Only part of my frame is exposing?

[cee_bee1]

<p>Hi this is probably a stupid question, but I just got a bunch of new alienbees, and I'm trying to set them up with my 5d Mk2. I'm shooting at iso 100, 250, f11, and the last 105 on the right hand side of the frame won't expose... what gives?</p>

 

[pcnilssen]

<p>I don't know Canons but what is the flash sync speed on the 5DMk2?</p>

[jcuknz]

<p>You are using a too fast shutter speed. Find out what the 'sync speed' of the camera is and never set it higher than that. I gather in some ccircumstances people use a shutter speed below 'sync speed'.</p>

<p>The reason is that your camera has two shutter blinds and to get faster shutter speed the second blind starts to cover the frame before the first one has fully exposed the sensor.<br>

'sync speed' is when the first shutter has fully exposed the sensor and the second blind has not started to cover the sensor. You can use slower speeds but not faster ones unless using flashguns with high speed sync where the flash is pulsed to cover the sync speed period.</p>

[jcuknz]

<p>Further thoughts .. don't these cameras have vertical shutters? so unexposure on the side is some obstruction to the field of view? I thought current DSLRs had a 1/250 sync speed.</p>

[ariel_s1]

<p>Even if you're within the camera's sync speed, if you're using triggers that aren't up to the job, you'll get partially exposed frames even at your sync speed. Read this enlightening article. The 5DII won't really sync well at 1/250, and sometimes not even at 1/160.<br>

http://strobist.blogspot.com/2010/01/know-your-sync.html</p>

[Alan Marcus]

<p>About flash synchronization:<br>

Many budding photographers have a false impression as to how shutters work and how flash works with the shutter. A straightforward design has the shutter mounted up front between the glass elements of the lens. This type of shutter consists of spring loaded metal leaves. When the go button is pressed, the shutter opens starting as a tiny opening at the center of the lens and quickly opening, forming a big hole (aperture). The shutter mechanism stays full open for a time and then closes quickly. This is the classic view most people have of shutter operation.</p>

<p>The shutter described is called a between- the- lens shutter. This design has advantages and disadvantages. The chief advantage is its ability to be synchronized with the light output of a flash unit. The disadvantages are, low efficiency, as it takes time to open and close. On cameras that allow lens interchangeability, each lens must be fitted with a shutter and this adds greatly to the expense of the lens.</p>

<p>These shutters are mechanical and they feature a switch that delays the flash firing circuit signal until the shutter reaches maximum size. When the shutter reaches wide open, the electronic flash is triggered and the flash fires immediately (timed to max shutter opening). This is called X synchronization. </p>

<p>SLR (single lens reflex) cameras and most all cameras that allow super high shutter speeds are not fitted with a between-the-lens shutter because they do not operate efficiently at high speeds and because including one with every lens is too expensive.</p>

<p>The SLR is equipped with a shutter mounted inside the camera body. It hovers only a few millimeters from the flat surface (focal plane) where the lens focuses its image. The problem is, this shutter must be quite large as it must cover all of the surface area of the focal plane. The design features a moving curtain with an adjustable slit.</p>

<p>When the go button is pressed the curtain races across carrying the slit. Only the area under the silt is exposed. The speed of the exposure is not how long it takes for the curtain to travel across the focal plane, rather it is the time it takes for the slit to move its own width. As an example the total travel time might be 1/200 second, but if the slit is narrow, it moves its width in 1/1000 second. Thus, the exposure time is 1/1000 sec.<br>

When we change the exposure time, the mechanism only changes the slit width. For flash work, we must set the shutter speed to the slower ones or the flash will only expose the area under the slit. For your camera this will be 1/200 second or slower. At these slow shutter speeds the silt reaches across the entire focal plane. Using too fast a shutter setting, you get synchronize failure and only a partial image results.<br>

Consult your camera manual for synchronization information. </p>

[Spearhead]

<p>I would ignore all the answers except JC Unkz at 3:17. You have a vertical shutter. Exposure problems on the RHS are not a sync problem. And there's no reason to know about mechanical leaf shutters, it's not going to help you.</p>

[Alan Marcus]

<p>Canon 5D Mk2<br>

Shutter type is vertical travel, mechanical, electronically controlled focal plane.<br>

Shutter speeds 1/8000 to 1/60 second.<br>

Synchronization X-sync at 1/200 second.<br>

Most modern cameras feature a focal plane shutter with a travel direction that is vertical across the full frame 24mm height by 36mm focal plane (chip dimensions). The advantages of vertical travel are; the shutter travel is 24mm vs. 36mm of the horizontal method. The shorter travel distance allows higher shutters speeds to be achieved. The slit width on this model, covers the entire frame at 1/200 or slower. If faster shutter speeds are used the frame will only be partially exposed. If remote flash units are used the triggering method used must maintain X-synchronization. If X-sync is not obtained it will be necessity to experiment with slower shutter speeds to determine the maximum speed to use that results in a full-frame exposure</p>

[Spearhead]

<p>That changes nothing, in fact, it makes it more obvious that the sync explanation is wrong. </p>

[frank_skomial]

<p>Cee Bee shots with studio flashes, and perhaps the camera was taking vertical portraits.</p>

<p>At 1/250 sec which is faster than X-Sync, you get sure darker edge on the right hand side. Depending how the camera is positioned in the vertical orientation, she could get left hand side darker edge.</p>

<p>Test for CC, tell exactly how the camera was positioned. Rotate the camera 180 degree and you will get left hand side darker edge at your shooting position and parameters. </p>

[mukul_dube]

<p>Cee Bee, please do not allow anyone to shut <em>you</em> up: because that may come next. Everything said here can be useful -- another day, if not immediately.</p>

<p>JC Uknz:<em> I gather in some ccircumstances people use a shutter speed below 'sync speed'.</em></p>

<p>This allows ambient light to have some effect, which is often a good thing.</p>

<p><strong>Rude or unhelpful posts will be deleted. </strong></p>

[michael_s10]

<p>Frank is right - the photographer is taking vertical portraits and it's a shutter speed issue.</p>

<p>Reduce your shutter speed.</p>

<p>Also, if you are using cheap-y triggers (I have some myself), you may find that you are OK at 200 - for a while - and then you'll get off sync part way through the shoot. Keep checking your work as you go paying careful attention to the right side, especially if you are using dramatic lighting (you might not notice the bar if it's a dark area and you are moving quickly). </p>

<p>I ended up dropping to 1/160 and haven't had a problem there. </p>

[jcuknz]

<p>It would help I think if you posted a small image 700 pixels across, <100Kb so we could see what your problem is becuase the more I think about it I doubt if it is a sync problem. If the camera was not syncing at 250 you would have an un exposed area at the top or bottom of the picture when shooting in 'landscape' mode. In portrait mode with camera held vertically the problem would be on one side.<br>

I am not a DSLR user so while I know the theory from years with SLRs I'm not with the modern stuff except for my Oly and Pany M4/3's which do have focal plane shutters but I have not bothered to checkthem out :-) <br>

The 'leaf shutter' in my book is known as a 'Compur' becuase they made a lot of them in the old days. To confuse the picture further I gather that some cameras have electronic shutter which I guess must turn of the sensors ability to record light on and off .... modern science URRGH! :-)<br>

Thern of course there is the origin[?] of the focal plane shutter but used immediately behind the lens with half-plate and bigger cameras of vintage days. Operated with the 'bulb' release.... a rubber ball with a tube to camera which operated the shutter when air squeezed out of the ball. Used one of them way back on a 10x8 camera.</p>

[James G. Dainis]

JC,

 

I think in your last paragraph you are talking about a Packard shutter. The Packard curtains formed a V slot not a straight slit as in focal plane shutters.

[scott_ferris]

JC ,

 

Relax it is just a sync issue when used in a portrait orientation. Ariel and Alan had it covered early on, Frank expanded on

that and Michael drove it home. How any experienced photographer could think it isn't a sync issue with a 5D MkII at

1/250 sec I am at a loss to understand.

[jim_momary]

<p>Here's a discussion on this very subject, apparent 'slow' 5DMkII cameras ...<br>

<a href="http://strobist.blogspot.com/2010/01/know-your-sync.html">http://strobist.blogspot.com/2010/01/know-your-sync.html</a><br>

Jim M.</p>

[jcuknz]

<p> <em>How any experienced photographer could think it isn't a sync issue with a 5D MkII at 1/250 sec I am at a loss to understand.</em><br>

I too am at a loss to understand how an experienced photographer would fail to realise I imagined that he was using the camera horizontally, although I covered the vertical condition too. I don't think this was made clear in the original message ... but I might have missed that. ... I wasn't and am not sure what he meant by '105'.<br>

<em>you are talking about a Packard shutter</em><br>

<em></em>From your description I am most definitely NOT talking about a Packard shutter but another system which had a number of horizontal slots organised in a roll of cloth which gave you different shutter speeds according to their width. The roll was spring loaded and one cocked the shutter by pulling down on a thin cord with the lens capped or with the holder slide closed and covering the plate. It was housed in a box and fitted between lens and camera.</p>

[Andrew Garrard]

<p>While we're all shouting at each other... with my software engineering hat on, while we're all saying "it's definitely this" or "it's definitely not this", Cee Bee - can you confirm whether you were using the camera in portrait orientation? If so, problem solved; if not, there's more to discuss (and I'm curious what's happening). There doesn't seem much point arguing about obscure shutter details until we know whether the first hypothesis makes sense. Like Jeff, it hadn't occurred to me that the camera might be used in portrait orientation without this being stated while describing the problem as being on "the right-hand side", so let's confirm this? With the most common portrait orientation (grip upwards) I think I'd expect the left-hand side to be underexposed, not the right.<br />

<br />

Cee Bee - I hope this thread has solved your problem; if not, I hope we can get back to solving it.</p>

[ariel_s1]

<p>I agree with Scott. JC, you keep pushing and pushing to continue this thread, when it is clearly a sync problem. 5DII at 1/250 is such an obvious sign that you shouldn't need to see an example. Anyone that claimed it wasn't a sync issue needs to go back to the drawing board and play with some strobes for a while before solving other people's lighting problems.</p>

[scott_ferris]

<p>JC,</p>

<p>I wasn't referring to you, when I talked about an experienced photographer.</p>

<p>For those wanting proof, or an example, it is easy to get. Here is a Canon DSLR set up to use one stop faster than its listed sync speed, in portrait orientation with the shutter release at the top. Though many use their cameras in portrait orientation with their button at the bottom all L plates that I know of put shutter release at the top (of course there is no reason to assume either orientation was used by Cee Bee.</p>

<p>But the kicker is the fact that at 1/250 it is impossible for a 5D MkII to not have a shutter shadow, this doesn't preclude another issue as well, but why speculate, when it is at least a sync problem?</p>

<p>The cause of the issue is a given, the beginner terminology for symptoms might throw some off, and those people, as Ariel says, are probably better of staying out of the Beginner Forum.</p><div></div>

[Spearhead]

<blockquote>

<p>I wasn't referring to you, when I talked about an experienced photographer.</p>

</blockquote>

<p><br /><br>

So who were you referring to?<br>

<br /><br>

The original poster still hasn't confirmed the orientation.</p>

[scott_ferris]

<p>The orientation is still irrelevant.</p>

 

<blockquote>

<p>"But the kicker is the fact that at 1/250 it is impossible for a 5D MkII to not have a shutter shadow, this doesn't preclude another issue as well, but why speculate, when it is at least a sync problem?"</p>

</blockquote>

[Andrew Garrard]

<p>Guys, come on. Jeff and JC (and I) are perfectly aware of how the shutter works, and as far as I know we would all consider the flash sync problem to be a perfectly good explanation so long as Cee Bee's original description of "the right hand side of the frame" refers to the camera being held in portrait orientation, and therefore to the start or end of the shutter's travel obstructing light (i.e. the top or bottom of the frame were the camera used in conventional landscape orientation). Scott, this absolutely <i>does</i> depend on the orientation of the camera, as I'm sure you're aware, because if the right side of the image <i>with the camera in landscape orientation</i> is dark, something else is going on, and may be going on even if the rest of the scene is fully lit by, e.g., a flash running in high speed sync mode (if I correctly remember what Canon call it).<br />

<br />

From the description given, it's by far the most likely thing that Cee Bee's camera was being held in portrait orientation and the description of the problem caused some confusion; however, until that's confirmed, we can't definitively say that we have or have not explained the behaviour. Attempting to speculate on other potential causes is likely to be counterproductive in this forum until we know it's needed, but nor is it helpful to be rude to anyone who had interpreted the issue as it was originally stated.<br />

<br />

I suggest that, at this point, we're just going to be name calling until Cee Bee is kind enough to tell us whether the suggested explanation makes sense - if we've not been so intimidating with this rant that we've lost a member. If there's still a problem to solve here, hopefully we can be told, and help.</p>

[scott_ferris]

<blockquote>

<p>The orientation is still irrelevant.<br /> "But the kicker is the fact that at 1/250 it is impossible for a 5D MkII to not have a shutter shadow, this doesn't preclude another issue as well, <strong>but why speculate, when it is at least a sync problem?</strong>"</p>

</blockquote>

[jcuknz]

<p>If the camera was in portrait mode it is a sync problem, if in landscape mode it is an obstruction problem ... the reverse would be true if I was using my old leica or pentax cameras of the 40's/50's.</p>