance for your feedback.

 

I am getting ready to purchase a Nikon D70 mainly for my wife to use

to grab those captures of my daughter that I am not always around for.

However, I was thinking about the huge stacks of Nikon glass that I

have, and how *I* would best be able to take advantage of using the

D70, and so here goes my question.

 

As a long time former Nikon user (before I switched to Leica), I was

always a little disappointed with the performance of Nikon glass wide

open (1.8 & 2.8 for my lenses). Mainly how the images were not quite

sharp from edge to edge wide open. I was thinking that with the 1.5x

factor that we get with the sensor of a D70, would performance of a

1.8 lens wide open be better with the 1.5x factor?

 

My thinking is that we are actually using less of the lens, or put

another way, predominantly the center of the lens, which would/should

result in better sharpness across the entire frame.

 

Does this make sense, or am I way off in my thinking?

 

Thanks you,

 

Erik.

The Nikon 50mm AF f/1.8D is not worth NOT getting. It only costs pennies (especially for a used one) and has an optical performance way beyond what you would expect of its finish and feel. You may get a good used AF (as opposed to an AF-D) which is built better.

 

Of course you get the 75mm 'view' due to the APS sized sensor but you know that already.

 

I have used the f1/.8 and now the AF f1.4D on my D70. Both are excellent.

Trevor,

 

I have all the Nikon glass I would ever want. In general I love all of it, but it lacks sharpness across the image when wide open.

 

I am really mostly looking for someone to set me straight on my thinking.

Here is an example. The AF (or me) caught the little woollen jumper instead of the eyes, either that or she was too damned fast!

 

<center><img src="http://d6d2h4gfvy8t8.cloudfront.net/3097485-lg.jpg"></center>

 

Just trying to find the type of image your wife may be getting.

Oh yes that was at f/1.4 and roomlight only (at night)

Sharpness right across the frame at f/1.4 (especially for captures of childhood moments in domestic setting where distances are close up and action is fast) is only as likely as all of the objects/subjects you require to be sharp obliging you by lining up in a straight line parallel to the sensor plane within very narrow boundaries set by the DOF.

Another at f/1.4, D70 @ ISO 1600, 50mm (75mm effective) roomlight only....<div></div>

Erik, If you have a lot of manual lenses, forget about the D70. Get a D2H, it meters with manual lenses and is now going for low prices ($1,700 at Cameta Camera on eBay). I got one recently, and it's great for taking pictures of little children. One of the problems is to get a child to keep still for a pose. The 8 frames per second (with 40 frame buffer) comes in very handy for this. Also, there are a lot of great Nikon manual focus lenses available for good prices. I have a bunch of 20+ year old lenses, and they work perfectly with this camera. Just dial up the ISO if you're in low light, and change the WB when the lighting conditions change to incandescent or fluorescent. They are as good as any Leica lens of similar focal length. People who say they are not as sharp at the corners forget that you don't need the corners with the 1.5 crop.

 

Unless you're printing wall charts, the D2H is more than good enough. I haven't touched film since I got the D2H. Ergonomically it is the best 35mm camera I have ever held or used.

 

Best of luck!

I think in your "thinking", your expectations are a little too high. I wouldn't expect any lens to be sharp from edge to edge wide open at 1.4 or even 1.8, particularly if not everything in the view of the lens is on the same focal plane.

Dredging my D70 library for children at f/1.4 and 50mm on D70....

 

<center><img src="http://d6d2h4gfvy8t8.cloudfront.net/3097586-lg.jpg"></center>

Trevor, I hope she's not saying: "Would you like that Supersized? That'll be an extra 59 cents."

LOL. No she is pretending to be her mum at work (At a computer network control centre for a global IT company.)

She looks like most computer/network operators I know. Unwashed coffee mugs, food on the desk, chocolate marks around mouth and lurid mobile phone case!

Yes, the corners will look very much the same as the centre when used on a D70. But the overall sharpness is worse because if you use such a lens on the D70, the lens limits the sharpness and the frame is just too small. On film, better results are obtained wide open than on DX format digital because of this. However, there are lenses which are excellent wide open, such as some of the 85-105 mm and longer primes from Nikon.

 

I don't use my D70 for available light photography indoors except if I absolutely must have the added reach (in concert photography). It's all black and white film for me.

Thanks for all of the responses so far. I guess maybe my question was not clear, because the responses don't seem to address (for the most part) what I am after.

 

Putting my question another way, can I expect better performance (contrast, sharpness, etc.) when using for example, a 50mm on a D70 than on my F4s (film versus CCD aside)?

 

I am strictly speaking in terms of the lens, nothing else. I leverage 100% of the lens on a 35mm camera, while I only leverage the center 66% on the D70 (or thereabouts). My understanding of lens design is that in general, the center of a lens in the sharpest, highest contrast part of the lens, and in general, performance begins to degrade as the edges of the lens are used, and that is the reason that once stopped down by 1-2 stops, we start seeing the best results from a lens.

 

Does this make more sense? If not, nevermind, I guess I am just thinking out load.

 

Erik.

<i>Ilkka Nissila wrote:<br>

.."But the overall sharpness is worse because if you use such a lens on the D70, the lens

limits the sharpness and the frame is just too small. On film, better results are obtained

wide open than on DX format digital because of this. "...</i>

<br><br>

Huh? This is utter nonsense.

<br><br>

If the lens doesn't limit the sharpness on film, and the D70 format is smaller than film and

you're getting the best part of the lens' performance, how can it possibly limit the

sharpness on the D70? You make no sense at all.

<br><br>

Godfrey

Erik,

 

I don't know what lenses you are referring to. Nikon makes/has made many many many

lenses with f/1.8 and f/2.8 maximum aperture, some of which were mediocre wide open

and some of which are excellent. It's impossible to know what you are using as a reference

without knowing which lenses you're talking about specifically.

 

Moving from 35mm to a D70, whichever lens you use you'll be asking it to cover only a

16x24mm format instead of 24x36mm, and any lens' best performance is in the center

area close to the lens axis, so regardless of which lens you are referring to it will certainly

appear to perform better edge-to-edge wide open on the D70. Actually, it will perform the

same, you'll just only see its best performance area.

 

Godfrey

Godfrey,

 

That is exactly what I was after. If you are correct, my thinking was right.

 

Thank you.

Using the D70, whatever lens abberations there are at the center portion of the lens will be magnified more because of the greater enlargement necessary for the APS sized sensor. So I'm not convinced you'll notice improved sharpness going from film to digital with the same lens.

But Joseph, doesn't the center of the lens usually give the highest resolution and lowest aberration of the entire image field?

... and remember that this is a digital capture, not film. "Enlargement" has a different

meaning when you are working with a digital image.

 

Godfrey

...But Joseph, doesn't the center of the lens usually give the highest resolution and lowest aberration of the entire image field?

...

 

Absolutely true but what I'm getting at is that in order to produce a print of a scene using a 35mm film camera and a digital camera with APS-sized sensor, suppose you use a 28mm lens on the film camera and 17mm lens on the digital camera (to get approximately the same field of view in both images), the image you get from the digital camera has to me enlarged more than the film image to produce the same print size. Hence, any lens aberrations at the centre of the 28mm lens will be enlarged too.

 

Am I right or wrong?

You're right, when you enlarge something an extra 50% you enlarge all the imperfections too. If reality were otherwise the Olympus Pen F would have put Nikon out of business 40 years ago and generations of studio advertizing photographers wouldn't have bothered buying 8x10 view cameras.

What you're saying is common sense when comparing the enlargement of a small film

format to a large film format to the same size print: enlargement of a film image is a

magnificaton process which magnifies everything, including grain patterns and lens

aberrations. Smaller formats always lose to larger formats, given equal quality lenses.

 

It doesn't make sense to compare a digitally captured image printed digitally to a film

image printed optically this

way. The digitally captured image is quantized to the same level regardless of the size you

print it and has no grain or emulsion defects to influence the appearance of sharpness.

You always print with the same full array of pixels, and, up to the point of visible

pixelation, the digital print will increase in perceived detail rendering where the film image

will become softer and less sharp in appearance. At the point of visible pixelation (or

slightly before), the digital print's perceived sharpness falls apart more rapidly.

 

The net effect is that the influence of lens aberrations in a film image is greater as

magnification increases than they are as print size increases from a digital capture.

Another way to think of it is that a sensor with adequate resolution, regardless of its

format size, will show the same degree

of lens aberrations at all print sizes.

 

This difference makes digital cameras more demanding of good quality lenses on the one

hand, but makes producing larger prints more tolerant on the other hand.

 

Godfrey

Godfrey,

 

I think I understand what you're saying but...

 

Going back to my previous example, suppose both the film camera's 28mm lens and the digital camera's 17mm lens both exhibit the same amount of aberration at the centre, say a 0.5mm thick fringe on a high-contrast boundary, and the film image is enlarged 10x and the digital image is enlarged 15x to get the same-sized print, then the digital print will show an aberration 7.5mm compared with the film print's aberration of 5mm, yes? The digital print's reproduction of the aberration may be sharper but it will still be larger than the film print's wouldn't it?

 

Don't get me wrong, I use both film and digital cameras and don't actually worry about lens aberrations but I think this is an interesting discussion (being an engineer).