Renting a Canon "L" Lens

[roadtripper]

So I just submitted an order to rent the Canon 17-40mm f/4L lens for the month of July from lensrental.com. If all goes well, I'll be using this rental lens a great deal more than the standard lens that came with my Canon Rebel Xsi.

Anybody have any thoughts on how much of an improvement I should be able to see with this L lens over the standard package lens?

The lens will be primarily used to photograph waterfalls. I typically shoot in the F/14-F/20 range at 25-40mm @ ISO 100. I always use manual focus, and I always use a tripod with a 2-second delay as well to improve sharpness. I also use a circular polarizer most of the time as well.

Here's a recent picture of Gunn Brook Falls in MA using the standard lens from the Rebel Xsi:

Other Questions I have:
~ Does an "L" lens go a heck of a lot further with a more powerful camera than it can with the 12MP Rebel Xsi? (i.e. 5D MII)
~ Where will an "L" lens make the biggest improvements? Details in the corners of photographs, shadows, etc.?

 

[DougPaul]

So I just submitted an order to rent the Canon 17-40mm f/4L lens for the month of July from lensrental.com. If all goes well, I'll be using this rental lens a great deal more than the standard lens that came with my Canon Rebel Xsi.

Anybody have any thoughts on how much of an improvement I should be able to see with this L lens over the standard package lens?

The lens will be primarily used to photograph waterfalls. I typically shoot in the F/14-F/20 range at 25-40mm @ ISO 100. I always use manual focus, and I always use a tripod with a 2-second delay as well to improve sharpness. I also use a circular polarizer most of the time as well.

Most lenses will be diffraction limited at F/14-F/20--if you shoot at those settings you are throwing away some of the sharpness. F/8 is the sharpest for most lenses. See, for instance,
http://www.kenrockwell.com/tech/focus.htm
http://www.kenrockwell.com/tech/diffraction.htm
http://www.kenrockwell.com/nikon/50-comparison/f-stops.htm
http://www.kenrockwell.com/nikon/50-comparison/sharpness.htm

Other Questions I have:
~ Does an "L" lens go a heck of a lot further with a more powerful camera than it can with the 12MP Rebel Xsi? (i.e. 5D MII)

The sensor size is more important than the number of MP. (Resolution only increases as the square-root of the number of pixels.) The 5DMkII is significantly better than the XSi largely because it has a full-frame sensor. See http://www.kenrockwell.com/tech/full-frame-advantage.htm for a sample comparison.

~ Where will an "L" lens make the biggest improvements? Details in the corners of photographs, shadows, etc.?

Depends on the lens and what you are comparing it to. Modern lenses are complex devices involving many trade-offs.

Prime lenses tend to have higher optical quality than zooms.

In any particular image, the resolution can be limited by any of several factors--focus, movement, lens quality, lens aperture, sensor pixel size, number of pixels, anti-aliasing filter (in the camera), smoothing and noise reduction in the processing, etc...


Sure, the L lens won't hurt but a full-frame sensor might gain you more. And if you are really serious, consider a larger format camera.

Doug

 

[Tim Seaver]

"L" Yeah

~ Where will an "L" lens make the biggest improvements? Details in the corners of photographs, shadows, etc.?

It's a great lens and will give you excellent results with the Xsi, but much of the fine "L" glass won't be used by a sub-frame camera.

After giving the 17-40 a spin, I would recommend trying out the 10-22mm EF-S if you really want to go wide ( equiv. of 16-35mm). It's very light and fast and WIDE, which is something you will forfeit with the full frame 17-40 (which will be like having a 27 to 64mm lens). Image quality is also excellent, plenty good enough for a full magazine page or prints up to the 16x20 range. The lens gets pretty good reviews - here's a somewhat dated one at LL. Like may lenses, the optimum sharpness is obtained at f5.6 to f8, so you may get better results using stacked ND filters vs. very small apertures if long exposures for blurring the motion of the water is what you are after.

 

[roadtripper]

Thanks for those tips!

It seems like I really need to move my range of aperture down to the f/8-f/11 range whenever possible. The circular polarizer should help me accomplish that.

I don't know much about stacking filters, but from what I've read, this can be problematic (i.e. vignetting/flaring/etc.). Does anyone have experience with this? Are there any specific implications of stacking a ND filter on top of a polarizer?

 

[Tim Seaver]

Vignetting is definitely an issue, especially the wider you go. Using a thin polarizer and the large square Cokin "P" (or larger) ND filters can help minimize those problems. Sometimes simply hand-holding an ND filter square in front of the lens can give you less vignetting than the plastic filter holders. Also, you would be best served by using single ND filters of different strengths rather than stacking them, to keep the thickness at a minimum. A hood or shielding the lens/filter surface with a handheld hat helps cut the glare from the multiple glass surfaces.

The best solution is to shoot at times and weather conditions that allow long shutter speeds without messing around with ND filters, but of course that isn't always possible.

 

[Woody]

Roadtripper, I like that picture of the falls.

I also use an XSi camera. I have a EF 24-70 L lens that I recently purchased but I have not yet used it on a hike because it is heavy. I have only used it for a wedding and for ice hockey. I've been thrilled with the images I get from it.

I was planning to use it to shoot some waterfalls on my hike on Monday. In shooting waterfalls previously I sometimes don't get a slow enough exposure to suit my tastes even using ISO 100. Today I went out and bought a 2 step neutral density filter for the 24-70 lens. I think that slowing down my exposure by two steps should give me the effect I am looking for.

I think that Tim's advice about getting a 10-22 lens is good as well. I haven't used this lens but it is next on my list to buy so I can get the really wide shots.

 

[DougPaul]

I think that Tim's advice about getting a 10-22 lens is good as well. I haven't used this lens but it is next on my list to buy so I can get the really wide shots.

I have one--a nice lens. The reviewers generally liked it.
http://www.kenrockwell.com/canon/1022.htm
http://bobatkins.com/photography/reviews/ef-s_10-22_review.html

Not too heavy: 13.6 oz.

Doug

 

[MichaelJ]

Whatever you do, don't stack a polarizer on top of a skylight. The result is less than desirable. That shot should have had vivid blues contrasted with puffy whites and a colorful ground surface.

 

[Brambor]

L or what.

Don't use a filter. There is no need to throw another piece of glass in frong of that L lens. Especially when you are shooting in such controlled conditions, on the tripod, safe from danger. Take the filters off and shoot under great light, right before sunset etc...L lenses are usually specialized to give you results wide open and to give you larger aperture. When you go beyond F8 the results are identical between L lens and regular lens. Some will claim you get a better color rendition when using an L lens but at small aperture F8 and smaller I don't think it makes a difference.

Maybe a graduated Neutral density in some cases...

 

[darren]

On my 20D I can clearly see the difference between my Canon consumer lenses (28-80, 75-300) and my Canon primes and L lenses. The primes and L lenses are sharper and do have better color rendition right out of the camera. The colors really pop much better than with the cheaper lenses. Even at f16. I have the 10-22 and it is a great lens. The sharpness / color rendition does approach prime / L quality. You do get some minor distortion at 10mm, but what do you want for 10mm?

Yes, you still need to put filters on L lenses - when they are needed. I never use the "skylight" or "uv" filters on my lenses. I only use a cir. pol. or graduated neutral density filters when they are needed.

For the waterfalls, if ISO 100 is too fast (desired shutter speed forces an f stop higher than 18 or so) then you will need to use a neutral density (not graduated) to slow down the shutter speed (I covered this in a different thread about velvia).

Tim makes good points on time and weather too - shoot early / late in the day and on cloudy days to get longer shutter speeds and more even light on the scene. Shooting waterfalls on sunny days can be an effort in futility.

 

[roadtripper]

Thanks for all the excellent advice!

I shot some waterfalls in Connecticut last weekend and I used an f stop range of 8-14 instead of my typical 14-20. The shots were generally a tad bit sharper this time around. I had no idea that f/8 was generally considered to be just about the sharpest of the apertures for most DSLRs.

I might have to pick up a new 77mm circular polarizer to use with this rental (mine is 58mm). The Hoya HD model looks great, but the price tag is a bit crazy ($225), so I'm going to have to think about that for a while. The benefit is that it offers one more f-stop than traditional circular polarizers, which I'd probably end up taking advantage of.

A new question.....anybody have any luck using warming filters in relation to waterfall photography?? If so, in which situations? From what I've read, you can almost do everything a warming filter could do using post-processing w/photoshop.

And Darren, you are totally correct about photographing waterfalls when the sun is out. It's just downright impossible to get a quality shot, even with using all the right tools and methods.

 

[Grumpy]

...I had no idea that f/8 was generally considered to be just about the sharpest of the apertures for most DSLRs. ...

Whoa, now! Don't get rigid about this one. The optimum aperture varies from lens to lens -- model or even individual lenses. And this is not something unique to the digital SLR world, either.

The old thumb rule is that lenses generally achieve their best performance about two stops down from maximum aperture. For a f/2.8 lens that would be f/5.6. Use the following to calculate where optimum aperture may fall on any given lens you are using. But remember, that is only the "thumb rule." Also remember that performance (sharpness) declines beyond the optimum aperture.

(The general sequence of stops, from largest to smallest is: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32 .... Each successive stop in that sequence lets in half as much light as its immediate predecessor.)

One thing that has happened with newer lens designs, in my experience, is that the premium quality optics manufactured today are likely to be much sharper at maximum aperture than they were years ago.

Bottom line: Only experience will show you where peak performance lies with any given lens you use. Try different things, and compare. And don't necessarily be afraid of using f/stops anywhere along the scale. You might find some pleasant surprises by being willing to give all options a whirl.

About Filters:

Most of my lenses are equipped with clear "filters" to protect the front element from fingerprints, scratches, etc.. I consider the filters to be cheap insurance. I do not stack (i.e., use multiple) filters. Lens shades also definitely are the lenses' friends.

I think Tim Seaver has it right about picking your light being preferable to using filters to achieve slower shutter speeds at optimum aperture. I do wish that camera manufacturers would give us digital image sensors rated down to ISO 50 or even 25, though.

G.

 

[DougPaul]

I do wish that camera manufacturers would give us digital image sensors rated down to ISO 50 or even 25, though.

That may not be possible without destroying the low light performance--once a pixel is full, it is full (saturated).

Doug