Yesterday I was shooting with my Nikon 85mm 1.8G lens on my d7100 body and all was normal. Then, for no apparent reason, autofocus simply stopped working. I took the lens off and checked autofocus with my Nikon 50mm 1.8d (a lens with no focus motor) and on my 35mm 1.8G DX lens (a lens with a focus motor). Both worked fine, so I eliminated the camera as a problem. I then cleaned the lens contact points on the lens with a clean cloth, reinstalled the lens, and it worked fine. At this point, I don't know if it is an intermittent focus motor issue with the motor in the lens, or if it was nothing more than something interfering with the contact points between the camera and the lens, or if it was something else. My concern is that I did not change lenses before this started. Autofocus was fine, then it was not. My question is whether anyone else has experienced a similar problem, and if so, was it and how was it corrected?

Most DSLRs have a stardard ISO range (say) 100-1600, which can often be extended/boosted by going to H1 or equivalent. Maybe increasing the range to 3200 or 6400, etc.

Some have a range of (say) 100 to 12,500, whcih can be boosted even further.

Question - is the effect on the picture generated any different when making use of an ISO within the "base" range versus the boosted range?

It is understood that the higher the ISO goes the more noise is expected due to an increase in the digital frequency. But, all else being equal, is there a significant difference as to whether the ISO comes from the base range or the extended range?

Stated another way - Is there a differnce if I use (say) an ISO of 12,500 from the Base range, or 12,500 from the boosted range?

Thank you in advance for your input.

Very interesting observation. I purchased a refurbished camera. As has already been discussed on this forum to the nth degree, I'm curious what the shutter count is. So, I snapped my first photo, loaded it and found the shutter count was 46. Cool. 45 photos taken before it was delivered.

Interesting, though, I am using a brand new memory card and the file sequence number is _DSC2477.NEF. hmmm. Methinks that the shutter count was reset during refurbishing process.

Trust me, I have no complaints. I'm loving the camera.