saltwaterfresh

Working on dialing in my focus. When set up with gimbal head, I the set the focus, but as the timer counts down the focus moves to the left and up a bit. At 75 feet this is 5-6 inches. I mostly shoot birds and am not getting great focus at f 6.3 thru f 11. Ideas?

robertjerl Loc: Corona, California

Do you have it on AI-Servo? The head it not 100% rigid and fixed and moves a tiny bit after you take your hand off the camera, then the AI-Servo setting changes the focal point. If so change it to one shot.

Pablo8 Loc: Nottingham UK.

I have the same lens , and never had problems with focus. BUT, I use it on Nikon cameras.

Pablo8 Loc: Nottingham UK.

I have the same lens , and never had problems with focus. BUT, I use it on Nikon cameras.

travisdeland Loc: deland, FL

do you have continuous autofocus set, This could be a problem. I shoot the same combo with great results and performance.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

Once you set the focus, switch to manual focus, it should stay where you set it with auto.

Nalu Loc: Southern Arizona

Have you fine tuned the focus on that combination. That could help. Gimbal heads are designed to move.

47greyfox Loc: on the edge of the Colorado front range

Agree and it may be obvious, but is your body and lens balanced on the gimbal?

TFH

I shoot with exactly the same equipment and do not have your problem. I use AI-Servo.

mrtaxi Loc: Old Westbury NY, Fort Lauderdale, FL

I shoot the exact same Equitpment I do not have the problem. I keep the lens on manual focus and the camera on one shot, I use a remote trigger. If time permits I zoom in 5x to nail focus prior to shooting.

imagemeister Loc: mid east Florida

It would be best to be in single shot AF, if your tripod has a center post, do not extend it, do not use/extend the smallest part of your tripod legs, have the weight of your camera/lens in BALANCE on your gimbal and lock it down. Consider using a lens stabilizer bracket to overcome the highly compromised tripod collar.
.

alberio Loc: Casa Grande AZ

I also found out my Tamron 150-600 seemed to move around slightly until I realized my image stabilization was turned on while on a tripod. Just a guess.

amfoto1 Loc: San Jose, Calif. USA

What do you mean when you say "focus moves to the left and up a bit"?

Is this because the camera & lens are actually moving?

Is this because image stabilization working and causing the image to "drift"?

Is this because you are using multiple AF points and the AF point is changing?

What "counter" are you referring to? Are you using the camera's self timer or something? When you "set focus" with One Shot, there is an internal timer that holds that focus for a short period of time, much like using AE Lock... those "self-cancel" after you lift off the shutter button half-press, after something like 10 or 15 seconds.

To shoot birds, at a minimum you should:

1. If at all possible, use a single AF point and focus on the bird's head.
2. Use AI Servo focus mode (NOT One Shot and NEVER AI Focus) so that the system will continue updating focus as long as you maintain half-press on the shutter release (...or, even better, use BBF, see #7 below).
3. DON'T use the self-timer or any other sort of delay. Simply use a fast enough shutter speed that pressing the shutter release directly won't cause any camera shake blur. If you are "losing focus" while waiting for the shutter to trip, this alone should solve your problem! (I won't say NEVER use a self time while shooting birds... but I also can't recall ever doing so in 40+ years of photography!)
4. Using that faster shutter speed (which may require a higher ISO) also should allow you to leave the gimbal "loose", so that you can quickly track any movement of the subject.
5. That Sigma has OS image stabilization, doesn't it? With my Canon lenses I would normally leave IS on, even on a gimbal. But that may not be the best approach with the Sigma lens. If you are able to use a fast enough shutter speed, you might try some shots without OS and see if this improves your keeper rate or not. It might or might not cause delays (a lot of people who use it say Nikon's VR slows down AF, so they turn it off when maximum focus speed is important... however, AFAIK this is not a problem with Sigma OS... and from using it for close to twenty years, I know it's not a problem with Canon IS).
6. If the lens has a Focus Limiter, use it! That will restrict the lens to working only within a select range, which can speed up focus acquisition.

It would also be very helpful and increase your "keepers" if you would:

7. Learn to use Back Button Focusing (Very easy to set up on 7DII.... go into the screen that allows you to customize button & dial assignments, navigate to the shutter release and change that from "AF" to "Meter". This "removes" AF function from the shutter release, leaving it only at the AF-On button, which you control with your thumb.)
8. For "birds in flight" (BIF), you may wish to use multiple AF points because it can be difficult to keep a single point of a fast moving bird. Use Zone or Small Zone, but take extra shots because there will likely be some focus error where the camera & lens lock onto the bird's closest wing tip or are "distracted" by a foreground or background object that one of the AF points momentarily covers.
9. You can "fine tune" the speed with which AI Servo focus "jumps" from focusing on one object to focusing on another with two settings in the menu. To prevent it from switching focus, you need to set these to the slower side. This works well when a subject is moving, but doesn't change direction. However, the opposite faster setting works better when subjects are moving unpredictably and erratically, changing directions. This will result in more missed focus shots, though.
10. Another pair of settings prioritize focus accuracy versus shutter release. There are two of these settings for AI Servo mode.... 1st shot and 2nd/subsequent shots. These apply when you are shooting continuous bursts at medium or high speed (as opposed to single shots). I increase these to the max for sports photography, since I have no need for missed focus shots. A news photographer might use the opposite setting, willing to miss focus slightly if it means "getting" a fleeting shot without any delay waiting for focus to be achieved.
11. You can increase your odds of in-focus shots by stopping your lens down a little, say to a middle aperture like f/8, f/9, f/10 or f/11. This increases depth of field a bit, which in turn means focus doesn't need to be as precise as when a lens is "wide open" and rendering it's most shallow depth of field (an extreme example, the 85mm f/1.2L lens is difficult to work with because of it's incredibly shallow depth of field).
12. I don't have the Sigma 150-600mm C lens, so don't know how fast if focuses, and that can be critical when shooting a quick subject like birds. The 7DII's AF system is very capable... but will work best with particularly high performance lenses. Canon's USM focus are their fastest. I think Sigma's HSM and Tamron's USD lenses are similar. Other types of focus drive (such as Canon's STM or "micro motor" are a little to a lot slower). f/2.8 and larger aperture lenses also tend to be faster focusing, because there's more light reaching the AF sensors in the camera for them to work with (Note: This isn't always the case, as in the original Canon 85mm f/1.2, which is widely known to be slow focusing, very probably by design because focus accuracy is so critical with a lens like that. The same is true of most macro lenses, which are slower by design, favoring accuracy. In addition they have to move their focusing elements a long, long way to focus from infinity to a few inches in front of the lens.)

Also be sure you are actually missing focus. Too slow a shutter speed can cause camera shake blur or moving subject blur in images, that can be mistaken for missed focus.

Finally, don't beat yourself up too much. We all miss focus at times. And more often than not it's no fault of the camera & lens. It's usually my fault when I miss focus and I just don't share those images! When I'm shooting sports I'm most familiar with, can anticipate and have practiced a lot, I usually get a high keeper rate.... very few missed focus shots. But when I shoot an unfamiliar sporting event... and especially when I shoot very quick wildlife like birds... my percentage of in-focus shots drops quite a bit. It's not the gear... It's me. The more I practice, the better I get focusing on active subjects. But I only share the shots where I nailed focus!

amfoto1 Loc: San Jose, Calif. USA

Really? You do this shooting birds?

If so, I bet you miss far, far more shots than you take!

Seriously. All those are precisely the OPPOSITE of what should be set or used with active, moving subjects like birds!

Maybe if the bird is stuffed and sitting on a shelf! Otherwise... do the opposite of all these things!

Also, there is no need to set the camera to One Shot AF mode when you have set the lens to manual focus! Unless you just want the the Focus Confirmation to work (if enabled, the audible confirmation "beep" might scare away birds).

skyspy

I use the same lens with a Sony A7r4 mounted on a gimbal and don't have that problem, but I use a remote trigger and an external monitor.