Fast Lens Only For Shooting Wide-Open?

LCSmith

LCSmith

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I confess to have found myself wading through the rotten dregs of lens reviews and a reviewer made the (strange, I thought) remark that one ought only to use a "fast lens" at widest aperture. Otherwise, the reviewer argued, why choose the fast lens over a slower lens? I have encountered the notion elsewhere as well, that "fast lenses" shouldn't be used during the day time without a ND filter, and definitely shouldn't be used for landscapes.

I recognized the shallow depth of the idea; but I try not to write people off tout de suite. I actually use "fast lenses" frequently during the day time, stopped down appropriately for the exposure or composition. I like to mount a fast lens especially if I am shooting film and only have one lens with me, just in case I find myself in a situation where I need the extra stop or two.

It occurred to me (however wrongly) that this idea, that fast lenses should only be used at widest aperture, might be born of a digital mindset? For me as a film user primarily, I simply find fast lenses more versatile. Am I missing something?
 
i've not encountered this line of specious reasoning online in photography blogs but I don't doubt it's there. I avoid the widest apertures like I avoid the smallerst apertures, though I prefer that they're there. The notion of "working apertures" seems to have been lost today.

In fact, there is much internet chatter about older, not-as-corrected, low element count lenses having more "depth", "3D-pop", "microcontrast" (what have you). I'm inclinded to think that people who use older lenses like this (like me) tend to avoid shooting everything wide open. Maybe you're shooting that 50/1.4 at f4. Depending on scene and subject distance, this will give you a more subtle and gradual "fading" of out-of-focus areas than if you shot the same scene at f1.4 "because you can", which will more abruptly blur the background with less focus gradation.

Thus, shooting at f4 will give a greater sense of depth in the scene.
 
It is sometimes argued that fast lenses aren't as good as slower ones when stopped down. Some fast lenses might indeed make compromises somewhere else, but I doubt it's true in a general sense at least in the age of good coatings. The higher number of elements generally needed to correct a fast lens used to mean less contrast, but with better coatings, this problem is mostly nil. People rarely complain even about zooms with 12+ elements, although on digital it's easy enough to add some contrast back.

So I think it's just bokeh-ism.

In fact on SLRs, fast lenses also provide brighter viewing and more precise focusing (unless they focus shift), benefits the latter of which one can especially reap when using smaller working apertures.
 
You can make a fast lens slower, but you can't make a slow lens faster. If you want to stop it down, stop it down. Use whatever damn stop you want/need to and delete the site involved from your bookmarks, if you have not already.
 
MTF data for just about any lens is available online in many locations, along with CA ratings, transmission, vignetting. Virtually all vignetting and most CA can be easily handled in post. Best place to compare tech specs of lenses is DXOmark. There's that, and see what pics look like on 500px (or Flickr but 500px is better imo). This is what I use (tech specs) with a sampling of actual pictures taken by the lens being the main determining factor.

I read -- but very much take with a grain, the online perseverating of armchair optical theorists and lens evincers. Same with "technical ratings/rankings". Most lenses out there today (a couple of exceptions), especially primes, are just fine. And the theories floated by said armchair optical theorists are silly.
 
retinax said:
It is sometimes argued that fast lenses aren't as good as slower ones when stopped down. Some fast lenses might indeed make compromises somewhere else, but I doubt it's true in a general sense at least in the age of good coatings. The higher number of elements generally needed to correct a fast lens used to mean less contrast, but with better coatings, this problem is mostly nil.
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This is interesting. So it is possible that I am committing actual photographic gaucherie when I stop down to f/8 with my ZM Sonnar?
 
Sarcophilus Harrisii said:
You can make a fast lens slower, but you can't make a slow lens faster. If you want to stop it down, stop it down. Use whatever damn stop you want/need to and delete the site involved from your bookmarks, if you have not already.
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I try not to frequent those sites, "Flesh-lover" (lovely!), but while the spirit is willing the flesh is weak.
 
NickTrop said:
Maybe you're shooting that 50/1.4 at f4. Depending on scene and subject distance, this will give you a more subtle and gradual "fading" of out-of-focus areas than if you shot the same scene at f1.4 "because you can", which will more abruptly blur the background with less focus gradation.
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This is also my line of reasoning. If you are close enough to the subject that subject separation is inevitable, why not allow yourself some room for depth of field? I rarely shoot a portrait under f/2.8 (unless the light demands a wider aperture).
 
LCSmith said:
This is interesting. So it is possible that I am committing actual photographic gaucherie when I stop down to f/8 with my ZM Sonnar?
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I don't understand how you take what I posted to mean that. I'm in violent agreement with the others who say "stop your fast lens down". Although I'm an armchair optical theorist, I meant to say that generally, fast lenses will perform just as good as or better than slow lenses when stopped down.
 
retinax said:
I don't understand how you take what I posted to mean that. I'm in violent agreement with the others who say "stop your fast lens down". Although I'm an armchair optical theorist, I meant to say that generally, fast lenses will perform just as good as or better than slow lenses when stopped down.
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Oh no! I have failed to communicate. I was only responding to the idea about lens design and the compromises of a fast lens, and that it was possible some logic existed in eschewing fast lenses for bright scenes. I apologize if I was unclear.
 
LCSmith said:
Oh no! I have failed to communicate. I was only responding to the idea about lens design and the compromises of a fast lens, and that it was possible some logic existed in eschewing fast lenses for bright scenes. I apologize if I was unclear.
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Ah I see. It depends on the lens I suppose. I'd certainly not go buy a slow lens in addition to a fast one unless there's some specific fault with the fast one. So nothing that can be generalized.
 
People come up with some weird habits based on half-baked ideas. I've seen lens comparisons between the faster variant of a manufacturers lens and the slow. It's not unusual to see the faster lens outperform the slower at the slower lens's fastest aperture. Faster lenses are almost always the more expensive, and more than likely use more elements, aspherical elements or high index glass. In a lot of cases, they're the better lens, so I don't see a good reason to throw out the advantages of the lens when shooting stopped down. I also don't see any reason to haul around two pounds of glass when taking landscape photos when a smaller, lighter, slower lens will do. I have a 35mm f3.5 LTM lens which isn't much bigger than a $2 stack of quarters. At f/8 I'd put it up against the latest 35mm f1.4 lens available.

But it's a rare, exceptionally poor lens which doesn't look good at f/8. So why bother using a heavy, highly optimized fast lens at small apertures when even the cheapest third-party lenses look good stopped down this far? Use what you have though, it's not like you're going to wear out a lens.
 
An f/1.4 lens has a little extra horsepower and torque when you need to accelerate. You can use it to cruise at f/8 as well.

I really don't get into the bokeh thing. Unless the OOF areas really suck (by my standards, not general consensus) to me they're just OOF and not really very important. As previously stated, most lenses these days--like most cameras--are good. Better than we are as photographers in most cases.
 
I think the C Sonnar 50 1.5 is wonderful also at f5.6. This always wide open idea was pushed by Thorssten von Overgaard for one....

I mostly shoot the new 28 Summaron wide open - f 5.6.
 
mich rassena said:
I also don't see any reason to haul around two pounds of glass when taking landscape photos when a smaller, lighter, slower lens will do.
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This is the primary advantage of slower lenses, at least in my mind. Sure, there are times when a faster lens offers additional flexibility, but if you know you're not going to be opening up beyond f/8 or f/5.6, why lug around something so much larger?
 
Many people buy a lens for it's focal length, or for the particular type of image signature and bokeh it produces, not whether it's a fast lens or not. Common sense would tell you that if you have a fast lens that has those features then that's the lens you want on the camera, especially if an opportunity comes up to shoot in low light.

Having said that, if you seldom need f1.4 or less there's not much need to pay a lot more money for a super fast lenss when a much cheaper f2 or f2.5 lens will do perfectly well, assuming that the image quality and bokeh are the same.
 
mich rassena said:
But it's a rare, exceptionally poor lens which doesn't look good at f/8. So why bother using a heavy, highly optimized fast lens at small apertures when even the cheapest third-party lenses look good stopped down this far? Use what you have though, it's not like you're going to wear out a lens.
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It all depends on personal preference, of course; but none of my rangefinder lenses, even the fast ones, is so heavy that I wouldn't want to carry it around all day. Maybe I will feel differently when I am middle-aged. That said, when I used to parade around all day with my digital M-P and 50 Lux ASPH, that combo did become a little burdensome.
 
I love shooting my fast little Elmar wide open.



There should be a picture thread titled Lens Wide Open.
 
A lot depends on whether you are only going to shoot what you set out to take. I carry a film kit with me every day and use it for my own work (as opposed to the DSLR set I use for work). I never know what I'm going to use the film cameras for until I see it or until I respond to a fire/rescue call as the volunteer fire company's photographer. I don't always carry all fast lenses, but I have learned to have at least one fast lens, either a 35 or a 50, with me at all times. I would rather have a 35 1.4 pre-asph Summilux and use it stopped down than a 2.8 Biogon C and not be able to use it at 1.4 when the need arises. I choose lenses based on whether they can get the photo I want.
 
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