tag:blogger.com,1999:blog-7826929655032307558.post7785393193583874480..comments2023-12-19T07:15:45.545-08:00Comments on Nikon CLS and TTL/BL flash: Moving the focus point can affect flash output !Desmond Downshttp://www.blogger.com/profile/13628907753894628059noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-7826929655032307558.post-31248811661906208302012-04-02T12:01:54.903-07:002012-04-02T12:01:54.903-07:00Hi Urgyen , a distance difference of 1 meter will ...Hi Urgyen , a distance difference of 1 meter will make quite a few changes to the output as distance info is still used to a small degree when the flash head is tilted. There are many variables with TTL-BL and you need to be in manual mode and find a place where moving the focus point changes exposure to do this test . Different models behave slightly differently and the D300 may not change exposure as much as my D90 so there will be differences between tests done with different models as well .Desmond Downshttps://www.blogger.com/profile/13628907753894628059noreply@blogger.comtag:blogger.com,1999:blog-7826929655032307558.post-19778350317312290342012-04-02T03:52:45.057-07:002012-04-02T03:52:45.057-07:00hi desmond
I did the samething which you've e...hi desmond<br /><br />I did the samething which you've explained here that the overexposure occurs when the focus point is moved from white to dark area. But i found there is no over exposure with the dark area under focus point comparing with the lighter one. I use d300 with sb 900. I then tried to check if its because of focus distance and you know what the shot with one meter behind focued is overexposed than shot focued one meter in front.urgyennoreply@blogger.comtag:blogger.com,1999:blog-7826929655032307558.post-80217158375453263052011-10-01T06:05:35.083-07:002011-10-01T06:05:35.083-07:00No problem :)No problem :)Desmond Downshttps://www.blogger.com/profile/13628907753894628059noreply@blogger.comtag:blogger.com,1999:blog-7826929655032307558.post-22184384273820492062011-10-01T01:53:13.150-07:002011-10-01T01:53:13.150-07:00Hello Desmond
Apologies for a delay in replying. ...Hello Desmond<br /><br />Apologies for a delay in replying. Thanks for the clarifications, very very useful.Anonymoushttps://www.blogger.com/profile/00158635453633257274noreply@blogger.comtag:blogger.com,1999:blog-7826929655032307558.post-54339505548306753592011-08-19T02:48:44.041-07:002011-08-19T02:48:44.041-07:00Hi Paul , thanks for the questions and input .
1.)...Hi Paul , thanks for the questions and input .<br />1.) I do only use TTL-BL now . No flash system is perfect but TTL-BL is the most consistent for me . <br /><br />2.) Yes , obviously the metering increases exposure when it sees the subject as being darker and appropriate exposure compensation would be needed . The primary purpose of this particular discussion is the fact that TTL-BL flash exposure can change "in the same scene" simply by moving the focus point since 3D matrix metering exposes strongly toward the part of the scene under the focus point - and yes , TTL-BL reacts accordingly when it notices the meter drop .<br /><br />3.) Regarding exposure compensation on the camera , the flash will also adjust proportionately . "-1" EV will also drop the flash to "-1" ."-1" on the body and "+1" on the flash will give the same flash exposure as no compensation on either .Desmond Downshttps://www.blogger.com/profile/13628907753894628059noreply@blogger.comtag:blogger.com,1999:blog-7826929655032307558.post-35045338993730220322011-08-19T02:38:00.830-07:002011-08-19T02:38:00.830-07:00Hello Desmond, just wandering around your blog and...Hello Desmond, just wandering around your blog and find it fascinating. No doubt I'll be asking questions on other blog posts you've made. For now a question or three about this particular post.<br /><br />First...do you now use BL exclusively or are there times when you use other flash modes?<br /><br />Second...in this blog post you used exclamation points relating to the brightening of the camera black once the focus point was placed upon it. Is this not a surprise? The camera meters such that an average exposure is achieved. Therefore, black objects cause the meter to increase exposure which may or may not be correct for the photographer. To render that darker subject correctly, ie darker, some degree of negative compensation is required. My understanding is that flash, BL or not, mirrors the camera meter and it's own sensor and will again fire harder than maybe required. So, negative flash compensation required.<br /><br />Third...Following point two above, if I use BL and factor in minus compensation on camera, will BL follow that and fire at a lower level of power? Here I'm thinking the subject backlit on a bright day and metering for the ambient. In camera dropping the ambient by say 1.5 stops. Does BL follow that and provide an appropriate level of power incorporating the -1.5 stops in camera? Or would I need to compensate that -1.5 in camera stops with +stops with flash exposure compensation?<br /><br />Thank you<br />PaulAnonymoushttps://www.blogger.com/profile/00158635453633257274noreply@blogger.com