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Why is performance wide open important?
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PostPosted: Thu Nov 05, 2015 9:08 pm    Post subject: Reply with quote
Michael, thanks for your example. I exactly know what you are talking about, I have a 200/2.8 lens as well. Wink
Though, for such portraits I might use my 85/1.4 lens instead if the background is too busy or too near.
Everybody has his own preferences. That's rather clear. Smile


PostPosted: Fri Nov 06, 2015 1:39 pm    Post subject: Reply with quote
I learned photgraphy first in the 1950s, using slow film, slow lenses and slow shutters. One of the things I was taught is that, for optimal
IQ, the lens aperture should be set at its midpoint and adjustment for lighting conditions should primarily be made with the shutter
speed knob. Adjusting the aperture should be almost the last resort.

I don't remember anyone ever talking about using wide-open apertures back then. It was like admitting you'd been cheating. To me it's
a relatively new phenomenon, resulting from the advances in camera, lens and film/sensor technology. Maybe this explains why younger
photographers seem to have less aversion to it than old farts like me.

However, one thing remains true. In low light there is always a trade-off between IQ and using wide open apertures, fast ISO/ASA and
slow shutter speeds. For this reason I've never really experimented with wide open apertures, and I've never given the depth of field
much thought. The interesting discussion in this thread might have changed my outlook a little, and these dull and dark autumn days are
the ideal time to give it a go.


PostPosted: Fri Nov 06, 2015 2:12 pm    Post subject: Reply with quote
If this thread makes even one photographer go out there and experiment and actually taking pictures then it was worth it.


PostPosted: Fri Nov 06, 2015 3:02 pm    Post subject: Reply with quote
peterqd wrote:
I don't remember anyone ever talking about using wide-open apertures back then. It was like admitting you'd been cheating. To me it's
a relatively new phenomenon, resulting from the advances in camera, lens and film/sensor technology. Maybe this explains why younger
photographers seem to have less aversion to it than old farts like me.


Although I'm a little bit younger and started only in the 1960's I see it exactly like you. That's how we learned it in the old days.
So it might be in our genes. Wink

However, the basic principle didn't change that much, although generally the lens technology has improved. There is no doubt about that.

I just came back from a test shooting with my Tamron lens (mentioned earlier in this thread) to look how it performs wide open.
Here is a test shot of this MAF 90/2.8 lens used MF with my Ricoh GXR (APS-C) at F2.8:



100% crop of the above:



I would have never done that in the old times to use a lens for infinity landscape fully open. However, the picture is more than only usable for my taste. But certainly not every lens is performing like this one, that's also clear. Wink


PostPosted: Fri Nov 06, 2015 4:08 pm    Post subject: Reply with quote
Impressive result
Like 1 small


PostPosted: Fri Nov 06, 2015 4:22 pm    Post subject: Reply with quote
hoanpham wrote:
Impressive result


I see it likewise; particularly because it is a 1:1 macro lens and therefore most probably optimized for shorter distances.
It was btw. the first time that I've used it as MF lens. It's very handsome and easy to focus manually.


PostPosted: Fri Nov 06, 2015 4:34 pm    Post subject: Reply with quote
tb_a wrote:
hoanpham wrote:
Impressive result


I see it likewise; particularly because it is a 1:1 macro lens and therefore most probably optimized for shorter distances.
It was btw. the first time that I've used it as MF lens. It's very handsome and easy to focus manually.


macro lens also has better resolution


PostPosted: Fri Nov 06, 2015 4:52 pm    Post subject: Reply with quote
visualopsins wrote:

macro lens also has better resolution


I am not too sure if this has any major impact on the shown picture shot with a 12MP/APS-C camera. I would assume that you need more pixels to show the difference in resolution.
However, the Ricoh lacks of any AA-filtering which makes pictures looking a little bit more crispy.


PostPosted: Fri Nov 06, 2015 5:16 pm    Post subject: Reply with quote
tb_a wrote:
visualopsins wrote:

macro lens also has better resolution


I am not too sure if this has any major impact on the shown picture shot with a 12MP/APS-C camera. I would assume that you need more pixels to show the difference in resolution.
However, the Ricoh lacks of any AA-filtering which makes pictures looking a little bit more crispy.


Would a non-macro 90/2.8 have more or less resolution? Guess which lens will be sharper wide open at infinity?

I think this may be characteristic:

SMC Macro-Takumar 1:4/100 -- not macro photos


PostPosted: Fri Nov 06, 2015 9:14 pm    Post subject: Reply with quote
visualopsins wrote:

Would a non-macro 90/2.8 have more or less resolution? Guess which lens will be sharper wide open at infinity?


Well, there is no easy answer to your questions.

E.g. my SMC Pentax macro 100/4 is tack sharp for it's intended use but far below the shown Tamron lens at infinity, though it's F4 instead of F2.8 wide open. That means that if I would compare both lenses at same aperture the difference would be even bigger (I've just checked infinity pictures from my Pentax at F4 from the same camera). However, interestingly the Tamron lens is also performing excellent at macro distances. My Minolta macro lenses (both 50 and 100 mm) are also rather optimized for shorter distances. I haven't checked my Pentax 50 macro for infinity yet. Would be an interesting comparison. Maybe I'll do that at a later stage.....

My main point was to show a lens performance when used FULLY OPEN and it turned out that this specific lens doesn't show any major shortcomings when used like this opposed to many other lenses in my collection (also the non-macro ones). The majority of my lenses benefit from using them rather stopped down (at least a little bit) as the final picture shows then more sharpness and contrast. Generally I would say that the fastest lenses improve more than the slower ones. However there are some exceptions as well. Wink

Finally, resolution is only one quality criterion of a lens and there are some others as well to contribute to the final impression of sharpness of the picture. But that would be a separate discussion. Smile


PostPosted: Sun Nov 08, 2015 1:31 am    Post subject: Reply with quote
Consider single-element simple lenses of different diameters.

Each lens has the same focal length.

The larger diameter lens is "faster" than the smaller diameter lens.

The larger diameter lens is also thicker through the middle, i.e., light travels through more glass in the faster lens.

A closing diaphragm aperture cuts off light rays entering the circumference of the lens. As the diaphragm closes, the aperture diameter approaches the thickness of the glass. Aperture diameter equal to glass thickness could be significant -- the sweet spot of some maximum performance perhaps.

Some of us are seeing better performance from faster lenses when both are stopped down to the same aperture -- for example a 2.8/90 lens and a 4/90 lens, compared at f/5.6; the 2.8/90 show better results.



Has anybody mentioned the importance of fast wide open for ASTROPHOTOGRAPHY?!!! Stopping down lens has virtually no effect on sharpness, because light rays from those far-away tiny points of light arrive nearly perpendicular to lens surface -- there is no bending to enlarge the airy disk.


PostPosted: Mon Nov 09, 2015 3:55 pm    Post subject: Reply with quote
Why wide open performance is important?

Well, there many good reasons to shoot wide-open, and many good reasons to shoot stopped-down. Someone could write a book about it. Many people with extensive photographic experience have already made many interesting remarks here, but I could not read all the posts. I hope I will not repeat what has already been discussed before.

There are many lenses for photographic (or related to) that can only be used wide open. It is the case of the mirror (catadioptric) and projection lenses, and a very important contemporary case, the smartphones' lenses. It is also important to note that there is a difference between the wide-open condition and the "speed" of a lens. A 600mm F4 telephoto lens is not "fast" compared to a 50mm F1.2, but there is little doubt that that super-telephoto lens is extremely difficult to design if the goal is to achieve high image quality despite the "slow" aperture F4.

Much has been discussed about fast lenses from the photographer's points of view. It is also interesting to see what are the optical designer's and the lens manufacturer's point of view. The graph below published by Zeiss shows the glass raw material cost as function of aperture, of a Double-Gauss 50mm lens. The F1.4 aperture is used as the reference of cost (100%).





Note that the glass raw materials in an F1.2 lens cost the double than the corresponding in an F1.4 lens. In contrast, the cost drops to only 1/5 for a F2 lens. Of course there are other costs involved in the construction of a lens. There is a mechanical part (barrels, mount, diaphragm mechanism); machining, grinding and polishing operations; design, etc., whose costs vary differently than shown in the graph above.


PostPosted: Mon Nov 09, 2015 5:46 pm    Post subject: Reply with quote
Gerald writes -
Note that the glass raw materials in an F1.2 lens cost the double than the corresponding in an F1.4 lens. In contrast, the cost drops to only 1/5 for a F2 lens. Of course there are other costs involved in the construction of a lens. There is a mechanical part (barrels, mount, diaphragm mechanism); machining, grinding and polishing operations; design, etc., whose costs vary differently than shown in the graph above.

That's interesting, Gerald. Can you let us know the source of your information about specific costs, please?
_________________


PostPosted: Mon Nov 09, 2015 10:59 pm    Post subject: Reply with quote
scsambrook wrote:
That's interesting, Gerald. Can you let us know the source of your information about specific costs, please?

The graph which I presented above is from a British Journal of Photography article, feb 1980, by Walter Woltche, Head of Mathematical Department, Photo Optics Division, Carl Zeiss Oberkochen.

The cost of glass raw material depends basically on the specific optical glass type, and the mass of the material, which is directly proportional to the volume. If you compare, for instance, a F1.2 lens to a F1.4, you should expect that the total mass of the optical parts of the faster lens to be about 60% greater. On the other hand, most probably the F1.2 lens uses optical glasses more expensive, so an increase of 100% in the price of the glass raw materials seems perfectly reasonable to me.

I don't have data on the costs of other factors that compose the total manufacturing cost of lens, but I think that an engineering reasoning can be used to make an educated guess. I said that the costs of the other factors don't increase as fast as the glass raw materials cost. Take for example the mount. The cost of the mount is the same, no matter the lens maximum aperture. The cost of the control rings and external finishing (anodizing, painting, etc) should also be essentially the same. On the other hand, the cost for machining aluminum barrels, grinding, polishing and coating of optical elements is proportional to the surface of these parts. I would expect that the surface of an optical element of an F1.2 lens to be not 100%, but something around 35% larger than the corresponding of a F1.4 lens. Finally, the cost of designing a 50mm F1.2 lens should be not too different than a 50mm F1.4 lens because the optical design complexity is basically the same (both are Double Gauss, 7-element lenses).


PostPosted: Thu Nov 12, 2015 8:11 pm    Post subject: Reply with quote
I've not been on the forum for a while and I see all the nit-picking going on in this topic. My answer to the question:

If I'm shooting film in low light, and as a necessity must use full aperture, I want the sharpest image I can get. Thats why performance at full aperture is important to me.


PostPosted: Thu Nov 12, 2015 9:01 pm    Post subject: Reply with quote
Yes, I understand. But the title, the question, was a rhetorical one chosen in order to grab peoples attention. The point of the thread, which was explained in my first message was that most lenses are not designed to be used wide open and that if you need a faster lens, then choose one that is faster and will still allow you to use it as it was intended, i.e. not fully open. If you don't have the budget. Fine. But theoretically it does not make any sense to always shoot wide open.


PostPosted: Fri Nov 13, 2015 2:26 am    Post subject: Reply with quote
I would expect a lens is designed to work at from wide open to fully stopped down. It will be another topic if we are going to disscus the 'sweet spot' of a lens.


PostPosted: Fri Nov 13, 2015 2:38 am    Post subject: Reply with quote
This one has been never ending topic since long time ago. (I mean before Pontus started this) But I'm glad there's a conclusion that Person who always shoot at wide open all the time and never stopped down is stupid. and I believe there's no one like this.
Laugh 1
There's a time when someone wants to shoot always wide open let's say for a month, but then he get bored. right?
A lens performance at wide open maybe not as good as it at stopped down, BUT there's a character in wideopen, that will show only in wideopen. in this case, not many people can do or want to try Smile
for example, Trioplan 100/2,8 in the right hand can be beautiful at WO, but on the other hand, it only produce soft images, and he claimed it's a bad lens.
oh I like to shoot wide open, so fast projector lenses is nice for me, sometimes I add paper as stopped down aperture. but mostly I shoot at wideopen. maybe I'm a bad photographer, beginner, stupid. who cares? I shoot what I want, sorry if anyone accidently see my pictures at wideopen.


PostPosted: Fri Nov 13, 2015 4:41 am    Post subject: Reply with quote
I have seen many times on this forum that people say they only ever shoot wide open. It is a deliberate choice but one founded of emotions, not on reason. Ultimately it is up to the individual, who are we to judge. And there is nothing to judge, it is an individual choice. We have listed maybe 15 reasons to shoot wide open, it is not about that, of course we shoot wide open from time to time. I just wanted to figure out the reasoning, what makes people decide to use lenses ONLY wide open. Because some people do.

I'm starting to sound like a broken record. I'll stop now Smile


PostPosted: Fri Nov 13, 2015 7:50 am    Post subject: Reply with quote
I mainly shoot wide open....


PostPosted: Fri Nov 13, 2015 9:15 am    Post subject: Reply with quote
Pontus wrote:
I have seen many times on this forum that people say they only ever shoot wide open. It is a deliberate choice but one founded of emotions, not on reason. Ultimately it is up to the individual, who are we to judge. And there is nothing to judge, it is an individual choice. We have listed maybe 15 reasons to shoot wide open, it is not about that, of course we shoot wide open from time to time. I just wanted to figure out the reasoning, what makes people decide to use lenses ONLY wide open. Because some people do.

I'm starting to sound like a broken record. I'll stop now Smile


It's simple, there's nothing wrong with shooting WO when the situation calls for it. However, shooting WO all the time is stupid.

Furthermore, many people shoot WO too often, resulting in flawed pictures.

The saying 'less is more' definitely applies.


PostPosted: Sat Nov 14, 2015 3:12 am    Post subject: Reply with quote
I saw many great shots WO. I respect people who did it because it's not really easy.
shoot WO is a kind of many techniques or genre. If you see bad pictures of it maybe it's good for the other.
and if it's really bad picture the man behind the gun whose to blame, but bear in mind maybe he's still learning
For me.. WO is challenging not everyone can do it perfectly like eg. Klaus
people who do it mostly are good photographers, even Steve Hufft wrote about WO in daylight with fast lens
like macro shot. If a man always shoot macro all time, but hihis results is not good enough what is wrong?
We will suggest him to shoot more, not call him stupid


PostPosted: Sat Nov 14, 2015 4:45 am    Post subject: Reply with quote
Yes, shoot more is good advice, but add to that a strong suggestion not to shoot WO all the time, but instead to learn to use the aperture to manipulate dof as that will improve their work.

WO is fine in the right situation, no doubt about it, but equally, it is wrong in other situations; therefore it is an important skill to learn how to discern when to shoot WO and when not to.

Stupid was probably a bad word to use to convey what I meant. I'm not sure of a better word to use; what I meant was that it is much better to learn to use the aperture and to manipulate dof for aesthetic advantage rather than just automatically, without any thought, choosing to shoot WO.

Of course, the lens being used also makes a difference. Here's an example of similar subjects shot with different lenses on the same camera (Sony a850):

First is a Schneider Cine-Xenon 2/90 WO, this is a high end projection lens that costs 2,600USD and is optimised for WO performance:

100% crop:


Second is a Bell & Howell 3.8/70-150 zoom, a mediocre lens at best:

100% crop:


The B&H zoom shot was taken at f11 with the lens mounted using a 10mm extension tube. I chose f11 for two reasons; firstly, when using the extension tube, the dof is reduced, so stopping down counteracts this and restores dof to a suitable depth; secondly, this lens is simply not sharp unless stopped down.


PostPosted: Sun Nov 15, 2015 4:02 am    Post subject: Reply with quote
visualopsins wrote:

Has anybody mentioned the importance of fast wide open for ASTROPHOTOGRAPHY?!!! Stopping down lens has virtually no effect on sharpness, because light rays from those far-away tiny points of light arrive nearly perpendicular to lens surface -- there is no bending to enlarge the airy disk.


I don't know if anyone has mentioned it in this thread or not, but it's virtually by definition that any telescope is a wide open optic. In fact, there's a simple formula for determining the focal length vs. the front element diameter vs. the f/ratio. For example, if a telescope has a 1000mm focal length and a 100mm front element diameter, then 1000/100 = 10 or f/10 is the f-ratio of the telescope. This gives us the formula: FL / feD = f/stop. Thus it also works if you know, say, the front element diameter (feD) and the f/ratio, and you want to see what the focal length is. Then it would be feD x f/stop = FL. In this case, it would be 100 x 10 = 1000. This same thing holds true with any optic, although camera lenses can be a bit trickier to obtain these same values.

Anyway, whether a telescope is a Newtonian or another type of mirror or if it's a refractor, when it comes to evaluating its performance, it is always evaluated wide open. Obviously, because there is no aperture in a regular telescope. Typically when I read a write-up on a telescope, coma and other off-axis aberrations are discussed, as is whether or not the scope is diffraction limited (almost all good scopes are these days). Here's more info on diffraction limited optics at Wikipedia:

https://en.wikipedia.org/wiki/Diffraction-limited_system

Actually, a more important determinant in the sharpness of a telescope -- or camera lens, for that matter -- is a property called angular resolution. Angular resolution is the smallest angle separating a pair of objects that can be distinguished in a lens's or telescope's field of view. An amateur telescope with excellent optics typically can resolve objects with angular resolutions as small as one arc second. However, "seeing" is rarely good enough for one to observe this sort of separation when viewing astronomical objects beneath the several kilometers of atmosphere we have to peer through.

Here's further explanation of AR at Wikipedia:

https://en.wikipedia.org/wiki/Angular_resolution


PostPosted: Sun Nov 15, 2015 5:34 pm    Post subject: Reply with quote
kds315* wrote:
I mainly shoot wide open....


Thanks kds315 for having the courage to admit this.

This thread has inspired me to shoot wide open more often, and I think I will try shooting wide open exclusively for a few months as an experiment. Why? Because I'm "stupid", of course! Twisted Evil
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