FA 100-300mm f4.7-5.8 silver autofocus

**SointulArt** · 12-05-2012, 06:44 PM

I experienced an odd focus problem with my FA 100-300mm f4.7-5.8 silver lens on my K5 yesterday. For no apparent reason the lens will now only auto-focus at 100mm. When the focal length is extended beyond 100mm, there is no auto-focus, but I do get focus confirmation (red dot, beep). It was working fine prior to yesterday morning. I am very new to the Pentax world and wondered if I have overlooked something, or whether this is an issue with the lens.

Anyone else ever experience this type of problem? Thanks for any advice.

cheers
Darryl

Eulogy · 12-05-2012, 10:20 PM

I don't think I've ever heard of such an issue, have you cleaned the contacts, and perhaps turned between AF and MF several times?

Also, any strange noises when the lens is focusing, or when zooming?

**SointulArt** · 12-05-2012, 10:23 PM

Originally posted by Eulogy

I don't think I've ever heard of such an issue, have you cleaned the contacts, and perhaps turned between AF and MF several times?

I've turned between AF and MF multiple times, also cycled power on off and switched between AF and MF. I did wipe the contacts, but I'll try being a little more aggressive with them and give them a good clean and see if that works. Thanks for the suggestion!

Eulogy · 12-05-2012, 10:24 PM

Originally posted by SointulArt

I've turned between AF and MF multiple times, also cycled power on off and switched between AF and MF. I did wipe the contacts, but I'll try being a little more aggressive with them and give them a good clean and see if that works. Thanks for the suggestion!

Seems peculiar, to say the least...swab it with isopropyl alcohol if you have some of the good stuff.(70%+)

**SointulArt** · 12-05-2012, 10:28 PM

Okay, tried cleaning the contacts and no joy. Although just noticed that when the lens is not at 100mm the LED display on the K5 flashes and the F stop is listed only as "--", moving the lens back to 100mm and the f stop is correctly registered and the display stops flashing.

**SointulArt** · 12-05-2012, 11:43 PM

I've just taken the lens off the camera and playing with the zoom and focus and noticed a "clunk" in the mechanism. I guess this is a serious issue with the internals of the zoom. Well, at least it worked for me for a week and a bit... :-(

**SointulArt** · 12-06-2012, 12:32 AM

I have a couple of manual zooms in this range, so I am going to give this one away for free, shipping only.

It really is a great lens, and I am glad that I picked up another one on eBay for $70.

Eulogy · 12-06-2012, 10:56 AM

I'd ask whoever you purchased it from about the issue. Perhaps they neglected to inform you of it?

Louicio · 12-06-2012, 12:05 PM

Make sure the aperture ring is on the 'A' and not stuck somewhere in the middle. It's a long shot but check everything before you try to return it.

12-05-2012, 06:44 PM	#1
SointulArt Site Supporter Join Date: Oct 2012 Location: Sointula, BC Photos: Gallery \| Albums Posts: 453	FA 100-300mm f4.7-5.8 silver autofocus I experienced an odd focus problem with my FA 100-300mm f4.7-5.8 silver lens on my K5 yesterday. For no apparent reason the lens will now only auto-focus at 100mm. When the focal length is extended beyond 100mm, there is no auto-focus, but I do get focus confirmation (red dot, beep). It was working fine prior to yesterday morning. I am very new to the Pentax world and wondered if I have overlooked something, or whether this is an issue with the lens. Anyone else ever experience this type of problem? Thanks for any advice. cheers Darryl

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12-05-2012, 10:20 PM	#2
Eulogy Veteran Member Join Date: Feb 2012 Location: Fredericton, New Brunswick Photos: Gallery Posts: 632	I don't think I've ever heard of such an issue, have you cleaned the contacts, and perhaps turned between AF and MF several times? Also, any strange noises when the lens is focusing, or when zooming?

12-05-2012, 10:23 PM	#3
SointulArt Site Supporter Join Date: Oct 2012 Location: Sointula, BC Photos: Gallery \| Albums Posts: 453 Original Poster	Originally posted by Eulogy I don't think I've ever heard of such an issue, have you cleaned the contacts, and perhaps turned between AF and MF several times? I've turned between AF and MF multiple times, also cycled power on off and switched between AF and MF. I did wipe the contacts, but I'll try being a little more aggressive with them and give them a good clean and see if that works. Thanks for the suggestion!

12-05-2012, 10:24 PM	#4
Eulogy Veteran Member Join Date: Feb 2012 Location: Fredericton, New Brunswick Photos: Gallery Posts: 632	Originally posted by SointulArt I've turned between AF and MF multiple times, also cycled power on off and switched between AF and MF. I did wipe the contacts, but I'll try being a little more aggressive with them and give them a good clean and see if that works. Thanks for the suggestion! Seems peculiar, to say the least...swab it with isopropyl alcohol if you have some of the good stuff.(70%+)

12-05-2012, 10:28 PM	#5
SointulArt Site Supporter Join Date: Oct 2012 Location: Sointula, BC Photos: Gallery \| Albums Posts: 453 Original Poster	Okay, tried cleaning the contacts and no joy. Although just noticed that when the lens is not at 100mm the LED display on the K5 flashes and the F stop is listed only as "--", moving the lens back to 100mm and the f stop is correctly registered and the display stops flashing.

12-05-2012, 11:43 PM	#6
SointulArt Site Supporter Join Date: Oct 2012 Location: Sointula, BC Photos: Gallery \| Albums Posts: 453 Original Poster	I've just taken the lens off the camera and playing with the zoom and focus and noticed a "clunk" in the mechanism. I guess this is a serious issue with the internals of the zoom. Well, at least it worked for me for a week and a bit... :-(

12-06-2012, 12:32 AM	#7
SointulArt Site Supporter Join Date: Oct 2012 Location: Sointula, BC Photos: Gallery \| Albums Posts: 453 Original Poster	I have a couple of manual zooms in this range, so I am going to give this one away for free, shipping only. It really is a great lens, and I am glad that I picked up another one on eBay for $70.

12-06-2012, 10:56 AM	#8
Eulogy Veteran Member Join Date: Feb 2012 Location: Fredericton, New Brunswick Photos: Gallery Posts: 632	I'd ask whoever you purchased it from about the issue. Perhaps they neglected to inform you of it?

12-06-2012, 12:05 PM	#9
Louicio Veteran Member Join Date: Mar 2012 Location: Melbourne Posts: 432	Make sure the aperture ring is on the 'A' and not stuck somewhere in the middle. It's a long shot but check everything before you try to return it.