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Sigma 50-500

bppowell 16 2.2k 2 England
7 May 2010 9:35PM
I had a little grub screw (bush) in the arm of my Sigma 50- 500 lens that allowed me to connect it to my tripod. It somehow became trapped on the tripod head when I unscrewed it and I had to trhough it away.

I have done a seach and found a couple of places that said I needed a 1/3 to 1/4 bush so I bought some but they do not fit the arm, they are too big.

Does anyone know what the size of the bush I need is?


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bppowell 16 2.2k 2 England
8 May 2010 3:47PM
Just Jas Plus
16 26.2k 1 England
8 May 2010 4:34PM
Have you contacted Sigma, Barry?
bppowell 16 2.2k 2 England
8 May 2010 5:23PM
Not yet, thought I might get a quicker answer here.

lawbert 11 1.8k 15 England
8 May 2010 7:10PM
I dont personaly know but if you have a good hardware store or independant builders merchant (probably the plumbing counter) locally they might be worth a try as they generally have trays and trays of odd sized grub screws and bushes and could probably find you one quicker and cheaper than Sigma.
Chrism8 11 903 21 England
8 May 2010 8:48PM
Hi Barrie, perhaps you can upload a pic of where the grub screw goes, had a quick look on the Sigma web site and it's not obvious, being japanese and recent build, the likelyhood is that it's going to be either M3 or M4 and easily available.

bppowell 16 2.2k 2 England
8 May 2010 9:47PM
Thanks for the suggestions.

Chris I am not an e2 member so cannot upload to a thread, but you could be right about it being metric.
If you have a look at the lens you can that that it has a support arm with the foot parallel to the lens, the bush fits in the bottom of this foot.

Just Jas Plus
16 26.2k 1 England
8 May 2010 11:24PM
Is it the bush that the tripod screw would fit into, to mount it onto the tripod? If so it would be a 1/4" Whitworth thread internally.

Or is it a locking screw that screws through the platform to secure it?

I am not quite sure what you are after.

If it is a bush which fitted into the tripod mounting arm of the lens, then I take that the bush pulled out when you tried to unscrew it from the tripod.

Was not the bush then trapped onto the tripod screw?

If so did you manage to remove it from the tripod screw.

Have you still got the bush or can you retrieve it?

If so you could probably re-fit it into the lens arm and secure it with something like Loctite. Perhaps roughening the outside of the bush before re-inserting it.

I guess what you want is a bush with the 1/4" Whit thread inside it, if the above is the case.
Just Jas Plus
16 26.2k 1 England
8 May 2010 11:44PM
The bushes you bought - do any fit onto the tripod screw OK?

If so, and it is too big for the hole it goes into on the lens arm, then drill the hole out to provide a tight fit and drive it in, say using vice jaws or similar.

Hope this helps, Barry.

Another possibility is a Helicoil, if you can find a motorcycle repairer to fit.

They are used in aluminium and alloy parts to provide a firm screw thread when fitted.
bppowell 16 2.2k 2 England
9 May 2010 3:13PM
Hi Jas, yes the screw on the tripod head fits ok. I may have to rebore the arm on the lens but I was trying to avoid it in case I sell the lens later.

Just Jas Plus
16 26.2k 1 England
12 May 2010 4:53PM

Quote:I may have to rebore the arm on the lens but I was trying to avoid it in case I sell the lens later.

At least you will have a fully usable lens to sell, if you do adopt this procedure, Barry.

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