Drake
TPF Noob!
- Joined
- Nov 19, 2007
- Messages
- 684
- Reaction score
- 10
- Can others edit my Photos
- Photos NOT OK to edit
So I've been thinking about turning my M42 Helios 58mm f2 into a cheap macro lens. I figured that probably the best way of doing that is getting some extension tubes.
But I'd like to know the effect first. Is there a way of calculating what magnification I'll get? I've read somewhere that an extension tube of the same length as the lens should give you 1:1 magnification, eg. 50mm extension tube used with 50mm lens. On a crop body at least. I found it hard to believe, since all lenses have very different minimal focusing distances.
But I decided to give it a try anyway, removed the lens and started looking through the OVF with the 58mm lens roughly 50-60mm from the camera. And, to my surprise, it looks about right. Of course there's a huge light spill because the lens were hand held and not actually on a tube, but what's important is that the magnification was about 1:1. Am I missing something, or it is actually possible?
Now let's say I get a 50-60mm set of extension tubes to go with my 58mm prime. How will it be optically different from a Canon 60mm dedicated macro lens? How much light approximately will I lose because of the extension? 1EV? 3EV? More? What about the DOF? Will the DOF of my lens on let's say f8 be the same as of a real macro lens or smaller? And lastly, how far can you go with extension tubes? What if I put 2 sets of them between the camera and lens? Will I lose too much light this way to shoot? I know the DOF will be very, very small, but then, 2:1 magnification isn't something surprising, is it? The question is, will it be usable in terms of the amount of light required?
But I'd like to know the effect first. Is there a way of calculating what magnification I'll get? I've read somewhere that an extension tube of the same length as the lens should give you 1:1 magnification, eg. 50mm extension tube used with 50mm lens. On a crop body at least. I found it hard to believe, since all lenses have very different minimal focusing distances.
But I decided to give it a try anyway, removed the lens and started looking through the OVF with the 58mm lens roughly 50-60mm from the camera. And, to my surprise, it looks about right. Of course there's a huge light spill because the lens were hand held and not actually on a tube, but what's important is that the magnification was about 1:1. Am I missing something, or it is actually possible?
Now let's say I get a 50-60mm set of extension tubes to go with my 58mm prime. How will it be optically different from a Canon 60mm dedicated macro lens? How much light approximately will I lose because of the extension? 1EV? 3EV? More? What about the DOF? Will the DOF of my lens on let's say f8 be the same as of a real macro lens or smaller? And lastly, how far can you go with extension tubes? What if I put 2 sets of them between the camera and lens? Will I lose too much light this way to shoot? I know the DOF will be very, very small, but then, 2:1 magnification isn't something surprising, is it? The question is, will it be usable in terms of the amount of light required?