Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon EOS dSLR

Reply
 
Thread Tools Search this Thread
Old Jan 6, 2005, 12:19 AM   #11
Senior Member
 
Join Date: Jan 2005
Posts: 301
Default

Hi NHL,

I agree that my first test was a bust because I used the white manual ... which is why I got out my handy-dandy color darkroom guide (knew I'd find a use for it someday) to try some shots using its grey card and color patches pages (grey card on the left, color patches on the right).

I made sure that when using * the center focus point lit up left of center of the open book ... just on the grey card. I wonder if even doing this I'm still catching a good portion of white from the color patch page ... hmmm

In the next day or two I'll try again just shooting the grey card so I can compare the results. I'll also take some time to re-read the manual (maybe twice? :lol before going any further.

I have a feeling that all I'm having is a technique problem. I know I can get good photos using bounce with the camera in manual (C.Fn-14 =1 seems to also help a bit). I'll probably use the other modes only for fill-flash situations. But I'd really like to figure out how to get consistent results using AE lock ... 'cause I know it's probably a great feature for certain situations.

Canon hasn't got back to me with regards to the 8 pictures I sent to them. Since they are RAW they will at least be able to see where the center focus pointwas when the shots were taken.

Regards,

Bob
BobA is offline   Reply With Quote
Old Jan 6, 2005, 8:54 PM   #12
Senior Member
 
Join Date: Jan 2005
Posts: 301
Default

Well ... I repeated the test, using only the grey card area and partial (instead of evaluative) metering. Every one of the 8 exposures was close to perfect.

Finally I think I may be ready to take pictures of ... gulp ... people!

I believe the main reason the test prior to this showed such variation in the results was due to using evaluative metering WITH auto selection of focus points instead of partial metering OR evaluative with the focus point manually selected. Thanks NHL for pointing out that the manual can actually have good info in it!

So far for taking pictures with my 420EX the following settings look like they should work:

1. C.Fn-14 set to 1
2. Bounce flash
3. Partial metering
4. Camera set to manual
5. Use AE lock based on the center focus point

or

1. C.Fn-14 set to 1
2. Bounce flash
3.Evaluative metering
4. Camera set to manual
5. Use AE lock based on a MANUALLY SELECTED focus point

It appearswhen multiple focus points light up, say one on grey and one on pure white, the camera wil underexpose (when using AE lock). The camera probably overexposes if one was on grey and the other on black (maybe I'll test this some day). By manually selecting a focus point the metering is based on the location of the selected focus point when using AE lock which should make it easier to set things up for a proper exposure.



Regards,

Bob A.
BobA is offline   Reply With Quote
Old Jan 7, 2005, 9:03 AM   #13
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

Bob you got it! :idea:

The Canon system is just as accurate as any other - I just see so many people blaming their flash heads when they don't get the basic understanding of how their camera meter work :?

- Are you ready to try the wireless mode? :G :G :G
NHL is offline   Reply With Quote
Old Jan 7, 2005, 11:46 PM   #14
Senior Member
 
Join Date: Jan 2005
Posts: 301
Default

One question ...

The picture Grant posted looks pretty nice at first glance, but when you view the histogram it's piled up on the left side for luminosity and RGB. Does it look to be 1/2 to 2/3 stops underexposed to anyone else?

I've been trying to get a luminosity histogram that isn't piled up on the left, extendingpretty far to the right without blowing out R, G or B. Sometimes (finally) I can get this without any FEC at all ... other times I need +2/3 to +1 stop FEC. The photos always look close to properly exposed if the histogram isn't all to one side.

I'm still not consistent, but if I use the histogram on the camera and shoot to spread the histogram to the right without getting an overexposure warning the result usually doesn't seem to need much digital exposure compensation.

Am I messed up with my approach here?



Bob
BobA is offline   Reply With Quote
Old Jan 9, 2005, 4:45 PM   #15
Senior Member
 
Join Date: Jan 2005
Posts: 301
Default

Well ... I think I learned a few things today.

My 420EX bounce flash photos are "spot on" without using FEC in Manual if I ensure that the background is exposed correctly, pumping up the ISO if necessary. The same goes for Av, Tv and P-Auto. In full Auto the Iso is automatically adjustedup to 400 to do this for you.

In P-Auto mode the camera will switch from flash illumination to fill flash depending on ambient light level. So, sometimes you need higher Isoor FEC and sometimes you don't.

IfI want to use a lower Iso for better resolution (say 100 whenI need 800 to expose the background correctly) then I need to dial in some FEC, otherwise the subject will be underexposed using creative mode settings (including P-Auto if the camera has decided to use it in fill flash mode).

One other thing that I've found is that FE lock (AE lock button) does not meter the same way as for when taking pictures without it. It appears to me that when you use FE lock, it uses some sort of spot metering instead of the complex system normally used. The manual gives a clue on page 95, implying that FE lock uses partial metering around the central focus point. I don't believe it is around the active focus point based on this quote from Canon: "ETTL-II is never linked to the active focusing point". Hmmm ... more tests are required.

Someexamples (center focusing point selected, camera in P-Auto or manual with Iso set high enough to ensure that background can be exposed properly):

Whitesubject on background with lots of different tones is properly exposed using "normal" exposure, but underexposed using FE lock.

Black subject on background with lots of different tones is properly exposed using "normal" exposure, but overexposed using FE lock.

For either of the above testsif I use FE lock off of a grey card at the same plane as the subject the photo is properly exposed.



So, my conclusions are:

1. To get consistently good flash photos either use full auto (with some risk of underexposure if you need greater than Iso 400) or usethe creative modesand adjust Iso, Av and Tv to ensure background is properly exposed. Meter for ambient light (i.e., the background), not the subject when setting up Iso, Av and Tv on the camera.

2. If you want to use an Iso that is too low to properly expose the background, then add some FEC, then look at the histogram after shooting. Most of my indoor shots with room lights on require a histogram that covers almost the full range (climbing immediately from the left and falling off just before reaching the right).

3. Be careful using FE lock, it doesn't work the same as "normal ETTL-II". I can get it to work using a grey card, but for me it doesn't seem to be worth the hassle for candid shots. I'll manually select a focus point instead to avoid focus-FE lock-recompose.



I'm just starting to learn how to use this camera properly (noob alert! :lol, and I'm sure that some of my conclusions could be wrong. If anyone can offer corrections, or confirm that what I've concluded is correct, I'd really appreciate it.



Regards,

Bob A
BobA is offline   Reply With Quote
Old Jan 9, 2005, 8:11 PM   #16
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

... double post
NHL is offline   Reply With Quote
Old Jan 9, 2005, 8:13 PM   #17
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

BobA

The only mode that works best is full-manual while the flash remains on TTL - In Av or Tv the camera try to do a fill with the ambient light so unless the room is totally dark there's always that possibility - While in P you lose both control of the shutter speed and aperture

Also you can disable E-TTL II by flipping the AF/M switch on the lens to manual the camera will then ignore the AF point (and its reported distance info) selected :idea:

FYI - http://www.stevesforums.com/forums/v...42&forum_id=37
NHL is offline   Reply With Quote
Old Jan 11, 2005, 1:19 AM   #18
Senior Member
 
Join Date: Jan 2005
Posts: 301
Default

Thanks for all your help NHL,

I'm finally able to get some pretty nice shots with flash ... even better than what I was getting with my EOS Elan II. I have a feeling if I came from shooting slide film instead of negatives my technique would have been much better to start with.

Getting the image close without blowing out the highlights really improves image quality. I have a few images from when I started this thread that were 2 full stops underexposed, and of course after correcting them they lack detail and are "grainy" looking ... not washed out like when you overexpose, but not great.

Any of the pictures I took that are not piled up on the left of the histogram and are not overexposed (RGB within range) can easily have DEC applied to make a very nice print.

Thanks again!



Bob A
BobA is offline   Reply With Quote
Old Jan 11, 2005, 6:06 AM   #19
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

BobA wrote:
Quote:
Any of the pictures I took that are not piled up on the left of the histogram and are not overexposed (RGB within range) can easily have DEC applied to make a very nice print.
BTW you can also apply 'normal' exposure compensation in combination with FEC flash exposure compensation to shift your histogram... Theses two functions are not mutually exclusive (since the camera also meters the ambient light), and will allow you to control the background!

This isdetailed in the flash manual of the 550EX (butnot the 420EX), but works for either:idea:
NHL is offline   Reply With Quote
Old Jan 11, 2005, 9:18 AM   #20
Senior Member
 
Join Date: Jan 2005
Posts: 301
Default

Thanks again!
BobA is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 3:14 PM.