Ultimate problem shifting focus

[Gogu]

Hello guys,

I noticed for some time now that when changing some of me lenses on the Ultimate I also have to make a slight adjustment to the EX1's focus ring.

I own a set of Zeiss ZF lenses and 2 Nikon zooms (17-35 and 80-200) the biggest change I see (and tested) is when I switched from the 50mm to the 17-35mm. I'll attach 2 photos showing this.

Is there a slight flange focal depth difference between the 2 manufactureres? I hugely doubt this.
Maybe you can come up with some educated opinions about this.

thanks,
Mike

 

[Shooter]

Surely your EX1 should be focussed to the ground glass and that would not change because of a lens change between the Nikkors and the Zeiss.

It is possible the lenses are out of collimation or have flange distance diferences but compensating it with the EX1 sounds wrong to me.

Nikkors are 46.5mm flange/film plane depth. (I use a tool to measure it and set up the Letus)
PL lenses are 52mm.

Zeiss maybe 45.5mm. (Check it)

 

[Taylor Rudd]

Isn't that what the backfocus adjustment is for on the Ultimate? There should be no difference in your EX1's focusing distance.

 

[FourLinkSun]

Once you have your EX1 focused on the GG, you shouldnt even need to change that.
Like the above are saying, check your backfocus for all your lens.

As Shooter pointed out, the flange focal length distance might be different among the lens.

 

[Gogu]

well...I adjusted the backfocus for my 50mm and the all the other Zeiss lenses seemed to obtain maximum focus at infinity but the 17-35mm focused beyond infinity adjusted like this.
I'll try to make them all adjusted but i'm afraid i won't be able to because of the difference.

Anyway thanks for the advice. i'll update if something changes

 

[Shooter]

You will be able to but you will need to adjust the back focus for each lens.

It is easy by design on the Ultimate and the Elite.

Make a little tool. Its like a T-Square. (I used two metal engineers flat rulers.)

Lay a flat edge across the flange and mark another rod with the distances to the film plane .

(I have 46.5 and 52mm precisely marked.)

 

[MitchLewis]

You only need to readjust back focus when you switch lens mounts. Like when you switch from using a Nikon lens to a Canon lens. I use Nikon lenses and have only adjusted the back focus once. But I do check the "focus" of the EX3 on the ground glass whenever I remove/reinstall the Ultimate. Maybe it's just for piece of mind....dunno.