nikonians

Even though we ARE Nikon lovers,we are NOT affiliated with Nikon Corp. in any way.

| |

Sign up Login
Home Forums Articles Galleries News Workshops Shop Recommended
members
All members Wiki Contests Vouchers Apps Newsletter THE NIKONIAN™ Magazines Podcasts Fundraising
Go to a  "printer friendly" view of this message which allow an easy print Print Go to the page which allows you to send this topic link and a message to a friend Email this topic to a friend
Forums Lobby MASTER YOUR TOOLS Nikon Speedlights & Lighting topic #38452
View in linear mode

Subject: "New CLS Preflash Sequence Images" Previous topic | Next topic
HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.   Phoenix, US  Charter Member Thu 15-Jan-09 08:25 PM
8551 posts Share on Facebook Share on Twitter Share on Linkedin    Click to send email to this author Click to send private message to this authorClick to view this author's profile
"New CLS Preflash Sequence Images"
Wed 21-Jan-09 12:19 AM by HBB


I finally got around to exploring the CLS preflash sequence in a bit more depth. The following pair of images and explanation are my latest effort.

Two D2X cameras were used, separated by about ten feet in a darkened room. The subject D2X was on a tripod with an SB800 mounted in the hot shoe. Beside it was a light stand with three more SB800s clamped to the column and aligned with the on-camera unit. This camera was set for 1/30 sec shutter time and rear curtain synch for the SB800 speedlights, to provide an interval between the preflash and image capture sequences. The shutter delay was set for ten seconds.

The second D2X (capture camera) was on a tripod with the a 14-24 mm F/2.8 lens. Its shutter time was set to three seconds. To capture the images, I pressed the shutter on the subject camera, starting the ten second timer. I walked to the capture camera and watched the red timing light on the subject camera. When it turned steady, I pressed the shutter on the capture camera and started rotating it through a ninety degree or so arc. With a few practice tries, I could capture the entire preflash and image capture pulse sequence in the center of the capture camera frame. You will notice slight timing variations in the images as I cannot guarantee that my rotational velocity was constant.

Top Image

This image shows all four SB800s in the CLS TTL mode at 0.0 exposure compensation. Under column "M" (master) the on-camera SB800 emits a series of pulses and calculates an exposure compensation value for itself. Then, under column "A" (group A) it exchanges a series of pulses with the Group A SB800 and sends it an exposure compensation value. This process is then repeated for groups B and C. During this interval, the shutter remains closed as indicated at the bottom of the chart.

The shutter opens at the left edge of the "All" column. Just prior to the end of the shutter interval, the on-camera master emits a low power triggering pulse. A short interval later, all four units fire in sync for image capture. Then the shutter closes.


Bottom Image

Two changes were made in this sequence. The on-camera master was set to OFF (---) and the Group B SB800 was set to manual mode at the M1/2 power level.

Under the left-most column "B", the on-camera master emits a pulse that delivers the M1/2 power level to the Group B SB800. This is a one way transmission, as there will be no reading of reflected light and exposure compensation calculation. In other tests, it appears that the Manual mode power levels are always sent prior to any TTL exchange and exposure compensation calculations.

Following this, the Group "A" and "C" preflash sequences are exchanged as in the Top Image.

AT the left edge of the "All" column, the shutter opens. Just prior to the end of the shutter interval, the on-camera master emits a low power triggering pulse. A short interval later, the Group "A", "B" and "C" SB800s fire in sync for image capture. Notice that the on-camera master SB800 does not fire in synch with the other units, as it has been set to OFF (---). Then the shutter closes.


Summary Comments

Without a four channel recording oscilloscope, I am unable to decode the preflash pulses in any greater depth. Earlier work with Nikonian Alson in Holland disclosed that some form of amplitude/frequency modulation coding is apparently employed for the preflash sequence, which must contain channel, group and exposure compensation data at a minimum. My current, ancient oscilloscope is a single channel, non-recording model. My NAS keeps overpowering my motivation to acquire such an instrument.

I suspect, but cannot prove, that the CLS technology makes some kind of negative exposure compensation calculation for multiple remote units to allow for overlapping coverage of the subject. Only Nikon knows, and they never reveal things like this.

Hope this helps take a bit of mystery out of the CLS preflash sequence.

Comments and questions welcome!

More later ... perhaps.

Regards,

HBB in Phoenix, Arizona
Nikonian Team Member

Go here for a list of membership upgrade benefits.

Photography is a journey with no conceivable destination.





Attachment #1, (jpg file)
Attachment #2, (jpg file)

  

Alert Print | Reply | Quote

Pinned topicNew CLS Preflash Sequence Images [View all] , HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources. , Thu 15-Jan-09 08:25 PM
 
Subject Author Message Date ID
Reply message RE: New CLS Preflash Sequence Images dgillilan Silver Member
29th Jan 2009
1
Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
29th Jan 2009
2
     Reply message RE: New CLS Preflash Sequence Images dgillilan Silver Member
30th Jan 2009
3
Reply message RE: New CLS Preflash Sequence Images bclaff Silver Member Awarded for multiple contributions for the Resources
03rd Feb 2009
4
Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
03rd Feb 2009
5
     Reply message RE: New CLS Preflash Sequence Images bclaff Silver Member Awarded for multiple contributions for the Resources
04th Feb 2009
6
Reply message RE: New CLS Preflash Sequence Images nrothschild Neil is an expert in several areas, including camera support
04th Feb 2009
7
Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
04th Feb 2009
8
     Reply message RE: New CLS Preflash Sequence Images jtzim
06th Feb 2009
9
          Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
06th Feb 2009
10
Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
15th Feb 2009
11
Reply message RE: New CLS Preflash Sequence Images bclaff Silver Member Awarded for multiple contributions for the Resources
15th Feb 2009
12
     Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
15th Feb 2009
13
          Reply message RE: New CLS Preflash Sequence Images bclaff Silver Member Awarded for multiple contributions for the Resources
15th Feb 2009
14
               Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
15th Feb 2009
15
Reply message RE: New CLS Preflash Sequence Images caprae
17th Feb 2009
16
Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
18th Feb 2009
17
     Reply message RE: New CLS Preflash Sequence Images nightcat
18th Feb 2009
18
     Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
18th Feb 2009
19
     Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
18th Feb 2009
20
     Reply message RE: New CLS Preflash Sequence Images bclaff Silver Member Awarded for multiple contributions for the Resources
18th Feb 2009
21
     Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
18th Feb 2009
22
     Reply message RE: New CLS Preflash Sequence Images Lakeesh
10th Aug 2009
46
          Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
11th Aug 2009
47
Reply message RE: New CLS Preflash Sequence Images john barlow
24th Feb 2009
23
Reply message RE: New CLS Preflash Sequence Images bclaff Silver Member Awarded for multiple contributions for the Resources
24th Feb 2009
24
Reply message RE: New CLS Preflash Sequence Images john barlow
24th Feb 2009
25
Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
24th Feb 2009
26
     Reply message RE: New CLS Preflash Sequence Images jrp Administrator JRP is one of the co-founders, has in-depth knowledge in various areas. Awarded for his contributions for the Resources
25th Feb 2009
27
     Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
25th Feb 2009
29
     Reply message RE: New CLS Preflash Sequence Images john barlow
25th Feb 2009
28
          Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
25th Feb 2009
30
               Reply message RE: New CLS Preflash Sequence Images john barlow
25th Feb 2009
31
                    Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
25th Feb 2009
32
                         Reply message RE: New CLS Preflash Sequence Images nl
26th Feb 2009
33
                              Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
27th Feb 2009
34
                                   Reply message RE: New CLS Preflash Sequence Images PAStime Silver Member
06th Mar 2009
35
                                        Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
06th Mar 2009
36
Reply message RE: New CLS Preflash Sequence Images ScottChapin Moderator Awarded for his high level skills in various areas, including Aviation and Birds Photography
09th Mar 2009
37
Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
09th Mar 2009
38
     Reply message RE: New CLS Preflash Sequence Images ScottChapin Moderator Awarded for his high level skills in various areas, including Aviation and Birds Photography
09th Mar 2009
39
          Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
09th Mar 2009
40
               Reply message RE: New CLS Preflash Sequence Images ScottChapin Moderator Awarded for his high level skills in various areas, including Aviation and Birds Photography
09th Mar 2009
41
                    Reply message RE: New CLS Preflash Sequence Images km6xz Moderator Awarded for his in-depth knowledge in various areas, including Portraits and Urban Photography
25th Mar 2009
42
                         Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
25th Mar 2009
43
                              Reply message RE: New CLS Preflash Sequence Images km6xz Moderator Awarded for his in-depth knowledge in various areas, including Portraits and Urban Photography
25th Mar 2009
44
                                   Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
25th Mar 2009
45
Reply message RE: New CLS Preflash Sequence Images picmax
04th Nov 2009
48
Reply message RE: New CLS Preflash Sequence Images picmax
11th Nov 2009
49
     Reply message RE: New CLS Preflash Sequence Images km6xz Moderator Awarded for his in-depth knowledge in various areas, including Portraits and Urban Photography
11th Nov 2009
50
     Reply message RE: New CLS Preflash Sequence Images picmax
11th Nov 2009
52
     Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
11th Nov 2009
51
     Reply message RE: New CLS Preflash Sequence Images picmax
11th Nov 2009
54
          Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
11th Nov 2009
55
     Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
11th Nov 2009
53
          Reply message RE: New CLS Preflash Sequence Images picmax
15th Nov 2009
56
               Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
15th Nov 2009
57
                    Reply message RE: New CLS Preflash Sequence Images picmax
16th Nov 2009
58
                    Reply message RE: New CLS Preflash Sequence Images picmax
16th Nov 2009
59
                         Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
16th Nov 2009
60
                         Reply message RE: New CLS Preflash Sequence Images picmax
16th Nov 2009
62
                              Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
16th Nov 2009
63
                              Reply message RE: New CLS Preflash Sequence Images gkaiseril Gold Member
16th Nov 2009
64
                              Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
16th Nov 2009
67
                                   Reply message RE: New CLS Preflash Sequence Images gkaiseril Gold Member
16th Nov 2009
68
                                   Reply message RE: New CLS Preflash Sequence Images picmax
17th Nov 2009
72
                              Reply message RE: New CLS Preflash Sequence Images picmax
17th Nov 2009
74
                              Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
16th Nov 2009
65
                                   Reply message RE: New CLS Preflash Sequence Images gkaiseril Gold Member
16th Nov 2009
66
                                        Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
16th Nov 2009
69
                                        Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
17th Nov 2009
70
                                        Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
17th Nov 2009
71
                                        Reply message RE: New CLS Preflash Sequence Images picmax
17th Nov 2009
73
                                        Reply message RE: New CLS Preflash Sequence Images picmax
17th Nov 2009
75
                                             Reply message RE: New CLS Preflash Sequence Images km6xz Moderator Awarded for his in-depth knowledge in various areas, including Portraits and Urban Photography
17th Nov 2009
76
                                             Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
17th Nov 2009
77
                                             Reply message RE: New CLS Preflash Sequence Images gkaiseril Gold Member
17th Nov 2009
78
                                             Reply message RE: New CLS Preflash Sequence Images picmax
17th Nov 2009
79
                         Reply message RE: New CLS Preflash Sequence Images Arkayem Moderator Awarded for his high level skills in flash photography
16th Nov 2009
61
                              Reply message RE: New CLS Preflash Sequence Images dondiego
28th Dec 2009
80
                                   Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
29th Dec 2009
81
                                        Reply message RE: New CLS Preflash Sequence Images dcayers Silver Member
22nd Feb 2010
82
                                             Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
26th Feb 2010
83
                                                  Reply message RE: New CLS Preflash Sequence Images ctadin Silver Member
27th Feb 2010
84
                                                  Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
02nd Mar 2010
85
                                                  Reply message RE: New CLS Preflash Sequence Images jhanes55 Silver Member
15th Mar 2010
86
                                                  Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
15th Mar 2010
87
                                                  Reply message RE: New CLS Preflash Sequence Images jhanes55 Silver Member
16th Mar 2010
88
Reply message RE: New CLS Preflash Sequence Images henryga
03rd Apr 2010
89
Reply message RE: New CLS Preflash Sequence Images picmax
04th Apr 2010
90
Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
05th Apr 2010
91
     Reply message RE: New CLS Preflash Sequence Images selectivecolour
01st May 2010
92
          Reply message RE: New CLS Preflash Sequence Images picmax
01st May 2010
93
          Reply message RE: New CLS Preflash Sequence Images selectivecolour
03rd May 2010
94
          Reply message RE: New CLS Preflash Sequence Images gkaiseril Gold Member
13th May 2010
95
               Reply message RE: New CLS Preflash Sequence Images selectivecolour
14th May 2010
96
Reply message RE: New CLS Preflash Sequence Images Nikonmel
19th Nov 2011
97
Reply message RE: New CLS Preflash Sequence Images HBB Moderator Hal is an expert in several areas, including CLS Awarded for his excellent article contributions to the Resources.
21st Nov 2011
98

Forums Lobby MASTER YOUR TOOLS Nikon Speedlights & Lighting topic #38452 Previous topic | Next topic