Free Shipping on ALL Products
camera reviewsbest cameraslens reviewsphotography tipscamera forumvideo toursphotography bookssupport me
It is currently Tue Jul 22, 2014 9:34 pm

All times are UTC




Post new topic Reply to topic  [ 14 posts ] 
Author Message
 Post subject: mm conversion?
PostPosted: Tue Aug 21, 2007 4:11 pm 
i am a little confused as to how lenses are rated...

my nikon 18-200mm is a "DX" lens, so as i understand it, it is designed to be used with a cropped sensor dslr...as the sensor is NOT the same size as a full 35mm film frame.... if this lens were mounted on a full frame camera would it be equivalent to a 27-300mm..... or am i missing something?

now, if i buy a lens designed for a 35mm or a full frame dslr, do i devide the listed spec by 1.5 to get the range for my cropped dslr?

example... a nikkor 14mm prime... is that a 9mm on my cropped dslr?


Top
  
 
 Post subject:
PostPosted: Tue Aug 21, 2007 4:30 pm 
Offline
Moderator

Joined: Tue Nov 21, 2006 10:13 am
Posts: 379
Location: Sale, UK
A 300mm lens on a camera with a 1.5 cropped sensor is still a 300mm lens. The magnification will always be 300mm no matter what the sensor size. The field of view will alter however. It's field of view is equivalent to a 450mm lens on a full frame sensor.

In your example, the 18-200mm Nikkor at 18mm on a cropped sensor would have the same field of view as a 27mm lens on a full frame sensor. It will not magnify the image.

_________________
Nikon D80, Nikkor lenses: 35mm f1.8 G AF-S DX, 50mm f/1.8 AF D, 18-70mm f/3.5-4.5G ED-IF AF-S DX, 70-300mm f/4.5-5.6G IF-ED AF-S VR, SB800 flash
My photos on SmugMug


Top
 Profile  
 
 Post subject:
PostPosted: Tue Aug 21, 2007 4:41 pm 
so what happens to the field of view when you use a traditional lens on a cropped sensor?


Top
  
 
 Post subject:
PostPosted: Tue Aug 21, 2007 5:43 pm 
Offline
Moderator

Joined: Tue Nov 21, 2006 10:13 am
Posts: 379
Location: Sale, UK
The same thing. You will always get a reduced field of view with a cropped sensor.

_________________
Nikon D80, Nikkor lenses: 35mm f1.8 G AF-S DX, 50mm f/1.8 AF D, 18-70mm f/3.5-4.5G ED-IF AF-S DX, 70-300mm f/4.5-5.6G IF-ED AF-S VR, SB800 flash
My photos on SmugMug


Top
 Profile  
 
 Post subject:
PostPosted: Tue Aug 21, 2007 6:04 pm 
so a traditional 50mm lens used with a 1.5 crop = the field of view of a 75mm lens mounted on a full frame?

but a DX lens 12-24mm = 18-36mm on a full frame? or do you divide when using DX lens on a full frame?

i don't get it..


Top
  
 
 Post subject:
PostPosted: Tue Aug 21, 2007 6:33 pm 
mwahlert wrote:
so a traditional 50mm lens used with a 1.5 crop = the field of view of a 75mm lens mounted on a full frame?

but a DX lens 12-24mm = 18-36mm on a full frame? or do you divide when using DX lens on a full frame?

i don't get it..

You do not divide for full frame (35 mm) - what is written on the lens, regardless of it being a DX lens or not - is what you will get on a full frame body. What a DX lens will cause on a full frame sensor is some serious vignetting...

Darrin


Top
  
 
 Post subject:
PostPosted: Tue Aug 21, 2007 6:36 pm 
OHHH OK... so a DX lens - or other crop sensor specific lenses (such as tamron di II lenses) provide the same field of view on crop and full frame sensors... but you don't want to use a crop sensor specific lens on a full frame body....

you multiply standard lenses only when mounting on crop sensor body's..

GREAT... thanks!

PS: tamron DI lenses (not DI II) are designed for full frame... right?

canon lenses -- ef lenses are traditional, while EF-S are for crop sensor cameras?


Top
  
 
PostPosted: Tue Aug 21, 2007 7:23 pm 
Offline
Moderator
User avatar

Joined: Sat Sep 30, 2006 4:30 pm
Posts: 9805
Location: UK
There is a quite detailed discussion of this topic in a Luminous Landscape Tutorial - click to follow the link. I think it will really help and doing so will help ease my conscience about copying some of the text from the article to label the picture below!.

So, on the assumption that a picture is worth a thousand words here is a picture and its accompanying description from that article just to whet your appetite.

Image
    The image circle created by a 35mm format lens is shown.
    The blue rectangle shows what a 35mm film, or a full-frame digital SLR will record.
    The inner red frame shows what a digital SLR with a 1.6X magnification factor will record.

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Aug 21, 2007 7:33 pm 
Offline
Moderator
User avatar

Joined: Sun Nov 05, 2006 11:08 pm
Posts: 7920
Location: Germany
mwahlert wrote:
so a DX lens - or other crop sensor specific lenses (such as tamron di II lenses) provide the same field of view on crop and full frame sensors

No! The croping depends on the body, not the lens!
And yes, the Tamron Di is for FF or smaller sensor bodies, the Di II is for APS-C or smaller format sensors. So if you use a Di II lens on a FF body, you will get dark corners or even dark borders :evil:

_________________
Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews, My Pictures, My Photography Blog
D800+assorted lenses


Last edited by Thomas on Tue Aug 21, 2007 8:18 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject:
PostPosted: Tue Aug 21, 2007 7:45 pm 
tombomba2 wrote:
mwahlert wrote:
so a DX lens - or other crop sensor specific lenses (such as tamron di II lenses) provide the same field of view on crop and full frame sensors

No! The croping depends on the body, not the lens!
And yes, the Tamron Di is for FF or smaller sensor bodies, the Di II is for APS-C or smaller format sensors. So if you use a Di II lens on a FF body, you will get dark corners or even dark borders :evil:


i'm confused by your statement...
tamron di is for smaller sensor bodies, while the di II is for aps-c or small format sensors.... aren't aps-c sensors considered "small sensors" as they are smaller then full frame sensors?

what sensors are smaller then aps-c?


Top
  
 
 Post subject:
PostPosted: Tue Aug 21, 2007 8:20 pm 
Offline
Moderator
User avatar

Joined: Sun Nov 05, 2006 11:08 pm
Posts: 7920
Location: Germany
Sorry, forgot the "space" between "FF" and "or". Corrected the error above. Hope the message get's clearer now.

_________________
Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews, My Pictures, My Photography Blog
D800+assorted lenses


Top
 Profile  
 
PostPosted: Sun Aug 26, 2007 7:32 pm 
Thanks, I am a newbie but I read the link and it make perfect sense. If I am not mistaken, 4:3 format is worse in this regard than other DLSR's. More like 2x than 1.6x. Is this correct? Then maybe a 4:3 is a bad choice for landscape?

What I don't understand is why 4:3 was chosen as the format for the new digital standard. Can anybody explain the benefits of it? Is it just because it scales to normal print sizes?

Thanks!
Cindi


Top
  
 
PostPosted: Sun Aug 26, 2007 8:38 pm 
Offline
Moderator
User avatar

Joined: Sat Sep 30, 2006 4:30 pm
Posts: 9805
Location: UK
Cindi wrote:
What I don't understand is why 4:3 was chosen as the format for the new digital standard.

From memory, and somebody please correct me if I've got it wrong, 4:3 was chosen because it was thought that most people would view their digital pictures on TV sets and/or computer monitors. Trouble was nobody at the time realised that wide-screen would soon become ubiquitous.

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 26, 2007 8:45 pm 
Offline
Site Admin
User avatar

Joined: Tue Nov 08, 2005 3:32 pm
Posts: 9962
Location: Queenstown, New Zealand
Yep, I think 4:3 was chosen as the native aspect ratio for compact digital cameras to match the shape of old-style TVs and PC monitors. It's interesting though that the Four Thirds DSLR system also adopted the 4:3 shape.

To be fair, most medium format cameras are also closer to this image shape...


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 14 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  

All words, images, videos and layout, copyright 2005-2012 Gordon Laing. May not be used without permission.
/ How we test / Best Cameras / Advertising / Camera reviews / Supporting Camera Labs

Webdesign by Alphabase IT
Powered by phpBB® Forum Software © phpBB Group