Why is there no AF f/1.2 lens available?

[Jim Radcliffe]

I do a lot of low light shooting with my cameras, the K5 is no exception. I have a number of fast primes (43, 77, 31).. but I wondered why Pentax does not offer an even faster lens such as a f/1.2.

I know there are older Pentax lenses such as the Pentax SMCP-A 50 mm F/1.2 MF Lens but there is no modern AF version of such a lens.

Can anyone shed any light on this? And yes, I know that with the high ISO capability of the new digital cameras a lens this fast may not be needed by most but still, there is something very appealing about that super shallow DOF that is achieved with an f/1.2 or faster (think Noctilux) and the resulting bokeh/blurred background.

Such subject isolation is not appreciated by all but for those of us who do like it, what are the alternatives if we are looking for such a lens with AF? My old eyes find it hard to manually focus such fast lenses on the K5 IIs.

I'm just curious.

 

[Knorp]

Hi Jim,

even with a MF lens like the Pentax-A SMC 1:1.2 50mm you can use the AF confirmation.
Not lightning fast, but it works fine for me ... :salute:

All the best.

 

[Godfrey]

If your old eyes are having such difficulty focusing an f/1.2 lens, imagine how hard an AF system would have to work. My experience with the accuracy and consistency of AF systems is mediocre at best with lenses faster than about f2.8 ...

My friend has the fabulous Canon 5DIII and EF 50mm f1.2. I spent a day shooting it with him recently. 80-90% of both our wide open shots were misfocused when we used AF, right on the money when we focused manually.

G

 

[Jim Radcliffe]

Hi Jim,

even with a MF lens like the Pentax-A SMC 1:1.2 50mm you can use the AF confirmation.
Not lightning fast, but it works fine for me ... :salute:

All the best.

Ahhh... did not know that.. must read manual again. Thanks.

 

[Jim Radcliffe]

My friend has the fabulous Canon 5DIII and EF 50mm f1.2. I spent a day shooting it with him recently. 80-90% of both our wide open shots were misfocused when we used AF, right on the money when we focused manually.

G

I had the 5D and the 5DII and got rid of both because of AF issues and the bulk of the cameras when lugging around my collection of L glass. Both cameras would often miss focus when using the 70-200 L 2.8 as well..

I tested the EF 50mm f/1.2 for three days and found the same issues with AF. Manual focus was also a bit difficult, maybe a different focus screen would have helped but in the end it was the bulk and weight of the Canon gear that prompted its departure.

I switched to the Pentax K5 and now the K5 IIs and am quite happy with the primes and the AF of that system.

I bought the Minolta 58mm f/1.2 Rokkor for use on my MFT gear and the Fuji X-Pro1 and have not had the difficulty in manual focus I experienced on the Canon gear... go figure.

At any rate, the old split image screen with micro prisms might be of help to my eyes but not willing to try that just yet.

When I had my M8 focus was great but there were often times when I missed shots due to my inability to focus quickly with that camera. Leica glass is lovely but I find I need AF much more these days than manual focus. Getting old is a pain in the ***.

 

[Knorp]

If your old eyes are having such difficulty focusing an f/1.2 lens, imagine how hard an AF system would have to work. My experience with the accuracy and consistency of AF systems is mediocre at best with lenses faster than about f2.8 ...

My friend has the fabulous Canon 5DIII and EF 50mm f1.2. I spent a day shooting it with him recently. 80-90% of both our wide open shots were misfocused when we used AF, right on the money when we focused manually.

G

Hi there Godfrey,

you may have a good point here, however I'm pretty happy with the results I get combining eyesight and AF confirmation.
Of course, it's not always spot-on but it's helpful.

All the best.

 

[Knorp]

Jim, one more thing ...
If you're looking for a fast lens with shallow DOF and AF, have a look at the Sigma 85/1.4 or Pentax FA*85/1.4 (expensive s/h).

Kind regards.

 

[4711]

Hi Jim,

to compensate for the smaller sensor and therefore bigger DOF and in the absence of a 1.2, you can only go more towards tele. As suggested already, you need an 85mm or even longer to achieve similar effects regarding DOF.

Regarding focus accuracy: Real Rangefinders are focussing per se more accurate than DSLRs. That is inherent in the different systems.

 

[Jim Radcliffe]

Hi Jim,

to compensate for the smaller sensor and therefore bigger DOF and in the absence of a 1.2, you can only go more towards tele. As suggested already, you need an 85mm or even longer to achieve similar effects regarding DOF.

Regarding focus accuracy: Real Rangefinders are focussing per se more accurate than DSLRs. That is inherent in the different systems.

Yes, I was aware of these facts but was wondering why no faster glass with AF for the Pentax. I'd much rather use a 35 or 50mm f/1.2 than a larger 85mm.

Also.. regarding rangefinders.. yes, they are more accurate but you do not always have the luxury of matching the patch as quickly as possible and the shot is often gone before you can accomplish that. I sold my M8 for two reasons: too much money tied up in it and missed shots while trying to obtain critical focus. Had it for a year and finally realized it was not the camera for me. If everything I shot didn't move it would be fine. Would I still love to have one? Yes, but only if I won it, inherited it or found it on my doorstep. Too rich for my blood. Great cameras, those Ms and Leica glass is amazing.. but not for me at this point in my life.

 

[raist3d]

I do a lot of low light shooting with my cameras, the K5 is no exception. I have a number of fast primes (43, 77, 31).. but I wondered why Pentax does not offer an even faster lens such as a f/1.2.

I know there are older Pentax lenses such as the Pentax SMCP-A 50 mm F/1.2 MF Lens but there is no modern AF version of such a lens.

Can anyone shed any light on this?

My guess here Jim is that as lenses go to wider apertures, AF systems are simply not that accurate. I got a hunch on this when I keep seeing Canon, Nikon and Sony advertising "center AF point cross sensitive for F2.8" or such. This leads me to believe that it's just not sensitive/built to strict tolerance enough to be reliable.

You see how many problems there is already with phase detection AF in general, this would probably be even more difficult to pull off.

- Raist

 

[raist3d]

Yes, I was aware of these facts but was wondering why no faster glass with AF for the Pentax. I'd much rather use a 35 or 50mm f/1.2 than a larger 85mm.

Also.. regarding rangefinders.. yes, they are more accurate but you do not always have the luxury of matching the patch as quickly as possible and the shot is often gone before you can accomplish that. I sold my M8 for two reasons: too much money tied up in it and missed shots while trying to obtain critical focus. Had it for a year and finally realized it was not the camera for me. If everything I shot didn't move it would be fine. Would I still love to have one? Yes, but only if I won it, inherited it or found it on my doorstep. Too rich for my blood. Great cameras, those Ms and Leica glass is amazing.. but not for me at this point in my life.

Yup, but as he pointed out, then you pay the price in AF accuracy. It's really the traditional pros/cons issue. Then you have current micro fours thirds which can focus blazing fast with relatively good accuracy but for static subjects.

Let's hope Fuji with the new X100s/X20 can get the best of both worlds here.

- Raist

 

[Godfrey]

SHEESH. Why does every discussion end up with some excuse for why you don't have a Leica M, Jim? I don't care one wit whether you have a Leica M.

G

 

[Jim Radcliffe]

SHEESH. Why does every discussion end up with some excuse for why you don't have a Leica M, Jim? I don't care one wit whether you have a Leica M.

G

Pretty rude of you, Godfrey. But I am not surprised, you really seem to have a chip on your shoulder. Anytime I mention Leica you either bristle or spring to their defense. I get it.. you are a Leicaphile. You have made that abundantly clear in post after post.

For the record, if I wanted a Leica I would have one. It's not the right camera for me and I refuse to spend that much money on a tool that does not work for me 100% of the time.

For your information, since you were not paying attention to the full thread, my reply regarding Leica/rangefinders was included to address an earlier comment made by another forum member:

"Originally Posted by 4711
Hi Jim,

to compensate for the smaller sensor and therefore bigger DOF and in the absence of a 1.2, you can only go more towards tele. As suggested already, you need an 85mm or even longer to achieve similar effects regarding DOF.

Regarding focus accuracy: Real Rangefinders are focusing per se more accurate than DSLRs. That is inherent in the different systems."

Get over it, Godfrey. You seem to enjoy making personal snipes. I'm sure you've got better things to do with your time. In the future, keep your thoughts and comments to yourself where I am concerned. I'm surprised the moderator didn't PM you. You're just downright rude.

 

[Jim Radcliffe]

Yup, but as he pointed out, then you pay the price in AF accuracy. It's really the traditional pros/cons issue. Then you have current micro fours thirds which can focus blazing fast with relatively good accuracy but for static subjects.

Let's hope Fuji with the new X100s/X20 can get the best of both worlds here.

- Raist

Yes, I agree but everything seems to keep getting better these days. The new features on the X100s look pretty impressive.

As you said, my MFT system is super fast but try tracking anything moving and you're out of luck... been there, done that with my GH2 and realized it's not the tool for any kind of action shots... but it still has a place for me to use it... I still have my GF1 and often use it with the 20mm pancake when I really want to just put a camera in my jacket pocket.

 

[Godfrey]

Your Leica comment is not relevant to the quote, there are other rangefinders in the world aside from Leicas.

Its a waste of time commenting otherwise.

 

[bensonga]

Without getting into the weeds with all the comments on this thread.....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.

Gary

 

[Jim Radcliffe]

Your Leica comment is not relevant to the quote, there are other rangefinders in the world aside from Leicas.

Its a waste of time commenting otherwise.

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.

 

[Jim Radcliffe]

Without getting into the weeds with all the comments on this thread.....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.

Gary

Gary, I apologize for the sidetrack the thread has taken. It was beyond my control and sometimes I have to respond to less than civil comments.

To answer your question, and I cannot do it by numbers or in any technical manner.. all I can say is that I have used a 50mm f/1.4 and 50mm f/1.2. The f/1.2 was the Canon and while I liked using it the AF seemed a bit off but the low light and shallow DOF was very good. I have also used a 58mm f/1.2 (Minolta Rokkor PG 58mm) and there is a difference between a f/1.4 and f/1.2. The Rokkor gives me a much creamier OOF background and foreground while also imparting a bit of glow that I find interesting and appealing. It is not a lens I use all the time because it is MF but when I have the opportunity to use it, I do so.

Here is a shot I took with it mounted on the Fuji X-Pro1. This was at f/2.8 because I did not want just one eye in focus.

I'm thinking of trying a MD to PK adapter to see what it will do on the K5 IIs but I'm not sure it will be worth it as there is a bit of an issue with MD lenses on the K5 via adapters.

I hope some other forum member can give you the technical stuff. I just know what I like when it comes to fast glass. The Noctilux and the Hyperprime have produced some pretty amazing shots. I believe Ashwin Rao has both.. check out his blog and work here: Ashwin Rao's Blog - A life at shutter speed

 

[bensonga]

I've owned many 50mm f1.4 lenses, both Nikon, Canon and Pentax, manual focus and autofocus, over the years and always wondered what I might be missing re the differences between 1.4 and 1.2. Other than the obvious built quality differences between, for example a Canon 50mm f1.4 and the 50mm f1.2L.

I would love to see some comparison shots, if anyone has them.

 

[raist3d]

Yes, I agree but everything seems to keep getting better these days. The new features on the X100s look pretty impressive.

As you said, my MFT system is super fast but try tracking anything moving and you're out of luck... been there, done that with my GH2 and realized it's not the tool for any kind of action shots... but it still has a place for me to use it... I still have my GF1 and often use it with the 20mm pancake when I really want to just put a camera in my jacket pocket.

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