I need information on Canon 40D

RobertoM · Post by **RobertoM** » Mon Mar 03, 2008 8:14 am

I see that Canon 40D have live view, but I'm not sure can help me to put on focus when I use the microscopy.
I have the Canon 30D and I ask your suggestion.... can I do better focus with live view in Canon 40D?
For me is very difficult put on focus when I see into the 30D and I don't know if the live view of 40D can help me.
It's possible connect 40D with live view to computer for a better focus?
Someone has the Canon 40D and can help me?
Sorry for my english language but I'm sure you understand me... (I hope)
Thanks in advance
Roberto

Cyclops · Post by **Cyclops** » Mon Mar 03, 2008 9:16 am

What is Live view?

lauriek · Post by **lauriek** » Mon Mar 03, 2008 11:06 am

I don't have a Canon, I have the old Olympus E330 which has two live view modes. One of those modes allows you to zoom 10x in on a section of the image (a user selectable area) - I find this useful for critical macro focussing when used with a bellows. I assume it would work the same way on a scope, allbeit with more magnification... I don't know if the 40D has an equivalent of my "Mode B" live view - which is the one with the zoom facility...

Cyclops - live view is simply live view from the sensor onto the LCD, like P&S digicams. DSLRs have only recently started to have this feature.

Cyclops · Post by **Cyclops** » Mon Mar 03, 2008 11:41 am

ah yea my Panasonic has a similar thing, you can select it as a focusing method when in manual focus.
Magnifies the central part of the image.

DaveW · Post by **DaveW** » Mon Mar 03, 2008 12:05 pm

Yes Cyclops, but the latest DSLR's have now added contrast based AF which allows the camera to autofocus with the mirror up, something earlier Canon DSLR's could not do . I am not sure but I think Nikon was first to do this with DSLR's because contraset based AF uses the taking sensor itself for autofocus, as do most compacts, not the usual separate autofocus sensor which is put out of action by raising the mirror. The main problem is contrast based AF is much slower than conventional autofocus. This is the blurb for the Nikon D300:-

"Nikon's live view implementation on the D300 is one of the most usable and comprehensive to date, the high resolution screen and addition of contrast detect auto focus, in addition to the now typical mirror down / mirror up passive auto focus system, mean that are more situations where live view becomes useful.

Live view (auto focus) mode

As noted the D300 supports two AF methods which Nikon call Tripod and Hand-held modes, both require you to use the AF-ON button to achieve auto focus. In Tripod mode auto-focus is achieved using the main image sensor in a "contrast detect" manner (the same as a compact camera), this tends to be slower than normal passive AF but does maintain the live view. In Tripod mode you can move the AF point anywhere within the frame using the multi-selector. In Hand-held mode the live view blanks out when you press AF-ON, the mirror drops and the camera focuses using the normal "passive" auto-focus sensor. Live view only returns when you release the AF-ON button, I personally found this a bit annoying, it should return as soon as the camera achieves AF lock."

See also:-

http://www.komar.org/faq/camera/canon-4 ... live-view/

Canon has also added contrast based AF to it's new cameras so they can now autofocus, if slowly, with the mirror up in Live View I believe.

DaveW

augusthouse · Post by **augusthouse** » Mon Mar 03, 2008 5:58 pm

Roberto,
If you go to www.youtube.com and type Canon 40D in the search box you will find a number of video reviews that demonstrate features including the 'Live View' aspect.

I would be interested to know just how much we will come to use the Live View in a serious way. The demos I have seen are rather impressive. Keep in mind that the Nikon D300 has 4x the resolution on the LCD in Live View. I mention this because I am considering either a Canon 40D or a Nikon D300.

Craig

Bob · Post by **Bob** » Mon Mar 03, 2008 9:49 pm

The Canon 40D Live View provides an excellent method of precisely determining and adjusting focus. I can see no reason it would not work out great for use with a microscope.

To use the Live view mode you first switch the lens to manual mode and then push the set button, which activates the Live view mode (if the camera custom functions have been setup that way). This lifts the mirror up and allows the light to reach the sensor. This signal is then relayed to the viewing screen on the back of the camera in real time. You then focus on the subject as seen in the viewing screen. For extra fine focusing you can magnify the image either 5X or 10X (which is more than sensitive enough to evaluate your focus and depth of field.)

I have found this approach to be very easy to use in the field with a 100 mm macro lens and it is extremely sensitive. It is also a lot better than any other method I know to precisely set focus.

I have also found Live view to be a an excelent method of reviewing the composition of the image along with depth of focus. The large viewing screen is like using the ground glass on a view camera but the image is not upside down. Another advantage is that the mirror will stay retracted during the total process, which therefore reduces the potential vibrations associated with the mirror motion. And, you do not have to stand on you head to get to the eyepiece when photographing low lying subjects.

Bob

elf · Post by **elf** » Mon Mar 03, 2008 11:38 pm

The 40d liveview when tethered to a computer should work quite well for focusing when attached to the microscope. I can't imagine why anyone would want to do it differently. One nice thing the Canon software does is let you adjust focus from the computer.

I have the Olympus e330 and unfortunately the SDK doesn't expose focusing or Mode B Liveview to computer control.

I'd really like to be able to shoot macro stacks without touching the camera, but will need a new camera to do so.

RobertoM · Post by **RobertoM** » Tue Mar 04, 2008 1:14 am

Thanks!
But when I connect the 40D to the computer and use the live view and the canon software, what I see in the computer's screen?
I see a full screen image or a little windows?
At the moment, if I buy a 40D, want use the live view only with a tube adapter connected to the trinocular microscope.
For the focus I use only the movement of the microscope table.
That I want to say, is I want use the computer screen (full image?) for put on focus better than to see into 40D lcd screen.
I hope you understand my poor poor english language...
Roberto.

RobertoM · Post by **RobertoM** » Tue Mar 04, 2008 1:51 am

I see on youtube and I understand.
Thanks.
Roberto.