Problem with 400mm L 5.6 clarity

[pahranagatman]

On image tests my 400mm L 5.6 is performing significantly less sharp than my new 100-400mm lense. The only think I can think of that would have damaged the 400 was condensaton in the body from temperature changes. Shots are all tribod and cable triggered. No filters on either lens. This is of course cropped way in. Any ideas? The 400 is about 9 months old. Can it be cleaned internally?

[ebiggs1 · Accepted solution]

The top photo looks OOF so if it is there is no way to tell if the lens is "sharp" or not. Maybe you were too close?

[ebiggs1 · Accepted solution]

The top photo looks OOF so if it is there is no way to tell if the lens is "sharp" or not. Maybe you were too close?

[amfoto1 · Accepted solution]

It is possible the lens' focus is out of calibration. Focus mechanisms can wear with use or just get out of adjustment with a bump or even be mis-adjusted from new. This can be adjusted and corrected, worn or faulty parts can be replaced if needed.

IMO it's unlikely that the lens needs cleaning inside. Usually stuff inside a lens - even a lot - doesn't effect focus and sharpness very much... It causes flare, veiling, loss of contrast and reduced color saturation.  If images showed uneven sharpness, that might indicate a decentered lens element or group, another problem that often can be corrected. But just judging from your sample images, there don't appear to be problems of those types. I doubt you'll find anything of significance, but you can inspect the inside of a lens with a flashlight. Just don't panic if you see some specks of dust here and there. Those are common and not a problem unless there's a lot... a whole lot!

You probably should just send the lens in and have it checked and calibrated.  

However, there are other things you can look for first, to rule out as possibilites...

1. As already suggested, that lens' closest focusing distance is about 3.5 meters (11.5 feet). If closer than that, you won't be able to focus So, yes, be sure you simply aren't trying to focus too close.  (Notes: For comparison, your 100-400mm's closest focusing distance is 1.8 meters/5.9 feet. Also, adding a macro extension tube will allow the lens to focus closer).

2. Do you have a filter on the lens? If so, try without it. Quality filters can be helpful in some situations, but cheaper ones can make a mess of images and some lenses simply don't work well with the filters (actually your 100-400mm is one that is pretty widely known to not work well with filters... even good ones).

3. You mention using a tripod and remote release, and those are good for tests like these. Are you also locking up the mirror? At certain longer shutter speeds (usually between roughly 1/30 and 1 second) mirror slap can sometimes cause enough vibration to give some camera shake blur in images. The 100-400's Image Stabilization should be able to correct for that. But the 400/5.6L doesn't have IS, so would be more prone to show any vibration effects. When using really long telephotos without IS, at times I've put a beanbag on top of the camera and lens to help prevent vibrations, too.

You didn't mention what camera you are using, but an APS-C 1.6X crop model is more susceptible to camera shake, than a full frame model would be. On the other hand, the larger mirrors in full frame models are more likely to give mirror slap effects (all have some dampening, I'm sure.... but it likely varies with different models) .  

Also, Canon has published a white paper about the 18MP APS-C cameras being particularly susceptible to any form of vibration... They recommend using slightly higher shutter speeds to offset this, especially with the crop cameras with very dense sensors.

4.  Hopefully you are using One Shot focus for those test shots. Be sure to restrict to only the center AF point. And  If your camera has it, try using Live View. That employs a completely different method of focusing and is a good way to test the camera and lens.

5. Use a clean rag lightly dampened with a few drops of isopropyl (rubbing) alcohol to clean the electronic contacts on the back of the lens. Perhaps some oils or dirt on the contacts are interrupting communication between the camera and lens, effecting focus.

Those are things you can try yourself at no cost. Since the lens is less than a year old, it should still be under warranty, so I wouldn't hesitate to send it in to Canon for calibration, if none of the above helps.

***********
Alan Myers

San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & PRINTROOM 

[TCampbell]

If it had anything on the lens elements you would notice by removing the lens and looking through it.  

The lens may be missing focus ... front focusing or back-focusing.  The EXIF data says you took that shot with a 7D... which will allow you to adjust the focus if it's consistent.  You'd need to use a focus test target.

You can buy them commercially or make your own... imagine a flat target with a nice high-contrast pattern on it, but then also imagine resting a ruler on a 45 degree angle along the side of that target.   When you focus on the target, the ruler should be most in-focus at the target distance.  If farther or nearer points on the rule are in focus, then it means your lens & camera missed focus.    That's the general idea. 

There are some guidelines for doing this because you really do want to isolate any issues to a lens or camera and make sure it's not you.

[pahranagatman]

Yup, just too close! Good call to those who thought so. I had the 400 set at 8.5m and I was just under that by half a meter. Hence the full sized picture looked focused to me before cropping the picture. Switched to 3.5m and it performed as good as I've come to expect from this lens. 

The results are not too surprising, the 400 is sharper and brighter. Now a bit disapointed with the loss of quality in the 100-400. It seems to be about a stop darker and even with mirror lockup it's no match for the sharp prime. I needed the zoom and IS for nature shots while walking around. Was missing lots of pictures with the limits of the 400, but seeing the difference in quality it's going to be hard to let the 400 go like I was planning to.

I did a test with filters too, and OMG......... If I can get away with it on a windless day in the photo blind, yeah, I'll take them off! Here's the comparison of the 400 and 100-400.

1.100-400 with lockup

2. 100-400 no lockup

3. 400 with lockup

4. 400 no lockup

P.S. yes the camera is a 7D and how did you get that info? Do you work for the NSA?

[TCampbell]

"P.S. yes the camera is a 7D and how did you get that info? Do you work for the NSA?"

I am not authorized to discuss how I knew that. 😉

Just kidding... You can get a plug-in for your web browser that let's you view EXIF data. It shows the basic exposure data and other misc. info such as the camera info, lens info, etc. You can strip that info out of an image if you don't want other people to see it, but it's very handy to leave it in if you ever need help on an issue -- others can frequently offer insight as to what may have happened when they can see that info.

[amfoto1]

"I did a test with filters too, and OMG......... If I can get away with it on a windless day in the photo blind, yeah, I'll take them off!"

I do just the opposite. Normally my lenses go filterless. For the lenses where I can fit them I do have "protection" filters... stored in my camera bag until they are actually needed, such as out shooting in a sandstorm, rainstorm or photographing paintball or other risky situations. I also use them at the seashore, since salt spray is hard to clean off lenses (hard to clean off filters, too... but I'd rather do that).

Realistically how much physical "protection" can a thin piece of glass be expected to provide? In fact I've seen lenses damaged by broken filters... They might have fared better without any filter. There is no truly accurate, scientific way to test whether filters actually protect or do harm (we'd have to buy 1000 lenses and 1000 filters and do hundreds of "drop tests"... and who is going to do that?) All I can say is that some of my lenses have been going around without protection for decades and are still fine. 30+ years shooting. I've yet to see one of my lenses damaged for lack of a filter, or actually saved thanks to one. I have seen plenty of images... my own and other peoples'... that were less than ideal due to a filter.

On the other hand, the lens hood... especially the nice deep ones on telephotos... give great "protection". I've definitely had lenses survive a bump thanks to a hood. Plus a properly fitted hood can only help image quality, cannot possibly do any harm to my images. I rarely shoot without a lens hood.

I used to use UV filters quite a bit... back when I shot film. Many films were (are?) overly sensitive to UV light. So a filter was frequently needed when shooting outdoors... Especially at higher altitudes where UV is stronger (I lived in Colorado for quite a few years). But today's DSLRs don't need UV filtration... it's built in.

It amazes me that people closely scrutinize at their images at huge magnifications (100% viewing on many modern computer monitors is the equivalent making a 5 ft. wide print from an 18MP camera image... and then viewing it from about 18 inches away)... Yet  they eagerly slap an extra piece of glass between the lens and the subject with very little concern.

Regarding using Focus Micro Adjust... That can surprise you sometimes, just how good a lens can be when fine-tuned. However it's more difficult to use with a zoom. And a very common mistake is using too close a target, too near the lens' minimum focus distance.

Canon recommends using a flat target with good detail set parallel to the film/sensor plane, set at a distance about 50X the focal length of the lens (i.e., with a 50mm lens the target should be 2.5 meters or about 8 feet away). A brick wall or a fence works well. Reiken FoCal recommends the same distance. With longer focal lengths such as 400mm, this might be impractical and FoCal suggests as close as 25X can be used.

The Canon method only works with lenses that have a focus distance scale, but doesn't require you to take any images at all. Instead, it compares the standard Phase Detection focus method with the Contrast Detection used by Live View. Simply set up with tripod and target, focus on the target with One Shot and the center AF point only, then switch to Live View, and... while watching the focus distance.. refocus the lens. If the focus distance scale moves, some MA is needed. The method of focus in Live View, which uses the imaging sensor itself, is inherently accurate. MA only effects focusing with the standard array of AF sensors. You can adjust up to 20 lenses on 7D (some newer cameras allow up to 40 lenses).

The Reiken FoCal software method of calculating MA uses a special target (provided) and does take and evaluate a series of images to arrive at a setting. It only uses the standard, AF sensor array/Phase Detection-based method of One Shot focus, but can optionally be double-checked using Live View/Contrast Detection focus.

Now, with 7D and a zoom such as the 100-400mm you may find you need to compromise with MA.  If you test the lens at different focal lengths, and you should, you might find slightly different amounts of MA are called for at each FL. But the version of MA in 7D (also 5DII, 50D) only allows for a single adjustment per lens. So with a zoom you may need to calculate and set an average of different amounts of adjustment called for by different FL of the zoom. Alternatively you could choose to make the amount of adjustment called for by a focal length you most commonly find yourself using. Note: The more recent version of Live View, such as is on 70D, 5DIII, etc., allows up to two adjustments with zoom lenses. It also allows up to 40 lenses to be fine tuned. The 20-lens version of MA also is lens-model-specific (adjustments made to, say, any EF 50/1.4 lens will be equally applied to all EF 50/1.4 lenses used on that particular camera). The 40-lens version of MA is lens-serial-number-specific (allowing for different adjustments to, say, different copies of EF 50/1.4 lenses used on that particular camera).

***********
Alan Myers

San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & PRINTROOM 

[pahranagatman]

Awesome stuff write up on the lens adjustments. I'll start messing with that over my holiday break. I live in the Mojave so our daily weather is sand with 30mph wind. So most of the time I actually might be the person who needs a filter. But when sitting in a blind with the wind at my back, yeah, that filter is staying OFF. 

With the images from the 400mm being so much better I'm going to keep it and use it for the times in the blind. Use the 100-400 as my walking around lens. Maybe the 70-300 would have been better for this, but I've got a small scratch on the bottom of the lens ri

I'm reading up on using the 1.4x with the 400mm. I would love to get a used 500, but even that is a bit too much right now. Anyone have experience with the 1.4x and 400mm? It seems that its a no go on the 100-400, but some are having good results on the 400mm.

[ebiggs1]

Almost everything you read on the web is malarkey. You really need to go out and use your equipment and see what it can actually do in the real world.

Is the prime sharper than a zoom, probably. Is there a slight difference with and without a UV filter, probably.

Is this a deal breaker in real world photography? Absolutely not, it hovers near the scale of ridiculous.

I own and shoot both and have for years.

One of my goto lens for weddings is the 100-400mm and not one client has complained why did I not use the prime!

I suppose if your gig is to shoot test charts and subjects, you better go with the prime and trash the 100-400mm.

But if you use it in the fantastic realm of real world photography,...well, the difference is mute.

So you need to decide, what are you a pixel peeper or a photographer? The choice is yours.

[pahranagatman]

Yeah, I'm a pixel peeper. Part of my job is photography for a wildlife refuge. Often I have to crop 3/4 of a picture or more to get a zoom close enough to use. Just can't get any closer. Usually it's the sharpness rather that the pixels showing up that is the deciding factor for keeping a photo or not.

What got me to do the initial text was my first impression of the lens after 2 days of shooting. Just didn't feel like the shots were as colorful or sharp. But I think a lot of that was just me still being new to the lens and being a newby to photography in general. With some time with the lens and maybe some help from the micro adjustment everything is just fine.