Why Full-Frame?

[Bobby Ironsights]

That's wrong! The maximum aperture depends only on the lens, not on the sensor/film you put behind it.

Wrong eh? Well I guess it's possible, it's happened before, let's think about this.

F number does not directly correlate to aperture, f-number is a ratio. Focal length divided by size of maximum exit pupil.

An f/1.4 50mm, is a 35mm exit pupil. A 35mm maximum exit pupil, with a new effective focal length of 85mm, is now 85/35 or f 2.4.

Right.....or Wrong? Teach Me.

 

[Steph]

Wrong eh? Well I guess it's possible, it's happened before, let's think about this.

F number does not directly correlate to aperture, f-number is a ratio. Focal length divided by size of maximum exit pupil.

An f/1.4 50mm, is a 35mm exit pupil. A 35mm maximum exit pupil, with a new effective focal length of 85mm, is now 85/35 or f 2.4.

Right.....or Wrong? Teach Me.

Wrong. The focal length of the lens does not change! It is still 50mm. The field of view on a cropped sensor of a 50mm lens is equivalent to the field of view of a 85mm on a full frame, that's all. The focal length of the lens is still 50mm, whatever camera you use behind it.

 

[Bobby Ironsights]

Wrong. The focal length of the lens does not change! It is still 50mm. The field of view on a cropped sensor of a 50mm lens is equivalent to the field of view of a 85mm on a full frame, that's all. The focal length of the lens is still 50mm, whatever camera you use behind it.

Absolutely, the NOMINAL focal length of the lens when focused to infinity is technically the same, but the EFFECTIVE focal length of the lens is increased by the change in angle of view.

I can quote the basic physics here from Wikipedia.

If two cameras of different format sizes and focal lengths have the same angle of view, and the same aperture area, they gather the same amount of light from the scene.

However, while in the case of a 35mm slr lens, the aperture area remains the same.....the ANGLE OF VIEW decreases, which, while not exactly the same, has the same effect on the equation as if the focal length had changed for all practical purposes.

If you have a reply, lets go to the other thread to avoid crossposting.:lmao:

 

[Steph]

If you have a reply, lets go to the other thread to avoid crossposting.:lmao:

OK. Done.

 

[Bobby Ironsights]

http://www.thephotoforum.com/forum/showthread.php?p=1060609#post1060609

Ok, Steph, you were right, I was wrong, above is the link to the post for anyone who cares to read it.

 

[Helen B]

F number does not directly correlate to aperture, f-number is a ratio. Focal length divided by size of maximum exit pupil.

An f/1.4 50mm, is a 35mm exit pupil. A 35mm maximum exit pupil, with a new effective focal length of 85mm, is now 85/35 or f 2.4.

Right.....or Wrong? Teach Me.

The focal length error has already been cleared up, but the f-number is calculated from the entrance pupil, not the exit pupil.

Best,
Helen

 

[Alex_B]

The focal length error has already been cleared up, but the f-number is calculated from the entrance pupil, not the exit pupil.

Best,
Helen

Is this because the exit pupil is usually large enough anyway so it is not the limiting factor?

 

[Helen B]

Yes, but the size of the exit pupil may be different from the size of the entrance pupil. To expand, in a simplified, brief way:

The amount of light entering the lens is determined by the size of the entrance pupil.

All the light that passes through the entrance pupil leaves the exit pupil (because they are both merely images of the iris, unless there is some other obstruction or 'stop').

The exit pupil may or may not be the same size as the entrance pupil, so the intensity of illumination of the exit pupil may or may not be different from that of the entrance pupil.

Symmetrical lenses are likely to have entrance and exit pupils of the same or similar sizes. Retrofocus lenses are likely to have an exit pupil that is larger than the entrance pupil. Telephoto (used in the sense of lens design, not focal length) lenses are likely to have an exit pupil that is smaller than the entrance pupil. If you have a look at your lenses from the front then the back you should be able to see this.

Does that make sense?

Best,
Helen

 

[Alex_B]

Does that make sense?

To me, yes. This is pretty close to what I thought (maybe just different wording). Just wanted to be sure.

By the way, be aware that some people confuse exit and entrance pupil in terms of words. At least I encountered this in discussions that they were pointing at the right thing giving it the wrong name.

 

[RyanLilly]

forgot one more ... if you also shoot film, you do not have to adjust your brain to two different media sizes when using the same lenses (as I do).

This also brings up a good point, that some people look down upon crop sensors compared to full frame, but really like you said I consider it like another media standard.

Crop sensors are a great format in many situations, just as medium format films are great in other situations where small formats won't do as well.

One sandwich, Makes a great lunch for one person, an d a 6 foot sub would be a waste.

conversely try to feed a family with one sandwich, but the 6 foot sub could be just right.

Ok, stupid analogy, I think I need a sandwich!:mrgreen:

Edit: that was actually a metaphor.
An analogy would be, Crop sensor is to sandwich, as Full-frame is to 6-foot sandwich.

 

[Seefutlung]

I use both a FF and a cropped sensor. I go between the two cameras quite easily. Typically I have a wide lens on the FF and a tele on the cropped.

When I shoot with one camera, it still isn't a big deal, it's all a matter of lens choice ... I need to use wider lenses on the cropped camera and longer lenses on the FF camera to get equalivent images.

My only regret is that I purchased some EF-S lens.

Gary

PS- I don't see a significant dif between the two sensors at 8x10 or less.

G

 

[usayit]

This is probably a similar discussion photogs had when professionals were contemplating a change from MF to 35mm film.

It is just easier to treat cropped sensors as another medium... just like MF shooters had to when they picked up a 35mm camera.

 

[table1349]

Nothing to do with the sensor and everything to do with the camera construction. But typically the expensive FF cameras do have expensive pentaprisms and expensive focusing screens/mirrors which make for a brighter viewfinder.

You are correct, the brighter viewfinder is a by product of that FF camera with the more expensive and larger pentaprisim and focusing screen/mirror.

 

[jstuedle]

What are the benefits of Full-Frame sensors?

Simply personal preference that is often influenced by your choice of lenses. Also, in any specific generation of sensor technology, the bigger sensor at any given resolution has the potential to have less noise at higher ISO values.

 

[Iron Flatline]

The reason I don't want a cropped sensor is because I can still crop later when I get home. Why limit my gear? The only reason cropped sensors exist at all is because technology, construction costs, and manufacturing tolerances made it impossible to create a competitively priced product at consumer pricing levels. Now we're getting closer. Yes, you can treat cropped sensors (APS-sized) as a different medium compared to "Full Frame" sensors (or Small Format, as they were still called a few years ago)... but I think they will disappear soon.

APS SLRs didn't work as a business either. In a few years no one will be making APS dSLRs either.