Laurie or Lee - Canon IS Question for You...

[bayhli]

I used my Canon 100-400L IS lens last night to try to capture the lunar eclipse. I used a tripod and shutter release cable and I also forgot to turn off the lens image stabilization system as you are supposed to with this lens.

The other factor was that it was (minus) -27C outside and I had the camera out there for over an hour.

My pictures are extremely blurry in some cases. At times I could actually see the lens move as I looked through the view finder, the focus point would move right off of the moon. The sensation while viewing was that of my tripod head slipping but that was not the case. I have had this happen with this lens on a tripod indoors as well.

My question is:

- is the extreme movement you see in the images below, soley the result of not turning off the IS on the tripod?
- could the cold temps be a contributing factor to the extreme blur as well in that the lens groups may not function properly in this kind of cold.







I'm pretty sure the following picture was taken after I remembered about the IS and turned it off; there is still blur here. However the camera and lens were still on the tripod when I switched it off and I think that might make a difference? (supposed to turn it off while off the tripod?) This was also at the end of my hour out there and the back of the camera was actually iced up from my breath, as was I so I can't be sure I didn't move something - everything was pretty cold by that time.



Here's where this topic originated - Tony has posted a link to a good article on image stabilization and tripod use.

http://www.elementsvillage.com/forum...ad.php?t=34813


I'm really interested in finding out if IS is responsible for this and if the cold is playing a role. If not then perhaps the lens groups themselves are faulty...

It would be great to hear from others who shoot in very cold weather about their experiences.

[Chuck S.]

Pat, was it windy? And what was the shutter speed, especially for the ones with the most blur? It definitely looks like the camera was in motion for the early pictures, likely exacerbated by IS being on. The final image looks like the shutter speed may have been slow enough that the moon moved enough in its orbit to cause the blur, or that the tripod was vibrating from the shutter release or wind...

[JulieM]

I wonder if using the mirror lock-up would have helped? (Not that I've ever used mine...)

[Chuck S.]

Julie, I was thinking the same thing as I was writing about sources of vibration.

[GaryK]

Pat

I'm with Chuck on the last one... the first few ??? I dunno... it's almost like a double exposure or something.

[Chuck S.]

Gary, I think the first few show just how much chaos can be caused by IS being 'constrained' by a tripod....

[GaryK]

Chuck

My camera bag is sans IS equipment. so no idea as to what the tripod contraints look like.

On a brighter note I have almost talked myself into a 40D.

[bayhli]

Chuck,

Other than the cold it was a beautiful night, not a breeze. But after reading all the comments I got to thinking about how stiff the shutter cable had gotten toward the end and remember it hitting the tripod a couple of times.

When the cold finally takes hold I find I start getting sloppy with what I'm doing - I quit shortly after that. It could very well have been camera shake at the end.

I've never tried mirror lock-up...

Yes Chuck, shutter speed was super slow for the last one - 13.0 sec
Looks like it was slow for all of them - the first three were all between 6.0 and 15.0 sec.

I'm going to spend some time testing all this out again - INDOORS!

[Whiplash-GT]

i never got a chance to do this shoot, but anytime i do long exposures everything goes into manual mode
camera, lens..the whole she-bang
also, on a moving target (where you know there will be motion over a specific time period) i'll crank settings up to limit the exposure...i prob would have shot the moon at iso 1600, f 5.6 and experimented with the shutter some 'til i got things right

i've done some cold shoots as well and even after being outside for a few hours i've yet to run into any equipment getting fidgety

i was going to mention something about a remote trigger or even a time delay too, but you posted mid-reply that initial trigger press can something mess things up, especially at longer focal lenghts

[Chuck S.]

Originally Posted by bayhli

Chuck,

Other than the cold it was a beautiful night, not a breeze. But after reading all the comments I got to thinking about how stiff the shutter cable had gotten toward the end and remember it hitting the tripod a couple of times.

When the cold finally takes hold I find I start getting sloppy with what I'm doing - I quit shortly after that. It could very well have been camera shake at the end.

I've never tried mirror lock-up...

Yes Chuck, shutter speed was super slow for the last one - 13.0 sec
Looks like it was slow for all of them - the first three were all between 6.0 and 15.0 sec.

I'm going to spend some time testing all this out again - INDOORS!

Pat: I've used small astronomical telescopes in the past, and I can vouch for the fact that in 13 or 15 seconds the image of the object will cross a relatively large portion of the eyepiece, particularly at higher powers. You can experiment with a non-eclipsed moon to see the effect: put your camera on the tripod, set the 100-400 mm lens at the long end, point it at the moon, center the moon in your viewfinder, then watch and see how long it takes to move to the edge. I think you'll be able to see it move pretty rapidly.

How to counteract this? Short of putting your camera on a tripod with an equatorial mount and a clock/motor drive, you can experiment with higher ISO ratings. It will get a little noisier but the shutter speed will be faster, reducing the amount of apparent movement of the moon across the lens. You should also have the lens set at its lowest f-stop (widest aperture). Depth of field is not a problem for an object 237,000 miles away.....