K3 - Is this caused by a weak pressure plate spring?

[Fedor Karpenko]

Hello, everyone! I recently bought a K3 on ebay and just finished getting my second roll scanned. Unfortunately, a lot of what would have otherwise been some nice footage came out unusable because of a very strange issue. Here are a couple clips that demonstrate the problem: 

 

Basically, at the start of a shot, the film will weave in and out of focus (there are always a few frames at the start of a shot that are in perfect focus) but then the film settles in a position where the center of the frame is blurred, while the sides seem to be in focus. I had only noticed this issue in a couple of shots in the past so I wrote it off as a one-off thing, but it was happening a lot with this last roll I shot.

From reading this post from 2008 which describes the exact same issue, (only with an Arri 16S) it seems like the pressure plate just isn't holding the film flat enough, and I need to either replace the current pressure plate spring or tighten it. In some other threads, I've also come across people mentioning that they have tightened the pressure plate spring on their K3's, but I'm having a lot of trouble figuring out how to do that.

Does anyone here happen to know how I could make that adjustment with my K3? Do I maybe need a new pressure plate in general?

[Dom Jaeger]

Try running some dummy film through and observing the pressure plate. Is it sitting flush against the gate or is it pulsing? Are the loop formers fitted? Is the loop OK? (When observing the transport with the lid off, make sure to manually depress the plunger that is normally activated by the lid, which retracts the loop formers.) If the first roll turned out OK it could just be that the pressure plate wasn’t seated right for the second roll. Sometimes you need to manually set the loop and check the pressure plate is seated properly.

If you suspect the pressure plate spring is too weak, you can remove it and bend the spring a bit by hand. 

Plenty of threads here about K3 loading, eg:

https://cinematography.com/index.php?/topic/80917-krasnogorsk-3-not-loading-properly/

[Fedor Karpenko]

18 hours ago, Dom Jaeger said:

Try running some dummy film through and observing the pressure plate. Is it sitting flush against the gate or is it pulsing? Are the loop formers fitted? Is the loop OK? (When observing the transport with the lid off, make sure to manually depress the plunger that is normally activated by the lid, which retracts the loop formers.) If the first roll turned out OK it could just be that the pressure plate wasn’t seated right for the second roll. Sometimes you need to manually set the loop and check the pressure plate is seated properly.

If you suspect the pressure plate spring is too weak, you can remove it and bend the spring a bit by hand. 

Plenty of threads here about K3 loading, eg:

https://cinematography.com/index.php?/topic/80917-krasnogorsk-3-not-loading-properly/

Thanks for the suggestions, Dom! The film runs very smooth, no pulsing of the pressure plate whatsoever. My camera does have loop formers and the loops are also very stable while the camera is running.

The first roll actually didn't turn out ok as there was a couple of shots that also had this issue -- shots where I was shooting with the wider focal lengths of the Meteor zoom. This current roll wasn't all bad either, some of the footage was ok but about a third of the footage was shot with that same wider range of focal lengths on the Meteor zoom and that's where this problem shows up. The rest of the footage didn't seem to suffer from this.

I think I have found the culprit, though. I reached out to someone who's had this exact problem with a different camera and it turned out that the flange distance was off and the camera and lens had to be collimated. I am going to see if I can get that done with my K3.

 

[Dom Jaeger]

If the flange depth was out the whole image would be soft. Plus you can see the focus  pulsing at the start, so something is shifting. I think your initial diagnosis is quite possible, since the softness is very noticeably limited to the centre. It’s as if the film is sitting flat on the edge rails of the gate, but bowing out in the centre, and the pressure plate is unable to keep it flat. Maybe the gate is a little under size in width, causing the film to bow, or it’s the natural curvature of the film and the pressure plate is just weak or not seating properly.

But it won’t hurt to get the flange depth checked I guess. 

K3s are very cheap cameras, and their quality is pretty bit and miss. Personally I think  too often they have issues like this that put new filmmakers off film because of the hassle and disappointment, so I don’t recommend them. They might be cheap initially, but the cost of wasted rolls adds up. 

[Simon Wyss]

There are too many laypersons tampering with cameras (and projectors). Grisly. The aperture plate must be centered on the lens mount or vice versa, the claw must be centered on the slot in the plate horizontally plus adjusted in depth as well as vertically, the film must run positioned relative to the aperture plus be guided laterally, the pressure plate must be correctly seated plus bring the right and even pressure, the loop formers have to be so adjusted that loops of optimal size are established, the take up needs to be regular and of good tension. It’s simply too much for non-trained to respect and weigh up.

PRAYER: Will people please leave fine mechanics alone in case of failure and take them to a specialist. And acknowledge that a good service costs something. I have nothing against anybody screwing around with clocks and watches since I despise them. But not photographic and cinematographic equipment.

 

[Matt Figler]

Have had the exact same experience over time with my K3. For the first few years it sat nice and flat, but the spring & pressure plate is not very robust & overtime can weaken. I've also noticed the pressure plate is quite flexible material so it too can sometimes be ever so slightly bent out of shape & not hold the film flat enough. There are a few small screws that hold the spring tension of the pressure plate -- You can see this issue pop up in this recent video, where the film is flat on the sides but out of focus in the middle. 

 

Who has a good recommendation for someone who can tune up these cameras, check FFD + pressure plate? 

[Fedor Karpenko]

20 hours ago, Dom Jaeger said:

If the flange depth was out the whole image would be soft. Plus you can see the focus  pulsing at the start, so something is shifting. I think your initial diagnosis is quite possible, since the softness is very noticeably limited to the centre. It’s as if the film is sitting flat on the edge rails of the gate, but bowing out in the centre, and the pressure plate is unable to keep it flat. Maybe the gate is a little under size in width, causing the film to bow, or it’s the natural curvature of the film and the pressure plate is just weak or not seating properly.

But it won’t hurt to get the flange depth checked I guess. 

K3s are very cheap cameras, and their quality is pretty bit and miss. Personally I think  too often they have issues like this that put new filmmakers off film because of the hassle and disappointment, so I don’t recommend them. They might be cheap initially, but the cost of wasted rolls adds up. 

I think I am going to go ahead and get a full overhaul done just to rule everything out.

Like you said, I still think that the pressure plate may be the culprit, however, it looks like my lens is not functioning as a parfocal lens should, which is another symptom of the FFD being off or the lens needing collimating. Perhaps it is a mix of all of these issues haha. Hence, the full overhaul!

I actually got the camera quite cheap, only $160 with shipping included, so I'm not really too upset about having to spend $250 to overhaul the thing. Considering that most of these go for ~$300 on ebay and are still a gamble at that price point, I'm happy to spend $400 total to have a fully operational, tuned up K3. I have seen many that perform incredibly when they are properly maintained!

[Fedor Karpenko]

3 minutes ago, Matt Figler said:

Have had the exact same experience over time with my K3. For the first few years it sat nice and flat, but the spring & pressure plate is not very robust & overtime can weaken. I've also noticed the pressure plate is quite flexible material so it too can sometimes be ever so slightly bent out of shape & not hold the film flat enough. There are a few small screws that hold the spring tension of the pressure plate -- You can see this issue pop up in this recent video, where the film is flat on the sides but out of focus in the middle. 

 

Who has a good recommendation for someone who can tune up these cameras, check FFD + pressure plate? 

I think I will send mine to Du-All: http://www.duallcamera.com/services/Upgrade_KrasnogorskK3.shtml

Is there a chance you could specify which screws exactly control the pressure plate spring? Thank you!

[Matt Figler]

[Fedor Karpenko]

1 hour ago, Matt Figler said:

Thank you so much! I suspected that this was the one, just wanted to make sure I wasn't adjusting something I shouldn't be.