gabriel_l1

May 2, 2010

PS—Jason, do you shoot in RAW? If so, you *might* have more detail recorded than is being displayed there. The key is to play around with things such as the "recovery" slider, the "highlights" control, curves, and levels—not merely making the entire photo brighter or darker, but selectively targeting the overexposed portions of the image. If the highlights have been truly clipped, there is no way to fix it, but otherwise judicious use of Lightroom will bring it back into the photo. It is easy to check—just lower the exposure drastically in lightroom, if the detail comes back, you can fix it, but if it stays "halo" shaped, you've lost the info forever.

May 2, 2010

This is an issue of dynamic range. Unless you changed the lighting in the scene, there is no possible way for your camera to get all the detail in *both* the highlights *and* the shadows.

However, if your camera is good enough (records at high bit depth, captures shadow detail well), you might have tried underexposing—losing detail in the black strap, for example, and even the hair—until you *just* got enough detail in the helmet, and then using post-processing (lightroom) to bring the shadows back up using curves. But it still comes down to prioritizing either the shadows or the highlights.

EXCEPT... it is *possible* that the light coming off the helmet was subsequently polarized (depends on the helmet material I guess), in which case a polarizing filter on your lens would have cut down on that light more than any other, helping to bring down the dynamic range.

ALSO, a graduated neutral density filter could have been used to make the top half of the photo darker while not changing the bottom half. It would have been a somewhat unusual use of such a filter (usually they are meant to bring sky exposures closer to ground exposures in landscapes), and it might have made the image look odd—maybe, maybe not—but it's another example of something you could have tried.

But as to camera settings? Nope, no camera setting will capture both the brights and the darks in a scene with this much dynamic range. Still, I usually prefer to underexpose and boost in post rather than clip the highlights (assuming that the choice is absolutely one or the other, with no possibility of improving the scene before the shot).

Cheers, —GL

May 2, 2010

Ah, I see, a bit more complicated. :-) I don't have this lens, so I can't help you out. Good luck though! I'll be looking forward to whatever the related article is that you are writing.

May 2, 2010

The question is almost like asking "I want my drawings to have more depth and fit in more of the scene, should I upgrade my office pencil to a staetdler?" The staetdler is a nicer pencil, but it is just a dumb tool, it doesn't magically draw different pictures.

First of all, the 50D is a crop sensor camera; a 50mm lens will give the exact same angle of view as on your 450D camera. No difference, period.

Second of all, what's wrong with a 50mm lens on crop sensor camera? 80mm-equivalent (on fullframe) is just one specific focal length, it is no way better or worse than another focal length UNTIL you start specifying use. 50mm on APS-C (or 80mm on full frame) is a decent portrait length for example. But if your wish is to go wider, say for landscapes or street photography, then by all means, get a wider lens.

Third, looking at some sample photos from both cameras will tell you ZERO—and I mean ZERO—about what each camera can achieve. Were the shots of the same scene? Taken by the same photographer? In the same conditions? Otherwise, you're comparing shots taken by people who spend more money on their camera (and are presumably, on average, more serious or experienced photographers) with people who spend less money on their camera (and are, again IN GENERAL, probably less likely to be pro photographers or the most serious amateurs). This of course means that buying a 50D doesn't magically make you a better photographer, nor does it mean the 50D takes better photos.

If there is a specific *feature*, or alternatively a specific detail in image quality (high ISO noise, for example) that the 50D is billed as having over the 450D, then go right ahead. But if your images lack "depth," buying a 50D is not the answer. Practicing photography more is.

Save your money, spend more time reading and practicing. If you must buy something, buy another lens, maybe a kit zoom so as to experiment more with focal length. The EF-S 18-55 IS is only, what, $170? And for that you get a sharp, image-stabilized, useful-range, close-focusing, lightweight/small lens? No-brainer for a beginner photographer if you ask me.

May 2, 2010

Seems like given the known max magnification and minimum focus distance you could derive this, no? If it's 0.20X at 1800mm away, I think that gives f=300mm (using M=f/[d-f]). HOWEVER that is very off-the-cuff, I hope you can find more solid figures than that.

April 27, 2010

David, there are at least several common "lens hood substitutions", usually with the wider-angle lenses, that some people like to make when mounting EF lenses on APS-C bodies. None of them are official, they're just ad-hoc improvements (in theory).

Also it doesn't make sense to say that a crop sensor will cause a lens to flare less. The lens will flare as a result of a light source reflecting internally. It doesn't matter what size sensor you put behind it, all that matters is whether light strikes the elements with certain angles and brightness. The only difference I could imagine is a very special case wherein light will reflect off of the sensor periphery at an angle, back into the lens, and cause flare that way—in which case a smaller sensor would conceivably be less flare-prone. But that's a very specific (and I suspect small) subset of flares that get recorded.

I agree that the 70-200 doesn't need any better hood than what it has got. Stick with the one it came with, Teo.

Cheers, —GL

April 26, 2010

PS—In fact, after reading Alan's link, I am even more impressed by FTM because it works on a different principle than I had thought—namely, the output ring is essentially a differential between the manual focus ring and the AF ring. It is attached to rollers that contact the manual ring and AF ring on each side; during AF, the rotor turns the rollers and they pass over the stationary manual ring, and during MF, the manual ring turns the rollers and they pass over the stationary AF ring! Very elegant.

April 26, 2010

Petr,

There are two kinds of USM—USM micro motor, and true "ring" USM. In ring USM, there is NO motor that is turned when the manual focus control is used. The AF works by vibrating a rotor over a stationary toothed ring ("stator"). This in turn rotates an "output ring," which is the actual focus control. Alternatively, the manual focus works by turning the output ring while the AF rotor does not move. If you are in AI Servo, the AF rotor will continually override the manual focus ring's influence on the output ring. You must be in "One Shot" AF mode to enable full-time manual focus, which will first focus by AF and then stop—meaning that all subsequent adjustments of the output ring via the manual focus will remain uncorrected, as it were.

USM and FTM are brilliant works of engineering indeed... There is no "clutch" at all, everything is simply competition over the output ring by the rotor and manual focus ring, all through friction.

April 25, 2010

Crop sensors are here to stay. Canon has never given the slightest indication otherwise—it always amazes me when people talk about a mythical future in which crop sensor cameras are no longer made and EF-S lenses suddenly become obsolete.

Lenses also hold their value better than the vast majority of other electronics out there. You will still lose money selling them, however, so if you are certain that you are going to go full-frame in the near future (e.g. one year), it makes sense to limit yourself to EF lenses exclusively. Otherwise, just get whatever is going to net you the best images now, and worry about the future later.

April 19, 2010

Thank you for your kind words Theresa.

Have a good week yourself, —GL

April 19, 2010

Scott,

Thanks for returning to this thread. I was secretly wondering if I was just getting muddled somehow, but it's good to confirm that we were each "half right" (FOV vs AOV).

Fully tracking how apparent focal length changes at macro magnifications is beyond my current knowledge of optics, but thanks for your explanation, which improves my understanding of this effect.

Judging from Theresa's post this thread hasn't been my greatest ever for positive contributions, so I think I'll let it rest from this post on.

Best regards,

—GL

April 19, 2010

I have the 60. It's great although I'd like a little more working room for bugs. But it's also a good length for portaits, where the 100 on APS-C might be a bit long.

April 17, 2010

Theresa,

I am so sorry to have made you feel that way! That was not my intent at all. I was just hoping to understand your question so that I could help you to the best of my ability—chalk up any complexity in my answer to my own apparent confusion and inability to see things from your perspective. I would hope that coming to photo.net with any questions you might have would be a positive experience, not a discouraging one, and I regret having contributed in any way to such a sense of discouragement.

Please accept my sincerest apologies,

—Gabriel L.

April 17, 2010

To continue my previous post, compare the lowly $90 nifty fifty to the 24-105. http://the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=355&Camera=453&Sample=0&FLI=3&API=2&LensComp=105&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=4

The 50mm obviously wins. $900 doesn't buy you maximum sharpness in that zoom; it buys you perfectly usable sharpness over a very wide focal range with solid build quality, constant f/4 aperture, well-controlled CA and flare, USM focusing, image stabilization, nice bokeh, etc. It's an extremely useful lens (on full-frame—a little long on a 7D if you ask me) with very good image quality. It's not meant to be an example of maximum image quality at the expense of everything else.

April 17, 2010

First of all, what do you mean by the xti was "sharper?" The XTi is a 10MP sensor and the 7D is an 18MP sensor. The 7D's much higher resolution density will probably surpass all but the greatest lenses, whereas the XTi *might* not even be showing the max resolution of the 24-105 f/4L. So at 100%, the XTi image will look "sharper" than the 7D, but the 7D will have much more actual detail to it. If you shrink the 7D image to the size of the XTi image, it should be notably sharper. Or looking at it another way, if you increase the size of the XTi image to that of the 7D, it should look far worse.

Also, the 24-105 is pretty sharp, especially in the center at f/5.6, but it's not the sharpest zoom and it's certainly not as sharp as the best primes (very few zooms are).

April 17, 2010

EDIT: I meant to say effective focal length INCREASES at 1:1. For instance, 12.2° (at 1:1) vs 15.4° (normal) in the 60mm macro represents a narrowing of angle.

You can see this effect on a macro lens by turning your focus ring to infinity and then to 1:1—the view will "zoom in" even though you're only changing focus.

If anything, this fact confirms my math. Since I was originally misremembering which direction the effective focal length changes, and then discovered my math told me it should go the opposite direction, I went and tested it with my macro lens. Sure enough, my math was right, not my memory. Math and direct experiment wins every time.

April 17, 2010

One last argument. The 60mm macro lens has a minimum focus distance of 90mm. The 100mm macro has an MFD of 146mm. That means the 100mm 1:1 focus dist. is 146/90 = 1.62 times longer.

The angular view of the 60mm macro at normal distances on APS-C is 25.4°. The angular view of the 100mm macro at normal focusing distances on APS-C is 15.4°. That's a difference of 25.4/15.4 = 1.65 times—assuming rounding or accuracy errors, pretty much identical to the difference in MFD.

Now, let's say (for the sake of your argument) we assume the angle of view DOES change at 1:1 focus. Basic trig will give us the angle of view difference between the two lenses. At 1:1, the diagonal of the sensor equals the diagonal of the subject = 31.1mm on APS-C. We know the MFDs are 90mm and 146mm respectively for the 60mm macro and 100mm macro. So the angle of view is equal to:

2 × arctan ( 0.5 × sensor diagonal / MFD ). [Note: you have to break the angle of view in half to get a right triangle, find the arctan of that triangle, and then multiply back by two to get the original angle of view.]

This gives us 12.2° for the 100mm macro, and 19.6° for the 60mm macro. NOTE that as I said, the effective focal length does end up shortening a bit due to macro optics. But 19.6/12.2 = 1.61 times as much angle of view, VIRTUALLY THE EXACT SAME AS BEFORE.

The above is absolutely impossible to get around. As long as Canon's listed MFDs are accurate, and you assume the macros are focusing at 1:1 so a subject that fills the frame has a diagonal of 31.1mm, the angle of view of the 100mm macro is ALWAYS ~1.62 times the angle of view of the 60mm macro. This is true at 1:1 or at infinity focus, even though effective focal length shortens somewhat at macro distances.

Pure math; I rest my case. If you want to prove me wrong, do a comparison shoot at 1:1 with identical subject framing and a background that is far enough away to see the difference from lens to lens.

April 17, 2010

Hold the phone. I think the problem *might* be the term "field of view" vs "angle of view." I was using the two interchangeably, which is technically wrong. "Angle of view"—which is what I should have been writing—is the diagonal angle of the whole scene. APPARENTLY, "field of view" is the linear diagonal of the SUBJECT. In that case, FOV is identical for a given magnification, by definition.

Is this the cause of our impasse? Or do you maintain that the angle of view is not significantly different for different focal lengbth macro lenses at 1:1? Because I maintain that that makes no sense... :-P

April 17, 2010

Hi Scott,

I'm not sure where the idea of "workable" and "of benefit" came into play. I never claimed that the background was ever particularly useful in the great majority of true 1:1 macro photos. It doesn't change the fact that the angle of view at 1:1 is still significantly different from macro lens to macro lens depending on focal length.

I think it odd that we seem to see the flower photos so differently. To me the difference in the amount of background included is very obvious. I've attached the flower pic with the change illustrated (the same color box means the same amount of background is included).

I seriously wish I still had the 100mm macro. I'd just do a quick setup shot against my 60mm macro, both at 1:1 with an identical subject, and a more obvious background. That would settle things pretty decisively. Unfortunately, even if you own multiple macro lenses I somehow doubt you're particularly motivated to do this setup shot and post it yourself—not something I will ask of you. But are you subscribed to this thread? If so, I'll try to eventually borrow a friend's long macro and do the shot myself, and post it—regardless of what it shows. If you're right, and the FOV doesn't really change, I will gladly eat my foot for the opportunity to have learned something about macro photography. :-)

Cheers,

—GL<div></div>

April 16, 2010

Scott,

<a rel="nofollow" href="http://www.the-digital-picture.com/Reviews/Canon-EF-100mm-f-2.8-L-IS-USM-Macro-Lens-Review.aspx" target="_blank">Look here</a>, two thirds of the way down the page for an example called background blur comparison, these examples are not even in the true macro range. I would hardly say that the two examples on the right demonstrate this statement of yours

</blockquote>

That link actually EXACTLY confirms my statement. The grass in the background is NOT just more or less blurred yet still the same view; in fact what is happening is that as you go from left (180mm) to right (60mm), MORE grass is being included—the background "shrinks." It appears less blurry because the depth of field does not change—each grass blade is blurred the same amount relative to its physical size, but the circles of confusion are smaller because of the different focal length.

For example, look in the upper-right quadrant of each flower pic. You see a light flattened horseshoe shape with a dark center? With the horseshoe "opening" to the left? Watch from pic to pic, and you can see how it effectively shrinks as you go to 60mm. That's because more of the background is being included from shot to shot, so each background detail shrinks accordingly.

In fact, Bryan says this himself in the description!

Background subjects in the 60mm picture appear to be more in focus. They are not - they are just about as blurred, but they appear much smaller in the picture - and there are more of them because of the 60mm's angle of view.

</blockquote>

April 16, 2010

PS—I wish photo.net let you edit longer. "Patently absurd" was a stronger phrase than I should have written; I was not trying to be ad hominem but rather point out the basic facts. No offense intended.

April 16, 2010

I personally would be tempted to return it on principle, due to misrepresentation. Even if it apparently works perfectly, I wouldn't want to support such a seller.

But it's up to you. If you like the camera and think it's a good deal, then as far as YOU are concerned there doesn't seem to be any good reason to return it, right?

April 16, 2010

Scott,

I'm surprised that you seem to think focal length in macro lenses does not affect field of view. This is patently absurd. It is true that due to the complexities of macro optical design, at macro focusing distances the effective field of view in most lenses does in fact shorten significantly from the official designation—i.e., a 100mm macro at 1:1 might actually end up being more like an 85mm. However, there is still a significant FOV difference between a 60mm macro and 100mm macro, for instance, with the 60 including a much greater angular coverage of a scene.

I think you're confusing focal length with how much of the subject is displayed in the viewfinder. At 1:1, a 2D planar subject perpendicular to the lens axis should be projected equally onto the sensor by any lens regardless of focal length. This is by definition of magnification. Of course this is due to a combination of both focal length AND subject distance.

HOWEVER, look at the background: on the 60mm macro, much more of the background is included, because of course the field of view is much wider than that of a 100mm macro.

Field of view is specified by the angle of coverage of the entire scene, NOT by any measurement of the subject the lens happens to be photographing.

April 15, 2010

Hi Theresa,

Sorry, I'm not sure I quite understand. First of all, what do you mean by "how close you can get to an image?" If you're talking about physical focus distance, well, that doesn't have any direct relation to the image formed; for that you also need to take into account the focal length of your lens.

Second, what do you mean by "capture very close but with more width?" If you get close to an object but use a wide angle lens, the object will still not take up a lot of the image, but more of the background will be included. Alternatively, if you mean the object will fill a large percentage of the view, then by that very assumption you cannot show more of the object! It's a contradiction in terms.

A macro lens is defined by its ability to project an object at its actual size onto the sensor, a ratio referred to as lens magnification. So regardless of macro lens focal length and minimum focus distance, all true 1:1 macro lenses will reveal exactly the same amount of an object in the frame at their maximum magnification. This is a simplification based on the assumption that the object is more or less planar and perpendicular to the lens axis, because foreground and background elements of a 3D object will be rendered differently depending on perspective.

I think you should do some reading on the photographic principles of perspective vs focal length, as well as distinguish physical distance to an object versus the size of the object's image on the sensor (and therefore in the viewfinder) as rendered by the combination of lens focal length and the focus distance to subject.

Sorry if this isn't very helpful, but I just can't figure out an interpretation of your question that doesn't result in a contradiction in terms (e.g., showing more of the subject in the frame yet still having the subject rendered just as big in the frame as before? That doesn't make sense, period).

April 14, 2010

I'm confused. You're returning a kit lens because it makes noise while <del>focusing</del> rotating the focus ring? This is perfectly ordinary, you're just hearing whatever cheap sealing internal filter material Canon used between the inner and outer barrels.

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Posts posted by gabriel_l1