D60 1.6 cropping effect on flash coverage.

I have a D60 and a 420EX flash. I can't help but think that I am not getting the full use of power from my flash. Example: If I have my 50mm mounted on the D60. My flash will set itself to 50mm also. When in reality, I need a flash zoomed to 80mm. The closest to that setting on the flash is 70mm. So it should be zooming to that, at least. This is something that Canon hasn't addressed what-so-ever. I can't help but think that this has something to do with the underexposing problem that everyone has. Now, the first thing people are going to say, is that the preflash measures the output to produce a properly exposed picture. Well, think about this. The preflash fires, the camera measures the light, and then fires the main flash according to the Canon algorythms for 50mm!. Then at 80mm, my picture is going to be underexposed, right? If anyone out there has a D60 and a 550EX, I would love for them to try some sample pictures with the flash at camera settings, and then manually zoomed. It may make a difference!

John

I don't see it this way. It is actually a cropping factor.

The flash covers the focal length of the lens, reguardless of what the image sensor records.

If our D60's had a full size sensor the same size as a piece of old 35mm film, your flash would cover all of the 24mm that the image sees. Our D60's however have a much smaller sensor, which only sees the middle portion of that piece of film.

So your flash is covering more than you are capable of recording with your D60.

I have had no problems with my D60 with a 380EX as far as coverage goes.

To all other who read this, Am I on the right track?

i see this issue the same way as GenEos. i have a 420ex as well & i've never had a problem or concern w/ it not being powerful enough... i think you're fine... a 50mm lens behaves optically like a 50mm lens.

I don't think there would be any problem with the exposure. but i think there are 2 issues that concern me:

1- since the flash (I use the 550EX) does not take the 1.6x factor into consideration, the extra output would be wasted. power is wasted in covering a wider angle.

2- since the power is 'wasted' on lighting up a wider-than-necessary angle, the range of the flash is sacrificed in a sense. of course, this only applies to lenses up to 65mm (which converts to about 105mm) for a 550EX (which has max zoom at 105mm).

i guess a solution for this would be to attach a telezoom adapter (of a 1.6x factor) to your flash head. unfortunately i haven't seen any yet. any recommendations?

For this explanation lets assume this senario:

Distance to subject is 10 meters.
Subject is a very large target with 10 rings around the center dot.

Example 1: Film Body, 100mm lens, flash.

At this distance with a 100mm lens you end up with a nicely lit shot of the entire target and its 10 rings.

Example 2: D1s, 100mm lens, 550EX flash

Same results as with the film body as far as what ends up in the image.

Example 3: D60, 100mm lens, and a 550EX

You end up here with a picture of the center of the target and 7 of the rings. Nicely lit from the flash.


Now, that same lens sees all that the other two bodies do, but the rest of the image is lost inside the body of the D60 because the image sensor is not big enough to capture it. Would more light help this? Not really. It calculates distance to subject and light needed to illuminte the subject. Setting the zoom to go any further may result in a hot spot, but if you are beyond the zooming capability of the flash, say over 105, then you need a flash attachment to make it go farther anyway.

Point here is that there is no zooming going on, we with D60's just aren't getting the whole picture.

It is almost a false positive for zoom shooters...it makes us think we have more focal length than we do, however, the high resolution capability of the sensor does a pretty good job of fooling us.

I know one thing, I have wanted a 16-35mm even before I got my D60 and now I want one even more...I almost require it now...

Just my 2 cents worth.

I don't think there would be a hot spot, since E-TTL would take care of it, right?

Good point, guess that is what I get for thinking about it too much....