# Prints appearing half black -- why?



## GrahamATX

Hello, I'm fairly to the world of photography and film photography especially.  I dug up my dad's old Pentax K1000 SE, which is most likely about 25 years or more old.  I shot a roll of film with it, and took it to my pharmacy to develop it (as I'm not ready to develop my own film yet... it'd be nice to get tips on that too) to confirm that it still worked.  Sure enough, some of the shots turned out great but at least 10 or so out of the 25 exposures were half-black, rendering them useless.  I'm curious as to whether this was the store at fault (which I doubt), the camera, or myself.  The camera is completely manual, so I was wondering if this had to with where I had the f-stop or something of the like.  If anyone can explain to me the root cause I would greatly appreciate it.  

However, as you can see below, when it works, it's pretty good


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## compur

Nice photo.  

Post one of the half black photos and maybe we can tell you what the problem is.
Most likely a shutter glitch.  Did you use flash with the half black photos?


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## Josh66

Two things could have happened...

Sticky shutter, or you exceeded the x-sync speed using flash.

If you were not using flash, I would say there is a good chance you have a sticky shutter.

Next time the camera is empty, open the back and look for a gummy residue on the shutter (look at the front too).  If you see some, it's the foam breaking down.  Replacing the foam would be a good idea, but you have to get that crap off of the shutter too.  What I have done is very carefully clean it off with cotton swabs and alcohol.

Then, fire off a few frames and repeat.  (With the camera empty...)

If there is no sticky stuff on the shutter and you weren't using flash - I don't really know what else it could be, but I doubt it's something the lab did.

How do the negatives look?  (That should tell you if it's the lab or the camera.)


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## GrahamATX

Thanks for the responses.  I didn't purchase any copies of the screwed up pictures, but I took a picture of the negatives:





Since they are also messed up, I'm guessing it's what you said about the sticky shutter.  I'll look into that.  I appreciate the help!

Here's a picture of the camera as well if anyone cares to check it out:


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## flea77

I'm betting flash sync was wrong.

Allan


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## GrahamATX

Is there anything I can do to adjust the flash sync?


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## STM

GrahamATX said:


> Hello, I'm fairly to the world of photography and film photography especially. I dug up my dad's old Pentax K1000 SE, which is most likely about 25 years or more old. I shot a roll of film with it, and took it to my pharmacy to develop it (as I'm not ready to develop my own film yet... it'd be nice to get tips on that too) to confirm that it still worked. Sure enough, some of the shots turned out great but at least 10 or so out of the 25 exposures were half-black, rendering them useless. I'm curious as to whether this was the store at fault (which I doubt), the camera, or myself. The camera is completely manual, so I was wondering if this had to with where I had the f-stop or something of the like. If anyone can explain to me the root cause I would greatly appreciate it.
> 
> However, as you can see below, when it works, it's pretty good


 
The K1000 is a pretty old camera and it is not unusual for a camera of that vintage to have shutter curtain problems. I suspect that is what it is, unless you are talking about photos taken with flash and you exceeded the max synch speed.  All it probably needs is a good CLA and I am sure it will go back to taking great photos.


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## Helen B

It looks very much like you had the shutter speed set higher than the flash sync speed (1/60?). This leads to the partial underexposure of the frame (it's part underexposed, not part blank)

Best,
Helen


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## Josh66

flea77 said:


> I'm betting flash sync was wrong.
> 
> Allan


 After seeing the negs, I agree.

GrahamATX, notice how the dark half still has somewhat of an image on it?  If it were a sticky shutter, that half would be totally blank.


GrahamATX said:


> Is there anything I can do to adjust the flash sync?


 No - it is a physical limitation of the camera, there is nothing you can do to change it.  It is the fastest shutter speed that both curtains are fully open.

Just make sure that when you're using flash your shutter speed is always longer than or equal to the max sync speed.


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## Josh66

Just to add...  I would still have a look at the shutter.  In this case, I am certain that it was due to the x-sync speed - but, all foams break down eventually.  It's only a matter of time.

If you ever notice a sticky residue on the shutter, it's time to replace the foam.


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## compur

The flash sync speed of a K-1000 is 1/60.

That means when using flash the shutter speed must be set at "60" or slower ("30", etc)

If you set it at a higher speed you will get partially blacked out negatives.


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## Big Mike

I agree...my vote is on a flash sync issue with too fast of a shutter speed.

This happens because of the design of the shutter, it's made up of two separate curtains.  The first one opens, the second one follows it to close the shutter.  The faster the shutter speed, the sooner the second one follows the first.  The max sync speed of the camera, is the fastest (shortest) shutter speed at which the entire frame is open.  Any faster, and the second curtain starts moving before the first curtain is fully open.  So at very fast shutter speeds, the second curtain follows the first very closely...only exposing the film via a little strip of light before them.  

This is important when we start using flash.  The burst of light from the flash is very short...probably much faster (shorter) than the actual shutter speed.  So if the flash fires when the shutter is not fully open, the part of the frame that is still covered by the shutter, won't get any of the light from the flash....so you end up with dark or black blocks in your photos.


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## Paul Ron

The black part has image in it, that might be an advancing problem. Count the frames? Overlapping images? No frame spacing?

EDIT:.... Another thing I just noticed is every other frame is black. advancing problem or sticking mirror? .. another symptom of seals gummy or rotting.... this camera needs service one way or another.

Most times a sync problem at fast shutter speeds will show up as a bar, not half black.since the 2 shutter curtains are flying by as a slit of varying widths getting smller as the speeds get faster. Below 1/60th it makes no difference, all shots will be perfectly fine. 

So, it may be a lagging shutter curtain or an advancing problem or mirror sticking in the up position dropping afdter every other shot.  The Pentax shutter curtain ribons tend to rot over time n eventually let go. The advancing and lazy curtains are early indicators of this problem. Have the camera over hauled for about $90. There are plenty of guys online that do this work cheap, just google em. Once over hauled that camera will work like a race car for another 30 years of relaiable service.


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## Josh66

Paul Ron said:


> .... or sticking mirror?


 It can't be the mirror, since the 'bar' is vertical.  Does the shutter  travel horizontally on the K1000?  I assumed that it did after seeing  the negatives, but I'm not sure...


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## compur

Yes, the K1000 shutter travels horizontally -- it has cloth curtains.


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## compur

Paul Ron said:


> The black part has image in it



This is consistent with shooting above flash sync speed.  The faint image in the blacked out portion is
from ambient light.


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## CCericola

Because there is a partial image in the darker part of the negative it was a flash sync problem.


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## Paul Ron

GrahamATX said:


> Thanks for the responses.  I didn't purchase any copies of the screwed up pictures, but I took a picture of the negatives:
> 
> 
> 
> 
> 
> 
> Since they are also messed up, I'm guessing it's what you said about the sticky shutter.  I'll look into that.  I appreciate the help!
> 
> Here's a picture of the camera as well if anyone cares to check it out:


 
But if it is a flash sync problem explain why every other frame is black? Why are there no clean frame spaces between frames?

Can you post a better pic of the negative strip backlighted please? 

.


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## Josh66

Paul Ron said:


> But if it is a flash sync problem explain why every other frame is black? Why are there no clean frame spaces between frames?
> 
> Can you post a better pic of the negative strip backlighted please?
> 
> .


 There are only 3 frames visible in the picture the OP posted, each half black.  Each also appear to have had the same shutter speed - that would explain why they are all 'cut off' at the same point.

Using flash on 3 consecutive frames with the same shutter speed doesn't seem far fetched to me.


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## compur

Or, to put it another way, it's not that every other frame is black. It's that every frame is half black


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## Paul Ron

And no clear frame spaces either? ummmm.... Where is the OP on this one? 

I'd like to see a better pic of the film strip, backlited. 

So what speed will cause  half black image if it was a sync problem? Let's do some research and have some fun with this. 

If memory serves me right, curtain shutters are a slit of varying widths flying over the film surface, 2 curtains chasing eachother. The faster the speed the smaller the slit. Now to have half frames exposed, it would be a pretty large slit or enough time for a slit to cover half a frame. Any guesses, maybe the OP can let us in on it? 

Anyway, it is fun to think this through.


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## compur

I think there are spaces between frames on those negs -- they're just 
blended in with the thin image content at the edges of the frames.

BTW, it's only a traveling slit at shutter speeds faster than the flash sync 
speed. At the sync speed or below the curtains are fully open for a moment. 
 This is what the flash is is being synced to -- that period when it's fully open. 

This is how it works on classic mechanical focal plane SLRs like the K1000 
anyway.  Some more modern cameras can sync at higher speeds by
using a series of flash bursts as the shutter opening travels across the
film plane.  For example the last of the Olympus OM-3/4 series cameras did 
this and I'm sure DSLRs can do something similar.


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## Paul Ron

Ah now you are seeing what I was thinking when I first saw the half black negs... 

it's a slit at higher speeds over sync 1/60th, so only a black bar should be exposed (the slit), not half frames. All speeds below 1/60th are safe flash speeds because the curtains are fully open (full frame slit). 

So the question is... at what speed is the curtain slit half frame to cause his problem?

*Newer focal plane camers use vertical blind shutters thus allowing higher sync speeds. Horizontal curtains all synced at 1/60 or less. Leaf shutter sync at all speeds. 

.


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## compur

Paul Ron said:


> So the question is... at what speed is the curtain slit half frame to cause his problem?



At whatever speed the OP had the K1000 set to. :mrgreen:


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## Paul Ron

Well not a very scientific answer. Aren't you curoius? 

NIce to see you know the basic Wiki theory but how about an experiment? 

Trying to reson it out... a flash burst is 1ms, so half frame exposed would mean the shutter speed was 2ms.... translates to what speed? 1/500th!



.


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## Josh66

It's not possible to figure out, since, for one, we can't see the other curtain.

Only half of the frame was exposed, but the 'slit' could be much larger than that.  We just know that it was 'at least' half the frame.

I would guess that the shutter speed was close to the x-sync speed though, since the slit is so large.  1/125 maybe.  Just a guess though...


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## Helen B

Normal 'first curtain' sync fires the flash when the first curtain reaches the end of its travel - so the fully exposed part at shutter speeds shorter than the sync speed doesn't appear as a slit within the frame but always shares a common edge with the frame.

The sync speed is approximately equal to the travel time of a curtain (or a little more). Therefore the travel time of a curtain is a little under 1/60 s if the sync speed is 1/60. Therefore, if the second curtain is about half way across when the first curtain reaches the end of its travel, the exposure setting could be about 1/125 because that is how long the second curtain still has to travel. Note that this has very little to do with the flash duration if it is an electronic flash (different story for flashbulbs, especially FP - focal plane - type).

How does that sound?

Best,
Helen


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## Paul Ron

And I'll bet you guys are right at 1/125. and of coursew there is the BUT.....

OK here are the shutter times in ms relating to their respective 1/second parts according to my shutter tester... The ms time is how long light is hitting the film, not curtain travel times. Cutains travel at a constant velocity regardless of what the shutter speed is. The exposure is determined by the size of the slit allowing light to enter ( how soon the second curtain chases the first), not by how fast the curtains travel. 

1/30-33ms
1/60-16ms
1/125-8ms
1/250-4ms
1/500-2ms
1/1000-1ms

So I figure if a flash burst is 1ms it would capture the slit in mid fleight causing a bar to appear. But since we are capturing half a frame it stands to reason the 1ms for flash plus the leftover half frame must be a total of 2ms... 1/500 is my guess. 

Now for the real world test... anyone game to try on your next roll? (I don't use 35mm). Shoot using a flash marking each speed to see exactly what the captured bar will be n post the results. This might be a very enlightening experiment for basic understanding how a curtain shutters actually work. Oh and be sure you have a horizontal curtain, vertical shutters have a different sync and characteristic bars.

.

.


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## Helen B

My calcs assume that the curtain travel time is constant and the distance between the curtains varies. The duration of an electronic flash has very little effect on the width of the fully exposed part of the frame, unless the duration is very long for an electronic flash.

You can estimate the curtain travel time from the sync speed.

1/60 s is 17 ms (to the nearest ms)

That means that the curtain travel time is about 13 ms or thereabouts - slightly less than the sync speed.

Here's typically what happens at 1/60 with flash, first curtain sync.

0 ms - first curtain begins to open, first strip of film begins to get exposed.
13 ms - first curtain fully open, flash triggered
13 to 17 ms - time for flash to fire and discharge
17 ms - first strip of film has had 17 ms exposure so second curtain begins to close
30 ms - second curtain closes fully 13 ms after beginning its travel = 17 ms after first curtain opened fully.

Here's what happens with the same shutter at 1/125 (8 ms)

0 ms - first curtain begins to open, first strip of film begins to get exposed
8 ms - first strip of film has had 8 ms exposure so second curtain begins to close
13 ms - first curtain fully open, flash triggered, second curtain is 5/13 (almost half) way across
13 to 14 ms - flash discharges while first curtain is fully open, second curtain is almost half closed
21 ms - second curtain now fully closed, 13 ms after opening and 8 ms after first curtain opened.

Does that make it easier to understand why the electronic flash duration is of little importance and why the curtain travel time sets the width of the fully exposed portion?

Best,
Helen


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## Paul Ron

I just looked at the repair manual of a Spotmatic. You are correct, a 36 millimeter wide film gate is @ 18 milliseconds 1/55th wide open. That is exactly what the constant curtain travel time is set to, 2 meters per second, regardless of shutter speeds. 

I now understand what you are saying, we are stopping a half open frame at mid curtain travel within the18ms cycle, regardless of flash duration. I also felt 1/125th should be correct at first but got confused by the flash timing at 1ms thinking the frame is 2ms wide (film exposure to light duration).    

Now we need to do a film test. I'm curious to see what we actually capture at different speeds. 

Thanks Helen, that was fun.


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## Athen

I am having the same problem I will post the pictures to show as well.  I have a Nikon D90 and it seems from time to time half the picture is black.  Has anyone experience this I am using a remote trigger and lighting system but the lighting system works well with my Canon 7D??


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## Big Mike

> I am having the same problem I will post the pictures to show as well. I have a Nikon D90 and it seems from time to time half the picture is black. Has anyone experience this I am using a remote trigger and lighting system but the lighting system works well with my Canon 7D??


Welcome to the forum.
For future reference, you don't need to dig up old threads if you have a new question.  Although, it is a good idea to read these older threads, as they can often answer your questions.

Your issue is almost certainly that you are exceeding your camera's max sync speed.  The photos are half-black because the 2nd shutter curtain is starting to close before the exposure is over...thus, in the instant when the flash fires, the shutter is blocking part of the frame...and that part doesn't see any of the flashed light reflecting from the scene.

The solution is to keep your shutter speed under the max sync speed...which is probably 1/200 or 1/250.  There may also be a slight delay introduced by the remote trigger, so I'd play it safe and use a shutter speed of 1/160 or longer.


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