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02-13-2012, 03:55 AM   #1
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The Need For Speed?

When looking for new (or, new to me, AKA "Used") lens, the three prime objectives I use have boiled down to; Faster, sharper, cheaper.
Lately, I've gone for # 1, mostly to the exclusion of #'s 2 + 3.
Why? Well, the old expression regarding lenses is, there's no replacement for speed.
Oh, sure, with digital cameras you can boost the ISO and pretend you have an f/1.2, but the results aren't quite the same, are they? ISO 1600 isn't ISO 100, not by a long shot. All the PP in the world won't alter that fact, although you can improve the 1600 somewhat. Which means you could have also improved the ISO 100 shot, too.
Anyway, I recently won a Kiron 28mm f/2.0, while owning a perfectly good Pentax M 28mm f/2.8. I forget what the Pentax cost, but it took an additional $110.00 plus shipping , to gain one extra f/stop. Sharpness comparison? I won't know until I receive the Kiron, but I doubt it's any sharper.
So, I (likely) violated rules # 2 and 3, at the expense of # 1.
Another recent purchase is the Tokina ATX- 80-200mm f/2.8, but I have several 80-200mm or 100-300mm Pentax/Takumars, mostly f/4.5-f/5.6's.
Here it cost me over $200.00 to gain 1-1/2 to 2 f/stops of speed. I also lost AF, the Tokina is MF, which is the only way I could come near a 200mm f/2.8, at that price.
What's the point? A couple of weeks ago I took a photo-trip to the old Union Station downtown. They're in the process of renovating the grand old train station and I wanted to document the stone structure while I had the chance.
The outside photos were a snap, plenty of daylight, so much in fact, I used a CPL and still had lots of light.
Inside? Well, lets just say it was...dim. Beautiful arched windows but not really much light, overall. I was struggling to get 1/125th at f/2.8 and some of the darker corners were more like 1/60th. I ended up with several under-exposed or poorly exposed shots, then (of course!) boosted the ISO and got reasonable results. One more f/stop of speed would have made the difference. DOF wasn't a problem, I was at or near infinity focus with my 28mm, it was the shutter speed that needed help. No tripod on this trip.
Same problem with concert photos. It LOOKS like the stage lighting is plenty bright, but that's because you're standing in the dark. One more f/stop or raise ISO? A faster lens or more noise?
Sports and action? Don't ask. There's a good reason the pros all have 7 pound bazookas on the sidelines and it's not not because they like carrying them around. Speed.
That's my reasoning, anyway!
Ron

02-13-2012, 04:21 AM   #2
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I don't suffer this personally, as I very rarely shoot under f/8 (usually 11ish for the shooting I do) and I don't think I can fathom the reason for faster glass, but that's simply because I don't do any wide open shooting, and have never seen any reason to and doubt I ever will. The fastest lens I own is 35mm 2.4 AL, which while a lovely lens, I still rarely use any faster than f/8.

What do you need the speed for? Animals? Children? Sports? Some sort of live events? I don't do any of that sort of stuff (of those, I generally only snap sleeping animals, too much of a bother to track, let alone capture while awake). I'm still relatively new to photography, though and also do it in a limited and perfectly controlled scope, so I guess I'm missing something fundamental in why speed is important.
02-13-2012, 04:28 AM   #3
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I've mentioned my priorities for kit-building:

1) Coverage. My Tamron 10-24, DA18-250, and Lil'Bigma 170-500 cover lots of territory.
2) Speed. My K50/1.2 and FA50/1.4, and MF 24-28-35-58-85mm f/2s fill my needs there.
3) Specialties. Fisheyes, mirrors, macros, enlarger|projector lenses on extension, as needed.
4) Character. Old slow lenses just render differently than modern over-corrected optics.
5) Mania. Whatever bizarre optical materials I can stuff onto the camera. Good clean fun.

What's missing from my kit are fast zooms. But they're expensive, and my fast primes are faster. My fastest zooms are both M42 f/3.5, a Sears-Tokina 55-135 (US$8) and the Vivitar-Kiron Series 1 70-210 (US$43). I don't know if spending hundreds of bucks on an AF f/2.8 zoom would be worth it.
02-17-2012, 11:36 AM   #4
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QuoteOriginally posted by Kona Quote
I'm still relatively new to photography, though and also do it in a limited and perfectly controlled scope, so I guess I'm missing something fundamental in why speed is important.
Hi Kona,
Yes, the need for faster lenses is primarily for shooting moving objects. The faster they move, generally, the faster the lens needed. As I mentioned, sports photographers have the super-fast telephotos so they can use high shutter speeds, fast enough to "freeze" the action. The only other way to generate a fast shutter speed (once the lens is wide-open) is to raise the ISO, which is a trade-off. The highest-quality photo usually is a result of the lowest ISO possible, although some of the quality can be recovered in PP.
But there other uses for fast lenses, most frequently in what is called "Available Light" photography. In other words, no added light, like a flash.
Many concerts, museums, shows and events prohibit the use of flash. Events that have a large crowd often restrict the use of tripods, since they pose a tripping hazard for bystanders.
Without flash or tripod, you have 2 options for producing a reasonable shutter speed (with or without SR), aside from possibly finding a solid obect to stabilize the camera.
(1) Raise the ISO.
(2) Open the aperture. The difference between an f2.0 (maximum aperture) lens and an f2.8 max aperture lens is twice the shutter speed (example; 1/60s vs 1/30s), which could, and often is, the difference between a useable photo and a blurry one.
Hope that helps to explain the need for speed!
Ron

02-17-2012, 12:35 PM   #5
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Besides the moving subjects and low-light photography that Ron mentioned, the other main reasons for fast lenses are 1) DOF control, and 2) bragging rights. Let's forget the latter. DOF control means that with a wide-aperture lens, you can have very thin DOF (depth of field), so as to surgically isolate a subject from their surroundings. A slower lens can only get thin DOF by shooting from further away. So I use my f/1.2 and f/1.4 lenses for dramatic DOF with close subjects.
02-19-2012, 07:06 AM   #6
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DOF

Yes, Rico, you're right and thanks for reminding me, I forgot!
Depth of field control is very necessary, especially in portraits and other types of photography where you want to isolate a subject and diffuse any distracting foreground or background objects.
Just as you may want deep DOF for a scenic shot, everything near-and-far in sharp focus, there are times when you want a nice blurry (out-of-focus) background. The classic example usually given in "Photo Composition + Framing" classes is the head shot with the telephone pole sticking out of the subject's head.
In other words, the aspiring photographer was so concerned with the subject, they forgot to check the background.
If this photo is taken at f/5.6 or f/8.0, that pole is usually nice and sharp, which means they flunk the course.
At f/2.0 or f2.8, it's just a blurry blob and they may slide by with a lecture.
Yes, that's an extreme example, of course they could move the subject or camera sideways and get the pole out of the shot. But the lesson of the OOF background is valid.
Most times when you see a good portrait or head shot, there's nothing else in the photo to pull your eye away, it's all nice and dreamy. Why? Because the photographer deliberately used a wide aperture to diffuse unwanted elements.
FYI, there's a whole subject devoted to the shape and quality of the OOF elements, it's called "Bokeh".
Hope this helps why some of us have a need for speed!
Ron
02-19-2012, 08:46 AM   #7
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All things being equal, faster is better. All things are, of course, never equal. Fast, sharp, and cheap is a rather rare combination, especially at FLs other than 50mm. And speed and sharpness are not the only qualities of a lens.

With certain lenses/subjects it is pretty rare for me to go below f/8, in line with Kona's comment. But I love shallow DOF effects and with other lenses I rarely seem to stop down past f/2 or so.

Another point about fast lenses -- brighter image in the VF, for easier manual focusing and more generally reliable AF. And for super-teles speed gives you more options for adding TCs.

In short, speed is one factor among many to consider when acquiring lenses, and how important it is depends on what the lens will be used for.
02-19-2012, 10:04 PM   #8
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QuoteOriginally posted by baro-nite Quote
In short, speed is one factor among many to consider when acquiring lenses, and how important it is depends on what the lens will be used for.
Yes, speed can be vital, but at a cost, and not just money. My K50/1.2 is absolutely brilliant -- and weighs 400g. My aluminium CZJ Tessar 50/2.8 (12 iris blades) is also quite brilliant and tips the scale at 110g. I'm still putting together my ultra-light minikit with that Tessar and two Ennas: Sandmar 35/4.5 (60g) and Tele-Sandmar 100/4.5 (110g). Those Sandmars are sharp, but with character, giving a certain 1950s look to images. My pancake Meyer Helioplan 40/4.5 (100g) is also a beauty. And those lightweight lenses were pretty cheap too. Yeah, I got lucky.

Other great slow (but somewhat heavier) lenses include my Meyer Primagon 35/4.5, Meyer Primotar-E 50/3.5, Isco Westar 100/4.5, Jupiter-11 135/4, Meyer Telemegor 180/5.5, the splendid Tele-Tak 200/5.6, and Alpa-Chinon (Cosina?) 300/5.6. At the other end of the scale are the huge fast Projection Optics 76/1.6 and Rodenstock XR-Heligon 120/1.8, but I'll have to get a NEX before I can use them for anything but close work -- PK register is too long.

With slower lenses, DOF is controlled more by lens-to-subject and lens-to-background distances, as well as attention to lighting. A fast lens allows DOF control without going through as many gyrations. So I can get similar DOF with a 100/2.8 as with 50/1.4; I just need to be twice as far away, and to be careful with backgrounds and placement and light, and of course there are perspective differences. Work work work...

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