Distance Vs Focus?

[russellsnr]

Hi, Having a little trouble with focusing at long distance with birds as the subject. I use a Canon 70D and a Canon 400mm F5.6 lens and wonder does the distance the subject is away from the lens cause focus issues? Close up birds within 15 to 100 feet shot hand held I get sharp images but when the bird/s are in the 3,4,500 feet or more away even when I use the centre focus option and rest the camera on the car side window with a bean bag seem to be OOF, not sharp around the eye area although focused on the head. Camera and lens have been calibrated with FOCAL. Any suggestions please? Thankyou, Russ.

[Manfred M]

Russel - as always, it would be useful to post a large image that you are having problems with as well as the shooting parameters; focal length (assume 400mm here), ISO and shutter speed.

It's very difficult to diagnose a shooting issue when you are describing the issue in words.

[DanK]

I agree with Manfred. I would add exif, in particular shutter speed, but also aperture. However, absent a photo, I strongly suspect camera motion. As distance increases, both DOF and the impact of motion increase, so focusing errors become less important while camera motion becomes more important. At 300 ft and f/8, DOF would be more than 52 feet, which means that only a really large focusing error would be apparent. If I am not mistaken, that lens has no image stabilization, and at 400mm, even slight motion is going to matter.

[russellsnr]

Far image at ISO 100, F11, shutter 1/100, 400mm lens.
Near image ISO 320, F8, 400mm lens.

[DanK]

Are these severe crops? The bottom one in particular certainly looks like it. Were the halos in the image before processing?

[Manfred M]

Neither image looks particularly sharp. Lack of sharpness will be more noticeable in the closeup. My suspicion is the shutter speed, even with resting the camera on a window or bean bag, may be far too low. Try pushing up your ISO and shooting at 1/500th or faster to see what difference that makes, not 1/100th sec.

With your Canon crop, you are looking at a full-frame equivalent of a 640mm lens. If you are cropping, as per Dan's comments, that will accentuate any camera movement issues.

[russellsnr]

Hi, yes think it is the shutter speed, I realised that after posting the data, even on the bag probably to slow. Thankyou, Russ.

[DanK]

you could also use a remote shutter release to lessen camera movement. Wired ones are very cheap.

[pschlute]

When I started in photography the rule was always 1/FL would give the minimum acceptable shutter speed for telephoto shots. Even with the advances of in camera or in lens stabilisation you will do better to aim for something close to this.

With apsc you should use the crop factor to increase the margin even more.

[DanK]

Also, keep in mind that even a sharp image won't appear sharp if it is sufficiently severely cropped and blown up.

[xpatUSA]

As an old geezer with hand tremors occurring too often these days, I favor:

Image stabilization ON.

Mirror-Up mode ON.

Time-delayed shutter, 2 or 10 sec.

... or, of course, a tripod but which is probably not convenient for birds shots.

[MrB]

The EXIF for the second image shows a shutter speed of 1/2000 sec which should be plenty fast enough for a camera resting on a firm base. It seems that you are expecting too much by taking small crops of the images and magnifying in PP. Just get closer!

Philip

[george013]

The EXIF for the second image shows a shutter speed of 1/2000 sec which should be plenty fast enough for a camera resting on a firm base. It seems that you are expecting too much by taking small crops of the images and magnifying in PP. Just get closer!

Philip

One can even count the pixels in it

George

[Manfred M]

Just get closer!

+1 to that Philip!

If you are not filling most of your frame, then consider not taking the shot and moving in closer. With a FF equivalent focal length of 640mm you are not going to scare away too many birds by trying to get closer.

[Geoff F]

Don't forget weather conditions which can cause distortion. Misty damp air or a hot haze from evaporating moisture can give problems and the greater the distance the greater the distortion. Sometimes I have considerable softness issues when facing towards the light but get perfectly clear results when I turn around to place the light behind me.

Shutter speed has already been mentioned and the old hand held 'rule' of having your minimum shutter the same as the lens size. For example 1/400 with a 400 mm lens.

False auto focus can occur if the lens is focusing on the 'wrong area' which is ahead of the intended subject and AF often prefers to focus on a hard edged object such as a bit of rock instead of a soft edged bird. Big lenses tend to have a rather shallow area of sharp focus depth.

I would suggest some controlled experiments using a tripod to see if you can achieve better results under perfect conditions.

But unfortunately, real life photography often means imperfect compromise. For example, today I was photographing birds with my Sigma 150-600 lens on a tripod and attempting to get a small fast moving duck which was too far away and against some water ripples which tended to produce false focus. I had to push the Iso to 800 in order to get a shutter of 1/640. After considerable cropping, I was able to confirm identification of the duck, but even the best of my images were useless for anything except basic identification.

Getting closer would have meant getting rather wet and although I asked this duck to come a little closer it just ignored my requests. I was in a bird hide and just popping my head above the hedge line would have scarred off all birds within a few hundred yards.

[William W]

Far image at ISO 100, F11, shutter 1/100, 400mm lens.

Shutter speed is way too slow. There may be other issues.

My advice is that you need to address your Shutter Speed first then you can better analyze other factors


The EF 400/5.6 does not have IS, therefore you are unsafe regarding Camera Movement Blur

The birds are living, therefore you are unsafe regarding Subject Motion Blur

IMO 1/500sec would be the SLOWEST shutter speed to consider, 1/1250s ~ 1/2000s, would be better.

WW

[rpcrowe]

The 400mm f/5.6L is an exceptionally sharp lens with fast and accurate focus. I shot with it for several years and replaced it with the 100-400mm f/4.5-5.6L IS II.

But the 400mm f/5.6L lens doesn't have IS - so I needed to either keep my shutter speed fairly high and I needed faster than the 1/focal length speed to ensure sharp images. This was especially true when shooting with a crop format camera. The 1/F.L. x 1.6 was the absolute minimum when shooting hand held. However, I often used a tripod or monopod without locking the head tightly. Thus I was able to follow a moving subject.

I normally used at least ISO 400 which most often gave me a shutter speed of somewhere between 1/2,000 and 1/3,000 second using an aperture of f/8 in bright sun lit conditions (depending on my subject area). This produced very sharp images - even of fast moving subjects. These boats were traveling upwards of 90 miles per hour and I shot them tripod mounted with loose ball head using 1/3,000 at f/8 using ISO 400.





If there was not enough light to give me at least 1/2,000 second, I would have no hesitation of opening the lens to its maximum aperture. I found the 400mm f/5.6L lens to be quite sharp wide open at f/5.6. If I still did not have enough light, I would increase my ISO. Even with my old Canon 30D, I found ISO 800 to be perfectly usable.

The second problematic area is focus point. It is very easy for the lens to choose other than the focus point I desired and in the heat of fast shooting, I could easily miss the correct focus point. In order to minimize this problem I most often would use single point center focus. That way, the lens did not have a choice but to focus on where I was pointing.

Shooting in burst mode would often give me sharper imagery from the second shot on - because the camera movement effect of pressing the shutter button was minimized.