Teleconverters and their effect on focal range

[jubbin2001]

Just curious how much teleconverters affect focal range. I have a Tamron 90mm macro that when shooting 1:1 I have to be really close, let's say 4". Now lets say I order a 2x teleconverter. Does that mean while shooting at 8" 1:2, I am actually shooting 1:1 (since I have effectively doubled the image using the 2x teleconverter)? The numbers aren't exact, I am just trying to get an idea of the concept behind them. I just wish I could get a little more distance away from my subject with the 90mm, since really skittish things tend to disappear when I get close enough to focus at 1:1. If infact this is how they work, perhaps a 1.4x or 1.7x might be in my forseeable future (I haven't heard much good about the 2x, but the 1.7x and 1.4x seem to be well respected). Thanks all.

 

[Taylor510ce]

Just curious how much teleconverters affect focal range. I have a Tamron 90mm macro that when shooting 1:1 I have to be really close, let's say 4". Now lets say I order a 2x teleconverter. Does that mean while shooting at 8" 1:2, I am actually shooting 1:1 (since I have effectively doubled the image using the 2x teleconverter)? The numbers aren't exact, I am just trying to get an idea of the concept behind them. I just wish I could get a little more distance away from my subject with the 90mm, since really skittish things tend to disappear when I get close enough to focus at 1:1. If infact this is how they work, perhaps a 1.4x or 1.7x might be in my forseeable future (I haven't heard much good about the 2x, but the 1.7x and 1.4x seem to be well respected). Thanks all.

The minimum focus distance is what you are asking about. A Teleconverter will do what you are looking for, allowing you to get some distance between you and your subject. Extension tubes will do the opposite, allow you to focus closer.

Also, in most cases the 2x teleconverters degrade the image too much. This may not be the case with Canon and Nikon converters ( never used them but hear great things ) I have a Kenko Pro 300 1.4x and love it.

 

[jubbin2001]

Thanks tons! I thought that is how it went, but I wanted to make sure.

 

[Dao]

Besides, the 2x TC will rob 2 stops of lights vs 1 with 1.4x.

 

[jubbin2001]

Right right. I wasn't going to get a 2x, I was actually just using it for the ease of math involved. I ended up picking up a Tamron SP 1.4x fairly cheap, so we'll see how it goes. Thanks for the replies!