Posted: 3/6/2010 6:00:25 PM EDT
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When I focus a lens, the picture zooms a little. (The picture gets about 10% bigger/smaller) Why does it do this and what kind of lenses do I have to buy to avoid this? (It was a cannon 85mm.)
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Almost every photo lens will do this to varying degrees. Fancy movie camera lenses are specifically designed to avoid this and will not change zoom when focused. It has a semi-technical term that I can't think of right now. I did some heavy googling and found out that it's called "breathing". My dads cheap Cannon lens "breathes" like a Spanish whore in confession during a...aw whatever, the picture crops in and out a lot. I'm looking at getting a 35 mm adapter for my movie camera. That'll allow me to put still lenses on my camera. Anyways I'm looking for lenses that don't do that that are under $300. Any suggestions anyone? |
| I'm trying to figure out why this really matters? Can you tell me more about what you are trying to accomplish? Are you shooting video through a DSLR? Doing a transition from out of focus to in focus? It is a fixed 85mm, right? If you are shooting stills, don't you want the best, sharpest focus anyway? Or taking a series of shots from OOF to razor sharp and then doing a PP presentation? Honestly, I've never paid attention to any of my lenses when they are OOF. |
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I'm trying to figure out why this really matters? Can you tell me more about what you are trying to accomplish? Are you shooting video through a DSLR? Doing a transition from out of focus to in focus? It is a fixed 85mm, right? If you are shooting stills, don't you want the best, sharpest focus anyway? Or taking a series of shots from OOF to razor sharp and then doing a PP presentation? Honestly, I've never paid attention to any of my lenses when they are OOF. The post right above yours: I'm looking at getting a 35 mm adapter for my movie camera. That'll allow me to put still lenses on my camera. Anyways I'm looking for lenses that don't do that that are under $300. Any suggestions anyone?
To the OP... what size is your sensor? Will a 2/3" lens work? I was thinking about suggesting going bargain hunting for some old canon YJ lenses. I've on many occasions seen complete cameras (with lens) that are being offered up at under $1k. So I would imagine you might be able to get into some clearance lens only deals at that price. I sometimes see deals like this on used broadcast equipment brokers/middle men websites. I would definitely expect these to be bargain quality at that price, as well. These lenses are broadcast lenses that most definitely do NOT have any creeping/breathing when you focus. However, non-bargain prices on them are not even close to your $300 mark. Other than that, I have nothing else to suggest, unfortunately. |
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I'm trying to figure out why this really matters? Can you tell me more about what you are trying to accomplish? Are you shooting video through a DSLR? Doing a transition from out of focus to in focus? It is a fixed 85mm, right? If you are shooting stills, don't you want the best, sharpest focus anyway? Or taking a series of shots from OOF to razor sharp and then doing a PP presentation? Honestly, I've never paid attention to any of my lenses when they are OOF. It looks something like this. 
Here's a sample clip (and no, that's not me being stupid with a gun! just a random clip I found.) http://www.vimeo.com/1342535 When you see characters in a movie talking back and forth and they go in and out of focus, that's what I'm trying to do. Smaller cameras have shorter lenses so it's difficult to achieve this affect like a $250,000 Arri camera could do. So you stick this adaptor on the front of your 72mm mount and you can attach regular camera lenses to your camera. I've played around with one and I'm thinking of getting it but they say it's around a 3,000 dollar investment so I'm trying to learn as much as I can. |
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I'm trying to figure out why this really matters? Can you tell me more about what you are trying to accomplish? Are you shooting video through a DSLR? Doing a transition from out of focus to in focus? It is a fixed 85mm, right? If you are shooting stills, don't you want the best, sharpest focus anyway? Or taking a series of shots from OOF to razor sharp and then doing a PP presentation? Honestly, I've never paid attention to any of my lenses when they are OOF. It looks something like this. http://www.expandore.com/product/add/Lenses/Lens_Accsry/Adapter/Sony_Z1_Letus35_Ultimate_5.jpg Here's a sample clip (and no, that's not me being stupid with a gun! just a random clip I found.) http://www.vimeo.com/1342535 When you see characters in a movie talking back and forth and they go in and out of focus, that's what I'm trying to do. Smaller cameras have shorter lenses so it's difficult to achieve this affect like a $250,000 Arri camera could do. So you stick this adaptor on the front of your 72mm mount and you can attach regular camera lenses to your camera. I've played around with one and I'm thinking of getting it but they say it's around a 3,000 dollar investment so I'm trying to learn as much as I can. Did you find the video to have this problem? They were rolling focus a lot. They listed the 50 f/1.8 and the 28 (I assume 2.8), which could be either canon or nikon. |
| I've got the Canon 50 1.8. I could play around with it and see what it does if that helps. It's something like a $90 lens. If you need some of the old school Canon lenses, I have a couple. But I cannot get the iris to move on them. Not sure how to manually operate a Canon iris. |