Aperture range on Canon G7

[Shiffi]

Okay, so I'm completely new to digital photography, but I want a relatively compact digital that I can have some manual flexibility with because I've been using SLRs and other film cameras for a while.

Can someone explain to me how the smallest aperture on the G7 can be 4.8?  My Canon SLR can go to 27.  4.8 seems a ridiculous aperture to set for a landscape shot, though I appreciate the great macro possibilities at the other end of the spectrum.

Is there another way that digital aperture is expressed?  Is this F2.8 - F4.8 range not as absurd as it sounds to a film SLR user?

Because I can't imagine taking a landscape with anything bigger (in size, not number) than at least 16.

Am I completely off track?  

Otherwise this camera looks good to me in terms of meeting my need for manual controls within a compact camera.

Please help!

[Per Ofverbeck]

Okay, so I'm completely new to digital photography, but I want a relatively compact digital that I can have some manual flexibility with because I've been using SLRs and other film cameras for a while.

Can someone explain to me how the smallest aperture on the G7 can be 4.8?  My Canon SLR can go to 27.  4.8 seems a ridiculous aperture to set for a landscape shot, though I appreciate the great macro possibilities at the other end of the spectrum.

Is there another way that digital aperture is expressed?  Is this F2.8 - F4.8 range not as absurd as it sounds to a film SLR user?

Because I can't imagine taking a landscape with anything bigger (in size, not number) than at least 16.

Am I completely off track? 

Otherwise this camera looks good to me in terms of meeting my need for manual controls within a compact camera.

Please help!


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Well, since the sensor is so much smaller, you´ll get far more depth-of-field than you would with a dSLR or film SLR at the same aperture number.  You simply don´t NEED very small apertures with a small-sensor digicam; if you could stop it down to 16 or 22, diffraction would ruin the picture totally.

There are numerous articles about this on the web (at least one recently on this very site).  You might Google for a few, but the best thing would be a number of test shots.  With digital, tests are free, you know.....

[cerebros]

Okay, so I'm completely new to digital photography, but I want a relatively compact digital that I can have some manual flexibility with because I've been using SLRs and other film cameras for a while.

Can someone explain to me how the smallest aperture on the G7 can be 4.8?  My Canon SLR can go to 27.  4.8 seems a ridiculous aperture to set for a landscape shot, though I appreciate the great macro possibilities at the other end of the spectrum.

Is there another way that digital aperture is expressed?  Is this F2.8 - F4.8 range not as absurd as it sounds to a film SLR user?

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Where are you getting that 4.8 is the smallest aperture? The specs for the camera show that this is a variable maximum aperture lens with at its widest end the maximum aperture being F2.8 and at the longest end it's F4.8, hence the "F2.8 - F4.8" marking

This is the same on lenses from other formats with variable apertures so unless you've only ever used constant maximum aperture lenses I'm surprised you've not come across this before.

[BJL]

f/2.8-4.8 is the range of minimum f-stops at the different focal lengths: stopping down to higher f-stops is possible; to about f/8 I think. Though as far as DOF is concerned, these are also comparable to about f/11-22 at equal FOV in 35mm format. That f/8 matches about f/32 in 35mm at equal FOV.

[wood]

Hello Shiffi,

Stop to cry with a compact digital, and buy a new Canon MKIII and you will forget "THIS" problem.


Wood

[dobson]

Here are some useful topics if you are still interested: depth of field, circle of confusion, lens dffraction, effects of sensor size, basic lens geometry, etc. There is a lot of data available on these topics, but making sense of it all will take some effort.

My Canon SLR can go to 27.
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By the way, it is unlikeley that your SLR has a built-in minimum aperture of f27. Both minimum and maximum apertures are determined by the lens you have mounted. While most lenses have a minimum of around 22, thre are lenses that go up well past f40.

Phillip

[peterpix2005]

Isn't this a question of variable aperture based on the lens magnification? 2.8 at the wide end, 4.8 at the long. These are widest apertures, not the smallest.

Peter

[PEHowland]

The G7 has an aperture range from f2.8 to f8.0 at wide angle, and f4.8 to f8.0 at full zoom.

However, this is more than enough.  Firstly, as others have pointed out, the depth of field achieved with f8.0 on a compact camera like the G7 is equivalent to a much smaller aperture on a larger camera.  Secondly, and importantly, with the small 1/1.8" sensor and 10MP, the camera is very limited by diffraction (from about f4.0 onwards).  Thus there is little point going beyond f8.0 as the loss of resolution would be too great.  Remember that the camera offers an ISO80 speed, as well as a builtin neutral density filter, to allow you to shoot with these larger apertures in bright conditions.