A few months ago I bought the Sigma 85 1.4 lens and it quickly became my go to portrait lens. A few days ago I was using it on a shoot and it seemed like everything was exceptionally bright, but I thought it was just an issue with the off camera lighting I was using and didn't give it much thought. I had the same problem today and I realized that the lens wasn't stopping down. The camera says it is, but I was shooting F16 and everything was blowing out. I assumed it was a lens problem, but decided to try it on my D7000 tonight just to see what happened. It worked perfectly fine on the D7000. I tried it again on the D800 and it has the same problem. There's a negligible difference between f16 and f1.6. My other lenses work fine on the D800.
So what could be causing this? Why would the lens not work on the D800 (after working correctly the past 3 months) but still work fine on the D7000? Has anyone ever encountered a situation like this? I'm really worried something is off with my D800 as it's been a little "buggy" since I bought it new last May.
It sounds like something peculiar is happening with the aperture stop-down lever connection between the D800 and Sigma lens. This would be tough to get Nikon to diagnose, but Sigma would most likely look at the combo if you sent them both items. (A notable pain in the you-know-what.)
You might be able to get a better idea if you were to get a magnifying glass, look at the mount on the Sigma lens where the aperture lever is, and compare it to other lenses that you have. Do the same with the D800 mount and your D7000.
No guarantees, but maybe something will be revealed.
Also, take a look at the lens alignment after mounting the Sigma on the D800 and D7000 to see if they both seem to line up the same.
Fri 19-Apr-13 12:03 AM | edited Fri 19-Apr-13 12:06 AM by sethjar
I'll check that out - thanks, Mick!
I definitely don't want to give up my D800 for any amount of time. Hopefully I can work something else out. I'm going to try to attach a a photo to show the very slight difference between 1.6 and f16. The aperture must not be completely "stuck", as you can see f16 is just slightly dimmer.
Fri 19-Apr-13 01:03 AM | edited Fri 19-Apr-13 01:52 AM by sethjar
Marty - You know, I've never once used the DoF preview button on any of my digital cameras.
I tried it with this lens. The viewfinder gets slightly darker but it's still a very shallow depth of field, probably 2.8-3.2 would be my guess. I did some new test shots and it just going by exposure, I can see absolutely no difference from 3.2 to 16. 1.4 seems normal as does 1.6 through 3.2 but after 3.2 it just stops changing.
After thinking about this more, I wonder if it ever went past 3.2 on my D800. I usually shoot very open & doubt I ever went beyond 4 or 5.6. I wasn't using off camera lighting with the lens until just this week, so I would have just compensated by adjusting the shutter speed and wouldn't have realized that the aperture wasn't changing. I only caught it this time because my ss was limited by the speedlights.
Mick is probably right about the indexing level not engaging. Usually is is due to a bent control arm in the camera but yours works with other lenses. Try comparing the pressure needed to move the little index level on the rear of the lens and compare the pressure needed to move it to other lenses. It should be smooth spring loaded resistance without and "rough" spots where differences in pressure are required. If the arm is the right height compared to other working lenses, and the arm moves freely controlling the aperture, the problem might be on the camera side. Pay close attention to the height of the lens index arm, if it any lower than other lenses, the arm inside the camera might be simply missing it, the control lever glancing over the top of the indexing arm on the lens. The little metal arm might be bent slightly and can be bent back with care. Stan St Petersburg Russia
Stan - I think you've got it. When I move the level on my other lenses, the lever "snaps" back into place. On the 85, it goes about half way and stops. I can physically move it and it doesn't feel like it's hard to move, but it definitely doesn't have that fluid, snappy movement that the other lenses possess.
Now the question is, should I fiddle around with the lens or send it in to Sigma for repair?
You probably have a bent arm or bad spring in the Aperture mechanism. It is likely that it isn't easily accessible without disassembling the lens.
Send it to Sigma, and they will fix it properly and also do a general lens check-up. My guess is it will be a warranty repair, unless there are signs of abuse.
IF you try to fix it and can't, then need to send it in, it definitely won't be covered by warranty.
The Sigma web site has the appropriate on-line form for submitting the service request, as well as information on shipping to them. You need to pay the cost of shipping it to them. If there is any cost to repair, they will notify you before doing any work. They are pretty quick and also very good.