15mm to 18mm - is there a difference

[JamesB]

On another thread, someone said I wouldn't see much difference between a 15mm and 18mm focal length (with an EOS 350D).

I have 18mm at the moment and need to go a bit wider. Can someone tell me if 15mm would be noticeably different?

Thanks

Jamie

[Millie]

Re: 15mm to 18mm - is there a difference

James not not if I understand the question.

To see the imapact of the 3mm
You could look at the difference between 21 and 18mm on your existing lens.?

Millie

[Millie]

Re: 15mm to 18mm - is there a difference

James not not if I understand the question.

To see the imapact of the 3mm
You could look at the difference between 21 and 18mm on your existing lens.?

LOL.. Translated to English, it should read.

James I'm not if I understand the question.

To see the impact of the 3mm
You could look at the difference between 21 and 18mm on your existing lens.?

Millie

[@imagesBV]

Re: 15mm to 18mm - is there a difference

theoretically the wider you go there should be a proprtionally smaller impact. Because if you had say 90 degrees in your lmage then you switch to 100 degrees then each degree is compressed into the frame a bit more.
but I'm sure I have read the opposite in reviews of 10 and 12mm wide zooms.
It might be worth looking up some reviews.
Try dpreview or photozone.

[JamesB]

Re: 15mm to 18mm - is there a difference

Thanks, I didn't think of that! The difference seems very little

[Mark]

Re: 15mm to 18mm - is there a difference

theoretically the wider you go there should be a proprtionally smaller impact. Because if you had say 90 degrees in your lmage then you switch to 100 degrees then each degree is compressed into the frame a bit more.
but I'm sure I have read the opposite in reviews of 10 and 12mm wide zooms.
It might be worth looking up some reviews.
Try dpreview or photozone.

It works the other way round, you will see big difference between 15mm and 18mm and more or less no change from 197mm to 200mm

10mm


11mm



14mm


17mm


18mm

[Canon-Fodder!]

Re: 15mm to 18mm - is there a difference

Hi James; I think it was me that made the comment about there not being a great deal of difference between 15 & 18mm, and if you look at Mark's examples above, you can see that... You're probably talking about taking one-step forwards or backwards...

If I recall, my comment was really aimed at your 'requirement' for a wider-angle; and, on a crop-sensor body, the only way you can get truly 'wide' is to go with a purpose-built lens such as the Canon 10-22, Sigma 10-20 or Tamron 10-24... Lenses starting with a native 15mm have 'field-of-view' of 24mm; while 18mm = 29mm; neither of which is truly 'wide'-angle - although, technically, anything less than 35mm FoV is 'wide-angle'... but that's a whole different discussion...

Mark; there's no EXIF data on those examples... what body & lens did you use - and how did you get that diagramatic on... that's quite effective...

[Millie]

Re: 15mm to 18mm - is there a difference

if those images haven't had the vertical and horizontals corrected in PP then I'm a monkies antie

In the interests of reality, let's see some straight out of the camera !
Millie

[Millie]

Re: 15mm to 18mm - is there a difference

I'm not denying 10mm or 16mm on a ff camera has creative and practical applications.

My reality is that most times you are forced have to ‘factor in’ the need for correction into your composition.

With respect those images are more in line with what you’d expect from a lens manufacturer selling the myth of un-distorted wide angle images to newbies.

I hope I’ve made my point in a pleasant, constructive way.

Millie

[JamesB]

Re: 15mm to 18mm - is there a difference

Thanks for all the replies.

I wonder, then, if I'd be better choosing a camera with a full-size sensor?

Jamie.

[Millie]

Re: 15mm to 18mm - is there a difference

I wonder, then, if I'd be better choosing a camera with a full-size sensor?

Not reallyJamie, 16mm on a FF is like 10 on a 1.6 crop.
Why do you want to go very wide, is it landscape or architecture or for large groups.?
You can make the distortion work in your favour, but for more 'record type shots' you’d be looking at correction in PP.

On the 10mm shot from the examples Mark kindly posted: The wall would be sloped; left to right, and the buildings would have converging verticals.
Is that something you'd be happy sorting out in PP, and perhaps having the crop the image in the camera to allow for 'fixing' ?

Millie

[Mark]

Re: 15mm to 18mm - is there a difference

I took the shots from the Tamron site where they have a focal length comparator thing, I'm sure I have seen a Canon one if the past too.

[Millie]

Re: 15mm to 18mm - is there a difference

Mark, I remember seeing a pretty good “focal length visualiser’ on a website somewhere.
You could select the sensor size, and the various focal lengths in mm. It showed the degree of distortion at the various lengths quite accurately. I can’t remember where.

If I get a chance I might take some wide shots and zoom the lens out in mm increments. Unless anyone else would volunteer to do it.
Millie

[JamesB]

Re: 15mm to 18mm - is there a difference

I want to be able to shoot interiors hence the need for a wide angle.

Jamie

[Millie]

Re: 15mm to 18mm - is there a difference

Jamie, If you’re buying a ultra wide to overcome the problem of not being able to ‘get back far enough’ to capture smaller rooms you will have a bit of PP to do, it’s no big deal really, it’s not hard to do.

With interiors the distortion can work in your favour in that it will make rooms appear bigger, ideal if you’re an estate agent You just have to contend with all the vertical and horizontals some software packages even allow you to ‘load lens profiles in’ for correction.

What size would you intend to print your images ?

Millie