any help out there

laffing gravy

laffing gravy

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14
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paul
Hi all, I class myself as a beginner having had a dslr for roughly 18 months. Anyway I have purchased a second hand sigma 300 2.8 lens I also have a sigma 150-500 lens . My main interests are birds, wildlife etc. Few things I struggle with using my new lens so maybe you could help. I tried using the back focus this week after kingfishers, I focused on its perch and waited everything is ok even when the bird is there the problem begins when the bird darts down to the water my camera dosnt fire even though its on multiple shots. Is it because the bird moves off the focus point? just a bit puzzeling why the camera dosnt fire at the critical time, it seems to work ok when larger birds are in flight, I was under the impression that the back focus would lock the focus so presumed the camera would fire whether i was in focus or not? hope this makes sense lol
cheers
Paul
 
The camera will not fire until focus is attained. There must be an issue with the focus, possibly too slow to focus? What body do you have?
 
There will be an option in the menu system which allows the camera to shoot regardless of whether the shot is in focus or not. It is probably set now to, "only release shutter when focus is locked". You need to ucheack this option. If the bird is only flying vertically downward it will be still within the cameras focus range. You could choose Manual focus, pre-focus on the branch and shoot around F11 if possible, the camera will then no longer try focusing and you should be able to shoot at will.
 
I have the nikon d3100 ( feel i have outgrown it now tbh) but stuck with it for the meantime. The new lens is a bit new on me in some ways also. For example when I put the lens on the camera it says "set aperture to maximum" so i rotate the aperture ring on the lens before i can use it, I mean whats the point of that ? i,m missing something there lol, also there was a manual auto button on all my other lenses but not on this one so have to alter it to manual in settings. Hope this helps put some shots up in my gallery
 
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yes I have no problem in auto focus but did notice for example i may be focused on something and say i move off the object even for a split 2nd it focuses on that then. I put it down to the learning curve, this is why i tried back focus. From what i can gather as long as the bird is in the centre focus point then ok but if it flies off and goes out of the centre then the camera wont fire. I will have another experiment with it in the week before i go out again
 
Please tell me if I'm wrong but, with BBF you say you are focusing on the perch. Well BBF, my understanding, will focus on the perch not the bird so when you are following the bird the camera is still locking on the perch. If you get the bird on the perch and expect it to move you BBF on the bird and then move with it. I've never really accomplished this very well, I know many others have. I rely on the good old tripod and gimbal head.
 
I read up different to that but i could be wrong. I thought back focus was basically using a 2nd button for your focusing instead of using the shutter release as the focus button. I was under the impression that once you locked it at something say for arguments sake at 20ft then it would stay at 20ft regardless of where you point it. So with that in mind I presumed I could lock it on either the perch or bird then when it dives (as its paralell to me the focus wont be a million miles out. I did get one or two shots i put them in my album but as I said that crucial moment when I was expecting it to fire off repeatedly it didnt.
 
BBF does separate the focus from the shutter release. Assuming you are in servo and not single point focus, If you put your focus point on the perch for example and hold the BBF while panning the focus will shift with the focus point. If you press the button and release it will lock the focus at that point, or that's how my camera seems to work. I tend to hold the button while keeping the focus point on the bird and press the shutter when I'm happy. The easiest way to keep the focus distance the same is to use manual and focus on the perch, then snap away as the bird moves
 
yes chris I will be trying manual next time, I do find it stupid where the back focus button is on the nikon just to the right of the viewfinder any other place would have been better for me lol
 
I believe the BBF helps conserve the battery so you don't have to constantly refocus with auto. Manual focus is great except I have trouble keeping up with the flying bird.
 
Ok. On all lenses that have an aperture ring on you have to set to the largest f number, you can still chance the aperture on the camera as normal. Iirc you will have a setting in the focus menu that will allow you to take a photo even if focus had not been acquired you could try that and see if it helps.
 
thx for the reply, I realise i can still change the aperture i was just wondering what the point of it was on the lens
 
So it can be used on film cameras that don't have camera controlled apertures
 
errr if you are using a 300mm f2.8 lens with aperture markings on the bottom of the lens .it WILL NOT work on a d3100 as the camera has no built in motor drive.,the sigma 150-500 will work but i would think fairly slowly ..these basic bodies were not really made for the lenses your using ,a minimum body would be a d90 ,d7000,d7100 or if you really want a good wildlife camera a d300 or 300s which can both be picked up fairly cheaply s/h
 
paul i also wanted to catch a kingfisher going/ coming out of the water they move to bloody fast but this one was shot at 1600 and was one of a few that came out, im sure i expanded my focus points and fired a few frames off to catch this , light on the day was rubbish but going to try again very soon hope this helps but you need to keep the firing loads off and you may get a keeper
 
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