Why is there no AF f/1.2 lens available?

[Jim Radcliffe]

I understand what you mean by "everything keeps getting better" but lenses like that is something that has a long history. Also it's possible maybe such AF could be built, but then it would be too much cash and nobody would buy it.

That said the more I read about some of the pros I admire, the more I see they still do manual focus for a lot of their critical shots. I hope there's more digital assist for manual focus in the future (see what Fuji is doing with the split screen) so that it makes it as easy as the old times with film. I would rely on it more, but that's just me. I use AF a lot on the Q though.

- Raist

Yeah, it probably would be expensive but there will always be those who are willing to pay for such items.

Often, when I do concert work, I prefer to use manual focus (depending on my distance to the stage) so that I am not waiting for AF lock and get the shot but it does not always work out as some of the artists are quite mobile when they are on stage and then AF is a blessing.

It seems like a no-brainer to me that Pentax would provide something better than Live View for critical focus when using manual focus lenses. Short of moving to an EVF with focus peaking or some other EVF method, I hope they will eventually find some way to make critical focus easier when using legacy glass on their bodies for those of us who prefer using an optical viewfinder.

 

[Godfrey]

... I've often wondered, assuming equal optical and build quality, can there be much difference between a 50mm f1.4 and f1.2 lens?

I mean really....a .2 f-stop difference? There must be more to this than I know. If so, I would appreciate it if someone here could explain the technical differences to me.

It's a 30% difference in maximum light gathering power between the two lenses, and the f/1.2 lens allows an even shallower DoF rendering, if you like that sort of thing. Here are some DOFmaster numbers for you to think about, using Jim's Pentax K5 as a basis:

50mm f/1.4

Subject distance 10 ft

Depth of field
Near limit 9.67 ft
Far limit 10.4 ft
Total 0.68 ft

In front of subject 0.33 ft (48%)
Behind subject 0.35 ft (52%)​

Subject distance 5 ft

Depth of field
Near limit 4.92 ft
Far limit 5.08 ft
Total 0.17 ft

In front of subject 0.08 ft (49%)
Behind subject 0.08 ft (51%)​

Hyperfocal distance 290.2 ft
Circle of confusion 0.02 mm

50mm f/1.2

Subject distance 10 ft

Depth of field
Near limit 9.72 ft
Far limit 10.3 ft
Total 0.57 ft

In front of subject 0.28 ft (49%)
Behind subject 0.29 ft (51%)​

Subject distance 5 ft

Depth of field
Near limit 4.93 ft
Far limit 5.07 ft
Total 0.14 ft

In front of subject 0.07 ft (49%)
Behind subject 0.07 ft (51%)​

Hyperfocal distance 345 ft
Circle of confusion 0.02 mm

What's telling isn't just the shallower DoF capability, it's how much further out the hyperfocal focus point sits. That increases the amount of out of focus blur by more than just the small difference in light gathering capability might indicate.

Of course, such hyper-speed lenses tend to be absolute, top of the line, premium products of a lens manufacturer and they pay a lot of attention to tuning the rendering on them. I have both Nikkor 50mm f/1.4 AI-S and Nikkor 50mm f/1.2 AI-S lenses ... the difference in rendering between them is fairly noticeable.

G

 

[Godfrey]

You are in no position to make that judgement, sir. I only shoot digital and to the best of my knowledge there is only one digital rangefinder available at this time and if memory serves me well.. it is made by Leica.

There's never a need to be un-civil, Jim. I was not un-civil at all. Just wondering why you belabor the point of not having a Leica M at every opportunity.

It's sad that you've gone to yet another camera system and still seem unhappy about it.

G

 

[Jim Radcliffe]

There's never a need to be un-civil, Jim. I was not un-civil at all. Just wondering why you belabor the point of not having a Leica M at every opportunity.

It's sad that you've gone to yet another camera system and still seem unhappy about it.

G

You were rude when there was no need to be so.

You are also reading way to much into anything I write, Godfrey. And your speculation as to my happiness is totally off the mark.. and really, why should you care? I use three camera systems and enjoy all three.

Pentax K5 IIs for DSLR: Concert and action photography and more
Fuji X-Pro1 for a small mirrorless system I can carry with me at all times.
GH2/GF1 as a backup for both systems and video

I am very happy with what I own and use. I am VERY happy that I can afford all three and have the time to use them. So enough about whether I am happy or not. Right now the only thing that makes me unhappy are your groundless comments.

I have no unhappiness or regrets for divesting myself of the Leica M or my Canon gear... none. They are both excellent photographic tools that just did not work for me any longer and so.. they're gone.

As for Leica, the thing you continually miss is that I am a fan of Leica and have been since the 1960s. I don't always agree with their feature sets (base-plate?) or their pricing but the Leica M is an extraordinary camera and as I have said over and over in posts here and in other forums.. Leica glass is amazing and to me, has always been the heart and soul of Leica. M bodies come and go but the glass remains some of the best ever created.

I read the Leica forums on several sites every day. I don't post often but I enjoy reading the posts and the photos posted in those forums. Leica owners tend to care more about photography than the gear.. a welcome change from so many forums dominated by GearHeads.

So, please, just do me a favor and ignore me and I will ignore you and we both can be happy. There, I think that was quite civil.

Note to Forum Moderators: This will be my last exchange with Godfrey on this matter. Sorry for the disruption.

 

[Godfrey]

Note to forum moderators:
I've put Jim on my ignore list now. I'll be neither reading nor responding to his posts from this point forward. He seems to take offense at any post I make, and I wouldn't want that to be disruptive to the forum.

I apologize to you, the moderators, for his un-civil behavior.

G

 

[Jorgen Udvang]

Jim and Godfrey,
Why are you having this pointless discussion? You are both among my favourite photographers and you both take great photos regardless of what gear you use. I don't care if you are civil or not, but it's annoying to see you wasting time and energy on what is essentially a non-discussion.

 

[bensonga]

It's a 30% difference in maximum light gathering power between the two lenses, and the f/1.2 lens allows an even shallower DoF rendering, if you like that sort of thing. Here are some DOFmaster numbers for you to think about, using Jim's Pentax K5 as a basis:

<SNIP>

What's telling isn't just the shallower DoF capability, it's how much further out the hyperfocal focus point sits. That increases the amount of out of focus blur by more than just the small difference in light gathering capability might indicate.

Of course, such hyper-speed lenses tend to be absolute, top of the line, premium products of a lens manufacturer and they pay a lot of attention to tuning the rendering on them. I have both Nikkor 50mm f/1.4 AI-S and Nikkor 50mm f/1.2 AI-S lenses ... the difference in rendering between them is fairly noticeable.

G

Thanks for this great info Godfrey! It's exactly the kind of technical knowledge that will help me to get some understanding of this topic. This weekend I will try and digest it all.

Gary