# EF 300mm f/2.8 ( non IS ) AF ISSUES



## rodrigo_luiz78 (Apr 27, 2013)

I have a 14YO EF 300mm f/2.8 ( non IS ).
Its perfect, and it was working perfectly until last week.
Today Itook it to make some shots, and it dindt work.
The AF keep hunting, and never focus, some times it does, but not properly.
I tried everything.
I try on EOS 10D, 40D 1D MK II N , 1D MK III.
It dindt work, always the same problem, keep focusing, and never achive the focus.
Does anyone know what could it be ?


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## East Wind Photography (Apr 27, 2013)

A fine lens it is. Check the gold contacts on the back. Sometimes cleaning GENTLY with a qtip and alcohol will help. Other than that you should call Canon and see if they will check it out for you. It's worth it to get it fixed even though 14yo. I bet it's the contacts though. They don't last forever.

I've also see this happen with dirty battery contacts since on some cameras the AF motor gets its power directly from the battery. However since you have tried it on several bodies, I would say it's likely the contacts. But it could be something internal that needs to be repaired.


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## brad-man (Apr 27, 2013)

East Wind Photography said:


> A fine lens it is. Check the gold contacts on the back. Sometimes cleaning GENTLY with a qtip and alcohol will help. Other than that you should call Canon and see if they will check it out for you. It's worth it to get it fixed even though 14yo. I bet it's the contacts though. They don't last forever.
> 
> I've also see this happen with dirty battery contacts since on some cameras the AF motor gets its power directly from the battery. However since you have tried it on several bodies, I would say it's likely the contacts. But it could be something internal that needs to be repaired.



+1 A pencil eraser also works...


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## East Wind Photography (Apr 27, 2013)

No you don't want to use a pencil eraser. The eraser can leave a residue behind as we'll as get debris possible in the lens. They are also too abrasive for gold contacts, possible wearing the gold surface down even more.




brad-man said:


> East Wind Photography said:
> 
> 
> > A fine lens it is. Check the gold contacts on the back. Sometimes cleaning GENTLY with a qtip and alcohol will help. Other than that you should call Canon and see if they will check it out for you. It's worth it to get it fixed even though 14yo. I bet it's the contacts though. They don't last forever.
> ...


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## rodrigo_luiz78 (Apr 27, 2013)

Thanks to everybody.
I already cleaned the contacts, changed the distance, everything you guys can immagine.
Now I will have to take it to Canon ( São Paulo ) and hope, pray what ever I need they fix it.
Once again thanks and sorry for the english, I am not english speaker.


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## Mt Spokane Photography (Apr 27, 2013)

Canon stopped servicing them long ago, but third party parties might be able to help you. It might be something simple, I hope so.

Pro Camera Supply does have a limited supply of parts.

http://www.ebay.com/itm/CANON-EF-300MM-2-8-L-USM-IS-FOCUSING-UNIT-REPAIR-PART-/390307106888?pt=LH_DefaultDomain_0&hash=item5ae01dd048


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## TexPhoto (Apr 28, 2013)

This place has done great work for me: http://www.sp-ts.com
They will give you an estimate over the phone based on your description.


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## kaihp (Apr 28, 2013)

I think the OP is in Brazil (since he mentions São Paulo), so a US 3rd-party repair center may not help him that much.
Since Canon has stopped servicing them, they might be willing to point to a 3rd party in Brazil that could help.

Mt Spokane: I think the part you linked appears to for the IS MkI version. A focus unit for the non-IS seems to be like $1250:
http://www.ebay.com/itm/NEW-CANON-EF-300mm-1-2-8-L-USM-FOCUSING-UNIT-AL-625-/390183359378?pt=Digital_Camera_Accessories&hash=item5ad8bd9392


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## Mt Spokane Photography (Apr 28, 2013)

kaihp said:


> I think the OP is in Brazil (since he mentions São Paulo), so a US 3rd-party repair center may not help him that much.
> Since Canon has stopped servicing them, they might be willing to point to a 3rd party in Brazil that could help.
> 
> Mt Spokane: I think the part you linked appears to for the IS MkI version. A focus unit for the non-IS seems to be like $1250:
> http://www.ebay.com/itm/NEW-CANON-EF-300mm-1-2-8-L-USM-FOCUSING-UNIT-AL-625-/390183359378?pt=Digital_Camera_Accessories&hash=item5ad8bd9392


\
\
You are right, I missed that even though I was looking for it. In any event, new and used parts can be had, but at some point, a lens becomes more valuable for parts.


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## East Wind Photography (Apr 28, 2013)

And a lens of this quality STILL has value as a MF lens. Not ideal but at least would help maybe pay for some of a new or used IS model.



Mt Spokane Photography said:


> kaihp said:
> 
> 
> > I think the OP is in Brazil (since he mentions São Paulo), so a US 3rd-party repair center may not help him that much.
> ...


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## privatebydesign (Apr 28, 2013)

East Wind Photography said:


> And a lens of this quality STILL has value as a MF lens. Not ideal but at least would help maybe pay for some of a new or used IS model.



No it doesn't. It is a fly (focus) by wire lens, if the focus motor is faulty then it won't manual focus either, this is a huge problem for all focus by wire lenses and makes early supertele ownership an ever riskier proposition.


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## East Wind Photography (Apr 28, 2013)

Ouch. I thought all of the 300's offered full manual focus. Guess I'm wrong on that. Then it's either a repair or sold for parts. Quite a shame too because the optics are great.



privatebydesign said:


> East Wind Photography said:
> 
> 
> > And a lens of this quality STILL has value as a MF lens. Not ideal but at least would help maybe pay for some of a new or used IS model.
> ...


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## privatebydesign (Apr 28, 2013)

Yes it is a whole heap of hurt. Of course it does do full time manual focus, but only when mounted on a camera and the power is on, but the focus ring is not connected to the focus group, it is just a big switch that tells the focus motor where to send that focus group to.

This is true of all the focus by wire lenses, I believe this includes, 200 f1.8, 300 f2.8 MkI, 400 f2.8 MkI and MkII, 500 f4.5, 600 f4 MkI, 1200 f5.6, the 85 f1.2 MkI and MkII and the 50 f1.0. And we have now taken another step backwards, the new line of STM lenses are also FBW, the 40 f2.8 pancake and the EF-S 18-135mm f/3.5-5.6 IS STM


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## Mt Spokane Photography (Apr 28, 2013)

privatebydesign said:


> Yes it is a whole heap of hurt. Of course it does do full time manual focus, but only when mounted on a camera and the power is on, but the focus ring is not connected to the focus group, it is just a big switch that tells the focus motor where to send that focus group to.
> 
> This is true of all the focus by wire lenses, I believe this includes, 200 f1.8, 300 f2.8 MkI, 400 f2.8 MkI and MkII, 500 f4.5, 600 f4 MkI, 1200 f5.6, the 85 f1.2 MkI and MkII and the 50 f1.0. And we have now taken another step backwards, the new line of STM lenses are also FBW, the 40 f2.8 pancake and the EF-S 18-135mm f/3.5-5.6 IS STM


 
Yes, my 600mmL MK I had FBW, it was wonderful. I could vary the focus speed to slow for fine manual focus, when I had two TC's attached, or fast for normal use. The downside being that a bad focus motor rendered it useless. Fortunately, those old AF motors were very reliable and seldom failed. 
If I had a otherwise mint 300mm f/2.8, I'd pay the $1800 to get a AF motor replaced.


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## rodrigo_luiz78 (Apr 28, 2013)

TexPhoto said:


> This place has done grew work for me: http://www.sp-ts.com
> They will give you an estimate over the phone based on your description.



Thank you Tex.
I will try here in Brasil,but if it doesnt work, I will have to find a way to fix it in US


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## wickidwombat (May 3, 2013)

brad-man said:


> East Wind Photography said:
> 
> 
> > A fine lens it is. Check the gold contacts on the back. Sometimes cleaning GENTLY with a qtip and alcohol will help. Other than that you should call Canon and see if they will check it out for you. It's worth it to get it fixed even though 14yo. I bet it's the contacts though. They don't last forever.
> ...



WTF? do you want him to ruin his lens?


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## ChilledXpress (May 3, 2013)

wickidwombat said:


> brad-man said:
> 
> 
> > East Wind Photography said:
> ...



The pencil eraser technique has been around for a long time... it won't necessarily ruin his lens, it might not be a great solution though. It's oxidation they are talking about. Check with a electrical shop and pick up a cleaner specific for this and use gingerly on the on contact surface. 

I don't mess with this stuff personally, I'd just send to CPS or find a third party repair shop. Here in the Bay Area there are only a few that can tackle the old stuff.


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## East Wind Photography (May 3, 2013)

No there is a REALLY good chance it will ruin the lens or get rubber particles inside. No no no never use a pencil eraser on gold contacts. I worked in the electronics business for many years and the best way is the correct way. Use your pencils and erasers for writing only!



ChilledXpress said:


> wickidwombat said:
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> 
> > brad-man said:
> ...


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## bchernicoff (May 3, 2013)

Please let us know what you find out. I have a 400mm f/2.8 Mk II that is no longer serviced by Canon and I worry about the day when I have AF problems with it.


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