query: Why is there a maximum focus distance when using an extension tube?
positive_passages.docid: 29080
positive_passages.text: How do extension tubes affect focusing distance?
negative_passages.docid: 51290
negative_passages.text: Does my crop sensor camera actually turn my lenses into a longer focal length?
negative_passages.docid: 106963
negative_passages.text: How can I calculate what the effect of an extension tube will be?
negative_passages.docid: 56821
negative_passages.text: Why does depth of field occur?
negative_passages.docid: 93638
negative_passages.text: How can I get the most possible depth of field out of close-up/macro shots?
negative_passages.docid: 59156
negative_passages.text: What lens is needed to change the minimal focus distance length of my camera?
negative_passages.docid: 10820
negative_passages.text: What is the formula for percent of frame filled at a specific distance and focal length?
negative_passages.docid: 95190
negative_passages.text: What should I look for in lenses for long range and close up animal and natural shots?
negative_passages.docid: 41934
negative_passages.text: How do zoom, magnification, and focal length relate?
negative_passages.docid: 47641
negative_passages.text: what is the purpose of condenser lens in a slide projector?
negative_passages.docid: 145622
negative_passages.text: How do constant aperture zoom lenses work?
negative_passages.docid: 142585
negative_passages.text: Is there a theoretical maximum for refractive index?
negative_passages.docid: 60690
negative_passages.text: Optical microscope magnification limits?
negative_passages.docid: 9671
negative_passages.text: Do gravitational lenses have a focus point?
negative_passages.docid: 130570
negative_passages.text: Why can't my SLR autofocus on certain parts of a scene?
negative_passages.docid: 26420
negative_passages.text: Possible to lock focal length on zoom lens? (SELP1650)
negative_passages.docid: 94271
negative_passages.text: What is the reference plane used when the minimum focus distance is measured?