50-500... mount broke! [now fixared!]

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chenko

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Meh, that will teach me to store the camera with the lens on (only way it all fits)

Must of got knocked and the mount has "ripped" out of the lens body.


What surprises me is, the four screws which hold the metal mounting ring onto the lens, they were sitting happy in the mount on the camera... and the screw holes, snapped? no... the screws will go back into the lens, so I have the mount back on the lens okay. It would be a fixed lens but it pulled the ribbon cable and ripped it in half.

How on earth did the screws come (all four!) out without breaking any of their mounts? It does seem to only take around 1/2 to 3/4 a turn to get the screws back in tight so there isn't much thread holding it into its screw hole :/
 
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I suspect that the mount is designed to be the weak point for good reason. These accidents do happen, particularly with longer lenses.
 
Was the camera being stored in a bag? I store my camera with a 120-400mm lens attached, which a pretty big heavy thing. I'd be gutted if that happened to me.
 
do i assume you mean to save damage to the camera or more expensive parts of the lens CT??
 
fletch5 said:
do i assume you mean to save damage to the camera or more expensive parts of the lens CT??
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Absolutely Fletch. When you think how securely that lens bayonets to the body, all the stress is going to be on the lens throat of the camera unless there's a deliberate weak point built in, and would probably end up with a fubar'd body or lens. With long heavy lenses, the danger of getting dropped is always there without careful handling, and when you think about someone barging into your lens from the side with something like a 500 or 600mm lens mounted, the leverage being inserted at the lens throat would be enormous.
 
I know to my cost that teleconverters come apart very easily indeed and I considered I got away light at the time. :D
 
CT said:
I know to my cost that teleconverters come apart very easily indeed and I considered I got away light at the time. :D
Click to expand...

better the TC than the 500 i think
 
If they are "supposed" to break away, it would be nice then if they put some proper ribbon connectors so it doesn't just rip the ribbon in half.

It wouldn't be so bad if it just pulled the solder part, but the ribbon has ripped half way across.
 
Just to let anyone know, if this happens to you, Sigma will want £130+VAT to sort it.

Probably because the ribbon is soldered in and will need to replace the small PCB (and whatever is connected to it...) to sort it.

I'm just going to find a matching piece of ribbon and sort it myself, the solder points are bigger than my face so its a piece of pee. Obviously wanted to see if sorting it "properly" at first was not going to cost too much, seems so.
 
Okay, finally after all this time of being lazy...

...I fixed it myself.


Sigma can go and shove their own £130 where the lens doesn't fit, which actually... is quite a lot of places.

Would have only taken me a few minutes, but decided to go with longer wires after realising short ones were being too stressed when bent in the way that the original ribbon was, which was in a pretty poor position to start with.

I still think that if this was a designed weak point, why is the ribbon cable attached by solder points...!


Here is my fix with the short wires, by time I changed to the longer wires, I couldn't be bothered to take pictures. :p



I still don't trust the screws though, they were never mounted that well, and feel worse now. I will need to get some longer ones (original ones are not long enough, seriously so)
 
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I get a bit worried about my Tamron 18-200 sometimes as it has a plastic mount. Could just imagine it snapping right off!
 
That tamron isn't that big, heavy or long, I wouldn't worry about it dropping off. Even if it did, might have better screws on it to start with and no silly ribbon cable to rip straight in half!
 
Okay - well this lens ruined any love of photography in the recent years - matched with the poor attitude from Sigma UK.


Though now I am trying my best to get it sorted but am not sure the best way forward.

Basically, it works, but the screws are way too short to hold the body on, and I wouldn't trust it, because the threads are only half engaged the ends have stripped.


I need longer screws of the same pitch - but have no idea where I could get screws so small (and what size they area) does anyone have ANY ideas on anything?

There isn't enough there for loctite or that kind of stuff.
 
Do you know much about them - minimum orders etc? I've seen a few others around like this, though mostly UK.

Will give them a try though - just need to figure this screw type out.

All I know so far is its 4mm long, granted I will get a 6mm or something. Major width is 2mm I think, no idea on pitch though, can't measure that myself.


edit: saying that - now I know the rough sizes I am looking for searching for "M2 countersunk" etc brings up more options - still guess work though on what the sigma uses.
 
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If you look for a fasteners company local to you they should be able to help, especially if you take one of the screws to them so they can measure thread pitch etc...
 
Microscrew came back - minimum £50.

I found some packs of 25 on ebay, and ordered some M2 for £1.69.

I have no places like you mentioned around here sadly - so for now will just compare them under a microscope and then give one a try.

And will use loctite as well :p
 
You have to be careful. Cheap screws = really cheap screws. Ever tried to drill Ikea-supplied screws into some hardwood? Yepp, cheap metal makes rubbish screws.
 
I can't do a huge amuont about it really - I'm not exactly going to buy £50 worth for the sake of 4 - and even then, it could be exactly the same.

I had an email from Sigma this morning (as I asked the screw type), they said they would send me new ones.

Which sounds good - but I no longer trust their screws as they are imo way too short.
 
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Feel free to post me one and I'll sort longer ones out for you. We have a fastener specialist about a mile away. I am away from tomorrow to Sunday though.
 
Forest Fasteners in Mitcheldean. Very helpful bunch of people :)

Where are you?
 
Thanks for the offer though - will wait for my others to arrive and see how they sit before treking off there.
 
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Received longer screws: they fit perfectly, hold well, but the head is slightly too big so it isn't flush enough to get the lens on the camera.

Received replacement original screws from sigma: they just pull out, so part of the threads are striped in the camera body itself.

The fact that the longer screws hold in means the "sigma length" screws don't make full use of the thread inside the body.
 
Very few fasteners do reach to the bottom of the hole, most are long enough to cope with the stresses and strains of normal use and overlength ones can put excess stress/strain on parts that can't cope with it.
 
You'd need to have a look at just how little of the screw sits, we're talking just under a whole revolution, which even when double threaded isn't enough for this imo.
 
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