Yep, it is true, just mutiply focal length by 1.5 to receive the len's effective focal length with the D100. So for the 300mm it is now a 450mm, a 35mm is a 52.5mm, 300mm + 1.4TC is a 630mm. You lose width on the wide angles, but have a distance gain on Tele's.
with this 1.5 conversion, I was wondering about about the "rule of thumb" for shutter speeds and handholding a camera. Do you now handhold a 35mm lens (effectively 52.5mm) at a shutter speed faster than 1/30 sec or 1/60sec?
Although the magnification factor will give, say, an 80 mm lens the angle of view of a 120, it is still an 80mm lens. Since the CCD is smaller than 24 x 36 millimeters, you are only capturing the center of the image transmitted by the lens, instead of the entire image. The result would be akin to taking a 35 mm negative, cutting around the edges, and then enlarging the image from the new, smaller, negative. You certainly would not say that the photo was taken with a 120 mm lens if you undertook that process on a negative shot with an 80 mm lens.
...and if you really want to split hairs, 200 mm lens on a D100 has the same field of view as a 300 mm lens on a 35 mm format camera. That is why many refer to this phenomenon as a "field of view" (FOV) crop factor.
What is important about this hair-splitting is that, for example, for purposes of calculating DOF, a 200 mm lens is a 200 mm lens is a 200 mm lens. On any camera. What changes from format to format is the acceptable circle of confusion (the smallest image element desirable to have resolved).
I think the FOV factor good for concert, or wild life photos. for me it's like shooting model with 200mm FOV and still get the "blur effect" of 135 mm. Try using 300 mm lens and you'll be far away from models.
The FOV is really unpleasant for me.
PS. It's still satisfy me in studio shooting, though.
Pinky Mirror Nikonians@Jakarta,Indonesia-- it's near Bali, if you don't know where it is
I'm confused, the answers starting sounding clear, then that changed. I guess what one needs to answer is this, will a subject appear 50% closer with the digital than it does a film camera with the 1.5 factor?
I suggest you scan one of your 35 mm negatives and using a viewer, crop out the center and blow it up 50 %. That is the view of the digital with the same lens. It is not truly a magnification, it is a Feild of View. If you could borrow a digi and move your lens back and forth between the film camera and the digi, you would see the subject remains the same size but the area around the subject is much reduced so the subject appears to fill the frame more.
The confusion comes from, what I consider a marketing guy's invention, the term magnification factor. There is no magnification and the more accurate description is Feild of View. Your lens does not gain in magnification, it actually loses some of the picture around the edges. You might also describe the DSLR as the poor man's medium format because the pictures appear to have the perspective and composition that would be used on a medium format...slightly closer to square, as against the rectangular 35 mm.
The short of the discussion is that you get no bargains in the lens used on the DSLR. Instead, you get a different shaped canvas upon which to paint your picture.
I think I get what you are asking. If you take a F100 and D100, with the same lenses and you are photographing the same subject from the same distance, the D100 will not make the subject "closer" in your viewfinder, from a spatial viewpoint. That is, looking through both cameras, the subject will be the same size, only taking up more space in the D100 viewfinder due to the FOV issue. Does that make sense???
The D100 film plane is in the same place as the film plane on the F100, for example. Therefore, the image circle created by any given lens will be the same size on either film plane. Ideally, the frame would just fit in the image circle, so the diameter of the image circle for most lenses for 35mm cameras is approximately equivalent to the diagonal of the 35mm frame (about 43.25mm). Design compromises for the D100 included the size of the CCD. The diagonal of the frame for the D100 is approximately 28.4mm. The D100 sees a smaller portion of the image circle. So why does Nikon talk about the focal length? It sounds better than just explaining that you see less of the image circle and your wide angles aren't as wide. All that said, I love my D100 and I haven't shot a single roll of film since I got it. Great lenses are great lenses on any camera, D100 included. Of course, I will buy the FF Nikon DSLR when it comes out.
...but the lack of frame-filling on the 35 mm frame is an illusory disadvantage. You could take that film image, crop out the middle 50%, and use that to fill the frame of a print with about the same quality, more or less, as the D100 image. Think of the D100 as "pre-cropping" your images: this makes your teles more useful, in that the subject will more easily fill the initial capture frame. This is helpful for a digital sensor since cropping out the middle 50% of a 6 Mpixel image is going to have a drastic impact on image quality. The downside is that "pre-cropping" the image circle of an 18 mm lens leaves you without most of the scene that lens could otherwise capture.
The bottom line is this: you look through the camera. You see what you see. If it is not big enough, get a longer lens. If it is too big, get a shorter lens. Subjects will fill the frame more than you are accustomed to in 35 mm format photography at a given focal length becuase of the smaller sensor in the D100. There is no magical "magnification" going on in the camera.
Right. I like your duck example. Look at the math.
1. 1/u + 1/v = 1/F
2. M = v/u = I/S
where; u is distance from focal plane to subject, v is distance from focal plane to image, F is focal length, M is magnification, I is image size, S is subject size.
Your example: The duck fills the frame on D100 and is only a portion of the F100 frame. I assume you take the picture form the same distance with same lens at same focal length setting.
Okay, u and v are the same in both cases. So, u is the distance from focal plane to duck (subject) and v is the distance from focal plane to film plane (image). So, F is fixed by equation 1 and M is fixed by equation 2. Said another way, the focal length and magnification are the same.
Let's say the duck is 300mm (about a foot) high and about 900mm (about 3 feet) from the focal plane. S = 300mm It fills your D100 frame so it's 15mm high on the film plane I = 15mm. So magnification = 15mm / 300mm = .05.
Now, let me point out that the math is exactly the same for the F100. The difference is that the duck is only a portion of the frame (15mm image in 24mm frame) because the frame is larger.
Focal length: The distance to the film plane from the focal plane is approximately 45mm so F = 1 / (1/45 + 1/900) = 42.9mm.
Again, F is the same for the D100 and the F100 (~43mm).
So what changed? The size of the frame on the film plane. Your duck is exactly the same on the film plane, but the CCD is smaller than the 35mm film frame. Make a circle with your thumb and index finger at arms length. Find an object at distance that fits in the circle. Now, make a bigger circle with both hands (thumbs and index fingers). The same object fills only a portion on the frame.
The difficulty comes in trying to evaluate image quality when comparing the CCD image to a film image. They really are not the same thing. Thom Hogan does it by comparing the CCD image to a scan of the film image. I'm not that clever, I just think of them as different.
But, in some ways the 1.5 thing makes sense. For example, if you leave a zoomable speedlight to its own devises on a D100, it will light the crop. You get better range with no loss of coverage if you zoom the DX speedlight to 1.5 times the focal length of the lens.
One real plus of the smaller frame is that the image circle you work with is the center of the lens. Optically, that's the best part of the lens.
PS: I would have answered quicker, but the duck wouldn’t hold still.
I can't believe how wrapped up on this "crop factor" "Field-of-view" thing so many people get. It's real simple.
Take an imaginary large format capable 100mm lens with an imaginary universal adapter and put it on a bunch of different cameras:
Camera type..........35mm Lens equivelent(approximate)
D1/D100..............150mm telephoto 35mm.................100mm telephoto/normal 6x4.5 medium format...50mm normal 6x9 medium format.....36mm normal/wide 4x5 large format......28mm wide 8x10 large format.....14mm ultra wide
Same lens, same physical characteristics, same perspective, just different portion of what the lens sees that's going onto the film/sensor.
DaveDosch Take nothing but pictures, leave nothing but bubbles.
DaveDosch Take nothing but pictures, leave nothing but bubbles.
Thanks dankeny and everyone else. I learn so much here and appreciate it a lot. I also have learned I have a lot more to learn. Main thing now though is to find me one of them measuring ducks and an imaginary lens (teasing, of course)
with the D100,the duck is really not "magnified" larger, he is just "cropped" to show less of him than the F100 view finder shows. In other words, the eye of the duck will be the same size on both cameras. Is that right?