K-50 with Sigma 170-500 giving F-- display

jswilson64 · 02-13-2016, 01:43 PM

I purchased a used Sigma 170-500 APO DG from KEH in January. When it came, I checked it out a bit, but weather and life really precluded me using it much until today. I mounted the lens to my K-50, mounted the lens foot to my tripod, powered up and saw F-- for the aperture display. Dismounted body from lens, double-checked the aperture ring was locked on Auto, remounted, same thing. Panicking, I tried again, pressing the body and lens together with a bit more "oomph" (not forcing anything), and when I powered up, this time the aperture displayed properly.

Is this something to be concerned about? I'm outside the 2-week return period for KEH but is it worth hitting them up for a RMA? Or can I address this myself (tightening the lens mounts? not sure...).

Any advice appreciated (except "dump it and buy a Bigma" - not in the budget). Thanks.

bertwert · 02-13-2016, 01:45 PM

Clean the contacts on the camera and lens?

KDD · 02-13-2016, 02:05 PM

Try turn on using Aperture ring??

Use AF-A and try AF-C???

---------- Post added 02-13-16 at 02:08 PM ----------

Have you reset your camera yet?

**jatrax** · 02-13-2016, 02:30 PM

"F _ _" indicates the lens and camera are not communicating.

Originally posted by KDD

Try turn on using Aperture ring??

'A' lens, so should not matter, assuming aperture ring is in 'A' position.

As Bertwert says clean the lens and camera contacts. Check the lens mount to make sure the screws are all tight. I have seen some reports of sigma lens mounts being slightly misaligned. THis can cause the contacts to be off just enough to miss contact. Check that the lens mount has no play in it. Try turning the lens a bit after it is on the camera to see if there is any play in the connection.

jswilson64 · 02-13-2016, 04:38 PM

Originally posted by jatrax

"F _ _" indicates the lens and camera are not communicating.

'A' lens, so should not matter, assuming aperture ring is in 'A' position.

As Bertwert says clean the lens and camera contacts. Check the lens mount to make sure the screws are all tight. I have seen some reports of sigma lens mounts being slightly misaligned. THis can cause the contacts to be off just enough to miss contact. Check that the lens mount has no play in it. Try turning the lens a bit after it is on the camera to see if there is any play in the connection.

There is a little play when the lens is mounted. I'll see if I can gently tighten the mounts. And clean the contacts...

jswilson64 · 02-14-2016, 09:50 AM

Tightening things seems to have helped, I'll see how it goes...

02-13-2016, 01:43 PM	#1
jswilson64 Senior Member Join Date: Jan 2011 Location: wilson_j_s@sbcglobal.net Photos: Albums Posts: 118	K-50 with Sigma 170-500 giving F-- display I purchased a used Sigma 170-500 APO DG from KEH in January. When it came, I checked it out a bit, but weather and life really precluded me using it much until today. I mounted the lens to my K-50, mounted the lens foot to my tripod, powered up and saw F-- for the aperture display. Dismounted body from lens, double-checked the aperture ring was locked on Auto, remounted, same thing. Panicking, I tried again, pressing the body and lens together with a bit more "oomph" (not forcing anything), and when I powered up, this time the aperture displayed properly. Is this something to be concerned about? I'm outside the 2-week return period for KEH but is it worth hitting them up for a RMA? Or can I address this myself (tightening the lens mounts? not sure...). Any advice appreciated (except "dump it and buy a Bigma" - not in the budget). Thanks.

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02-13-2016, 01:45 PM	#2
bertwert Veteran Member Join Date: Jun 2015 Location: Golden, BC Posts: 15,172	Clean the contacts on the camera and lens?

02-13-2016, 02:05 PM	#3
KDD Veteran Member Join Date: Sep 2013 Photos: Gallery \| Albums Posts: 403	Try turn on using Aperture ring?? Use AF-A and try AF-C??? ---------- Post added 02-13-16 at 02:08 PM ---------- Have you reset your camera yet?

02-13-2016, 02:30 PM	#4
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	"F _ _" indicates the lens and camera are not communicating. Originally posted by KDD Try turn on using Aperture ring?? 'A' lens, so should not matter, assuming aperture ring is in 'A' position. As Bertwert says clean the lens and camera contacts. Check the lens mount to make sure the screws are all tight. I have seen some reports of sigma lens mounts being slightly misaligned. THis can cause the contacts to be off just enough to miss contact. Check that the lens mount has no play in it. Try turning the lens a bit after it is on the camera to see if there is any play in the connection.

02-13-2016, 04:38 PM	#5
jswilson64 Senior Member Join Date: Jan 2011 Location: wilson_j_s@sbcglobal.net Photos: Albums Posts: 118 Original Poster	Originally posted by jatrax "F _ _" indicates the lens and camera are not communicating. 'A' lens, so should not matter, assuming aperture ring is in 'A' position. As Bertwert says clean the lens and camera contacts. Check the lens mount to make sure the screws are all tight. I have seen some reports of sigma lens mounts being slightly misaligned. THis can cause the contacts to be off just enough to miss contact. Check that the lens mount has no play in it. Try turning the lens a bit after it is on the camera to see if there is any play in the connection. There is a little play when the lens is mounted. I'll see if I can gently tighten the mounts. And clean the contacts...

02-14-2016, 09:50 AM	#6
jswilson64 Senior Member Join Date: Jan 2011 Location: wilson_j_s@sbcglobal.net Photos: Albums Posts: 118 Original Poster	Tightening things seems to have helped, I'll see how it goes...