Lenses How do you figure out the zoom it will provide

Jonesy101

Ive been looking all around the internet to figure this out but cant find the answer anywhere. I went into the shop today and asked the attendant about a tamron 70-300mm lens for example because its quite cheap and im only starting in photography. He then asked me with which camera i was planning to use it with and i said a Canon EOS400d. And he did some calculations in his head and said 15x zoom. First off all does anyone know if this is true and how can u work it out. I asked him but im in france at the moment for the rest of the year and dont speak fluently so i couldnt undersand him fully.

melekalikimaka

Zoom lenses are sometimes described by the ratio of their longest to shortest focal lengths. For example, a zoom lens with focal lengths ranging from 100mm to 400mm may be described as a 4:1 or "4×" zoom. The term hyperzoom or "super zoom" is used to describe zoom lenses with very large focal length factors, typically more than 4x and ranging up to 10x (e.g., 35-350mm) and even 12x. Currently, zoom lenses beyond about 2× or 3× cannot consistently produce images of a quality on par with prime lenses. Thus most "professional" photographic zoom lenses are restricted to this range (e.g., 28-70mm, 70-200mm).


so it was not x15 at all

Roen

Avoid that shop like the plague, if someone is giving you out dud information in the hope of making a sale they are either lying or haven't a clue what they are on about.

JMcL

Yep, he's talking through his ars3. A 70-300mm lens would have a 4.something X zoom (and 18-200mm would be 11x for example) if you wanted to apply those descriptions. Avoid.

If you're in Dublin, try Gunns on Wexford St, Camera Exchange (Georges St. and Trinity St.), or Conns (Clarendon St? - anyway, just behind Brown Thomas). Buying in Ireland isn't very cheap, but if you're looking for advice, these shops will be your best bet

mervifwdc

Agree with the others.

a 18-200 is just over a 10x zoom. A 35-350 is a 10x zoom. Irrespecitive of what crop factor a camera has, they still have the same zoom multiplier range, it just starts and stops at different 35mm equivilent points.

Merv.

kuroino

Jonesy101, first of all you have to stop thinking in terms of zoom ratios. While whatever melekalikimaka said is completely true, the zoom ratio is not what you are really interested in.

What you are really interested in is something like "how big is this bird going to be on the picture if I shoot it from 50 meters"? That is totally controlled by the focus distance of the lense and the size of the sensor in your camera. In very lame terms, for your camera (400d) the focus length of 28mm is something you would very likely percieve as "no magnification at all" looking at 10x15" print of it in your hands or on 17" screen from reasonable distance (although there is no strict science behind it, it is just a perception).

So, the lense you are talking about gives you something approximately between 2.5 to 10 times of that.

Of course here a boringly note must me made, saying that focus length is not about maginification, but about changing proportions of your foreground to your background and if you want something to be just bigger on your picture - come closer

davmigil

Sounds like maybe he was referring to the crop factor. Canon 400D has a sensor smaller than 35mm film by a factor of 1.6. Thus a lens with 70-300mm on a 35mm sensor will effectively act as a 112-480mm (ie multiply by 1.6) lens on your camera. Else he doesn't know what he is talking about as 300/70 = 4.3 X zoom

sionnach

What kuroino said,you need to stop thinking in terms of "zoom", it's a silly term used to simplify cameras for the masses. Start thinking in focal lengths. 70-300 is tons of reach for a telephoto lens, especially with the crop factor of the 400d.

mervifwdc

As we've moved from answering the question to giving advise, I think you need to have a feel for what photography you'll be doing with the lens. If it's indoor portraits, anything over 200mm is a bit overkill. If it's small birds at the end of your garden, anything less than 500mm is not going to cut it.

That said, if your getting started, and have a "regular" lens giving something like 18-55 or whatever it is, then a 70-300 or 70-200 is a good next lens. If in doubt, get the longer one, as there are always situations where you could do with a little more reach.

Merv.

Shiny

mervifwdc wrote:

If it's small birds at the end of your garden, anything less than 500mm is not going to cut it.
Merv.

Bloody Hell!

Merv how big is your garden!


My zoom is a 70-200 and like merv said, it is overkill for many
indoor situations but outdoors i often wish i had a 2x Teleconverter
for shots of the moon,birds, distant objects etc....

melekalikimaka

kuroino wrote:

if you want something to be just bigger on your picture - come closer

or crop

Calina

Start with a 70-300mm - this is what I did and in general, you can get a decent enough Sigma for the Canon for not horrifically lots of euros and I got some great shots with it (I shoot watersports mainly). I think it costs around 200E new in Conns.

I also got a 50-500mm Sigma which was noticeably more expensive but which I do use.

You really would be better off sitting down and deciding what exactly it is you want to shoot with that zoom lens. Alternatively, find a group of like minded people who have said lenses that fit your camera, and have a little try off them before you purchase. The thing is, while you can say to yourself I have so much zoom, what that means in "looking at the photograph" terms is difficult to imagine. When I bought the big Sigma, almost the first thing I did was stand on Dollymount Strand and take a series of photographs of Poolbeg lighthouse zooming it in closer just to see what the difference was on a photograph rather than in terms of "oh I've loads of reach now"...

mervifwdc

Shiny wrote:

Bloody Hell!

Merv how big is your garden!

Not that big, but the birds are very small



Merv.

Jonesy101

thanks for all the advise guys. its really helpful.
what would b the difference between say a 50-200mm lens and a 100-400mm lens. they both have the same Zoom ratio of 4x but how much closer would the 400mm one be.

kuroino

the objects will appear twice as big on your picture on 400mm, than they will do on 200mm

In fact, 100mm-400mm may be too much if you are not shooting from tripod. Unless it is really bright of course.

What lenses do you use now and what do you want to do with this telephoto lense?

mervifwdc

the "closeness" of the lens is the MM figure. a 400mm lens is twice as close as 200mm (which is in turn, twice as close as a 100mm). Do you have any lenses at the moment? If you look through the lens, and zoom in and out you'll see the effect.

The zoom ratio relates to how much zooming or range a lens has. so, a 35-350 has a 10x zoom, but does not go as far as a 100-400 because 350mm is less than 400mm.

Peteee

Jonesy101 wrote:

And he did some calculations in his head and said 15x zoom.

I'd say what he was going for was the "zoom" factor. In this case, compared to your eyes, with the 300mm lense (With the 1.6x factor of the 400D), what you would be seeing is about 15 times closer then what you are seeing now

Thats my rationale anyway