70-300 mm in terms of optical zoom: Nikon DX SLR (D40-D90, D3000-D7500) Talk Forum: Digital Photography Review (2024)

Hi:

I am thinking to buy 70-300mm nikon lens for Nikon D90. Is it safe to say at 300mm it will equivalent to 18 times optical zoom? If not what it will be? Thanks

The zoom ratio of a 70-300 zoom lens is 4.3; 300 divided by 70 = 4.28571. I'm not sure what you are asking about when you say 18 times optical zoom? At 300mm the lens will have the equivalence of a 450mm lens on a 35mm film camera or Nikon FX (Full Frame) digital camera.

Many P&S cameras will say they have a 8x or 12x zoom, that just means that the longest focal length is 8x or 12x longer than the widest focal length. A camera with a 16mm focal length at its widest setting and an 8x zoom would then have a 128mm focal length at its longest focal length. This terminology has no meaning on DSLR cameras, as you can see the 70-300 lens has a 4.3x zoom yet its longest focal length is 300mm. The 18-105 has a 5.3x zoom and its longest focal length is only 105mm, or the 18-200 has a 11.1x zoom and it only goes to 200mm.
--

While amateurs change the camera’s settings; many Pro’s prefer to change the light.

Brooks
http://bmiddleton.smugmug.com/

Thanks Brooks P, I was trying to establish zoom on canon sx20 point and shoot camera. But your explaination make sense.

Also, I am thinking to buy Sigma 70-300mm APO DG MACRO Lens. Do you guys have any opinion on the quality of this lens for outdoor shooting nature, landscape, birds etc.

Nikon version is almost twice as much.

It's a budget lens - and you get what you pay for. I had one and think it was one of my worst photographic purchases. Some people get passable results in really good light and seriously stopped down but you are better off saving the money and putting it towards something better.

David

JD001wrote:

Also, I am thinking to buy Sigma 70-300mm APO DG MACRO Lens. Do you guys have any opinion on the quality of this lens for outdoor shooting nature, landscape, birds etc.

Brooks Pwrote:

The zoom ratio of a 70-300 zoom lens is 4.3; 300 divided by 70 = 4.28571. I'm not sure what you are asking about when you say 18 times optical zoom? At 300mm the lens will have the equivalence of a 450mm lens on a 35mm film camera or Nikon FX (Full Frame) digital camera.

Many P&S cameras will say they have a 8x or 12x zoom, that just means that the longest focal length is 8x or 12x longer than the widest focal length. A camera with a 16mm focal length at its widest setting and an 8x zoom would then have a 128mm focal length at its longest focal length. This terminology has no meaning on DSLR cameras, as you can see the 70-300 lens has a 4.3x zoom yet its longest focal length is 300mm. The 18-105 has a 5.3x zoom and its longest focal length is only 105mm, or the 18-200 has a 11.1x zoom and it only goes to 200mm.

Just to add, I've seen many posts by people coming from P&S that erroneously equate zoom ratio to telephoto "reach".

While true that an 18x P&S camera will appear have a tele equivalence of probably somewhere over 400mm (in 35mm terms), depending on where is starts at the wide end, a large zoom range is not required to obtain that narrow field of view with (D)SLR systems.

For example, the Nikkor 200-400mm high power tele-zoom is "only" 2x, but will give the same field of view on a camera with a DX sensor as a 300-600mm lens would on a 35mm SLR or an FX DSLR.

I believe that if you take a 70-300mm lens and do the conversion to give it a times minimum lens length like you would in the P&S world, you need to have a beginning minimum lens length. In the Nikon DX world that would probably be the 18mm lens since the 18-55 and 18-105 are fairly standard kit lenses. So if you take 300 and divide it by 18 you get the equivalent of it being a 16x lens, meaning that it goes 16 times what the base mm is.

For us in the SLR world, it is basically a useless calculation, but for someone trying to decide what moving to the SLR world would mean, it might have some use.

you guys got it all wrong. 70-300 is only 70-300 on a 35mm body. on DX sensor it is 105-450. So you'll get longer range on D90. I always calculated the zoom X number by dividing 300/70 and get 4.3. So the 70-300 is only a 4.3 zoom.

In 2002 my Sony F717 had a 5x zoom, 38 to 190mm and its replacement (the F828) had a 7x zoom, 28 to 200mm. A competing model at the time, the Nikon Coolpix 5700, had an 8x zoom – 35 to 280mm. So even in P&S cameras the “x” zoom factor had little or no relationship from one manufacturer to another, or even among models by the same manufacturer, it was simply the longest focal length divided by the shortest focal length.
--

While amateurs change the camera’s settings; many Pro’s prefer to change the light.

Brooks
http://bmiddleton.smugmug.com/

The focal length remains the same regardless of the size of the sensor; the focal length is a constant. The 70-300mm is a 70-300mm on a FX camera, a DX camera, a Medium Format camera, or even a Large Format view camera. In simple terms the focal length is a measurement of the distance from the lens to the point where the light rays converge (focus).

Because the DX sensor is smaller the 70-300mm lens functions like a 105-450mm lens on the larger sensor found in a FX camera. That is because the image is being cropped, only a portion of the image is captured by the smaller sensor. The diameter of the lens can be made smaller so that image circle is smaller but the distance from the lens to the point of convergence does not change and therefore objects in the image will still be the same size.

Due to this phenomenon the DX sesnsor has what is called a crop factor, and that crop factor is 1.5. The focal length of all lenses, whether they are FX or DX, must be multiplied by the 1.5 crop factor to get their equivalent focal length. The operative word is equivalent, because the actual focal length , the focal length printed on the lens, never changes, no more than does the number of inches in a foot or the number of feet in a mile.
--

While amateurs change the camera’s settings; many Pro’s prefer to change the light.

Brooks
http://bmiddleton.smugmug.com/

I somehow had this idea that we start with a 50mm (standard 35mm film camera); convert to DX equivalent by adjusting with the crop factor; thus 50mm on my old AE-1 is 35mm give or take on DX; then we take the max reach of the lens and divide by 35. So, 35mm is 1x, 70mm is 2x, etc, and 300mm is what, 8.5x.

Likewise, a Panasonic GH-1 with 2x crop factor will have its 50mm be a 25mm, so the 14-140mm zoom would be 140/25 = 5.6x.

That gives a more 'meaningful' comparison because we all know what 50mm equivalent is with our given crop factor. I'm probably wrong and will be flamed to extinction

JD001wrote:

Thanks Brooks P, I was trying to establish zoom on canon sx20 point and shoot camera. But your explaination make sense.

Also, I am thinking to buy Sigma 70-300mm APO DG MACRO Lens. Do you guys have any opinion on the quality of this lens for outdoor shooting nature, landscape, birds etc.

Nikon version is almost twice as much.

In terms 35mm film/FX sensor size the SX20 has an effective focal range of 28 - 560mm while a 70-300mm zoom lens on a DX camera will have an effective focal range of 105-450mm.

Regards

Paul

I think that this thread shows that while photographers have done a great job at establishing a transferable base line for exposure they have not done such a good job at developing a useful standard for lenses.

Any knowledgeable photographer can work his way around any camera--aperture--ISO (film or sensor)--shutter-speed combination and if armed with a working meter can get a properly exposed image. While I've never used a large format camera I'm reasonably confident that I could make a picture with one as long as I know my film speed and shutter speed and have control of my aperture.

Unfortunately this inter-format continuity does not exist when expressing zoom. When someone on this forum states that they were using their 85mm lens for a portrait it means very little. We need to know the size of the sensor that is being used for a focal length to have any bearing. 85mm on a D3 means something very different than on an Olympus E3. Every camera has it's own sensor size and subsequent zoom ranges. After a while most of us get a handle on the big conversions that are needed for common DSLRs and we all seem to use a baseline of 35mm film. I convert quite quickly in my head that the 85mm lens on a D3 is about the same as that same lens on a 35mm film camera. The E3 behaves more like a 170mm lens on film.

For me, this automatic conversion breaks down when I start thinking of very small or very large sensors or film. There is just no way to express the zoom factor of any given shot. I know it's too late to change things and I'm waaay too small a player to get such a thing done but a universal expression of zoom would have been very handy. Something perhaps based on that old standby of 50mm on a 35mm film camera. The 53 degree field of view that humans have is very close to the 50mm lens on a 35mm film camera so that could be considered N. Everything else would be derived from N. 2N would be 100mm on 35mm film N/2 would be a 25mm lens on the same camera. On our Olympus camera 2N would be 50mm and N/2 would be a 12.5mm lens.

Anyway, it ain't gonna happen......so

The answer to the OP's original question is better expressed as a 35mm equivalent of 560mm. In other words zoomed all the way out you will frame an image that is the same as using a great big 560mm lens on your old film camera (and lets just hope your other camera's not an Olympus). Using my proposed method the camera and it's 5-100 lens can frame images from N/1.78 to 11.2N (I'd probably say N/2 to 11N).

Here's a quote from Canon's site:

The PowerShot SX20 IS is equipped with a 20x Optical Zoom lens with a focal length of 5.0 - 100mm (35mm equivalent: 28 - 560mm)

Unfortunately it isn't that simple. There are a number of different formats other than 35mm, such as Medium Format (the Hasselblad is probably the most popular) used by many professional photographers in various forms of photography, such as Fashion, advertising, and others. Then there are a number of motion picture and video formats. The simple truth is that the “x” zoom number has never had much relevance because without knowing what the minimum focal length is the number is useless. Saying that the base number is 35mm doesn't work because that would mean that a 18-200mm zoom would have a 5.7x zoom, but what about the zoom range from 18 to 35mm, do we just ignore that? A 10-24mm zoom currently has a 2.4x zoom factor, but with your method it doesn't have any zoom factor at all, not that the x zoom factor has any real significance in the real world. Manufacturers use it to make their cameras, almost exclusively P&S models, sound good. Sort of like naming the image processing engine EXPEED; having a name doesn't make it work any better, but Canon named their engine and Nikon felt compelled to do likewise.

While the 50mm was a popular focal length on 35mm SLR cameras, and probably the most popular kit lens, it was not really a normal or standard lens. The so called normal lens would actually be a lens with a focal length equal to the diagonal of the sensor or film, and with 35mm film that would be 43.3mm. I have never seen a 43mm lens and I doubt if any manufacturer ever built one. Nikon does have a 35mm lens and some photographers prefer it to the 50mm and the difference between 35mm and 43mm, and 43mm and 50mm is only 1mm. My first 35mm SLR was a Ricoh and several companies made 45mm lenses for it.

On a Nikon DX DSLR the diagonal is 28.4 and Nikon does produce a 28mm lens, but the 35mm comes very close to producing the same results that the 50mm did on a 35mm camera. That makes the 35mm almost a duplicate of the 50mm that so many people are accustomed to using on 35mm cameras.
--

While amateurs change the camera’s settings; many Pro’s prefer to change the light.

Brooks
http://bmiddleton.smugmug.com/

Hi,i wanted a budget 70-300mm lens for my D90.I paid $60 Aus for a Tamron 70-300 Ld di.I was quite surprised with the pics i got for such a cheap lens.Thought id show you a few samples from the lens.Ive got the Sigma 150-500os now but i still use the Tamron now and then.Bit slow focusing but adjust your technique to suit the lens and you will get your pics.You get what you pay for they say but i rekon this was a bargain for $60.
good luck Paul

JD001wrote:

Also, I am thinking to buy Sigma 70-300mm APO DG MACRO Lens. Do you guys have any opinion on the quality of this lens for outdoor shooting nature, landscape, birds etc.

David Lalwrote:

It's a budget lens - and you get what you pay for. I had one and think it was one of my worst photographic purchases. Some people get passable results in really good light and seriously stopped down but you are better off saving the money and putting it towards something better.

personally i liked my 70-300 APO. i found that although it had its limitations, as long as you worked within the confines of those limitations you would get good, sometimes great, results.

for instance, this lens was soft when shot wide open, and it was soft when shot at full 300mm telephoto.

if you shot at 300mm f/5.6 (wide open) you would get maybe 1 out of 10 "decent" shots. the rest were very soft. too much so for my taste.

but if you shot wide open at 200mm, you'd get a good picture. if you shot f/8-f/11 at 300mm, you'd get a good picture.

if you shot f/5.6 (stopped down)-f/8 at 200mm, you'd get a very sharp picture.

could it compare to 70-200 f/4L that i replaced it with? absolutely not. but for $200 it was a great "starter's lens".

HOWEVER, i would like to point out that for $200, the 55-200 VR is a better value. that lens (and the canon 55-250IS, since i shot canon back then) did not exist when i bought my sigma 70-300 APO.

so the sigma 70-300 APO is a decent beginner's lens, but there are better options. and i don't think that 200-300mm is the biggest draw for a lens. i found the difference to be insignificant. and remember: even with the 70-300 APO, if you want sharp pictures you will be scaling back to 200mm to avoid the softness at 300mm anyway.

Nikon's 70-300mm VRII is a very sharp lens and the VRII does allow for 3 extra stops.

It's not fast pro-glass and you know it. The lens really shines at f8 and 11.

Can't compare apples to oranges.....but even this lens on a D3S with it's low light capabilities...is actually surprisingly nice...try it!

That was a good summary SNGX1327, pretty much mirroring my experiences too - but I am very picky when it comes to image quality and birding (the reason I bought the lens) and so was greatly disappointed with the lens. Eventually I gave it away to a beginner for nothing.

As it happens, I've developed a passion for birding with very short lenses and in that respect, Trumpyman, have a look at the rainbow lorikeeets photographed with a 60mm lens by a fellow countryman of yours:

Here's one of mine, a snow bunting - Nikkor 50mm/F1.8

Budget zooms? No thank you!

David

all those numbers with no trace of fundamental math.

A 70-300mm lens has a zoom ratio of 4.28.

It is a 70-300mm no matter what camera you mount it on.

All the equivalence is based on the sensor size which is behind the lens and not a part of the lens. They are two different components of the camera system.

So, put the 70-300mm on a DX body and the image is cropped because of the smaller sensor. To get the same image border to border, you would need a longer lens on the FX body soooooo, we refer to the equivalent of 105-450mm. Now, take a look at what 450/104 equals. HOLY COW, it's 4.28 just as if it were a 70-300mm lens.

Oh, wait, it IS a 70-300mm lens, I just have it on a DX body so, I lose some of the image projected by the lens. There isn't a sensor there to capture the light beams, photons, wavicles or whatever your particular flavor of physics prefers.
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Yep, that is what I was saying in my posts throughout this forum, but some people ant to make more out of the situation than it deserves. Focal length is a measurement pure and simple, measured from point "A" to point "B", it's just that simple.
--

While amateurs change the camera’s settings; many Pro’s prefer to change the light.

Brooks
http://bmiddleton.smugmug.com/

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