Crop factor

Hi, guys and gals.

Im still new with my canon 350, but just had a thought and cant answer it so thought maybe someone here could help

I know the crop factor is 1.6. so for a 50mm lens i times it up by 1.6 to get the correct 80mm figure for the lens.

my query is, when your down at the wide angle lengths, do you still times the crop factor or is it a case of dividing. i.e. does the 18mm wide angle become 28.8mm or 11.25mm.

Just curious really. and many thanks for any comments.

hilandor

18mm wide angle become 28.8mm

Always multiply by 1.6

Many thanks for your reply.

If you have any more crop factor questions, you can probably find the answer here:
https://photography-on-the.net …388&highlight=c​rop+factor

It's perhaps easier to remember that the focal length of your lens won't change regardless of whatever format of camera you attach it to. Ie, a 50mm lens remains a 50mm lens when attached to a 1.6 crop camera but, the angle becomes narower because the sensor doesn't see such a big area of view through the lens as would, for instance, a full-frame sensor

Thanks guys, for your info and links, sifting through them just now

Hilandor, the "crop factor" is something that you don't really need to worry about if the 350D is your only camera. The only reason that anybody needs to even consider the "crop factor" is when comparing shots taken by a 35mm camera (or a "full-frame" digital) to shots taken by a 350D, for example.

In other words - assume that you own a 350D, and you see a shot taken from a known place or distance with a 35mm camera and a 100mm lens. You want to figure out what lens to use on the 350D to duplicate the shot with your camera. You would divide the 100mm by 1.6 and select something around 62mm.

As said above, LENSES DO NOT CHANGE when applying them to cameras with different formats. Only the field of view changes.

Something that is very important to know about your 350D is that a "normal" lens for it is about 28mm to 31mm, depending on your frame of reference. For a 35mm camera, a "normal" lens is about 45mm to 50mm. Any lens with a focal length shorter than the "normal" is classified as a wide angle, and any lens with a focal length longer that the "normal" is classified as a telephoto.

Folks often ask for and get recommendations for focal lengths to do certain tasks (like portraiture) on this and other forums. The responses frequently do not contain the format of the body used, and this can become very confusing. Always make sure that, if you are trying to use this sort of information, that you understand what format the focal length relates to. It can make a significant difference. For example, with 35mm cameras the most-often suggested portrait lens would be about 80mm. For the 350D, the equivalent (again, a calculation with the "crop factor) is a 50mm lens. Use an 80mm lens on the 350D, and you will find that it is usually a bit too long for portraiture at normal camera-subject distances.

Hope this helps your vision of the "crop factor".

Thanks Skip for a detailed understanding of the crop factor. Very helpfull indeed.

I use the term "crop factor" too, and it is the best way to explain what is going on. However, it can also give people the wrong impression ... you're still getting a FULL SIZE image. That's why it's easier to think about it as a focal length magnification ... a 100mm lens on your 1.6x camera will give you an image (angle) like a 160mm lens on a film or FF camera.

BUT, you still get the same DOF (depth of field) regardless of crop factor. So a 100mm lens on your 350 will have a narrower image but the same DOF as that 100mm lens on my D12N (1.3x), which in turn will have a narrower image but the same DOF as that 100mm lens on a 35mm film camera or a FF digital like the 5D or 1Ds2. So while you get more "reach" with your lenses, you don't get the same amount of depth compression. That can be good or bad (just like the "magnification") depending on what you are trying to do.

There is no such thing as crop factor. Your camera shoots the pictures it shoots with any given lenses. Learn what the lens will do on your camera and forget about what it would do if it was on somebody elses camera. It is a waste of time and effort to keep thinking about what a lens would do on a full fram camera if you do all your shooting with a 350.

If you must think about full frame cameras, remember that to calculate what your lens would do on a full frame camera you have to divide by 1.6. Your 50 mm lens acts like a 31.25 mm lens when you put it on a full frame camera. Unless you need a 31.25 mm lens, avoid full frame cameras.

That is certainly a controversial opinion.

I think the religious wars will now commence.

Let's see, this forum has how many hundreds of threads on crop factor?

---Bob Gross---

Too many to count...Everyone (most everyone) calls it the crop factor no matter what it really is and we'll leave it at that. No need beating that horse again. Let's not sit around picking fly poop out of pepper.

Great explanation Skip.

It's not meant to be a controversial opinion. All I am trying to say is that you should concentrate on learning to use your camera and not worry about what your lenses would do if mounted on some other camera. If you are using a 20D it is a waste of time to decide that you would use a 16-35 lens if you had a full frame camera and then work backward to determine you need to get out your 10-22. You are far better off to work at developing your eye so you can just look at a scene and reach into your bag to pull out the 10-22 because that is the lens that will do the job.

I used full frame SLR film cameras for about 25 years before I got my first D60. When I first went digital I would know what 35 mm lens I needed and then have to use that to decide the equivalent lens for digital. It did not take me very long to switch my visualization so that there was no need for the conversion process.

Many young photographers starting out today are going to learn on a 350 or similar camera. Learning a conversion factor is a complete waste of time for them because they do not need it. If they ever switch to a full frame camera they can start to worry about conversions then, if they want, but in my opinion they should just learn to use their new equipment.

Scott

How about we sign a petition to have Canon release a range of lenses that are labelled specifically to be used on amaller sensors. For example, the EF 17-40 would be exactly the same lens, however labelled 27-64 and sold "For use with Canon APSC sensors only". Just think of how many forums will be saved the pain of these Crop Factor Threads in the future.....

The Question was well put, asked and answered. Some good info here,..

I say we quit while were ahead

For anyone finding this action controversial,. I would like to point you once again to this thread as explanation;

10,000,000 Posts on the X-factor

Chris,. Welcome to the forum,.
...based on your post,. I think you'll get a boot out of that link