Long lens/vehicle problems

[Frank Kolwicz]

I've been using a 600/4 L IS (1) with a 1.4x on a 7d or 5dII for a couple of years and it has given me great results reliably, but recently I switched from a heavy-duty pickup to a RAV4 for a couple of reasons and now I can't get anywhere near decent quality sharpness.

I'm using the same home-made ballhead window mount as before and I get fine sharpness when using a gimbal head/Gitzo on stable ground.

Has anybody had any experience with a problem like this?

[Frank Kolwicz]

I've done some testing ( I've done way too much testing! )

In my driveway, I put a jack under the driver's side of the RAV4 to see if suspension movement was part of the problem. I'm not sure how much help that was, since I only have one jack and should probably have put the car up on 4 of them for a real test (if I was a bit younger, I would have done that). It had no noticeable effect.

Now, I'm in the process of rebuilding my window mount with a stiffer platform and tighter-fitting support brace (it was originally made for my pickup and modified for the RAV4). When the glue dries, I'll run the test again. It's hard getting the window mount just right as the car's door panels are curved and the arm rest is angled and the whole thing is a bit springy, but there was a noticeable improvement when I was fitting it together, just with hand pressure on the mount.

Frank

[Frank Kolwicz]

I'd say that the changes did help after doing some bird photos in my regular spot, BUT, it's still not nearly up to the reliable quality that I had before the lens repair/truck sale fiasco back in April.

I'm sure that the lens is working well, so it's not that, it's something about the way I use it in the new RAV4 compared to the Chevy Silverado 2500.

[Frank Kolwicz]

Trying to isolate the source of the problem, I went out today and did some birds with bean bags on the window mount, minus the Studioball head and, at first, I thought that did it, but a close look on my editing computer showed only a few critically sharp images (where with the ball head there were none) and one whole series (16 frames) of a still Great Blue Heron that should have been the easiest thing to focus on and ALL were very soft. Lighting was good with shutter speeds above 1/2000 sec at f/8, ISO 1600. The frame immediately after the heron was a Goldfinch at about 50 feet and that was sharp.

As always, the image in the viewfinder looked sharp and steady and most of the birds were still, not tracking. So, it's better, but not the way it was as of early spring this year, and it's totally unreliable.

I think I'm going to have to find a completely different way of mounting the window platform for the ballhead or the bean bags.

Any suggestions or ideas I've missed would be appreciated,

Frank

[KeithB]

Could be your new car mount is too good. Do you have IS on or off? This is a wild stab, but it could be that the old car had enough movement to keep IS going, if the new car is more stiff, the IS might think it is on a tripod and shut down.

[Frank Kolwicz]

Hi, Keith,

I've tried with and without IS and didn't see any difference in the image files, but yes, the mount seems to be at least as stable as the tripod, considering that I am often following a subject, but even static subjects have problems.

What I see in the viewfinder is that with IS on, the image really does stabilize compared to without, when I can see my pulse shifting the image around, just like with a gun sight. The image in the viewfinder looks sharp and steady, that's why I can't figure out what could be wrong.

How would I know when the IS is turning off? I can't see it in the viewfinder and I can hear it running.

Thanks for your reply,

Frank

[KeithB]

I don't know how to tell. I just know that some of the more recent IS systems turn off when they sense no movement to prevent drift. I don't even know if it ends up in the EXIF.

[Bob Atkins]

I can't imagine that the vehicle itself (i.e. mass and suspension) makes any difference. Any vehicle is way more massive than a tripod and unless you're photographing in a high wind I can't see any vehicle moving around of its own accord. Presumably you (and any passengers) are sitting pretty still when taking any shots.  The fit of your window mount might be different on the two vehicles though. so if there's wobble in it on your new vehicle, that could be one source of your problems.

I assume you are shooting with the engine off and with no heater or air conditioner on. If either is on then turn them off as the cool/hot air coming out of the vehicle will create turbulence in front of the lens. That could be different between the two vehicles.

 

ALL were very soft. Lighting was good with shutter speeds above 1/2000 sec at f/8, ISO 1600

That doesn't really sound to me like an IS issue. You could almost handhold an 840mm lens at 1/2000s and expect some sharp images with IS off. With IS on there should be no problem at all. I can't see a window mount making things worse.

I used to shoot with shutter speeds slower than that with a 500/4.5 + 1.4x just using a beanbag on the door frame with the window open - and that was with a non-IS lens. Not every shot was critically sharp but many of them were.

[Frank Kolwicz]

Thanks, Bob,

Of course I was doing everything possible to avoid inducing movement into my car - no engine or anything else and my movements were as little as possible, including holding my breath when shooting.

I was about to add an update when I saw your remarks: I borrowed a 7d and used that yesterday for some shorebirds and got much better results, so I guess Canon didn't do such a good job fixing my camera, but the lens does seem to be OK as is the new version of the window mount I'm using, including a Custom Brackets gimbal mount in place of the large Studioball head that I've used for years.

So, I'm getting a 70d and retiring the 7d and hope that my expectations for the new body are matched by its performance.

[Frank Kolwicz]

Vehicle - NOT!

It is definitely the lens. After the initial repair from having dropped it, I returned it to Canon 4 more times because of the soft focus problem and it seems like they simply refused to repair the optical misalignment. I have since used two other 600/4 lenses and both worked fine from my car window (as long as it wasn't windy - when it was windy, images looked just like my lens at its best).

Further tests comparing my lens performance to the others in detail shows that it was OK at near distances, up to somewhere around 30 feet or so, but soft at anything much longer. This is the reason I was fooled by my back yard tests and kept using it in the field and then fretting over the poor results.

One thing good came out of it - I rebuilt my window mount again, it is much sturdier and safer and still does one thing the commercial mounts can't do - slide back and forth on the window sill to make different angle shots easier.

[Bob Atkins]

Glad you found the problem. Didn't sound like a mount issue to me so a lens focusing fault makes sense.

Did you try AF microadjustment? I guess if it was focusing perfectly at 30ft but not at 300ft then microfocus probably wouldn't be the solution since it would affect all focus distances. However you might be able to set AF microadjustment for distant subjects and turn it off for closeups. Obviously not an ideal solution but it might help out until you can get Canon to look at it properly. Sounds like an unusual fault.

[Frank Kolwicz]

Thanks for your reply, Bob,

After 5 tries, I can't imagine what I would have to do to get Canon to actually fix the lens. Maybe, with the new version out, they just can't be bothered with an almost-obsolete model, like all of its predecessors. Like the Army and Adobe - up(grade) or out!

Microfocus adjustment does not affect the focus problem, that's the first thing I tried and I did it at least 4 times and with different cameras when I was trying to isolate the problem.

[Bob Atkins]

If AF microadjust doesn't work, maybe it's not a focus issue. Can you get sharp images using manual focus? If not, then maybe it's a lens aberration showing up at long focus distances.

[Frank Kolwicz]

Sure, I tried manual focus with Live View at 5 & 10x - no good.

The lens is optically misaligned and Canon doesn't want to deal with it.

Frank

[Bob Atkins]

Since you can borrow a good 600/4, what I'd do would be to take some calibration test shots of a distant target using both AF and MF with a good 600/4 and your 600/4, then I'd give Canon those test shots and ask them to look at them and tell you what they think is wrong with your lens. If you present them with proof of a problem you're much more likely to get it fixed than if you just send in the lens telling them that it isn't sharp.