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What are all the advantages of fast lenses?
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Jan 27, 2021 12:19:51   #
cyclespeed Loc: Calgary, Alberta Canada
 
I know that lenses that open to F 1.8 and even bigger on some have an advantage when shooting in low light. Are there any other situations when this larger amount of light coming through would have an advantage.
I am about to try and use macro lens / settings to capture one of the fluffiest snow flakes we have seen in some time. So for example would a fast lens be better to use in this case?
Thank you for your thoughts.

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Jan 27, 2021 12:27:34   #
Longshadow Loc: Audubon, PA, United States
 
Wider apertures also have a shallower depth of field, many times allowing a more selective focus and resulting in a nicer bokeh. Depends on the effect one desires.

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Jan 27, 2021 12:30:42   #
CHG_CANON Loc: the Windy City
 
In today's world of digital cameras capable of delivering excellent images at ISO-3200 and higher, the 'low light' benefits of 'fast lenses' is not what it used to be. Rather, wide aperture lenses provide two distinct benefits:

1) Artistic depth of field
2) Better auto focus accuracy and speed in low light.

For artistic depth of field, that kind of depends. If say an f/1.4 lens is noticeably sharper at f/2, what's the benefit of f/1.4? The individual photographer has to decide if the cost is worth the results and whether that cost being justified as compared to the options that begin at f/2.8 or f/4, etc.

For autofocus, a lens opening to f/2.8 or wider performs much better in lowlight vs even a lens opening at f/4. Keep in mind, modern lenses focus wide-open and then the aperture is dynamically closed by the camera at the moment the image is captured.

How your snowflakes look between wide open and stepped down will be determined by your focal length and artistic intent. If you're manually focusing, especially using the 10x zoom via the camera's LiveView, the max aperture of the lens probably has little impact on the actual results, beyond maybe a very shallow depth of field, if desired.

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Jan 27, 2021 12:36:04   #
amfoto1 Loc: San Jose, Calif. USA
 
cyclespeed wrote:
I know that lenses that open to F 1.8 and even bigger on some have an advantage when shooting in low light. Are there any other situations when this larger amount of light coming through would have an advantage.
I am about to try and use macro lens / settings to capture one of the fluffiest snow flakes we have seen in some time. So for example would a fast lens be better to use in this case?
Thank you for your thoughts.


No, a larger aperture is not necessary for photographing something like a snow flake at very close or macro magnifications. In fact, it's the opposite of what you want. Stop down for sufficient depth of field. Put the camera on a tripod and use a longer exposure if need be (to allow you to keep IOS low and minimize digital noise in images).

While "low light" is one use of a large aperture lens, I'd argue the ability to render shallow depth of field effects and blur down backgrounds is at least as important and maybe even more-so. This effect that's only possible with a large lens aperture helps make subjects stand out and is useful for sports, portraiture and other purposes.

But it's the opposite of what you need shooting high magnification close-ups, where depth of field is awfully shallow already. It's also not desirable for many landscape shots and may not be necessary if shooting in a studio where you can control the background and lighting to similar effect. In those cases, smaller apertures are likely to be "better".

Something else that a large aperture lens does is often overlooked: It can help autofocus work better under marginal lighting conditions. This also isn't something needed for most macro shooting, though, where focusing is often done manually anyway. It's most useful for action photography such as sports.

So, again, a large aperture "fast" lens isn't likely to be of much or any help shooting macro photos of snow flakes.

EDIT: Chg_Canon mentions another important consideration: While there are exceptions, often "fast" lenses aren't their sharpest wide open. They need to be stopped down a little if critical sharpness is wanted. An f/1.4 lens I use is usable, but slightly soft wide open. So I often stop it down to f/2 or f/2.2 when I want to assure sharpness. The same can be said of most lenses... They aren't at their sharpest wide open. So, does that make an f/1.4 lens a "waste of money", compared to say a less expensive f/1.8 or f/2 lens? In my opinion and for my purposes, there is still added value to the f/1.4 lens. I could have bought an f/1.8 lens (2/3 stop slower) for half the price... but for that lens to render its sharpest shots might require it to be stopped down to f/2.6 or f/2.8. This, plus the fact that there may be times when the extra 2/3 stop of light and/or stronger background blur possible with the f/1.4 lens wide open make the more expensive lens "worth it" for me, even if there's a trade-off off slightly less sharp images. Other image quality factors come into play, too. The "more premium" f/1.4 lens has more aperture blades for nicer looking background blur... and, more subtly, it has better coatings that make for better contrast and color saturation.

When it comes to macro shots of snow flakes, you're likely to want as much sharpness as you can get out of a lens... as well as optimal contrast and color rendition. Macro lenses are "flat field" designs, meaning that they use an optical design that will render edge-to-edge sharpness at very close focusing distances (non-macro lenses are likely to "go soft" in the corners of images, particularly at larger apertures). Most macro lenses also deliver great contrast and color saturation. Even illumination across the image is another typical feature of a macro lens... I.e., lack of optical vignetting.

It all depends upon what you want... how you want your images to "look". It isn't a "bad thing" for parts of images to be soft or for vignetting to occur. For the shot of a rose bud below I deliberately used a non-macro f/1.4 lens forced to focus closer (with macro extension tube) and at a larger aperture (f/2), because I knew it render shallow depth of field, would "go soft" and would vignette... I wanted those things to occur in this shot. They may or may not be things you want to see in your snow flake close-ups.



Conversely, for the small product close-up shot below I used a similar focal length lens, but a tilt-shift design, at a smaller aperture (and longer exposure, on a tripod) to assure that the entire subject was in focus.



I'm guessing that snow flake shots will be at a lot higher magnification than either of the above... and because of that you have more issues with shallow depth of field. The freshly hatched snail below was shot at about 3.5X life size with an ultra high magnification macro lens... It was stopped down to the maximum possible (f/16), which in macro photography makes for an extremely small "effective" aperture (at 3.5X mag, effective aperture is approx. f/72).



In the image above you can see how shallow DoF becomes at very high magnification ... a plane less than one millimeter in depth is in sharp focus... even using an incredibly small effective aperture (which also risks softening the image due to an effect called "diffraction"). Of course, that snail is a 3 dimensional subject and a snow flake will likely be more 2 dimensional and that should help. Plus I don't know how high magnification you'll need. Depends upon the size of the snow flake. The snail above is maybe 4 or 5mm in length.

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Jan 27, 2021 12:42:29   #
cjc2 Loc: Hellertown PA
 
For indoor sports, fast lenses are my go to for many reasons. Faster focusing, better bokeh, and lower ISO. All of this makes for superior image files. I also use my fastest lenses for portraits/headshots for their legendary bokeh. Best of luck.

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Jan 27, 2021 12:58:46   #
Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)
 
cyclespeed wrote:
I know that lenses that open to F 1.8 and even bigger on some have an advantage when shooting in low light. Are there any other situations when this larger amount of light coming through would have an advantage.
I am about to try and use macro lens / settings to capture one of the fluffiest snow flakes we have seen in some time. So for example would a fast lens be better to use in this case?
Thank you for your thoughts.


There are benefits to fast lenses - shallower depth of field, faster/more accurate focus, brighter viewfinder, and as most lenses stopping down a couple of stops gives you excellent image sharpness and freedom from vignetting and CA from corner to corner - on an F1.4 lens that already happens at F2.8.

The downsides are that when used wide open, the center of the field may be very good to excellent, but the corners and edges stink. CA and vignetting is high. Then there is cost, bulk and weight. In the film days, using black and white film at ASA 800 gave acceptable and somewhat better results with Acufine but going much higher was a compromise due to increasing amounts of grain and base fog. With digital, it is not uncommon to see excellent results at 12,800 ISO with some of the better cameras, so the need for lenses that are faster than F2 is somewhat diminished. In the fashion and portraiture business, as well as some artistic/creative styles shallow depth of field and the corresponding bokeh is still highly desirable.

A fast lens is not necessary for snowflakes. A sharp lens is, however.

Pretty much what Paul (Chg Canon) said. . .

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Jan 27, 2021 13:08:30   #
BassmanBruce Loc: Middle of the Mitten
 
I’m posting just to request you post some of your shots. Sounds quite interesting.

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Jan 27, 2021 13:11:02   #
User ID
 
The single benefit of fast lenses is that they transmit more light. Every other aspect is a deficit, but you didn’t ask about that.

The benefit of more transmission can be a faster shutter, lower iso, brighter SLR view, AF working well in dim light.

The larger front section often means ~zero vignetting in the general use f/stops like 4.0 to 8.0.

——————————————————

You might start a separate thread about the deficiencies. That thread will surely introduce the creative uses of certain of those deficiencies.

There’s one deficiency, lack of DoF, that can positively influence focus, thus it’s also a benefit. Very narrow DoF makes manual focusing sooper accurate if you don’t shoot a wide apertures.

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Jan 27, 2021 13:32:33   #
Longshadow Loc: Audubon, PA, United States
 
User ID wrote:
The single benefit of fast lenses is that they transmit more light. Every other aspect is a deficit, but you didn’t ask about that.
...
...

Sure he <kinda> did, first sentence. He knew about the low light benefit. At least I understood it that way. He asked if there were other benefits.

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Jan 27, 2021 13:46:08   #
CHG_CANON Loc: the Windy City
 
If people envy your gear, that's worth something, isn't it?

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Jan 27, 2021 14:44:51   #
User ID
 
Longshadow wrote:
Sure he <kinda> did, first sentence. He knew about the low light benefit. At least I understood it that way. He asked if there were other benefits.

Typical knee jerk Hogster post. If you wanna advise the OP, advise the OP. I have no need of your review. Address the OP.

Please try reading to at least my third sentence. That stuff is in there as well.

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Jan 27, 2021 14:48:07   #
Longshadow Loc: Audubon, PA, United States
 
User ID wrote:
Please read to at least the middle.
That stuff is in there as well.

I simply replied to your one (first) sentence. Particularly, the last six words.
Or did the remainder that you wrote negate that sentence?

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Jan 27, 2021 14:50:59   #
cyclespeed Loc: Calgary, Alberta Canada
 
Thank you all for your thoughtful replies. If I get any results that I consider worth saving I'll post same. Many of the photographers in our club are not envious yet, since they are relatively speaking newbies. Yesterday we got side tracked on our 2 hour zoom meeting discussing "if they bought post processing software which one" I helped get to the conclusion by asking how much they knew about the free software their computers / cameras came with. We get great submissions and often the photographer won't have a clue as to how they managed it. But hey, we do enjoy the hobby, each in our own way. b.t.w. be cautious about what you envy. I got envious of a lens baby lens, it was given to me since the owner never uses it and I regularly get asked how I like it.

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Jan 27, 2021 14:58:22   #
User ID
 
Longshadow wrote:
I simply replied to your one (first) sentence. Or did the remainder that you wrote negate that sentence?

If you’re too busy to read past the first line, then it’s really none of your business what I write.

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Jan 27, 2021 15:00:20   #
Longshadow Loc: Audubon, PA, United States
 
User ID wrote:
Really none of you business. You’re too busy to read a whole post, so who needs your useless literary review ?

I read it, only replied to the first line, but okay.
Have a nice day.

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