Confus-ed ...
May 27, 2012 14:54:37 #
Question on converters ... I have a Canon XSi and Tamron lens (24-135, 70-200, and 200-500). If I look for a 1.4 or 2.0 converter, do I look for a Canon or Tamron compatibility? Or both? I have a converter that works on my 70-300 kit lens that came with the camera, but that doesn't work with the 18-55 lens that also came with the kit lens, so I'm confused on how to get them that work with what I have.
May 27, 2012 15:03:34 #
What doesn't work? Does the lens not fit the converter or not operate the auto-focus?
May 27, 2012 16:11:03 #
jimni2001 wrote:
What doesn't work? Does the lens not fit the converter or not operate the auto-focus?
The lens doesn't fit the converter. As a side note, I think I read someplace that the AF probably wouldn't work on a converter...???
May 27, 2012 16:21:22 #
Photo-Al wrote:
The lens doesn't fit the converter. As a side note, I think I read someplace that the AF probably wouldn't work on a converter...???
jimni2001 wrote:
What doesn't work? Does the lens not fit the converter or not operate the auto-focus?
The lens doesn't fit the converter. As a side note, I think I read someplace that the AF probably wouldn't work on a converter...???
Canon AF will generally work on a converter (extender) if the lens f-stop + the lost f-stop from the converter does not exceed 5.6. For example, if your lens is an F4, a 1.4 converter adds 1 f-stop, so you end us with an effective 5.4 which should auto focus most of the time in good light. However 2 x converters add 2 f-stops which is effectively creates a lens with an f-stop of 6 which usually will not auto focus very well, if at all depending on light and contract. Generally, converters work best on wider aperture lenses, such as f2.8.
I'll let others address the electrical and mechanical compatibilities you asked about.
May 27, 2012 16:28:01 #
Photo-Al wrote:
The lens doesn't fit the converter. As a side note, I think I read someplace that the AF probably wouldn't work on a converter...???
jimni2001 wrote:
What doesn't work? Does the lens not fit the converter or not operate the auto-focus?
The lens doesn't fit the converter. As a side note, I think I read someplace that the AF probably wouldn't work on a converter...???
Some of the converters do have the electronics to operate the AF.
May 27, 2012 18:08:26 #
Originally, though, my question was whether or not I had to find a converter specific to the lens (i.e. Tamron) or to the camera (Canon)... or both? I am using a 450D, plans to upgrade to a 7D, and I use Tamron lens. My most used is the 70-200mm f/2.8, my walkaround is a Tamron 24-135mm f/3.5-5.6. I also have a 200-500mm and while I would love to see what a converter would do with that, I am mainly concerned with the other two lens. The Tamron SP lens would work on a full-frame as well as the crop sensor, and I assume that makes a difference on the converter, but ....???
May 27, 2012 18:19:17 #
I guess I am confused. If your lens fits the camera without a teleconverter then I would think that a Canon converter would fit both. If that is not the case I am at a loss.
May 27, 2012 18:28:21 #
A Canon EFS lens will not fit a standard doubler or 1.4 either. The reason is that on the EFS lens' they have added an extension behind the rear element that linits the spread of light to the sensor corners. The doubler should work with all EF series lens'.
This is simply another bill of goods being foisted on the lens buying public which makes extra money for the manufacturers. My personal opinion is: EFS lens' do nothing to make better images when using a camera having an APS-C Sensor.
This is simply another bill of goods being foisted on the lens buying public which makes extra money for the manufacturers. My personal opinion is: EFS lens' do nothing to make better images when using a camera having an APS-C Sensor.
May 28, 2012 09:39:27 #
ole sarg
Loc: south florida
Back to the question. E mail B&H or Adorama and ask which tele converter fits both the camera and the lens.
May 28, 2012 23:04:27 #
Photo-Al wrote:
Question on converters ... I have a Canon XSi and Tamron lens (24-135, 70-200, and 200-500). If I look for a 1.4 or 2.0 converter, do I look for a Canon or Tamron compatibility? Or both? I have a converter that works on my 70-300 kit lens that came with the camera, but that doesn't work with the 18-55 lens that also came with the kit lens, so I'm confused on how to get them that work with what I have.
You probably won't find one to work with your 18-55. Canon says this about their converter/extenders "This tele extender can be used with fixed focal length lenses 135mm and longer (except the 135mm f/2.8 Softfocus lens), and the EF 70-200 f/2.8L, 70-200 f/2.8L IS, 70-200 f/4.0L, 70-200 f/4.0L IS USM, and 100-400 f/4.5-5.6L IS zoom lenses." Other brands will have similar requirements.
May 28, 2012 23:43:15 #
glojo
Loc: South Devon, England
Photo-Al wrote:
Question on converters ... I have a Canon XSi and Tamron lens (24-135, 70-200, and 200-500). If I look for a 1.4 or 2.0 converter, do I look for a Canon or Tamron compatibility? Or both? I have a converter that works on my 70-300 kit lens that came with the camera, but that doesn't work with the 18-55 lens that also came with the kit lens, so I'm confused on how to get them that work with what I have.
Can't help with the Canon, Tamron specific question BUT... Certain Sigma lens loose the automatic focus ability when using certain ratio converters on the Nikon camera which to me compares to your Tamron with Canon option? You are definitely right to ask before putting hand into pocket :thumbup: I was told to tamper or muck about with the relevant pins on either the camera body or lens, I can't remember which as there was NO WAY I was going to risk damaging either the camera or the lens.
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