A7S and the Canon 24-105 F4 - Is it parfocal?

This may be a silly question but I can't find a answer for it!

When adapted to the A7S is the 24-105 still parfocal? I suspect not...

Cheers

Why should the lens behaviour change just because you place it on a different body? IF it was parfocal on a canon body, it will be parfocal on another camera.

jimmyjimmy said:

This may be a silly question but I can't find a answer for it!

When adapted to the A7S is the 24-105 still parfocal? I suspect not...

Cheers

Click to expand...

ricleo said:

Why should the lens behaviour change just because you place it on a different body? IF it was parfocal on a canon body, it will be parfocal on another camera.

jimmyjimmy said:

This may be a silly question but I can't find a answer for it!

When adapted to the A7S is the 24-105 still parfocal? I suspect not...

Cheers

Click to expand...

Click to expand...

Well I don't know but I read somewhere (I think this forum but cannot find the post) that due to it being a different distance from the sensor than it was designed to be it loses it's parfocal nature. I hope you're right, I will be testing next week so will post back to clear things up!

jimmyjimmy said:

ricleo said:

Why should the lens behaviour change just because you place it on a different body? IF it was parfocal on a canon body, it will be parfocal on another camera.

jimmyjimmy said:

This may be a silly question but I can't find a answer for it!

When adapted to the A7S is the 24-105 still parfocal? I suspect not...

Cheers

Click to expand...

Click to expand...

Well I don't know but I read somewhere (I think this forum but cannot find the post) that due to it being a different distance from the sensor than it was designed to be it loses it's parfocal nature. I hope you're right, I will be testing next week so will post back to clear things up!

Click to expand...

if you use it with an adapter, then the distance should be the same as if using it on a Canon camera, shouldn't it?

muvovum said:

jimmyjimmy said:

ricleo said:

Why should the lens behaviour change just because you place it on a different body? IF it was parfocal on a canon body, it will be parfocal on another camera.

jimmyjimmy said:

This may be a silly question but I can't find a answer for it!

When adapted to the A7S is the 24-105 still parfocal? I suspect not...

Cheers

Click to expand...

Click to expand...

Well I don't know but I read somewhere (I think this forum but cannot find the post) that due to it being a different distance from the sensor than it was designed to be it loses it's parfocal nature. I hope you're right, I will be testing next week so will post back to clear things up!

Click to expand...

if you use it with an adapter, then the distance should be the same as if using it on a Canon camera, shouldn't it?

Click to expand...

I guess so! Oh, well I must have gotten my wires crossed somewhere or just read some bad information... Good to know, thanks for the replies.

jimmyjimmy said:

This may be a silly question but I can't find a answer for it!

When adapted to the A7S is the 24-105 still parfocal? I suspect not...

Cheers

Click to expand...

I have just seen that there is now a APS-C and a FF forum for E-mount so this is in the wrong place! My apologies.

muvovum said:

jimmyjimmy said:

ricleo said:

Why should the lens behaviour change just because you place it on a different body? IF it was parfocal on a canon body, it will be parfocal on another camera.

jimmyjimmy said:

This may be a silly question but I can't find a answer for it!

When adapted to the A7S is the 24-105 still parfocal? I suspect not...

Cheers

Click to expand...

Click to expand...

Well I don't know but I read somewhere (I think this forum but cannot find the post) that due to it being a different distance from the sensor than it was designed to be it loses it's parfocal nature. I hope you're right, I will be testing next week so will post back to clear things up!

Click to expand...

if you use it with an adapter, then the distance should be the same as if using it on a Canon camera, shouldn't it?

Click to expand...

I would imagine different adapters would be built to different tolerances and hence the distance may be slightly different from being on a native Canon EF mount Camera system

bigley Ling said:

I would imagine different adapters would be built to different tolerances and hence the distance may be slightly different from being on a native Canon EF mount Camera system

Click to expand...

In order to focus on the sensor (or the film for that matter), the lens has to be at a specific distance from the sensor for a specific distance to the subject. This distance is the same for ALL sensors and cameras (digital or film).

What you may have heard is that some cheaper adapters make the lens focuses "past infinity" when the lens is set to the infinity stop because the adapter is a tiny bit too short. In order to focus at infinity one has to set the lens a bit closer than the the infinity stop.