IQ loss with tele-converter

[Ron Evers]

I have often read that you loose IQ if you use a tele-converter so I wanted to see for myself. I used a Vivitar series 1, 70-210/3.5 & a Vivitar 2x converter for the experiment on my G1. I set a tripod on our balcony & shot the bird bath in the back yard with a salmon tin sitting in it. The ISO was set @ 100 & I used f5.6 for the shots.


1. Lens set ~ FL 200, no converter, 1/1600s

2. Lens set ~ FL 100 with 2x converter to equal FL 200, 1/400s

There is definitely a loss of light & IQ with the converter in this simple trial.

 

[pellicle]

are these 100% segments?

 

[Devon Shaw]

I've appreciated seeing your tests with all these old lenses.

One possible problem I see with this test though is that the lens might not have the same image quality when used alone at the different focal lengths.

 

[Ron Evers]

are these 100% segments?

I cropped off snow top & bottom only.

 

[Ron Evers]

I've appreciated seeing your tests with all these old lenses.

One possible problem I see with this test though is that the lens might not have the same image quality when used alone at the different focal lengths.

I expect this is true of any lens.

 

[pellicle]

I cropped off snow top & bottom only.

no wonder it was hard for me to pick any significant difference.

I'd feel comfortable using that TC ....

 

[Tullio]

Both images look very similar (you can actually see more details under the water on the second shot). I have a Kenko 1.5x tele-converter (Pentax mount). I'll check it out just out of curiosity.