Camera Settings Challenge - Flash, Night Portrait, Rear Curtain Synchronization

June 23rd, 2015
Do some of the camera settings intimidate you? Do you want to learn how to develop your photography skills and learn how to use your camera effectively without always going back to the “auto” function? These challenges are for you!

These are designed for those experienced photographers to share their knowledge with others who are anxious to learn and improve their skills. This fortnight's challenge is ..

Flash Operation, Night Portrait and Rear Curtain Synchronization

We'll investigate how the flash cooperates with the camera. We will only scratch the surface, so if you want more detail, please consult the references below. You will be able to accomplish these exercises with your built-in flash. Of course if you have a Speedlight, that will be fine too.

We'll then discuss two common “synchronization” modes that can afford you lots of fun creative opportunities to use some of the flash features. We'll give you step by step instructions on to how to achieve them.

First, a bit of techie information to get us grounded. If you don't care for even this small level of detail, you can jump to the challenges, but you might need to come back here at some time.


Flash Duration and Shutter Speed

The flash pulse is extremely short., typically 1/5000 of a second or shorter, but the camera will typically not let you use a shutter faster than about 1/150 of a second. How can that be?


Flash X-Synch Speed

Modern digital cameras have two “curtains” that control the opening and closing of the shutter. The first curtain opens the shutter by traveling downwards. A second follows it closing down the shutter. It takes about 1/150 of a second for the curtains to travel from top to bottom.

At shutter speeds faster than this, both curtains will be moving at the same time across the frame, leaving only a horizontal slit open at any moment. If the flash fired, only the open slit would see the light, the rest of the frame remaining dark. The X-Synch Speed is the fastest shutter that will allow the shutter to be fully open if only for a moment.

You can determine your camera's X-Synch Speed easily. Raise your flash, Set S (Tv), or M mode and shorten the shutter until it will go no further. That will be your camera's X-Synch Speed. Or you can simply consult your camera specifications. :)

Adjunct Speedlights and more advanced cameras can “beat” this shutter limitation with the High Speed Synchronization feature, but most entry level DSLRs do not support it, so we will not consider it further this fortnight.


Flash Synchronization

When does the flash fire? The camera will tell the flash exactly when to fire, but it must be when the shutter is fully open. Two options are provided. The first is to fire the flash as soon as the shutter is fully open called Front Curtain Synchronization (or First Curtain Synch). The second is to fire the flash at the last possible moment just as the shutter begins to close down, called Rear Curtain Synchronization (or Second Curtain Synch).

Front Curtain Synch is the default for almost all cameras. The second challenge below looks at the possibilities of Rear Curtain Synch.


Flash Light on Subject and Continuous Light on Background

In many "flash" shots in low light like at night, the flash will be the main source of illumination for the subject. Some continuous light, however, will illuminate the background, usually a lot weaker than the flash. And in almost all cases, the flash light will not be able to reach this background, so this is the only light it will have..

Shutter speed has no effect on the lighting due to a flash, but it does on the background just as you might expect. The important piece to understand is that the shutter can be manipulated to change the exposure of the background without changing the light level on the subject.

The light from the flash can, of course, be changed, and the flash and the camera's metering system can work together to determine power for a "correct" exposure of the subject, TTL or Through the Lens metering. Or as we did last time use the Flash Exposure Compensation feature on top of the TTL setting. The power level can also be set manually independently of TTL and FEC, but we will not consider that further here.

Lens Aperture and ISO still regulate both exposures, the first letting more light in and the second amplifying the digital signal more.

With that (very brief) background, on with the challenges.


CHALLENGES

Challenge 1 - Flash Portraits with Background

In low ambient “continuous” light conditions, night time especially, we will want to illuminate the front subject with the flash. However, the background might also be interesting and worthy of being better lit. We can slow the shutter to have this light register more effectively.

This will require you to break out your tripod, as we will be dealing with exposures of a second, sometimes considerably longer, for this background light to be recorded.

We can proceed in several ways, but we'll settle on one that requires no new settings to be learned.

1. Put your camera in “M.” Turn off any Auto ISO and set a moderately low ISO, 200 is a good start.

2. Set Auto White Balance. The color of the flash light will be different from the color of the background light, so for now let the camera work it out. WB can get very complicated for mixed light sources, but we'll defer that discussion for now.

3. Set a reasonably narrow aperture if you you want some background detail, say f/11 to f/16. If you want background light blur (light bokeh especially) instead of light detail, open the aperture wider. A fast prime at f/2.8 to f/4 should be fine. Try to avoid the very widest and very narrowest settings.

4 I prefer a relatively long focal length, 100mm or more since it gives me room and not be on top of the subject; it can make for a more comfortable DoF too. But a normal “Nifty Fifty” (35mm on a cropped sensor body) will certainly work.

5. Determine a shutter speed that will render the detail you want to show in the background. Take a few shots at different speeds of just the background without your subject and without the flash raised. Pick the one you like best and dial it in. It could well be a second or more, and that's just fine.

6. Have your subject move into the frame and raise your flash. Before you shoot explain that you would like her to remain reasonably still to prevent possible ghosting after the (default Front Curtain) flash fires.

7. Focus on your subject. In AF mode, the “flash assist” light might flash to help your AF in low light. You can, of course, manually focus, and it might be necessary if your camera will not lock an auto focus in the low light.

8. And fire.

There, that was easy, right? :) I hope you got a nice balance between the well lit subject and an interesting but not too distracting background. Here's a nice example. I apologize that I do not know the copyright. It is shot with an off-camera flash, note the light coming in from the left, but don't let that hold you back with your built-in flash.



For extra credit, you can experiment by varying the shutter. Faster will darken the background, slower will brighten the background. This is where you can let your creative juices really flow.

You can automate this shutter selection if you shoot in “A” or “Av” mode. Consult your manuals if you want to try this, there a lot more settings that must be dealt with. Canon and Nikon operate differently from each other, and other manufacturers also have their own terminology and settings variations. Leave a note below if you need more help for your camera. One warning that isn't in the manuals, turn Auto ISO off in all cases. You'll thank me later for reminding you.



Challenge 2 – Rear Curtain Synch

Now let's again consider flash and longer exposures, but this time add in some subject motion. We want to have this motion add creative blur, but still have the flash “freeze” the main subject at some point along the trajectory of the motion.

We can freeze the subject at the beginning of the motion blur with Front Curtain Synch flash mode, or at the end of the motion blur with Rear Curtain Synch flash mode.

It is commonly felt that the Rear Curtain Synch mode projects a stronger sense of the motion with the blur behind the subject showing where it has been and provides the feeling that motion still continues into the uncharted space.

An illustration is worth a thousand words. This shot is courtesy of the Digital Photography School.



So how do we go about this?

1. Find how to change the synch mode of the flash to Rear (or Second) Curtain Synch. Consult your manual and if you have trouble working it out, once again leave us a note below and we'll help you out with your camera specifics.

2. Try to light your subject that will be moving with some natural light to record the blur, as in the example. If you have decided to look at light trails the light sources themselves will be self illuminating.

3. Work out the approximate time the motion will cover the frame. The further back the subject is the more motion you can record, but remember the subject must end up close enough to the camera to be lit by the flash when it fires at the end of the shutter.

4. “S” (Canon “Tv”) will be the easiest mode to shoot with here, so dial in the time you estimated.

5. Mount the camera on a tripod.

6. Set the focus on the point where the subject will finish and the flash will fire. Manual Focus will probably work easiest here, but using AF and then locking the focus will work fine. Locking can be achieved with the AF-ON/LOCK buttons, or simply switch your lens to Manual when you have the focus.

7. Synchronize the beginning of the motion in the frame to one side as you trip the shutter. And fire.

You may need to experiment several times to get the motion path exactly right in the frame. Do not be discouraged if it takes several attempts.

For Extra-Extra Credit, combine Challenges 1 and 2 to give you the creative Rear Curtain Synch motion and have an interesting background. It will be a little more complex than you might expect. :) If you can do all that though, you've really nailed this whole fortnight.


Please post any results you achieve for either or both challenges here, and ask any questions that might come up. We are definitely getting into advanced settings and technique here, so please do not get discouraged if it takes several attempts to nail it. These challenges are definitely not simple point and shoot exercises, and do need thought and preparation.

All the best!









June 23rd, 2015
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All ready to go. Sorry it took a day to get it up and in (reasonably) good shape. Have fun with it...
June 24th, 2015
That is a LOT of information but I think it is all very good and well written. Thanks for posting!
June 24th, 2015
Thanks Frank..........I hadn't spotted this post, but decided to try and get better with my speedlites as it frustrates me that I don't know what I am doing!....so here is my effort
June 24th, 2015
Pretty! If you put your camera on a tripod, M mode and set the shutter to a second or so, you might get some background to show. But it is nice as is on black, most effective. I see from your album you ventured into High Speed Synch? Good luck. Please ask if I can help out any further. @pixiemac
June 26th, 2015
@pixiemac @frankhymus I could use some help please. I shot this at 1/8000 with High Speed Sync and was unable to blow out the background without some serious etsooi in Lightroom.

June 26th, 2015
Here's the etsooi version:

June 26th, 2015
@bill_fe Shoot in M, of course. Turn off ISO Auto ( I suspect you have it on with the ISO 160 you shot at). choose a narrower aperture, and since you have a D810, you can natively cut your ISO to 64.

If you keep the same 1/8000 (that is probably unnecessarily fast, your flash will fire many times and you just might run out of flash power even this close), set f/16 and ISO 64 to give you 6+ stops down for the background from what you shot. It should send your very bright background sufficiently dark.

Remember, Fast Synch is best controlled with the lowest possible ISO (always remember to turn off ISO Auto and take explicit control for any flash work) and "M" for explicit speed and aperture settings too. Let me know if you still have a problem.
June 26th, 2015
@frankhymus Thanks Frank, I'll try again tomorrow or the next day. I don't use auto ISO, but I must have had it turned up for a previous shot, I usually do keep at 64. I was in M also. So, I'll try with a smaller aperture.
June 26th, 2015
@bill_fe hi Bill, think @frankhymus Frank has suggested all I would have done..... hope next try is more successful for what you want to achieve.
June 26th, 2015
@frankhymus thanks Frank :) I am going to a butterfly farm on Saturday and hope to use flash to enhance the photos.
June 26th, 2015
@pixiemac Thanks Sarah, your image was my inspiration. I'm going to try again today before it rains again.
June 28th, 2015
@frankhymus @pixiemac
My second attempt. I like it much more than the first. I kept the ISO at 64, the aperture at f16, and tried several different shutter speeds to get this:

June 28th, 2015
@frankhymus @bill_fe

I've been having great fun with my speedlite :) An outdoor portrait
June 28th, 2015
I was particularly proud of this one. I was holding the flash in my hand, connected to the camera with a cable. I've got one more to post, hope you don't mind :)

June 28th, 2015
and this one, which kept the ant lit, despite the bright background
June 28th, 2015
@bill_fe I think the background turned out nicely on this one. Just a little detail in the bottom right, and I think that's just fine.
June 28th, 2015
@pixiemac I especially like the insect. The light is good, and with it remote in our hand you don't have it shining right down the barrel of the lens.

Both mostly a "fill flash" technique, strong background and darker subject, rather than "night portrait," weaker background that needs a longer exposure, certainly not a fast synch, but they are both very nice.
June 28th, 2015
@pixiemac Nice use of Fast Synch, the shower portrait, if only at 1/400 shutter. Any slower and the background would have certainly clipped in the highlights. Fast synch is definitely an almost must when you want "fill flash" with strongly lit background.
July 2nd, 2015
@frankhymus Hi, I am quite lost with this challenge. I have canon eos 650 D. I am ok with all the suggested settings on M but I don't understand where the 1st and 2nd curtain part comes in. I see there is a setting for them and also for Flash sync Speed in Av mode, Auto , with the Flash control menu. Are we selecting these settings before we take a shot?
July 3rd, 2015
@jennywren Yes, we do set these before we shoot.

The difference between first and second curtain only becomes apparent when we have a *long exposure* and *motion* in the shot. The motion will be recorded as a blur by the ambient light (there must be some for it to work), and the flash will "freeze" the subject - at the *end* of the motion for second curtain and the blur will be behind the subject, and at the *beginning* for first curtain and the blur will be in front.

In Av mode with flash, you have to worry about telling the camera what the *shortest* shutter it should use (this is the synch speed and can only be as fast as the x-synch speed of your camera) and the *longest* it can use. It govers how darkly or brightly the background is exposed of course, bot affecting the "flash" exposure at all. The camera is, after all, choosing the shutter speed.

For your Canon 650D (marketed as the T4i in the United States) as with most Canons, you have only three options to choose from, and for less experienced "flashers" they can be simpler to understand and use, than, for instance, Nikon, although not providing the granular choices that Nikon has. Canon users can always shoot M if granular choices are needed, of course.

1. A fixed 1/200 shutter, the x-sych speed of the camera. This will get you the darkest background you can get with the camera.
2. A shutter between 1/60 and 1/200, no slower and no faster. In dark situations, it will usually come in at 1/60 the slowest, to get as much light in the background.
3. AUTO. The camera will choose a speed to get a "good" background exposure. In dark situations this will usually get you a very slow shutter, and indeed is the "easy" way to shoot "Night Portrait" for Canon, exercise 1. Sometimes this will be too slow ad the background might be too light, but there is no choice, the camera will choose.

Does that help? If you want to talk more about this, perhaps have me go a little slower, please email me hymus@optonlie.net, and we'll see what we can do.


July 4th, 2015
I used my Samsung S6 at night on automatic exposure before reading your writeup on this challenge. Then I used Leonardo to edit the background and finish the portrait. It was taken at night. Now that I've read what to do, I will get my Canon EOS 70D out and follow your directions.
July 4th, 2015


This is my photo for the Night Portraiture Camera Savvy Challenge. NOBODY would be my model so I had to use my Trusty Teddy Bear. This is the front of our house.

All shots are f8 @25 ISO 200 AWB

I took the first shot with no flash and then took a series of shots at -2, -1, 0, +1, +2 FCE. I found it interesting that I can't see any difference between the various FCE settings. Is that normal for Night Photography.

Obviously there is a big difference between the No Flash & Flash Shots.

Also the in No Flash Shot the Walls of the house are a different shade to the Flash Shots. Is that normal as well?
July 4th, 2015
@jennymallett Hi Jenny. I wonder what the shutter speed came in at? And did you shoot in "M" or "Av"? Just wondering. I can't explain the equal exposure in the foreground and will have to think about it a little more Teddy is a small object to catch the light but the grass does look equally exposed, so I really don't know. It shouldn't appear that way.
July 4th, 2015
@kathyboyles Hi Kathy. A nice portrait composition however you shot it! The color of the light though, did you try to operate on that and return it to a more natural color cast? Or perhaps that is what you were trying for? Just wondered. Was there detail in the background before you went to Leonardo?
July 4th, 2015
@frankhymus Many thanks for all the details here. I have taken a portrait shot but havnt posted it. I will email you if you don't mind to clarify some points.
July 5th, 2015
@frankhymus Hi Frank, The settings that I was using are listed below, the only thing that I changed between the shots was the FCE.

Shooting Mode Manual Exposure
Tv( Shutter Speed ) 25
Av( Aperture Value ) 8.0
Metering Mode Evaluative Metering
ISO Speed 200
Auto ISO Speed OFF
Lens EF24-105mm f/4L IS USM
Focal Length 28.0 mm
July 5th, 2015


Here's a photo I took a couple of weeks ago using Rear Sync on my Flash - I must have had a premonition :). I took this at f5.6 Shutter was 1/6 ISO was 800.

I wanted to get the Knucklebones trailing as they went up & then freeze them at the top of the throw.

It took quite a while to get them frozen at the right spot.

Looking at my settings I don't know why I went up to 800 ISO. It was at night, but since I wanted a slow shutter speed I should have gone for a lower ISO. I think I must have gotten stuck on the fact that I was taking the shot at night & just set a higher ISO automatically without thinking about it! If I had chosen a lower ISO, my shutter speed could have been slower & I might have caught the shot a lot easier.

I guess it shows that I need to stop & think and plan a bit more before I start shooting.

It was fun playing around though.
July 5th, 2015
@jennymallett A lot going on for sure! You've got the idea for sure of the rear curtain stuff. It takes some trial and error to get the motion just right. The FEC stuff, I just can't quite understand why the three flashes look about the same in the foreground. Sorry.
July 5th, 2015
@jennywren Sure
July 6th, 2015
@frankhymus Thanks for thinking about it anyway Frank.
July 6th, 2015
@frankhymus Hi Frank, I sent you an email but it came back as out of time. However I think mostly my question was as the first curtain is set as automatic default then i presume you don't have to go into flash and set it. I had all my settings as suggested and was in manual and just giving a 1" 3 speed which seemed to work on a late evening portrait shot. Obviously you need to change to 2nd curtain for the moving challenge. Many thanks for your time on the previous detailed reply.
July 8th, 2015


Top Photo the flash was set on +1 FEV
Botton left flash was set on 0.0 FEV
Bottom Right flash was set on -1 FEV
There is a noticable change through the photos, I would possably go with the +1 FEV as the subject has a good amount of light.

Thanks for the challenge, enjoyed it and will use the method in the future.
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