tristanlaing Posted June 1, 2006 Share Posted June 1, 2006 So, I bought the sigma 18-35 and it's great. Unfortunately, it seems to have damadged the AF of my F90x. I used the sigma and my nikkor 28-85 af zoom the day I bought the new lens, both worked fine, and at the end put the camera away with the sigma left on it. 2 days later I get out the camera, start fooling around with it (I wanted to take 2 more shots so I could get the rest developed), and noticed that it will no longer AF with my 28-85 zoom. Closer inspection reveals that the AF screw (or rather, the slot the screw fits into) is much more recessed on my 28-85 zoom than on my new 18-35. When I mount the 28-85 the camera af motor runs, but doesn't grip the lens. It just whirrs. I tried my 50 1.4 AF (non D), and it still autofocuses, but sounds clunkier than before - distinctly clunkier, like it isn't engaging the screw as positivly as before. Has anyone else had this issue? It seems that leaving the camera with the sigma lens on has pushed the af screw farther into the body? Is it normal for the af screw on the 28-85 to be recessed much more than on the 50 1.4? Do people know how the AF motor works? thanks for any help. Link to comment Share on other sites More sharing options...
fred aspen Posted June 1, 2006 Share Posted June 1, 2006 Don't know if this will help but had the same problem with F100. Turns out the M-S-C autofocus.manual switch (looks like the N90 has the same switch lower right hand next to the lens) appeared to be in the "S" mode but was half way between M-S. When in the "M" mode, the autofocus drive shaft is retracted. When half way, it makes intermittent contact. HTH, Ron Link to comment Share on other sites More sharing options...
tristanlaing Posted June 1, 2006 Author Share Posted June 1, 2006 I know the problem you are referring to, and I have had that happen a few times, but this isn't it. I checked multiple times, changing lenses, putting it in C or S af mode. Has anyone had an off brand lens somehow push the af screw back into the body? Does anyone know how to repair this? Link to comment Share on other sites More sharing options...
fred aspen Posted June 2, 2006 Share Posted June 2, 2006 There might also be some grit/grime lodged in the drive shaft guide. I would be inclined, if it were my problem, to use the smallest drop of isopropyl alcohol on a toothpick and apply it to the drive shaft and immediately exercise it. Good luck! Ron Link to comment Share on other sites More sharing options...
tristanlaing Posted June 2, 2006 Author Share Posted June 2, 2006 Where is the drive shaft? I can't seem to find out to get at it in the camera? Link to comment Share on other sites More sharing options...
jay_miao1 Posted June 2, 2006 Share Posted June 2, 2006 If you face the front of camera body without a lens attached the screw driver head (just like a philips screw driver) is at about 7 o'clock position, and it should be moved out and in properly when rotating the M-C-S button at lower right, in which case you may simply tell whether the "shaft" on your N90X works correctly or not based on a common sense. BTW, I just checked my Sigma 28-105mm 2.8 lens and F100 instead, which both have the screw driver head (male and female, respectively) well recessed to each other while its flattened out with base properly on the lens part. I guess yours might be out of position or misaligned on either side or both (hopefully not that bad). Use the suggested method to correct it carefully. Link to comment Share on other sites More sharing options...
tristanlaing Posted June 2, 2006 Author Share Posted June 2, 2006 Alright. So, I think my initial formulation is correct. I found the AF drive shaft, and as I assumed, when I push it in it springs back in a spring like fashion. However, when I hold the body upside down, or pull slightly on it, it comes out an extra 1/2 mm or so. This, I believe, is the reason why it will no longer turn the AF screw on my 28-85. I suppose its possible that leaving a lens on a body for a few days might warp the tiny spring that pushes the AF screw out. Does anyone have any idea how to repair that? sounds like repair centre for me. Is there a nikon repair place in Toronto, Ontario? Tristan Link to comment Share on other sites More sharing options...
jay_miao1 Posted June 2, 2006 Share Posted June 2, 2006 Try to narrow down the problem for you as just checked my F100 again although I do have also a N90s at home but the AF mechanism should be the same, I believe. I found that the 1/2mm free movement thing does exist as to be normal on the driver shaft. Therefore, I'd check the lenses as well as if they might have any issues in regards of screw loosening, worn out or misaligned, etc., especially on the 28-85, prior to conclusion of N90s fault. Link to comment Share on other sites More sharing options...
tristanlaing Posted June 3, 2006 Author Share Posted June 3, 2006 interesting point, and thank you for checking with your F100 (I have no other nikon SLRs). I suppose I only paid 70$ for the lens anyway. I'll take it to a dealer to see if they can determine the lens to be at fault. The really ironic thing is, I almost dropped that lens on the ground while riding the other day, but didn't. Link to comment Share on other sites More sharing options...
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