cjshh

Is there a straight forward way to compare lens focusing speeds. For several years I have been taking pictures of motorsports event. Most of them are cars on dirt 3/8ths mile to 1/2 mile tracks. Race cars typically are travelling at 100+ mph so focus speed is important. I normally use a 70-200mm lens. I have tried a few other lens and have spoken to some “camera store folks” about others in the size range I need. Again the one I use is a Nikon 70-200 2.8 lens. I shoot a lot at night/evening so am looking, perhaps, for a faster lens. For instance, the Sigma 135mm F1.8 DG HSM | A. (since I’m often shooting between 120 and 140 mm). There seems to be no resource that objectively provides focus speed (Not looking for a specific time of speed of acquisition just a relative speed or index that allows me to compare performance to what I have). Thanks for any help.

Architect1776 Loc: In my mind

The 70 -200 lens you have is at the top of the heap for speed. Frequently though it is the camera that is slow or camera lens combo that is slow.
As far as other lenses like you mention it would need to be a review of the specific camera with different lenses as their same lens on a different camera could be totally different by comparison to other lenses on that same camera.

cjshh

First of all, the current body is a Nikon D5 and I have been told that the 70-200 is the "best" or some such statement but I was just curious as to how I could research this on my own or compare it to any new lens. Also as I stated I was wondering if there was any other "low light" lens that might be "comparable".

Thanks for you response.

SS319

When, Old Dave is going to go off on a tangent... Perhaps you will discover that focusing speed of your camera lens system is not quite so important if you allow yourself to avail yourself of the world's greatest Imaging engineers that work for the camera and lens manufacturers. The manufacturers are spending millions of dollars on focus systems and subject tracking.

When you take a picture, you focus then shoot, but how long is it between focus acquisition and shutter operation? At 100 miles per hour, your subject moves 15 feet in 1/100 of a sec (10 milisecond). But if you use the subject tracking feature, your camera tracks and continues to focus right up until shutter operation. Seems like a good reason to listen to the engineers and try it their way.

Here is a link to a DP Review article: https://www.dpreview.com/techniques/5004008634/subject-tracking-why-it-matters

speters Loc: Grangeville/Idaho

That Sigma you're talking about is pretty slow!

cjshh

Thanks... good to know. Hate to ask those questions... wish there was a single place too see and compare. Appreciate your reply

BebuLamar

I don't think any lab test them the way you want. I take that you want to know how fast the lens focus (not how long it takes to achieve focus) I think you can test them yourself. Manually set the lens to infinity, aim the lens at a target that can not be focus on like something with zero texture. Start focus and see how long it takes for the lens to move from infinity to the closet focusing distance.

JPL

This is a really difficult question, because the focusing speed will not only depend on the lens used or camera used but also on the subject in the frame and the light at the venue.

To give you a simple idea of how to get the best results I think you should rather compare camera/lens combos from different manufacturers rather than comparing different lenses on the same camera in different situations.

If you could f.x. use your D5 and the 70-200 lens for one event and check afterwards how many keepers you got.
Then for the next event rent a Canon1dxII or whatever is their opponent with the D5 and see how many keepers you get from that combo.
And at last get the new Sony A9 and 70-200 lens and count your keepers afterwards.

Then you would at least see if there is a difference between those and if it really matters.

Or, if it is only about finding the fastest focusing lens for your D5, then you would have to test all the candidates in a similar way. And if I am correct about the D5 it is also important what focusing mode you are using, single point, focus tracking, group focus etc. I think you will have to do the job your self

jerryc41 Loc: Catskill Mts of NY

Get this book -

https://backcountrygallery.com/secrets-nikon-autofocus-system/

cjshh

Thanks for your thoughtful replies. I guess, as always, I was just looking for the "easy way out" and as I suspected ... there is NONE.... Appreciate all your input.

paulrph1 Loc: Washington, Utah

Large aperture can be your enemy and ISO can be your friend. try this
http://just-shot-it.blogspot.com/2017/07/20-cheatsheets-infographics-for_31.html

Kmgw9v Loc: Miami, Florida

Go back and discuss the issue further with those "camera store folks". They will sell you the right lens for the D5.

Notorious T.O.D. Loc: Harrisburg, North Carolina

I think your math is a little off but the key is to use continuous focus mode as you say. Perhaps you meant to say 1.5 feet per 1/100 second. But 60mph is 88 ft per second if I recall from my high school physics class. So, if we double that to 120mph that is 176 ft per second, or 1.76 feet in 1/100th of a second. Much less than 15 ft per second. It also depends on the angle to the subject and your camera. If the camera is 90 degrees to the movement the motion will be more apparent than if it is coming toward or away from the camera. High shutter speeds are your friend here... I usually shoot drag racing at 1/2000 if I am trying to freeze motion.

Best,
Todd Ferguson

Notorious T.O.D. Loc: Harrisburg, North Carolina

There are other factors such as the focus modes and parameters that you select...at least in my Canon 1Dx MkII. You can select whether the camera is to take the shot first or achieve focus first. There are also parameters that determine if the camera hunts continuously for focus if it cannot achieve focus or not. The light level and the contrast of the subject can also impact focus speed. if the subject is in a low contrast area or lacks sharp lines it will be harder to achieve focus. There are also different types of focus sensors on your focus system at different locations and some detect both vertical and horizontal and some only one or the other. The center focus point and single point mode may be the best place to start. Many sports shooters use single point focus mode.

The other thing that can be a factor in shooting dirt track racing is the level of dust in the air. I am not a dirt track shooter but used to shot motocross outdoors. I know several dirt track shooters and the dust in the air can sometimes throw off the focus system, especially if you are shooting over a longer distance. That may be part of the issue of having trouble obtaining focus in some cases.

Best,
Todd Ferguson

cjshh

To perhaps expand (or better explain) my original post..... Recalling back in the 70's and 80's with the automotive gas mileage comparisons, still one of my favorite sayings (abbreviations, whatever) is YMMV (Your Mileage May Vary). I realize this is a problem "somewhat" unique to my target subject so that's why I was looking for a more general "index" to compare lens'. My "subjects" are typically about 100+mph on a circular track from 3/8ths to 1/2 mile. Typically arrive in clusters of 2 or 3 cars at a time and difficult to pan with due to constant traffic stream from right to left, hence the need for fast (quick?) focus. As far as advice from store personnel, they are often of "some" help but I have yet to find one that even knows what a Sprint Car is, so its difficult for them to relate. Is it a bird, or a plane.... no its a sprint car..... well you get the idea. I guess I was just canvassing UHH a bit to see if there were others in the audience that could help shed more light on my dilemma, I appreciate all the input but the bottom line here seems to be ... the current combination (D5/70-200) is pretty good and to do better I need to experiment more and perhaps do some Lens rentals to compare... Thanks again for your time.