Parafocal EF zoom?

[Julio Quintana]

What do you mean you "rest your case" Jacek?

You state every lens is designed as parfocal when virtually no EF mount glass actually is.

I have to say I find communicating with you challenging my friend

Thanks to those who answered the OP. Leica R seems like the best path for us currently...

Don't worry about Jacek. He is extremely knowledgable, but unfortunately his credibility is compromised since every post he makes feels like a snarky Optitron ad. Too bad because I think he really knows his stuff.

 

[Jacek Zakowicz]

Haha Sherlock you're right. It's a conspiracy and I'll take over the world through the device. (enter the evil laugh ;-)
So you agree that checking the back focus and flange is not necessary and the parfocal lenses miraculously fix these issues?
Yes buy more lenses instead of fixing yours- now that's a consumer mentality solution.
Oh wait- is this another "snarky" ad?

 

[PC Greene]

Jacek,

For such an obviously smart guy, you really can come across like an ass.

Apologies for the honesty but it's been a long day...thanks for the "help".


PCG

I mean that you don't even know what the back focus on your lens is and the flange depth on your camera but you already decided which lenses are or aren't par focal. I.E you are an expert.
I do this for living.
I conceived , designed, built and manufacture peripherals that utilize these features and have tested and repaired lenses for for 25 years before that.
Sorry -parafocal won't fly here haha ;-)

 

[PC Greene]

:cheers2:

Oh dear I've been driven to emoticons lol.

Thanks mate...

Don't worry about Jacek. He is extremely knowledgable, but unfortunately his credibility is compromised since every post he makes feels like a snarky Optitron ad. Too bad because I think he really knows his stuff.

 

[PC Greene]

Look Jacek,

The idea of adjusting flange and back focus in the field is asinine and I suspect you know it. I'm not even certain that adjustment of these things would make non parfocal lenses like the Canon 70-20mk2 IS parfocal as you seem to suggest.

That said, there *are* several non PL lenses out there (as evidenced by the constructive posts from other members) including Leica, Canon and Nikon that "miraculously" provide parfocal performance without surgery, and that's really the end of it for me and perfectly answered the query in my original post.

It's gotta be tough being so damn smart and knowledgable...I feel like my wife must when she just wanted someone to listen and instead I try to engineer the ultimate solution :-/



Peace,

Haha Sherlock you're right. It's a conspiracy and I'll take over the world through the device. (enter the evil laugh ;-)
So you agree that checking the back focus and flange is not necessary and the parfocal lenses miraculously fix these issues?
Yes buy more lenses instead of fixing yours- now that's a consumer mentality solution.
Oh wait- is this another "snarky" ad?

 

[Jacek Zakowicz]

I rest my case haha - again. You're right- personal attacks are the way to go. Peace...

 

[Nick Morrison]

Look Jacek,

The idea of adjusting flange and back focus in the field is asinine and I suspect you know it. I'm not even certain that adjustment of these things would make non parfocal lenses like the Canon 70-20mk2 IS parfocal as you seem to suggest.

That said, there *are* several non PL lenses out there (as evidenced by the constructive posts from other members) including Leica, Canon and Nikon that "miraculously" provide parfocal performance without surgery, and that's really the end of it for me and perfectly answered the query in my original post.

It's gotta be tough being so damn smart and knowledgable...I feel like my wife must when she just wanted someone to listen and instead I try to engineer the ultimate solution :-/



Peace,

For whatever it's worth, Eddie the lens doctor mentioned to me in an email that all Canon FD 35-105's came out of the factory "parfocal", but then over time easily slipped...and lost consistent focus. From what I understand, Eddie used to work at Canon back in the day, and knows how to realign these zooms to act "like new." But it did get me thinking that possibly many STILLS zooms are designed to be parfocal, but slip out of alignment probably easier than say....a rugged Cooke 18-100.

Point being - my hunch is many stills zooms start parfocal, then slip. I've heard of cine zooms needing to be realigned as well, but my guess is their robust construction makes them much less susceptible to this kind of "slippage".

 

[Jacek Zakowicz]

Back in the day when I worked at a rental house and later when I serviced and repaired lenses for rental houses, there was a full time position in every rental house called lens technician. All they did all day long was cleaning, refocusing and realigning cine lenses every day. There was plenty of work for them. cine lenses, when extensively used are pretty high maintenance as well. There was also a position called camera technician. All those guys did all day long was cleaning, servicing and, yes, verifying and adjusting flange depth on cameras. the flange depth was probably the most important task. In many cases proper focus required collaboration between the lens tech and camera tech an tweaking back and forth until adequate compromise was achieved .
Unfortunately digital cameras did not alleviate this issue. If anything- they made it worse with power hungry heat dissipation through the body.
There is no miracle "parfocal" lens. All it (still) takes is skill, experience and proper equipment. But who has the time and money for it these days?
It's much more convenient to dream of a miracle lens...
My opinion- nothing else ;-)

 

[PC Greene]

Sincerely not an attack my friend but an honest assessment with the intention that it might help.

I was very interested in Optitron a while back, but your demeanor among other things convinced me to look elsewhere for different solutions. Lo and behold, Fool Color & our RT Motion have us quite happy...

http://www.goodreads.com/quotes/5934-i-ve-learned-that-people-will-forget-what-you-said-people

And in case you can't tell, I and others seem to have a lot of respect for you


All The Best,

I rest my case haha - again. You're right- personal attacks are the way to go. Peace...

 

[PC Greene]

Now this & Nicks reply are quite constructive & helpful. Do I take it then that you guys believe even the aforementioned parfocal lenses - in fact *all* lenses to be susceptible to parfocal degradation given enough use & time? I have to believe there are a few exceptions given reasonable care and yearly maintenance?

Thank you,

Back in the day when I worked at a rental house and later when I serviced and repaired lenses for rental houses, there was a full time position in every rental house called lens technician. All they did all day long was cleaning, refocusing and realigning cine lenses every day. There was plenty of work for them. cine lenses, when extensively used are pretty high maintenance as well. There was also a position called camera technician. All those guys did all day long was cleaning, servicing and, yes, verifying and adjusting flange depth on cameras. the flange depth was probably the most important task. In many cases proper focus required collaboration between the lens tech and camera tech an tweaking back and forth until adequate compromise was achieved .
Unfortunately digital cameras did not alleviate this issue. If anything- they made it worse with power hungry heat dissipation through the body.
There is no miracle "parfocal" lens. All it (still) takes is skill, experience and proper equipment. But who has the time and money for it these days?
It's much more convenient to dream of a miracle lens...
My opinion- nothing else ;-)