Parfocal zoom

I would like to know if the following two canon lenses are parfocal or not.

1. EF-S 18-55 mm 1:3.5-5.6 IS II

2. EF-S 55-250 mm 1:4-5.6 IS II

nope.
AFAIK, the only canon lenses that are parfocal are the cinema lenses.

decisivemoment wrote in post #17235595
I would like to know if the following two canon lenses are parfocal or not.

1. EF-S 18-55 mm 1:3.5-5.6 IS II

2. EF-S 55-250 mm 1:4-5.6 IS II

"A parfocal lens is a lens that stays in focus when magnification/focal length is changed."

You're mentioning two consumer lenses which have been designed with consumer budget in mind. Building a parfocal zoom (rather than a varifocal zoom which you have to re-focus after zooming) is expensive as it restricts other design choices. I find it unlikely that a consumer zoom would be parfocal.

I did find: "Parfocal zooms in the Canon EF lens line-up are essentially limited to the fixed-aperture L-series categories and front-focusing zoom lenses."

I don't know if I can link to another forum here, but there is a list on another forum if you google "Parfocal Canon Lens".

You can also just pop down to the store and try them out for yourself.

Why are you searching for a parfocal lens? Any special purpose in mind?

DoughnutPhoto wrote in post #17235935
You're mentioning two consumer lenses which have been designed with consumer budget in mind. Building a parfocal zoom (rather than a varifocal zoom which you have to re-focus after zooming) is expensive as it restricts other design choices. I find it unlikely that a consumer zoom would be parfocal.

I have three "L" class Canon zoom lenses and none of them are parfocal. None of the Canon zoom lenses belonging to others (I don't have a list) were parfocal either.

MattPharmD wrote in post #17235926
nope.
AFAIK, the only canon lenses that are parfocal are the cinema lenses.

There are a few lenses out there that are parfocal. I remember Chuck W. provided a list a while back. If I remember the 70-200s were on there and the 75-300s as well. There were a few more, I think the 17-40 or 16-35 was on the list.

gjl711 wrote in post #17236325
There are a few lenses out there that are parfocal. I remember Chuck W. provided a list a while back. If I remember the 70-200s were on there and the 75-300s as well. There were a few more, I think the 17-40 or 16-35 was on the list.

My original version Canon 70-200 f/2.8L IS is definitely NOT parfocal. Neither is my original version 16-35 f/2.8L or my original version 24-70 f/2.8L.

24-105 is on the list.

gonzogolf wrote in post #17236704
24-105 is on the list.

The 24-105 I used was not parfocal.

The difference is between practically parfocal and actually parfocal.

Seems that several canon L zooms are so close, that under most conditions they seem parfocal (again, something is in focus at 24mm and 105mm without changing focus).

Seems I was wrong, I believe the cinema lenses are the only ones canon claims are parfocal. Roger has a much shorter list here...
http://www.lensrentals​.com …/photo-lenses-for-video/4

It's a ten + year old list now, but the following from Canon's Chuck Westfall is the best info we've got...

There's been some discussion about some of the above listed parfocal lenses being "nearly" parfocal and not "truly" parfocal.

MattPharmD wrote in post #17235926
nope.
AFAIK, the only canon lenses that are parfocal are the cinema lenses.

this^

and any lens that is manufactured for video cameras or permanentaly mounted on a video such as broadcast cameras that are 1/3" or 2/3" sensor size. well that are actually parfocal.

amfoto1 wrote in post #17237587
There's been some discussion about some of the above listed parfocal lenses being "nearly" parfocal and not "truly" parfocal.

That's absolutely the case for the three lenses that I have (and all are in the list).

I wonder if those listed are parfocal when focused at infinity? I think the 17-40 might have been pretty darn close if that is the restriction. At closer distances, definitely not.

So, the STM lenses (I think only when paired with certain bodies but could be wrong) use the STM drive to actually adjust the focus while the zoom ring is turned and remain in focus. A cute technological fix to a complex optics problem.