How accurate is your camera?

[Merlin66 (Ken)]

Good article on the sensor to flange distance of cameras.....
https://www.lensrentals.com/blog/202...-cine-cameras/

[multiweb (Marc)]

Had no idea the distance were so tight.

[Merlin66 (Ken)]

the critical focus zone on a fast camera lens is next to nix.....

[Outcast (Carlton)]

So, has anyone tried shimming a lens on a DSLR to get a lens to focus at say, the infinity hardstop...?

I'm curious... I have a manual focus Samyang 14mm f2.8.. I've just started to play with it for wide view Nightscapes.. I notice infinity focus is not at the hard stop which makes it a bit finicky for achieving true infinity focus... if it were simple to shim the lens to make the hard stop the true infinity focus point that would be great...

[glend (Glen)]

This is also a good reference for any DSLR,

https://en.m.wikipedia.org/wiki/Flange_focal_distance

And do not forget that adding any filters ahead of the sensor will affect the focal length, for example a clip-in filter. The Rule of Thirds applies as always.

[Outcast (Carlton)]

Hmmm, this is interesting...

Anyone been brave enough to try something like this on a lens?

https://dslr-astrophotography.com/ca...he%20markings.

[Outcast (Carlton)]

Actually... a friend just suggested a somewhat (in hindsight) obvious & less fraught with danger approach...

Find where the actual infinity focus point is & mark it with a white marker or, put tape around the focus ring & mark that...

A whole lot less scary than fiddling with screws & stuff...

[Hemi]

Originally Posted by Outcast

Actually... a friend just suggested a somewhat (in hindsight) obvious & less fraught with danger approach...

Find where the actual infinity focus point is & mark it with a white marker or, put tape around the focus ring & mark that...

A whole lot less scary than fiddling with screws & stuff...

Thats what I do Carlton, I don't have any Lenses where the The Infinity marker or stop is the actual point of focus.....even with marking, its not always spot on, I presume that's temperature effects on the optics, housing, focus ring etc.

Hemi

[gregbradley]

Most lenses focus beyond infinity, perhaps for this reason. Also different temperatures they may focus at different points like our telescopes do.

What lens stops at infinity? I only had one that had a click stop at infinity that was accurate but it still was able to go further. All the other lenses go beyond
infinity.

Greg.

[multiweb (Marc)]

Originally Posted by gregbradley

All the other lenses go beyond
infinity.

The Buzz Lightyear series.

[Derek Klepp]

I have a Ziess Distagon 15mm f2.8 and it is in focus at infinity with no more adjustment left.Very handy when I forget my glasses when doing nightscapes.Mind you they are very expensive.
Derek

[Sunfish (Ray)]

My Samyang 14mm has a hard stop at infinity and it is just great for that wide field work where there is no focus lock. An adjustable click focus lock Like my 800 is the alternative. The Samyang may be just a teeny bit out on my camera compared to the design camera but perhaps in that field you would not notice that.

I know that camera repair techs check and shim the mount on a lense and my 2x Pentax 67 is shimmed with a stack but imagined that had as much to do with collimation. Interesting to see part 2.

[Sunfish (Ray)]

Also interesting that zwo claim two cameras have equal back focus difference but if I change between them the focus varies hugely.