Digital Rebel front focusing

msvadi wrote:
Tom,

I have to say that this is a fantastic picture Seriously, great results.

Today I spent another couple of hours on testing. (My wife looks at me like if I were going mad. I wonder why... It cannot be the target charts hanging on every wall in our aprtment )

The results varied from bad front focus to almost okay. User erros (me ), poor light conditions, distance from the target, target properties all can affect the outcome.

Anyway, here's the result with 50mm 1.8 at 1.8:

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And another one:

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Thanks! I appreciate it, and the lens does as well. Frankly, I was a little surprised at how well it did, considering how I struggle with it sometimes in that very shallow DOF.

The red stripe really pulled that focus into the middle! One of the problems with using the bare chart is that you have quite a few hash-marks that the camera can potentially lock focus on. Here's a link to a shot of the focus sensor arrangement overlaid with the focus indicator boxes:

http://www.pbase.com/i​mage/18920257

The reason I used an external focus point was to avoid the camera locking on to the wrong thing (and this is especially true in low light). That center cross is quite big, and for some reason, the 50's like to grab focus on the wrong subject sometimes. They're accurate, but incorrect if you know what I mean.

Check out Pekka's test setup here:

https://photography-on-the.net/forum/showthre​ad.php?t=10526

Thanks Tom, very usefull info

If you have 300D, you cant lockup the mirror unfortunately. However, here is one tip that will help. If you are taking a picture that is in the timing range in which mirror slap affects the picture the most, turn the camera vertically and take the picture. This will reduce mirror slap almost completely.

Thanks for the advice. I've been thinking about it more, and the possibility of vibrations coming up from the floor seems most likely. BTW, it's a 300D. No one was walking around, but I did have the height extension cranked way up and I did notice that the camera wobbled quite a bit. It steadied out by the time the timer was up, but that's only what I could perceive through the viewfinder. Perhaps it was moving still... Or else it was this "mirror slap" that you speak of.

Thanks again...

Bill

Having the extension cranked up can amplify any small vibration. It doesn't take much movement considering that your target is several feet away.

OK, re-confirmed it tonight. Everything the same, tripod head extension fully retracted. Much better and mucho gracias.

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