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Focus calibration tools?

Gromit

Gromit

Plasticine Dog
I've been having a play with the Sigma USB dock thingy to adjust the focusing accuracy of my Sigma 50 Art. My previous copy of this lens was utterly spot-on but this one does front-focus a tad - it is consistent though so easy to get around by adjustment. It's now virtually there, but would like to get it perfect.

Trouble is, my 'method' (I use that term very loosely) is about as scientific as welly-wanging and got to wondering if any of you folk had tried some of the tools/programmes available out there? Reikan FoCal seems quite popular but I know of very few others.

Thanks for any info. :)
 
I used this method when I had my Pentax K-5. It worked on all my AF lenses, bar one, which needed collimating.

The majority of my lenses are manual focus, and I've got to admit, it was infuriating trying to get accurate focus with no split screen to assist in nailing it. In the end OCD got the better of me, so I had a focusing screen custom made and re-shimmed the focusing screen to suit. Manual focusing was superb afterwards.

I've since sold most of my camera gear - only got about ten left :D most of them film cameras. Film is having a resurgence just now, just like vinyl.
 
Having been to a service facility (Nikon, Olympus) and seen the specialised Factory equipment they have for calibration of bodies and lenses, I'd not faff around with it myself and instead send it to the authorised service agent.

Would that be a warranty issue, Gromit?
 
Thanks for the link, Paul - that's a different slant on what I've read about and looks interesting.

Rico - the camera (D700) is well out of warranty, the lens itself just needs a bit of adjustment which the Sigma USB dock allows in 4 different focusing distance zones. It's more sophisticated than the AF adjust in-camera which only gives one setting for all distances. I have read that Sigma will match a lens to a specific camera but not sure if this service is available in the UK.
 
I have been using a tape measure on the floor and a coin to focus on, then you can see what numbers on the tape is focus.

Pete
 
Thanks for all the links/suggestions fellas - it's much appreciated. :)

Went shopping in Lincoln this morning so nipped into LCE (didn't spend any money - wahey!!) who suggested a Spyder LensCal which seems to get good reports. LCE don't sell it but I shall investigate further. It would appear though that with PDAF there will always be very slight variation in absolute focus accuracy - am just hoping this is a way of getting the baseline as accurate as possible.
 
I think you have to very careful here, micro focus adjustment seems to be the road to unhappiness for many on other forums. People seem to spend a long time continually adjusting their lenses, until they are at the point where they are not happy and end up sending the lens back or even loosing interest in that camera system completely.

My take, for a prime it is probably a good thing, I'd get the tools (or get someone who has the experience to do it), do it once and forget about it for the rest of time. Most peoples problems seem to come from zoom lenses, where they claim that it needs x adjustment at y mm, x1 at y2 mm, x2 at y2 mm and so on. You could be in this situation with different adjustments at different focal distances........

Take Rico's advice, find some one to do it.
 
I agree, calibrating a zoom is a minefield which is why I'd never go there - fortunately my Sigma 70-200 is just about spot-on and am very happy with it. If it hadn't been, it would be going back for exchange.

The 50 Art is performing well and has been quite interesting (and actually surprisingly therapeutic) to get it dialled-in with the USB dock. Have also found out that Sigma will in fact match a Global Vision lens to a specific camera body which I will get done at some point in the near future. The 50 Art is such a stunning lump of glass it would seem daft not to. :)
 
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