Author Topic: 500mm f/4.5 focusing help?!?!? (Read 2854 times)

DMITPHOTO · « **on:** August 16, 2012, 04:34:29 PM »

So I recently got a 500mm f/4.5 I bought the lens of course for the focal length. So, I popped it on the 5D mark 3 expecting the image quality to be fantastic! So, I went out front where I have a bird feeder, and set the lens on a tripod about maybe 20-30 feet away from the feeder. When birds would fly in and land bam, focus was snappy and lock on instantly to take the picture. The images looked dead sharp on my LCD. But when I put them in my computer non cropped or zoomed in the images would be sharp where I focused. However if I zoomed or cropped in to a bird the bird would be soft. Yet the feeder or something next to it would be sharp. So I tried micro adjusting the lens many many many many many many times lol, and cannot tell a difference. From far away, up close medium range they are all dead sharp and when I zoom or crop in I cannot tell a difference. They all look exactly the same. Does anyone know if maybe I'm to far away from the small bird and if I want to take a picture of one it needs to be closer? Or am I doing something wrong as far as using the lens sense I'm new to the super telephoto range?? Also, if the lens is at f/8+ they are super crisp and sharp. So if anyone can help please please post lol thanks

canon rumors FORUM · « **on:** August 16, 2012, 04:34:29 PM »

Random Orbits · « **Reply #1 on:** August 16, 2012, 06:26:52 PM »

Try focusing at a large flat target at a distance. Is that sharp wide open? The AF sensor is larger than the square in the viewfinder. If the objects within the square has significant depth than the AF sensor might not lock onto the feature you intended. Try spot AF.

marekjoz · « **Reply #2 on:** August 16, 2012, 08:23:11 PM »

Did you shoot this bird with this lens at 1/2000 or faster?

jasonsim · « **Reply #3 on:** August 16, 2012, 09:10:14 PM »

My first thought is perhaps your shutter speed was too slow; rendering the birds a bit blurry due to their movements while leaving the feeder in sharp focus. This because the feeder is largely stationary.

What were your settings for the blurry shots? You might need to bump up your ISO on the 5D MK III. Try starting at ISO 400. With a 500mm that has no IS, you will want to be above 1/1000 second shutter speed. You might also check the minimum focus distance for that lens and make sure that you are at least that MFD away from the where the birds will most likely be positioned on the feeder.

Also practice your long lens technique, by placing your free hand ( I assume you are using the set on a gimbal or sidekick apparatus ) on the top of the barrel midway down the length of it. This will help dampen the vibration transferred to the camera's sensor.

Another possibility, albeit a potentially costly affair, is that your current tripod legs and head are inadequately stable for the combined weight of the 500mm + 5D MK III. I recommend a 3 series tripod at very least and a beefy ball head or gimbal such as: RRS BH-55, Arca Swiss Z1, Wimberley WH-200 or Jobu Design Pro1.

Hope this helps and best of luck shooting.

--Jason

DMITPHOTO · « **Reply #4 on:** August 16, 2012, 09:30:20 PM »

I know a couple of shots were 1000 or 1250, but most of the time I was just on av just so I could capture them faster, so I'll try bumping up the iso and try to be at least 1/2000. But my settings were iso 100 f4.5 on ap priority, with al servo, with no flash. However, on...oh 80% of the shots the birds were stationary ish I believe haha sometimes they would bob their head in for food and out and so I would just hold down the shutter trying to always be right in the eye at 6fps and they'd be sharp unless I zoomed in in post or cropped closley. As far as the tripod, its a gitzo... Explorer so it's not as sturdy as some of the other beefyer ones, and it's just a standard ball head. I actually posted another thread about what kind of gimbal head to get lol, so maybe it's not micro adjustment at all?? Haha maybe it's my nooby lack of super tele lens with a non sturdy set up

jasonsim · « **Reply #5 on:** August 16, 2012, 10:19:56 PM »

Yes, it is probably not the support system since the feeders were sharp. Do you have the photo that you can send to me? You can email to jlsimmons1414@gmail.com . I can take a look.

If you think you need sturdier support though, I would recommend a Wimberley WH-200 full gimbal. You will love it. This makes birds in flight a breeze. Of course the trade off is that it's pretty bulky and 4.5 lbs. If you don't care for a gimbal, then a RRS BH-55 is also a gem. It's a ball head that is built wonderfully and holds substantial weight: 50+ lbs. You might want a Wimberley sidekick for this setup, if you want to track birds in flight (BIF).

hmm...if most of your shots were at 1/800 to 1/1250 s, then I'd suspect a back focusing issue. Do this, take a page from a book and place it at a 45 degree angle on a table. Then with the 500mm on a tripod at the same height as the book, move it to the minimum focus distance away from the book. Then focus on a particular line in the book and judge if the AF is back or front focusing. If it is, then play with the micro auto focus adjustments in increments of +/- 5. Then once you are getting close, move +/- 1 increments.

Kind regards,
Jason