Tamron 200-500 help needed

[bobrandklev]

I can't complain about the cost of my Tamron lens as it was gifted to me for some volunteer work I did (non-photography).

It replaced an ok Canon 70-300 base lens so I will say it's better both in quality and the added zoom when motion isn't involved.

My problem, like any long lens, is the outer reaches of the lens are less crisp and blurry.

So a few weeks ago I was at a football game, sitting on the sidelines, sun at my back, Canon 50d, with the Tamron 200-500 on a mono-pod.

So my first camera settings were to put the camera in TV mode and set the shutter to the reciprocal of the longest focal point. So I set it to 1/500th of a second and let the camera pick the ISO and aperture. Not bad photos, little blurry. So I bumped up to 1/640 and 1/800 even trying 1/1000.

First question is with the 1.6 crop factor of the 50d I actually have a 750mm lens so should I set my shutter faster like 1/750th of a second?

Next I set the camera in AV mode and opened up to the widest aperture 5.6 the lens would allow. I noticed the 1/500 or greater froze the action but the colors were very weak. My goal here was better lighting and color.

Problem now was color was better but shutter speeds fell to 320 and 250 at times so there was noticeable blur. I then tried bumping up the ISO but as I got to high I started getting grain.

So my biggest question: Was I just doing this wrong and is there a better way to think about this situation balancing Shutter, Aperture and ISO?

OR:

Is it just time (in these situations) to think about getting a faster lens?

Thanks for any feedback,

Bob

[ziggy53]

Before someone jumps down your throat, I suggest a clarification. A crop sensor does not change the focal length of your lens. It does affect the field-of-view, and that makes the given focal length "seem like" it is longer.

The reciprocal of the focal length is a colloquial method for setting shutter speed but it fails at both very long focal lengths and very short focal lengths. For a 500mm lens on a crop camera I use, and I recommend, shutter speeds above 1/1000th. Part of the reason is how the mirror slap affects the entire moving mass of camera and lens. If you can, you should be using a tripod and mirror-lock-up (MLU) as well. (The Canon 50D has a "live view" mode that works very well for both reducing camera vibrations and allowing critical focus.)

Some photographers will also use 2 tripods, one for the lens and another for the camera, to effectively dampen vibrations from very long focal lengths.

The Tamron SP 200-500mm f5-6.3 Di LD (IF) also needs some stopping down for best results. I suggest f11 at the 500mm focal length. You can see that this lens loves strong sunlight and contrasty scenes for best results.

Also test some scenes with varying depth to rule out consistent front or back focus issues. (You can also use the live view mode to confirm focus.)

[bobrandklev]

Thanks for your reply Ziggy and I hope no one ever "jumps down my throat" we are here to learn, ask questions and help each other... I thought :thumb

Yes the crop camera doesn't change the focal length technically but you then in a way said the same thing, not to use 1/500 on a full out 500mm lens, rather use 1/1000 or as I was suggesting 1/800 (500mm x 1.6 = aka 800mm). You do make a good point for the high and low end of the lens not matching with the reciprocal of the focal length, I'll make some adjustments.

I have not tried dual tri-pods but I will for my next landscape shot. For sports I'll have to do what I can with my mono-pod to stay with the action.

I'll keep working to improve my results, thanks for the feedback and again I can't complain too much about a free lens!

[ziggy53]

...

I have not tried dual tri-pods but I will for my next landscape shot. For sports I'll have to do what I can with my mono-pod to stay with the action.

...

If you use either the mirror lock up or live view, you won't need to use 2 tripods. I suggest the live view method because it allows for very accurate focus, eliminating the potential for problems which may be associated with auto-focus, as well as reducing camera shake due to mirror slap.

For sports, a monopod is very useful. :thumb