cold weather shooting with a canon 600 f/4.0L IS

[Rob Stratton]

Hello all
Looking for a little advice here. I am the proud owner (finally) of a brand spanking new canon 600 f/4.0 L IS. I have had some amazing shots prior to the weather turning cold but am having some issues now. Shooting in cold weather, the only way I can get a tack-sharp shot is to keep the camera and lens stored outside at ambient temperature. when shooting out of my truck, I drive to and from with the heat off and windows down to keep the lens acclimated. I can't blame the camera-1DmkIII-as I have used it extensively while skiing, snowmobiling and any number of cold weather sports with no regard for "cold-sinking" and had amazing results. I have shot from my truck with any of my 3 bodies and lens combinations(up to 500mm) and never encountered this problem(My 12 year old sigma 500/f4.5 gave me better results than the 600).
Is it just the size of the canon 600 that makes it that much more susceptible to temperature change? Just to be clear, this is not a condensation issue-on the rare occasion that I bring the gear inside, it is via a plastic bag, filled with (outside)ambient air, etc, etc. I thought maybe heat shimmer radiating from the warm vehicle, but in the wimberley head, away from the vehicle yields the same results-soft focus.
If this is a common problem, then I can adapt to that. However, it seems strange that I can carry an ancient sigma 500 on the heated seat beside me and throw it out the window at will, while still achieving acceptable results, yet my new "pride and joy" 600 is so finicky that I have to banish it outside at temperatures of only around zero in able to get a decent picture.
Any and all comments would be greatly appreciated.
Thanks
Rob

[adrian dancy]

I think Roger Clark may have elluded to this problem. A camera may need micofocus adjustments for extreme weather. I might be inclined to agree with him. Temperature change in the lens is dealt with by the camera but temperature change in the camera will render results that only be changed by the operator. A 600 lens will reveal minor focusing issues far more than a much shorter lens, I suppose.

[arash_hazeghi]

Not normal, something is wrong with your gear or with the way you are using it.

I have no solid data with respect to thermal drift but Doug and I shot in 28-33F in ocean shores two days in a row, I was shooting with 500 f/4 with TC and Doug with 600. We got very sharp files. I have shot many times in sub 30F and never had a problem.
Canon officially rates their pro gear for a temperature range of 32F-113F so the circuit in various modules should compensate for thermal drift in this range at least (very easy BTW).

If you don't have absolute perfect eyesight condensation is sometimes subtle and hard to see through the finder but at pixel level images will not be sharp. My guess is condensation is developing on the interior elements and you just don't see it. A test is to use Live View when this happens and see if you can get the image pin sharp on the LCD at maximum zoom with manual focus, if you can then focus is off, if not, it is condensation.

[Doug Brown]

Can't say that I've ever noticed a problem with my 600mm. And I've shot extensively in cold weather; at Bosque del Apache the sunrise temperatures are frequently in the single digits. I keep my gear with me in the hotel room at night too.

[Rob Stratton]

Thanks everyone. Doug, how much time do you allow for your gear to cool or acclimate before you start shooting? I don't think I explained myself very well initially. I am getting good results once everything is cool, but during the transition it's horrible. With all of my other lenses, I have been able to shoot from inside the cab of a truck in -30c, or hop out and get great results with the gear still being warm in a cold environment. Is it unrealistic to expect to be able to cruise in the winter with the gear in a warm vehicle, stop, get out and shoot, without waiting an hour or two for everything to "cool"? I hope I don't sound like I'm complaining, I just want to have realistic expectations. Unfortunately, I have no one around locally who has experience in these areas.
I will post some pictures this afternoon that may help with my poor explanation.

[Roger Clark]

Hi Rob,

A couple of things. First, it can't be condensation, as your are taking a warm lens in cold. Condensation happens when bringing a cold lens into a warm location, What camera bodies do you have? Do you have one with live view? If so, take the warm lens out in the cold from while the lens is warm and focus on a subject. Then turn on live view and zoom in as far as you can, and check focus. Then focus again (half press the shutter; best to use a cable release with he lens on a tripod). Does the focus get better? If so you need microadjustment.

Another possibility. When imaging from a warm car, when you stop and roll down the window there is a lot of atmospheric turbulence with the exchange of warm and cold air. Depending on wind direction, if that turbulent air was blown in the direction you are imaging, image quality would be reduced.

Third possibility is that the lenses in the 600 may be distorted due to differential thermal stresses as the lens cools. The lens barrel will cool first (shrinking) and the center of the largest lens elements will cool last, putting stress on the optical shapes, reducing image quality. This could be a problem on a single lens element, for example if a retaining ring were too tight.


Having said all of the above, I have imaged from my car with a canon 500 f/4 and various bodies in cold. I also photograph the Moon and planets with my 500 (as a challenge--I also have much larger telescopes), taking the lens and camera out from the house into sub-freezing cold and start imaging within a couple of minutes start imaging with no problems. I've also imaged at Bosque and other locations in single digit temperatures with no problems after getting out of the car with no problems.

I have also not seen any microadjustment problems with my 500, but I have found microadjustment issues with my 300 in various temperatures. Different temperatures require different micradjustment with my 300 (from say 20F to 85F).

Roger

[Rob Stratton]

Thanks Roger. With the info I have been able to find so far, I'm leaning towards your third possibility. I've attached a photo with some results that may explain what I'm encountering. Both shots were from the Wimberley head on a stout tripod away from the vehicle or any other possible heat source. Both shots are wide open and at ISO 200. The deer on the left is @ 1/1000 sec and the Waxwing is @ 1/800 sec. Both images are straight out of the camera (1d mkIII) and at an air temperature of approximately -15c. The deer shot is typical of what I get when trying to shoot with the gear warm-it was perhaps 2 minutes out of the warm vehicle. The waxwing was shot with the gear cold and I am quite pleased with the results. This is what I typically get when I've left everything outside at ambient temperatures. I am going to try a test today-as you suggested above with live view-but also to see how long it takes from room temperature warm until I get acceptable images again.

[Alan Stankevitz]

I am 99.99% sure it's heat refraction.

Heat refraction is caused by either the difference in air temperature between the lens and the surrounding air or the vehicle and surrounding air or heat refraction between the ground and air. Living in Minnesota, I see this all the time. (I also have a 600mm, but I have seen it even with a 70-200 lens. The greater the magnification, the greater this problem will rear its ugly head.)

The easiest way to verify this is to take a video of what you are shooting, then play it back on your computer. (Or in your case, use Live View on your Mark III) If you see the image moving with IS turned off and the camera steady, you are experiencing heat refraction. The kicker is that you cannot see it normally in the view finder. It's only when it's viewed on a larger display (and its a live view or video) that you can readily see this occurring.

There have been a lot of people that have mistaken this for a problem with their lens/camera and sent them in for repair when no repair is needed.

Alan
www.iwishicouldfly.com

[John Chardine]

I've been there Alan and you are right. A similar way to verify is to set the rig on tripod, focus on a subject and put on Live View. Magnify to maximum and with refraction you will see the image moving in and out of focus completely on it's own!

[Charles Glatzer]

I would bet subjects taken closer are rendered much sharper than those taken at distance. Many images taken greater than 75/100 feet in winter conditions exhibit a big loss of detail due to shimmer, etc.
Using 600/800 plus lenses to shoot images of distant subjects is not the answer. Look at a subject at distance with Live Preview and you will be amazed at what you are trying to shoot through.

Chas in Japan

[Roger Clark]

I agree with the possibility that the problem is shimmer. In astronomical circles, this is called seeing. Even with a telescope looking up, a significant fraction of the seeing is caused by the atmosphere closest to the ground. In photography looking horizontally, the situation could be worse over a short distance than look up all the way to space. Seeing usually limits detail to about an arc-second, 2-arc-seconds is more common, and when there is significant differential heating, seeing can be 3 or 4 arc-seconds (and worse). With big telephotos and the small pixels in digital cameras, we often get close to the arc-second range. A 600 mm with a 7D for example gives 1.5 arc-seconds per pixel with a 600 mm lens.

The computation is 206265 * pixel size in mm / focal length. The 206265 factor is the number of arc-seconds in one radian.

The 7D has 4.3 micron pixels, 0.0043 mm so we get 206265 * 0.0043 mm / 600 mm = 1.5 arc-seconds.
The 1DIII, with 7.2 micron pixels gives 2.5 arc-seconds with a 600 mm lens, thus also in the range of image problems on tough days.

But Rob described the image getting better with time. I may be a coincidence with the atmosphere settling down, or may be a lens issue. In either case, the live view check should tell if it is heat shimmer.

For reference, the Moon is about 1800 arc-seconds in diameter. So if you image the Moon and it comes out about 1800 pixels across, you have close to 1 arc-second per pixel. That is really small.

Roger

[John Chardine]

I can imagine a warm lens taken out in the cold could produce local shimmer as it heated the air up around and in front of the lens. This would vanish as the lens cooled down and equilibrated to outside temperatures.

By the way, in cold weather I universally get poor results from a vehicle unless the windows are down and wind is blowing the cold air through the cab, and I wait for everything to equilibrate. Grab shots just after rolling down the window, even with the heat off in the cab do not work for me.

[Roger Clark]

Hi Rob,

This morning I observed the condition you describe. I usually do not image from my car, but I was headed to a local bird spot when some mule deer were walking along a ridge line. The situation could be interesting, so I got my 500 ready and took a couple of frames from my car window to test exposure. The jeep was warm and outside was 43 F, so about 20 F colder. I checked the image and it was not sharp at all. Light levels were low (1/80 second at ISO 1600, f/5.6) as it was near sunrise and no sun yet on the subjects. At first I thought my hand holding at low shutter speed was the problem, but then I noticed the grass in front of the deer was sharp. Light levels rose and my exposure got up to 1/500 second, reducing the problem of camera movement. But every shot was very front focused, even though I had the focus point clearly on the head. Then I tried the brighter fur on the rump--still the same. So I started changing the microadjustment. Suspecting a heat problem, I rolled down other windows. The amount of front focus was changing and after a few minutes the focus was back to its normal spot (microadjustment = 0). Heat shimmer was not an issue, and not observed. The sharp grass in front of the subject clearly showed the adjustment of the lens/camera was different during cool down so the problem was definitely due to temperature differential during cool down.

Roger