[bdery]

The fastest I've used is probably the DA40 limited. But I haven't used every lens there is.

[Uluru]

Sorry for all your theory man but it is much more basic than that: using the OVF I don't see the deph of field precisely enough to take the photo correctly. No more, no less. Typically I can turn the focus ring quite a bit before I see a difference. The only way I can do manual focus with current gear is to use live view with magnification and focus peaking. As to me for fine AF tuning manually I don't want to change the focusisng screen with issues arround metering, the risk to add OVF back/front focus and the limitation that many time when I'am after fine AF tuning, I don't want to focus on the center.

So even through you think I continuously make the worst decision one can make, I'll continue.

What you describe is subject-dependant and a matter of getting to know your camera.

EQUIPMENT

Does your camera have metering problems with a new focusing screen? Establish that fact before you do any work!
See how much, whether you need to compensate a little, much, or not at all. Maybe all is so negligible you can address all issues in PP anyway. I see people changing exposure in PP much more than what any focusing screen would affect, because they find ordinary and well-metered photos .. just ordinary.

When we have sensors — installed in everyday cameras — capable of such latitude that it makes -3eV underexposed photograph perfectly fine in PP, I think we are well over any genuine concern for discontentment, but well into the territory of complaining for complaining's sake.

SITUATION

If you are taking macro shots, you have all the time in the world to do focusing. So any type of complaining is useless here — do what pleases you.

If you are doing street photography, real life's photography and not staged scene, you must know your DoF in advance because when forced to think really fast when taking shots, you must have focusing already sorted out in advance. Only concern is framing then — no time even for super-fast AF, because you will lose framing, you will lose that moment that meant everything.

If you wait for the AF, subject may be in focus, but everything else — that leaf, that blade of grass, that puff of wind that waves branches in the wrong direction, the shape in the background, special gesture, that wink, smile — won't work anymore. It's gone. You are late 0.5 sec — enough for AF to lock on and you to consciously recognise AF beep and press the shutter release — but all is ruined. Those 0.5 sec — necessary for conscious response in humans — ruined it all.

In short, if you rely all the time on AF to take a photograph, it is not photographing taking, it is no creating — it is charity business. We are not masters but beggars of photography, that only receive something AF finds suitable for us to receive.

[Nicolas06]

What you describe is subject-dependant and a matter of getting to know your camera.

EQUIPMENT

Does your camera have metering problems with a new focusing screen? Establish that fact before you do any work!
See how much, whether you need to compensate a little, much, or not at all. Maybe all is so negligible you can address all issues in PP anyway. I see people changing exposure in PP much more than what any focusing screen would affect, because they find ordinary and well-metered photos .. just ordinary.

When we have sensors — installed in everyday cameras — capable of such latitude that it makes -3eV underexposed photograph perfectly fine in PP, I think we are well over any genuine concern for discontentment, but well into the territory of complaining for complaining's sake.

SITUATION

If you are taking macro shots, you have all the time in the world to do focusing. So any type of complaining is useless here — do what pleases you.

If you are doing street photography, real life's photography and not staged scene, you must know your DoF in advance because when forced to think really fast when taking shots, you must have focusing already sorted out in advance. Only concern is framing then — no time even for super-fast AF, because you will lose framing, you will lose that moment that meant everything.

If you wait for the AF, subject may be in focus, but everything else — that leaf, that blade of grass, that puff of wind that waves branches in the wrong direction, the shape in the background, special gesture, that wink, smile — won't work anymore. It's gone. You are late 0.5 sec — enough for AF to lock on and you to consciously recognise AF beep and press the shutter release — but all is ruined. Those 0.5 sec — necessary for conscious response in humans — ruined it all.

In short, if you rely all the time on AF to take a photograph, it is not photographing taking, it is no creating — it is charity business. We are not masters but beggars of photography, that only receive something AF finds suitable for us to receive.

If I want to pre focus, I can do that with autofocus too. I focus on something at the distance that match my need. Easily done and more precise than distance scale. I guess this is how one does with manual focussing too. The key here is to think of pre focussing, not how it is done. Somebody fully relying on manual focussing and not thinking of it would be much slower than the one relying of AF that didn't think of it neither. Once it is done, and this completely unrelated to the focussing method, the same result is achieved: not time wasted on focussing. The gain is obviously bigger for manual focus, so it more important to master the practice, but that's all.

Also if one allow himself to understand how autofocus work he can also use AF-C, give priority to shutter, follow the subject, give the order to take the photo (or a burst) when the framing is perfect and be done. This would allow to use more reliably a fast apperture and achieve more interresting result than always relying on the pre focussing trick. Pentax is not quite here yet, but maybe it is already there with 70-200...

I wonder how big master of manual focussing, if you take a burst of a dog comming running to you at wide apperture, would you manage with your wonderfull manual focussing skill to have all intermediate photos in focus. Even a 8.5 fps of K3?

Despite what you seems to think, it is not because we use the technology that we are inherently more stupid and less able than you to deal with the situation.

[ScooterMaxi Jim]

Some of the comments have gotten pretty defensive. Everyone has a right to do what works best for their shooting style. As Pentax shooters, we really cannot hold out that AF is the only way to go because we still trail most of the RoW - but the K-3 has finally closed the gap somewhat.

If you are insisting on a big hunk of glass faster than f/1.8 to focus precisely on a very narrow DoF, the only way to do this successfully on the vast majority of near-open shots is MF with live view and focus peaking; your failure rate with AF and OVF will be considerable higher if you have mastered the various techniques.

If you want quick AF, in most instances you'll be more successful with smaller glass (relatively small aperture on long lenses, medium apertures on the shorter lenses). This is a matter of basic physics; inertia is an issue with fast glass.

Technically, the Sigma 30mm 1.4s (Art and original) are sharp lenses with no major faults optically. Many Pentax shooters use these lenses and post interesting shots - and many are excellent photographers. Oddly, though, I'm yet to see an image that rendered warmly or in a stirring way. I prefer a film look, and these lenses just seem about as far away from that as any high-end lens I've researched. Not that the coloration is poor (try the original Sigma 15-30 if you want horrid coloration), just seems so neutral.

[Nicolas06]

ScooterMaxi, the idea is simple, you do the best with what you have. If you are not that great at manual focussing, maybe because your eyes are not good enough, then you concentrate on using AF. You would use LV + focus peaking in last ressort. After all is that was the most comon use of your gear, you would not buy a DSLR to begin with but more a mirrorless. The LV + focus peaking is acceptable because you use it sparinginly, DSLR are not made for that and without tripod, you have increase risk of camera shake too this way.

You say the only way is live view + focus peaking on fast lenses with very thin deph of field. But for sure for most of photography history, live view and focus peaking where not available and people already used f/1.4 lenses. So with the proper focussing screen and with good enough eyesight, you can do it, even at f/1.4. Reality was also many time the pictures, even with the pro weren't that sharp and well focussed in many occasion. And the tendancy you need to always use f/1.4 on the nearest focussing distance to make abstract bokeh shoots or to have portraitures with 1 eye sharp, the other blured is not the ultimate goal in photography. It is not from yesterday that many studio shoot where done at f/8 anyway. Nobody say that f/1.4 is only usefull in such occasion. To me I really consider more artisitically f/1.4 to isolate a big subject like a full body portrait that to play on the eye that would be in focus.

As if only small glass can focus fast and efficiantly, explain me then why the fastest autofocus glasses we typically have are 70-200 f/2.8 like the latest Pentax that kenspo is evaluating now. And don't say yes but f/2.8 has more deph of field than f/1.4... This is true for the same framing or same focal length, but the formula say that at 200mm f/2.8, same focussing distance, the deph of field is 16 time less than at 50m f/1.4...

I can say one thing overall, I use an FA77 f/1.8... at the same focussing distance, the deph of field is not greater than FA50 f/1.4. With the K3 and FA77, the AF work sufficiantly well to have much more keeper with it than by manual focussing. It also allow to be much faster in the process too.

I'am not against manual focus, I'am not against LV and focus peaking. Everybody can does how he like. I think this is stupid on the contrary to say that AF can't work and to explain to thoses that are disabled in a way or another that they are not good enough for photography because real men does it with manual focus. I'am sorry I do not think this is a good argument. I don't think this is the way to think.

One should try to achieve the best he can with whatever is at it's disposal. If he has only MF lenses etc he might use the most advanced tricks to take nice pictures even of sport. After all one did with a large format film camera at the Olympics and you can be sure there was no LV or focus peaking neither. And if one is not good/comfortable/unable to use manual focussing it is its own right to use the AF of the camera to achieve what he want. And if he wish to do so at f/1.4 even he has a smaller keeper rate, one must understand that this is his own right to do so.

Trying to find the few exceptions where a particular model of gear would fail in such circonstance desperately, and honestl, pretty narrow limitation like 1:1 macro (where a tripod is often used anyway) or f/1.4 at minimal focussing distance is a bit of a joke. You can make a whole carrier at a professionnal, have picture in galeries, do many style and never feel the need to deal with such use case... Or you can do it properly with a tripod in a studio. Or, handled you can take several shoots, use AF-C to compensate for the subject movement anyway and take a burst of photos too to increase your chances.

Or you may change your gear for another brand that work better. Over the 3 last years, I have seen many that where disapointed by AF on Pentax. I was too and it is only K3 that is really good. We can complain on the lazy guys or bad photographic practices. Many didn't care and gone the Canikon route in the end. That's reality.

[Uluru]

I think this is stupid on the contrary to say that AF can't work and to explain to thoses that are disabled in a way or another that they are not good enough for photography because real men does it with manual focus. I'am sorry I do not think this is a good argument. I don't think this is the way to think..

Now that is silly proposition.
Everybody knows real men wear moustache, open beer bottles with their teeth, are chain smokers and use manual focus only.

We can complain on the lazy guys or bad photographic practices. Many didn't care and gone the Canikon route in the end. That's reality.

Those are ooh-aah effeminate faux-photogs. But real men shoot Pentax.

[ScooterMaxi Jim]

My post was not intended to favor AF or MF, nor did it in any way indicate that manual shooters are somehow superior. I have my share of f/1.4 lenses, and it is quite clear that when shooting near wide open with them you are more likely to nail focus manually because you know exactly where you want the focus - and the sensors aren't that fine (assuming your vision is decent); live view with focus peaking is more precise - even with an aid to the OVF (focusing screen, or magnifying attachment). In any event, old non-AF film viewfinders were far better for precise focusing because they were designed for that.

This thread shows that some dSLR shooters are threatened by the idea that an alternative to the OVF can be better, and, yet, a lot of great photography is done without one. The vast majority of my shooting is with the OVF, but when I'm in live view (or shooting with the K-01), often I'm getting a better perspective - and shooting more creatively.

Obviously at most times AF and OVF will be more effective, especially when dealing with quick movement. Big glass often has focus limiters; those lenses tend to perform well. All things being equal, though, moderate aperture AF glass tends to perform better than really fast glass. Look at all the AF problems Sigma has encountered with the 18-35.

Historically, our expectations of what qualifies as sharp has changed as sensors, lenses and monitors have generally improved. My point is that if you want the best sharpness possible, differing situations require a variety of approaches.

[DavidSKAF3]

I should then add to my original post that in particular what I want is to be able to more readily take photos of moving trains under cloudy skies or in fading light, at the lowest possible ISO.


So I figured (with my scant knowledge) that what I want is a fast lens and fast AF. But which focal length? And which lens? The 50 1.8 I got is too long. The 35 2.4 is better. But I believe I need wider. And that's how this started. I thought that the Sigma 30 1.4 might be the low light answer for me.


Now I don't know if I'm on the right course at all!

And even machismo has been brought in to the question!


I have a M 28mm 2.8, but I've never tried it. I didn't think there would be enough time for MF with moving trains.



LOL

[ScooterMaxi Jim]

No doubt that AF would be beneficial for moving trains. At the same time, you know where the train is headed, so you can pre-focus on the optimal spot as the train is approaching - panning as a you snap off a few shots. I mention this because you should check to see if 28mm is anywhere near wide enough - and try your M lens to get a feel for the right focal length. My guess is you'll want to go to at least 24mm, or possibly even wider.

Extremely wide, fast lenses really do have trouble nailing AF - the combo is brutal. This was found to be the case with the Sigma 24mm f/1.4.

If I was primarily considering the shots you're specifying, it seems to me that the faster wide zooms would be your best bet, such as the Sigma 17-50 f/2.8, or the new 17-70 f/2.8-4. Both these lenses are better-than-average optically, and they seem to be especially good in terms of AF speed and accuracy. Both lenses do especially well corner-to-corner once you hit about 20mm.

[Nicolas06]

I should then add to my original post that in particular what I want is to be able to more readily take photos of moving trains under cloudy skies or in fading light, at the lowest possible ISO.


So I figured (with my scant knowledge) that what I want is a fast lens and fast AF. But which focal length? And which lens? The 50 1.8 I got is too long. The 35 2.4 is better. But I believe I need wider. And that's how this started. I thought that the Sigma 30 1.4 might be the low light answer for me.


Now I don't know if I'm on the right course at all!

And even machismo has been brought in to the question!


I have a M 28mm 2.8, but I've never tried it. I didn't think there would be enough time for MF with moving trains.



LOL

If you want to freeze the movement, you'll want fast shutter speed. I would guess that flashes are out of question and could be quite distracting for the train driver. If you use a fast lense, you'll get less deph of field, meaning part of the background or even part of the train could be really blured.

The first obvious think that I suppose you already tried is that you can always go much higher in high iso than you may think at the begining. By shooting raw, having good exposure, using a good noise removal sofware (DxO prime being maybe the best or among the greatests). Also the faster the shutter speed and the more light you have the less noise you get, even with high iso numbers.

You might find yourself with truely great pictures at 1600 isos and quite decent ones a 3200 on APSC. At 800iso really you'd be hard pressed to see any visible issue in most situations if you really used the technique correct.

If we follow the basic explanation of exposure and the Sunny Day rule (Sunny 16 rule - Wikipedia, the free encyclopedia) we can see that in shadows or at sunset, correct exposure is got with f/4, 1/100s, at 800 iso you would be already at 1/800s. Playing with the parameters you could use f/4 1/1600s, iso 1600 or f/2.8, 1/1600 iso 800!

You might not need that fast lense in the end and while you are at sunset the light drop dramatically anyway... The additionnal gain you'll have with f/2 instead of f/2.8... might give you maybe 1 or 2 minute more before you'll need to increase the isos again...

So really, I'd say try. From reasonable distance, on a somewhat wide angle lense (seem to be your case with M28), you should have wide enough deph of field anyway. Dof master (Online Depth of Field Calculator) explain that at f/2.8 with you M28 you have 25m of deph of field if your subject is at 10 meters. You can either manual focus or use AF to prefocus on the railway, where you intend the train to be and be just fine. No need for fast tracking. Just fire a burst of a few frames when the train enter the frame until it leave it and keep the one with the best composition and you are done.

Really you could use f/1.4 is that was really important for light gathering... But to compensate a part of the train would be out of focus then, question yourself if it what you are after or not.

But with a train where you can really predict where and when the train will be at some position in the frame it look easy to me to imagine the composition of your shoot in advence, prepare everything and just click on the shutter when needed. Might be easier than to wait for the train to come to focus on it, at least in dim light and large apperture.

[IchabodCrane]

My post was not intended to favor AF or MF, nor did it in any way indicate that manual shooters are somehow superior. I have my share of f/1.4 lenses, and it is quite clear that when shooting near wide open with them you are more likely to nail focus manually because you know exactly where you want the focus - and the sensors aren't that fine (assuming your vision is decent); live view with focus peaking is more precise - even with an aid to the OVF (focusing screen, or magnifying attachment). In any event, old non-AF film viewfinders were far better for precise focusing because they were designed for that.

This thread shows that some dSLR shooters are threatened by the idea that an alternative to the OVF can be better, and, yet, a lot of great photography is done without one. The vast majority of my shooting is with the OVF, but when I'm in live view (or shooting with the K-01), often I'm getting a better perspective - and shooting more creatively.

Obviously at most times AF and OVF will be more effective, especially when dealing with quick movement. Big glass often has focus limiters; those lenses tend to perform well. All things being equal, though, moderate aperture AF glass tends to perform better than really fast glass. Look at all the AF problems Sigma has encountered with the 18-35.

Historically, our expectations of what qualifies as sharp has changed as sensors, lenses and monitors have generally improved. My point is that if you the best sharpness possible, differing situations require a variety of approaches.

The points you bring up in this and your prior post reinforce my hunch that many current DSLR users will eventually migrate to MILCs. I haven't yet because I haven't found one that I really like along with the lenses that I think I'd want. CDAF is similar to MF with focus peaking as you were writing about except the camera does the work. For the most part, the accuracy of CDAF isn't limited by aperture at all. Instead, it's limited by light level and focus speed in comparison to PDAF but those limitations are slowly eroding as the technology improves.

[Nicolas06]

The points you bring up in this and your prior post reinforce my hunch that many current DSLR users will eventually migrate to MILCs. I haven't yet because I haven't found one that I really like along with the lenses that I think I'd want. CDAF is similar to MF with focus peaking as you were writing about except the camera does the work. For the most part, the accuracy of CDAF isn't limited by aperture at all. Instead, it's limited by light level and focus speed in comparison to PDAF but those limitations are slowly eroding as the technology improves.

CDAF require different lenses design, to focus fast with CDAF, the focussing group must be much smaller/lighter or the motor must be much stronger/heavier/bulky. This is an explanation from sigma that explained that has an excuse to not have that many lenses for FE mount. They could not port directly standard design from DSLR lenses into mirorless and have efficiant lenses. The market doesn't justify yet such investment.

Sony also understood that: Their adapter to use "legacy" DSLR Sony lenses into their A7 also come with a PDAF module with 19 AF point to ensure a minimum efficiancy from theses lenses.

We can typically check it for ourselve and understand why CDAF tend to be quite slow on DSLRs while it is quite better on dedicated devices.

Counpound that with the fact that teles tend to be even longer than on DSLRs (there 3 full cms to had as it is removed from the body...) and the high price to pay to use modern quality AF mirorless lenses and this future might come later than initialy foreseen... Or never if another alternate technology proove to be better (I don't say this would have to be DSLRs).

As of PDAF, to my understanding it isn't impacted by apperture exactly how one might think f/1.4 module would work well only with f/1.4 lenses or faster. That why there f/5.6 AF sensor, to ensure slow lenses can still function properly and that also why as a tradeoff there f/2.8 AF module optimized for fast lenseson high end cameras. The faster the lense overall the better PDAF can work provided the lense is contrasty enough but any lenses no slower than f/5.6 would work just fine.

[IchabodCrane]

CDAF require different lenses design, to focus fast with CDAF, the focussing group must be much smaller/lighter or the motor must be much stronger/heavier/bulky. This is an explanation from sigma that explained that has an excuse to not have that many lenses for FE mount. They could not port directly standard design from DSLR lenses into mirorless and have efficiant lenses. The market doesn't justify yet such investment.

Sony also understood that: Their adapter to use "legacy" DSLR Sony lenses into their A7 also come with a PDAF module with 19 AF point to ensure a minimum efficiancy from theses lenses.

We can typically check it for ourselve and understand why CDAF tend to be quite slow on DSLRs while it is quite better on dedicated devices.

Counpound that with the fact that teles tend to be even longer than on DSLRs (there 3 full cms to had as it is removed from the body...) and the high price to pay to use modern quality AF mirorless lenses and this future might come later than initialy foreseen... Or never if another alternate technology proove to be better (I don't say this would have to be DSLRs).

As of PDAF, to my understanding it isn't impacted by apperture exactly how one might think f/1.4 module would work well only with f/1.4 lenses or faster. That why there f/5.6 AF sensor, to ensure slow lenses can still function properly and that also why as a tradeoff there f/2.8 AF module optimized for fast lenseson high end cameras. The faster the lense overall the better PDAF can work provided the lense is contrasty enough but any lenses no slower than f/5.6 would work just fine.

So maybe Sigma is slow to design properly for MILCs. That doesn't mean Olympus, Panasonic, Samsung, and even Sony aren't doing this right. Also, the new hybrid focusing systems are speeding up focusing all by themselves.

[Winder]

I should then add to my original post that in particular what I want is to be able to more readily take photos of moving trains under cloudy skies or in fading light, at the lowest possible ISO.


So I figured (with my scant knowledge) that what I want is a fast lens and fast AF. But which focal length? And which lens? The 50 1.8 I got is too long. The 35 2.4 is better. But I believe I need wider. And that's how this started. I thought that the Sigma 30 1.4 might be the low light answer for me.

I think ScooterMaxi Jim has the right idea. You need to practice zone focusing with whatever lens works for you. Any manual lens will be fine. Trains are pretty predictable subjects, so set up your tripod and get your composition ready.


I did a whole series of train pictures with a 4x5 field camera back when I was in college.

[Nicolas06]

So maybe Sigma is slow to design properly for MILCs. That doesn't mean Olympus, Panasonic, Samsung, and even Sony aren't doing this right. Also, the new hybrid focusing systems are speeding up focusing all by themselves.

That just the difference of say insentives. Olympus, Panasonic, Samsung and Sony they have no choice. Their own product require it. Sigma (or Tamron) is free to do what give them the most money and is most efficiant as a lense maker for multiple mount.

As for speed, it work ok because of theses dedicated designs. I didn"t say that no design would work.

This just mean that contrary to say DSLR, you can"t reuse any of the old design, you can't neither directly use the lenses of previous generation and get good performance while this work perfectly on all DSLR. This also mean that for now there far less choice in the mirrorless systems and even for the most established and advenced player like Oly/Pana there was no breakthrough that made mirorless the dominant platform.

Eventually mirorless will dominate, if no better technology come in the meantime. This is just then that with less third party offering, less direct offering too, you tend to pay more for the same. All still have the compromize for size bundled in their offering meaning that the m4/3 high end lenses are quite expensive but f/2.8 zoom offer no more than f/4 on APSC or f/6 on FF in term of iso/deph of field. This also mean they are optimized for small wide angles but tele of reasonable quality are quite big. Sony is the one with an FF sensor but their lenses price are simply a joke and without sigma/tamron for now, that really anoying.

It is not like there a new thing with only positive aspects. At least for now. And that's not even going on the polemics to know if one prefer an OVF or EVF...

The fight between the different systems will be longer than many think due to that.