The pentax 645 FA* 300/4 issue

ethan8331 · 06-09-2023, 12:30 AM

Hi, I just brought a used FA* 300/4 and on my 645D, it won't focus, when it turns on auto focus, it just keep turning. Is it some setups I need to do on the camera？ or maybe the lens is broken? only used some mf lens before. thanks a lot!

pschlute · 06-09-2023, 12:59 AM - **2 Likes**

Originally posted by ethan8331

Hi, I just brought a used FA* 300/4 and on my 645D, it won't focus, when it turns on auto focus, it just keep turning. Is it some setups I need to do on the camera？ or maybe the lens is broken? only used some mf lens before. thanks a lot!

I believe you have to push/pull the focus ring to engage/disengage AF on this lens. Have you tried performing this a number of times ?

ethan8331 · 06-09-2023, 06:59 PM

Originally posted by pschlute

I believe you have to push/pull the focus ring to engage/disengage AF on this lens. Have you tried performing this a number of times ?

hi,thanks for the reply, I tried a couple of times but no luck. right now I think maybe I should update the firmware, right now mine is 1.00, I hope I can still download the 1.33 and hope that will fix it,thanks =)

Wickie · 06-10-2023, 06:13 PM

Hi, you have to put the camera and the lens to AF.
Is "AUTO FOCUS" above the distance scale of the lens visible?

Sandy Hancock · 06-10-2023, 06:22 PM

Unfortunately, there is something wrong with your lens. I have my own 645 FA*300 sitting beside me as I type.

In MF mode, there is a hard stop at infinity and minimum focal distance.
In AF mode, I can not rotate the focussing ring at all.

It's a *really* good lens though. Worth getting repaired if that's an option for you

ethan8331 · 06-11-2023, 12:15 PM

Originally posted by Wickie

Hi, you have to put the camera and the lens to AF.
Is "AUTO FOCUS" above the distance scale of the lens visible?

yeah, I tried that, still not working , I think I need to repair it, thanks for the reply and have a good day!

---------- Post added 06-11-23 at 12:16 PM ----------

Originally posted by Sandy Hancock

Unfortunately, there is something wrong with your lens. I have my own 645 FA*300 sitting beside me as I type.

In MF mode, there is a hard stop at infinity and minimum focal distance.
In AF mode, I can not rotate the focussing ring at all.

It's a *really* good lens though. Worth getting repaired if that's an option for you

looks like it, anyway, I will put it in repair, thanks!

06-09-2023, 12:30 AM	#1
ethan8331 New Member Join Date: Oct 2011 Posts: 4	*The pentax 645 FA 300/4 issue** Hi, I just brought a used FA* 300/4 and on my 645D, it won't focus, when it turns on auto focus, it just keep turning. Is it some setups I need to do on the camera？ or maybe the lens is broken? only used some mf lens before. thanks a lot!

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06-09-2023, 12:59 AM - 2 Likes	#2
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,216	Originally posted by ethan8331 Hi, I just brought a used FA* 300/4 and on my 645D, it won't focus, when it turns on auto focus, it just keep turning. Is it some setups I need to do on the camera？ or maybe the lens is broken? only used some mf lens before. thanks a lot! I believe you have to push/pull the focus ring to engage/disengage AF on this lens. Have you tried performing this a number of times ?

06-09-2023, 06:59 PM	#3
ethan8331 New Member Join Date: Oct 2011 Posts: 4 Original Poster	Originally posted by pschlute I believe you have to push/pull the focus ring to engage/disengage AF on this lens. Have you tried performing this a number of times ? hi,thanks for the reply, I tried a couple of times but no luck. right now I think maybe I should update the firmware, right now mine is 1.00, I hope I can still download the 1.33 and hope that will fix it,thanks =)

06-10-2023, 06:13 PM	#4
Wickie Junior Member Join Date: Nov 2022 Posts: 29	Hi, you have to put the camera and the lens to AF. Is "AUTO FOCUS" above the distance scale of the lens visible?

06-10-2023, 06:22 PM	#5
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,275	Unfortunately, there is something wrong with your lens. I have my own 645 FA300 sitting beside me as I type. In MF mode, there is a hard stop at infinity and minimum focal distance. In AF mode, I can not rotate the focussing ring at all. It's a really* good lens though. Worth getting repaired if that's an option for you

06-11-2023, 12:15 PM	#6
ethan8331 New Member Join Date: Oct 2011 Posts: 4 Original Poster	Originally posted by Wickie Hi, you have to put the camera and the lens to AF. Is "AUTO FOCUS" above the distance scale of the lens visible? yeah, I tried that, still not working , I think I need to repair it, thanks for the reply and have a good day! ---------- Post added 06-11-23 at 12:16 PM ---------- Originally posted by Sandy Hancock Unfortunately, there is something wrong with your lens. I have my own 645 FA300 sitting beside me as I type. In MF mode, there is a hard stop at infinity and minimum focal distance. In AF mode, I can not rotate the focussing ring at all. It's a really* good lens though. Worth getting repaired if that's an option for you looks like it, anyway, I will put it in repair, thanks!