FOCUSING reproduction of paintings

[ALAIN]

Hello,
I use an HC120 on an H5D-60, for reproduction photos of paintings.
Focusing with the standard viewfinder is quite imprecise.
I tried to put a Rollyflex magnifying glass on the frosted surface: it's better, but it's still not grown much.
To be precise, I focus at full aperture and shoot at F11, mirror up front.
If any remarks or solutions can be shared, thank you in advance.
Beautiful pictures to all,
Alain (from France)

[brian]

try tethered to a computer or monitor?

[Alex]

(Fine) focus at f4 using the (tethered) Live View at 100% positioned at 33% from the centre - properly aligned to flat subject matter and with a decent optical quality unit you should be able to get your lens to f7-8 (which will resolve more from that sensor than f11 will).

Alex

[ALAIN]

Thank you. But no live-view with CCD sensor, or I don't know how...

[Alex]

Thank you. But no live-view with CCD sensor, or I don't know how...

try tethered to a computer or monitor?

[Conner999]

Shoot tethered and control the focus from the laptop in small increments while observing completed shots. The key will be getting the sensor plane parallel to the painting.

A printed focus target is an option, but I'm assuming you are not able to have any contact with the artwork. If they're own a wall and flush to it, you could place a target on the wall and lock-in the focus. You could also doing something similar with the easel they sit on.

[ALAIN]

Thanks again for your advice.
I use the Passport Colorchecker both for the white balance, the profile, but also for the distance.
With a 10x magnifying glass resting on the frosted glass, it starts to be pretty reliable.
It is true that a computer control with 2 or 3 photos would be good, but for the moment I have not found any advice to open the back and access the broken firewire socket ...
Beautiful images to all, and what a class the medium format !!!
Alain (from France)

[Alex]

Alain,

Sorry, I forgot that the port of your Firewire card was broken.
Seeing that you were working with a combination of manual lens adjustment and a focusing target (and hence have a repeatable methodology of practice) - I was reminded of a past post by citzin where he tweaked the camera's autofocus to give more repeatable accurate results:

To adjust the manual focus there's small alignment screws on either side of the ground glass, and if the lens goes past infinity there's alignment screws under the real barrel,  I knew alignment screws for the AF sensor has to be somewhere.  After removing the tripod mount/bottom base plate, there's two holes with recessed t3 on either side of the tripod screw hole. 

I turned them 1/16th rotation, re-assembled, mounted, tested, it was was closer.  Repeated these steps till it was perfect.

I haven't tried this myself but seeing as you're generally confident with opening up the cameras;
Being familiar with what optimal quality you can get out of the focusing target from your setup, you could tweak the autofocus system to reach a similar level of accuracy as achieved manually and hopefully achieve it a bit more expediently thereafter.