Assume using a 100mm f2.8 macro lens. If i take a shot at f2.8 1/250s at a fixed distance I get a certain depth of field.
Now I add a 1.4x tele to the lens and keep the same lens / subject distance. The tele looses 1 stop of light. Is the actual aperture still 2.8? (so 2.8 1/125 the new exposure) OR has the aperture actually changed to f4(f4 1/250). Will the teleconverter change the depth of field seen.
Not sure I am putting this into words very well. Does adding teleconverter affect depth of field? Obviously the effective focal length is increased which would reduce the depth of field but does the aperture component actually change?
Please let me know if this makes any sense at all?
Duncan
I think the short answer for your example is that the DOF remains the same. Think of the teleconverter as merely an optical method of cropping in-camera. I hope this helps.
Randall
Think of the teleconverter as merely an optical method of cropping in-camera.
Randall
Randall
Thanks, what a nice clear description!
That is kind of what I thought.
Many thanks!!
Duncan
Hi
quick question regarding teleconverters.
Assume using a 100mm f2.8 macro lens. If i take a shot at f2.8 1/250s at a fixed distance I get a certain depth of field.
Now I add a 1.4x tele to the lens and keep the same lens / subject distance. The tele looses 1 stop of light. Is the actual aperture still 2.8? (so 2.8 1/125 the new exposure) OR has the aperture actually changed to f4(f4 1/250). Will the teleconverter change the depth of field seen.
Not sure I am putting this into words very well. Does adding teleconverter affect depth of field? Obviously the effective focal length is increased which would reduce the depth of field but does the aperture component actually change?
Please let me know if this makes any sense at all?
Duncan
The 1.4 teleconverter extends the focal length to 140 mm at the same time reduces the fstop to 4. Since a 140 mm f4 lens has the same DOF as a 100 mm f2.8 the short answer is that it will be the same in this example. Not true if you need to change fstops of course to get the exposure.
