HELP......Sigma 70-210 lense

Emmanuel · 05-12-2008, 02:19 AM

I recently got a sigma 70-210mm f4-5.6 UCII lense for my Pentax K10D (second hand and quite cheap)
Its auto focus and everything worked fine when I got it. I took the lense off to put one of my other ones on, when I put my 70-210 lense on again the auto focus wouldn't work!!! I can feel that the focus motor has connected with the lense. On the camera lcd display for apature it says F----- . The Crazy thing is that I can still adjust the apature using the rear e-dial but I just can't see it untill after I take the photo and I check the photo info. the other crazy thing is that even though it is only a f4.0 lens if a flick the rear e-dial all thy way back ( and keep flicking for a while) I take the photo and looking at the photo info it says that it was taken at f1.2 apature (wow what a great lense!!!!)
All these problems happend once before but it suddenly started working again
I hope somone can help me!!!

Last edited by Emmanuel; 05-12-2008 at 02:53 AM. Reason: typos :)

little laker · 05-12-2008, 09:17 AM

I would think that there's dirty contacts. SO I'd start by cleaning the contacts on the lens.

JMS · 05-12-2008, 09:20 AM

Definitely dirty contacts. If all the contacts are shorted, a lens will appear as an f1.2 lens.

Emmanuel · 05-12-2008, 07:53 PM

Yes I actually had a suspision that the contacts where shortened but I rubbed them with a lint free cloth but they seem to have gone shorter!!!!! how do I lengthen the contacts
??????? I really like this lense and would like it to work

**Canada_Rockies** · 05-12-2008, 08:14 PM

Originally posted by Emmanuel

Yes I actually had a suspision that the contacts where shortened but I rubbed them with a lint free cloth but they seem to have gone shorter!!!!! how do I lengthen the contacts
??????? I really like this lense and would like it to work

The contacts are actually like little ball bearings sitting on a spring. The problem is that they are not returning to make contact, from your description. Use a loupe or magnifying glass and check them out carefully. You might actually have a piece of lint from the cloth keeping them down.

Dont' forget to clean the camera contacts as well. Use a micro fiber cloth with a drop of methyl alcohol on the cloth. Clean gently, not forcefully.

Emmanuel · 05-12-2008, 08:20 PM

Right-ee-oo I'll give it a go
Thanks for your help

Emmanuel · 05-13-2008, 06:30 PM

I took the lens to a friend (who knows heaps more about the technical side of things than me) and he examined it with a magnyfiying glass. there is one contact that is not sticking up as much as the rest. He said that is has hardly been worn while the other contacts have got a worn patch on them. He thought that it was probably a manufaturers fault because it apears to have been like that for a long time. Anyway we cleaned them using methylated spirits and a micro fibre cloth..
the lense has been working fine ever since ....................well so far at least. perhaps that contact was dirty and with the short conection it wouldn't take much to stop it from conecting.

it is still shorter than all the rest of the contacts
anyways I'm happy

Peter Zack · 05-13-2008, 06:37 PM

That contact is supposed to be down and it's normal. What fixed the problem was the cleaning. As CR said always use a microfibre cloth because they are much more lint free. Clean the camera contacts a s well periodically too.

Emmanuel · 05-13-2008, 06:45 PM

Ok thats interesting....... Do you have any idea as to why they have some contacts up and some down???

05-12-2008, 02:19 AM	#1
Emmanuel Junior Member Join Date: Apr 2008 Location: Australia Posts: 39	HELP......Sigma 70-210 lense I recently got a sigma 70-210mm f4-5.6 UCII lense for my Pentax K10D (second hand and quite cheap) Its auto focus and everything worked fine when I got it. I took the lense off to put one of my other ones on, when I put my 70-210 lense on again the auto focus wouldn't work!!! I can feel that the focus motor has connected with the lense. On the camera lcd display for apature it says F----- . The Crazy thing is that I can still adjust the apature using the rear e-dial but I just can't see it untill after I take the photo and I check the photo info. the other crazy thing is that even though it is only a f4.0 lens if a flick the rear e-dial all thy way back ( and keep flicking for a while) I take the photo and looking at the photo info it says that it was taken at f1.2 apature (wow what a great lense!!!!) All these problems happend once before but it suddenly started working again I hope somone can help me!!! Last edited by Emmanuel; 05-12-2008 at 02:53 AM. Reason: typos :)

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Sigma 70-210 F4-5.6 uc-ii	CWyatt	Pentax SLR Lens Discussion	1	08-11-2009 12:17 PM
Issues regarding Sigma 18-50mm f/2.8 lense.	i am pentaxian	Pentax SLR Lens Discussion	4	05-19-2009 02:00 AM
Sigma Lense, 50-500 mm F4	steven smith	Photographic Technique	6	07-03-2008 08:20 AM
1st Day out with my Sigma lense	Red_R1	Post Your Photos!	1	04-17-2008 07:06 PM
For Sale - Sold: FS: Sigma 1.4X (works on Tokina and Sigma 70/80-200/210 2.8s)	Mountain Vision	Sold Items	0	02-06-2008 04:30 AM

05-12-2008, 09:17 AM	#2
little laker Veteran Member Join Date: Sep 2006 Photos: Gallery Posts: 5,697	I would think that there's dirty contacts. SO I'd start by cleaning the contacts on the lens.

05-12-2008, 09:20 AM	#3
JMS Senior Member Join Date: Oct 2007 Location: Wisconsin Posts: 273	Definitely dirty contacts. If all the contacts are shorted, a lens will appear as an f1.2 lens.

05-12-2008, 07:53 PM	#4
Emmanuel Junior Member Join Date: Apr 2008 Location: Australia Posts: 39 Original Poster	Yes I actually had a suspision that the contacts where shortened but I rubbed them with a lint free cloth but they seem to have gone shorter!!!!! how do I lengthen the contacts ??????? I really like this lense and would like it to work

05-12-2008, 08:14 PM	#5
Canada_Rockies Loyal Site Supporter Join Date: Nov 2007 Location: Sparwood, BC, Canada Photos: Gallery \| Albums Posts: 12,385	Originally posted by Emmanuel Yes I actually had a suspision that the contacts where shortened but I rubbed them with a lint free cloth but they seem to have gone shorter!!!!! how do I lengthen the contacts ??????? I really like this lense and would like it to work The contacts are actually like little ball bearings sitting on a spring. The problem is that they are not returning to make contact, from your description. Use a loupe or magnifying glass and check them out carefully. You might actually have a piece of lint from the cloth keeping them down. Dont' forget to clean the camera contacts as well. Use a micro fiber cloth with a drop of methyl alcohol on the cloth. Clean gently, not forcefully.

05-12-2008, 08:20 PM	#6
Emmanuel Junior Member Join Date: Apr 2008 Location: Australia Posts: 39 Original Poster	Right-ee-oo I'll give it a go Thanks for your help

05-13-2008, 06:30 PM	#7
Emmanuel Junior Member Join Date: Apr 2008 Location: Australia Posts: 39 Original Poster	I took the lens to a friend (who knows heaps more about the technical side of things than me) and he examined it with a magnyfiying glass. there is one contact that is not sticking up as much as the rest. He said that is has hardly been worn while the other contacts have got a worn patch on them. He thought that it was probably a manufaturers fault because it apears to have been like that for a long time. Anyway we cleaned them using methylated spirits and a micro fibre cloth.. the lense has been working fine ever since ....................well so far at least. perhaps that contact was dirty and with the short conection it wouldn't take much to stop it from conecting. it is still shorter than all the rest of the contacts anyways I'm happy

05-13-2008, 06:37 PM	#8
Peter Zack Pentaxian Moderator Emeritus Join Date: May 2007 Location: Edmonton Alberta, Canada Photos: Gallery \| Albums Posts: 10,643	That contact is supposed to be down and it's normal. What fixed the problem was the cleaning. As CR said always use a microfibre cloth because they are much more lint free. Clean the camera contacts a s well periodically too.

05-13-2008, 06:45 PM	#9
Emmanuel Junior Member Join Date: Apr 2008 Location: Australia Posts: 39 Original Poster	Ok thats interesting....... Do you have any idea as to why they have some contacts up and some down???