Focal length

Azbubu

Azbubu

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How does this work? Is 28-140mm a wider lens than 36-180mm? What should I look for when buying a camera with a wide angle lens?
 
The 28-150mm is wider than the 36-180mm and the 36-180mm has more "reach" than the 28-150mm :) If you want wider thne you need to go for a 10-20mm :)
 
EchoZA said:
The 28-150mm is wider than the 36-180mm and the 36-180mm has more "reach" than the 28-150mm :) If you want wider thne you need to go for a 10-20mm :)
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Thanks but still confused. What do you mean by "reach"? I want to be able to take panoramic sort of shots.
 
If you are wanting to take panoramic shots, then you need to go for a wider lens. I bought a 10-20mm lens yesterday (Ultra Wide Angle) for this purpose.
 
You can take a panoramic with a 600mm lens as well. It is case of stitching photos together as you pan though the scene you want to make a panoramic of. Off course a 15mm lens would would better since it means about 2-3 photos for one panoramic as opposed to 8+ with a 600mm.

Reach = Zoom. A 180mm lens can zoom tighter than a 150mm.

18mm cannot be considered wide angle on most entry-level digital SLR's since the image sensor is usually smaller than a full 35mm frame, hence you have to multiply your focal length by approximately 1.6 to get the true value. (18mm x 1.6 = 28.8mm). It means you have to get a much shorter lens to get true wide-angle, e.g. 12mm. You will not have this issue on some prosumer and pro level digital SLR's since the have a full-size 35mm image sensor.
 
EchoZA said:
If you are wanting to take panoramic shots, then you need to go for a wider lens. I bought a 10-20mm lens yesterday (Ultra Wide Angle) for this purpose.
Click to expand...
Aren't you thinking of 360/720-degree shots, in which a fisheye lens like yours would be ideal?
 
Oh perhaps I should mention that I'm talking about compact cameras i.e point & shoot.

My current has a wide-angle lens of 28-140mm lens and looking to buy a new one also with a "wide-lens" so looking to see which to buy.
 
The first number is how wide it is ; the closer to 0mm, the wider. The second number how far it zooms.

So if your current is 28mm-140mm and the potential new one is 36mm-180mm ... Then the new one isn't as wide as the older, but zooms more.
 
Dolby said:
The first number is how wide it is ; the closer to 0mm, the wider. The second number how far it zooms.

So if your current is 28mm-140mm and the potential new one is 36mm-180mm ... Then the new one isn't as wide as the older, but zooms more.
Click to expand...

Thanks. But how does the new one zoom more? my old one is 5x zoom and the potential new one is 3x zoom.
 
abzo said:
Thanks. But how does the new one zoom more? my old one is 5x zoom and the potential new one is 3x zoom.
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The "potential" one is also 5x. 180/36=5.
 
abzo said:
Thanks. But how does the new one zoom more? my old one is 5x zoom and the potential new one is 3x zoom.
Click to expand...

Yup - like Bwana said

The 5x is calculated from the wide focal length - so a 5x on a lens starting at 10mm would be mean the maximum would be 50mm ... But a 5x on a lens starting at 50mm would be 250mm

So in this case both are 5x
 
Oh i see. Thanks guys!

Just one more Q, I'd they're both 5x zoom and one is 28-140 and the other is 36-180, what's the advantage of the second one? Didn't really understand the part about it having more "reach".

Merry Xmas.
 
"Reach" just means you can zoom in further. 180mm is further than 140mm. If you are more concerned about panoramic shots then you should choose the 28-140. Best is to go into a store and try both out to physically see the difference...
 
abzo said:
How does this work? Is 28-140mm a wider lens than 36-180mm? What should I look for when buying a camera with a wide angle lens?
Click to expand...

I think most of the uncertainty has been answered but just to clarify the difference between "zoom" and "magnification".

Zoom is the ratio between the longest and shortest focal lengths of a zoom lens. So a 36-180mm lens will have a 5X zoom 180/36 = 5

Magnification is the relative enlargement of the image projected onto the sensor/film compared to a 50mm lens (the 50mm lens has the same approximate perspective and magnification as the human eye, but not field of view). Therefore the 36-180mm has a higher magnification ratio as calculated by 180/50 = 3.6 whereas the 28-140mm is only 2.8.

The 28-140mm is therefore the wider lens but it has a lower maginification at the long end (140mm) compared to the 36-180mm.

I assume this is a compact digital camera zoom lens and caution must be taken when comparing different compacts. The actual zoom focal length is most likely 5-25mm and the "relative to 35mm film zoom ratio" is calculated from the sensor size. Many compacts have different sensor sizes and different manufacturers seem to calculate the 35mm equivalent zoom in different ways... Wider lenses on compacts are certainly handy but they often suffer from poor resolution the wider they are so in the end it might be a better idea to purchase a compact camera with a slightly narrow min focal length (36 instead of 28mm) for this reason.
 
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