Focal lenght indicator

[antbrown]

Does anyone know if the G3 will display focal lenghts as you zoom in and out? I'd like to use hyperfocal settings for low light photography but I need to know what focal lenght the lens is using.

Thanks,

Michael

[darrylr]

There is nowhere on the camera that displays the focal length. The only way I know of is to look at the EXIF data stored in the JPEW/CRW files after transferring to your PC.

-Darryl

[dtrayers]

Czech :D out this thread:

http://photography-on-the.net/forum/showthread.php?t=10973

[Andy_T]

Shouldn't you zoom out completely for Hyperfocal anyway??? ?

Regards,
Andy

[Man-Fai Wong]

andythaler wrote:
Shouldn't you zoom out completely for Hyperfocal anyway??? ?


No. That's only true if you're using a hyperfocal distance for full wideangle focal length. Basically, every combo of focal length and aperture has its own hyperfocal distance (and corresponding DoF).

You're probably confusing the whole concept of hyperfocal distance w/ just the one specific, popular case used by many for the G3 (as found on someone's webpage).

For example, if you find that you generally enjoy shooting at say 50mm equiv, which seems common for portraits, you might want to create a custom mode w/ different appropriate hyperfocal settings just for this -- say f5.6, manual focus at 10ft for DoF from 5ft to near infinity. Now, in practice, you may not really want this for shooting portraits since high DoF is not what people usually want for this, but it's a possibility.

And since we don't have very many custom modes for storing presets, that's why a DoF calculator or chart/table can be very useful on the field (and why having focal length indicator would be nice beyond just figuring it out from EXIF or doing carefully measured focus lock, etc.). And yes, a DoF calculator is useful in more general application than just figuring out hyperfocal distance since we don't always want near infinite DoF.

_Man_

[PFlor]

andythaler wrote:
Shouldn't you zoom out completely for Hyperfocal anyway??? ?

Regards,
Andy

In theory, no. But in real-world use on the G3 you can only use it effectively when completely zoomed out (7.2mm) or at full zoom (28.8mm) since there is no easy way to get a focal reading anywhere in between.

[Man-Fai Wong]

PFlor wrote:
andythaler wrote:
Shouldn't you zoom out completely for Hyperfocal anyway??? ?

Regards,
Andy

In theory, no. But in real-world use on the G3 you can only use it effectively when completely zoomed out (7.2mm) or at full zoom (28.8mm) since there is no easy way to get a focal reading anywhere in between.

Unless you do as suggested in the link above it seems. :D

Anyway, it's not all that hard to find a particularly focal length beforehand and apply it to a preset custom mode for later usage, if so desired. It just requires some effort (and checking the EXIF data). No, this means you can't do this on-the-fly in the field, but if all you want is a custom mode for a certain type of shooting that you frequently do (or expect to do for a certain occasion), then it's certainly doable.

And of course, you could resort to tricks/workarounds like the one found in the link above although one wouldn't be able to use that one w/ a Lensmate adapter attached.

BTW, one possible trick I noticed, but have not really tested out, is making use of the zoom head readout of the Canon speedlight external flashes, if you own one and don't mind keeping it attached for this purpose. IIRC, the 420ex, for example, is supposed to zoom its flash head to the closest setting that's equal to or one step shorter (ie. wider angle) than the camera's own lens focal length. Based on this, if you map out the lens focal lengths that correspond to the various zoom steps of the flash (at the points where the flash zoom changes), you will at least have a reasonably useful way to figure out some of the focal lengths in the field.

For example, the 420ex has zoom steps of 24/28/35/50/70/105mm. With that, you should be able to map out the 2 focal lengths that are just below and above 50mm (let's say 46mm and 54mm hypothetically) and use the flash to help you find the focal length position in the field based on the LED readout.

It's a bit of a kluge, but it can be better than nothing. And in the large majority of times when you really need this, ie. low light/indoors yielding difficult AF, you'll probably also want your speedlight attached anyway, even if you're not going to fire it for a particular shot you're using this trick for.

_Man_

[Andy_T]

Man-Fai Wong wrote:
andythaler wrote:
Shouldn't you zoom out completely for Hyperfocal anyway??? ?


No. That's only true if you're using a hyperfocal distance for full wideangle focal length. Basically, every combo of focal length and aperture has its own hyperfocal distance (and corresponding DoF).



My impression was that the DOF tends to decrease rapidly on the G2/G3 once you zoom in making it too shallow for quick hyperfocal shots at any zoom but 7.2 ... but I'd love to be wrong :)

Regards,
Andy

[Man-Fai Wong]

andythaler wrote:
Man-Fai Wong wrote:
andythaler wrote:
Shouldn't you zoom out completely for Hyperfocal anyway??? ?


No. That's only true if you're using a hyperfocal distance for full wideangle focal length. Basically, every combo of focal length and aperture has its own hyperfocal distance (and corresponding DoF).



My impression was that the DOF tends to decrease rapidly on the G2/G3 once you zoom in making it too shallow for quick hyperfocal shots at any zoom but 7.2 ... but I'd love to be wrong :)

Regards,
Andy

Yes, for any given hyperfocal setting, if you zoom toward longer focal lengths, you will decrease DoF quite quickly. BUT that's not what we were talking about. We were talking about trying to figure out hyperfocal distance for any given combo of focal length and aperture. So if you want infinite DoF for say 80mm focal length, you can do it as long as the G3 allows, which it may or may not depending on its manual focus capability. Of course, it's also not easy to know your focal length on-the-fly since the G3 doesn't tell you.

_Man_

[antbrown]

Is this something that could be fixed with a firmware update?

Michael

[wibbly]

antbrown wrote:
Is this something that could be fixed with a firmware update?

Michael

Possibly, but it won't likely happen now the G3 is discontinued.

Actually, accurate focus distance is also hard to judge with the current firmware.

What would be really cool would be a hyperfocal mode:

- Set any focal length and aperture
- Camera locks in hyperfocal distance
- Just point and shoot
- Half press of shutter indicates go/no-go 'focus in range' for the current subject in the frame

W

[civis]

wibbly wrote:
What would be really cool would be a hyperfocal mode:

- Set any focal length and aperture
- Camera locks in hyperfocal distance
- Just point and shoot
- Half press of shutter indicates go/no-go 'focus in range' for the current subject in the frame


If you're going to ping the target to get the distance, doesn't that pretty much add back in most of the lag that you just got rid of with your hyperfocal preset?

[wibbly]

Only if you have to wait for it to complete.

Press the shutter half way and wait for go/no go or just press it all the way to shoot. The lens is already focused at the hyperfocal distance (so doesn't have to to re-focus).

Only gotcha I can think of is that the lens may have to re-focus to determine the current range?!? - unless of course another type of range finder could be provided for the purpose...

W