# Lens/Zoom

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#### desmondnwj

##### New Member
To all Veterans out there,

Scenario: There's a subject that Peter would like to take a picture of. However, it is too far away. How should Peter decide what lens to buy to achieve the zoom that he need?

#### Rashkae

##### Senior Member
He should decide by calculating which lens will allow him to maintain a positive balance on his bank account.

#### zac08

##### Senior Member
To all Veterans out there,

Scenario: There's a subject that Peter would like to take a picture of. However, it is too far away. How should Peter decide what lens to buy to achieve the zoom that he need?

Check :

a) is it possible to get closer to the subject?

b) is it possible to use a TC to get the range required at the expense of the aperture loss.

c) buy a long lens which can allow you to reach the distance required, budget willing...

d) buy a long lens with a TC to get the range required (cheaper than a full long lens) i.e.
70-200 f2.8 with a 2x TC would be cheaper than getting a 400mm f2.8. But you lose 2 stops of light and get a 140-400 f5.6 instead...

#### desmondnwj

##### New Member
Rashkae: Can assume "he" is beri rich =]

zac08: Thanks for your valuable feedback. From a layman point of view, I was wondering if say a pigeon is 50m away what spec of lens can home in on it and cover about 50% of the picture. Is there a formula for this (size of object, distance away, size on picture)?

#### zac08

##### Senior Member
Rashkae: Can assume "he" is beri rich =]

zac08: Thanks for your valuable feedback. From a layman point of view, I was wondering if say a pigeon is 50m away what spec of lens can home in on it and cover about 50% of the picture. Is there a formula for this (size of object, distance away, size on picture)?
Let's just average a pigeon at about 40cm long. To get this inside 50% of the image sensor, you'd need to know the sensor size, the focal length as well as the angle of view.

According to a calculation website I visited, 2796.8 mm would be required to get it fully in view. So Half of that would be 1350mm or so...

you got the dough for a 1000mm lens?

PS : this calculation was done on a Nikon 1.5 x crop DSLR. So if you are calculating it on a different system, pls try it again here :

http://www.cambridgeincolour.com/tutorials/camera-lenses.htm

#### desmondnwj

##### New Member
zac08: You are a serious photographer! Thanks for spending the time explaining. Conclusion, unless you are a fifthly rich, use a high res camera to capture than digitally enlarge from there and crossfingers that you got the details :bsmilie:

#### Rashkae

##### Senior Member
zac08: You are a serious photographer! Thanks for spending the time explaining. Conclusion, unless you are a fifthly rich, use a high res camera to capture than digitally enlarge from there and crossfingers that you got the details :bsmilie:
No, never digitally enlarge, you'll make it look grainy. Crop crop crop!

(yes, this is where megapixels does matter)

#### giantcanopy

##### Senior Member
zac08: You are a serious photographer! Thanks for spending the time explaining. Conclusion, unless you are a fifthly rich, use a high res camera to capture than digitally enlarge from there and crossfingers that you got the details :bsmilie:
There is a 1700mm prime by zeiss :bsmilie:and a 1700 - 1200 zoom by nikon

Actually there is a limit to having more MP for ur sensor. apart from noise the lens might even be outresolved.

Ryan

#### desmondnwj

##### New Member
Rashkae: ahhh... "I must crop, I must crop, I must croppppp....."

giantcanopy: Thanks for insights!

Anyone tried placing camera to a telescope? maybe I am digressing :bsmilie:

#### icebox

##### New Member
Yea, astrophotography =P

#### desmondnwj

##### New Member
I dun mean specialize equipment. Literally, 1 x camera and 1 x telescope. :bsmilie:

#### zac08

##### Senior Member
I dun mean specialize equipment. Literally, 1 x camera and 1 x telescope. :bsmilie:
Yes... all you need is a adapter for the telescope to fit the camera.

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