Original 1.4x TC

[rpcrowe]

I have an original Canon Mark-1 1.4x Teleconverter which I am going to try today on my Canon 7D2 with 100-400mm f/4.5-5.6L IS II lens. I have had this TC for years and years. I tried the 1.4x TC on my 7D Mark-1 with a 300mm f/4L IS lens attached and the images came out reasonable well. However, I never used that combination in real life shooting since I owned a 400mm f/5.6L lens.

Has anyone tried the combination of the older TC with the 100-400L Mark-2 lens? ? If so, what should I be looking for.

The addition of the 1.4x TC will reduce the aperture of the 100-400L Mark-2 (at longer focal lengths) to f/8 which is within the center spot auto focus capabilities of the 7D2 camera.

Of course, using a crop format, I am effectively eliminating the outer edges of the image circle. It is these outer edges of the image which, I think, would show the first impact of the 1.4x TC on image quality. Am I correct in this logic.

I am going to shoot in RAW and apply the normal sharpening I apply to all my images. I will also apply any anti fringing controls. In other words, I will treat these images exactly the way I treat any other images... I will shoot these images wide open and also around f/11.

I plan on shooting the images from a sturdy tripod with the lens set on 300mm and 400mm. My rationale for this choice of focal lengths is that I would not use the 1.4x TC at focal lengths that I could achieve with the lens alone.

I will also try to compare the IQ of the image shot with the 1.4x TC with the lens at 400mm and a crop from the image I achieved from the bare lens which would bring my subject to approximately the same size as the image shot with the 1.4x TC...

Any other ideas???

[William W]

...
I will also try to compare the IQ of the image shot with the 1.4x TC with the lens at 400mm and a crop from the image I achieved from the bare lens which would bring my subject to approximately the same size as the image shot with the 1.4x TC...

I think that is a good test. Probably the best test for a practical useful study.

Look for aberration, especially chromatic. Also look for acutance (edge sharpness). I'd use the naked lens at both F/5.6 and F/8 for this test. The reason for F/5.6 is to get an idea what you can get from cropping with one stop lower ISO.

WW

[Stagecoach]

I would recommend that you also undertake a test to check for near/back focusing Richard if you intend primarily using AF. Very easily done wide open at f/8 and targeting the markings on a steel rule placed at around 45 deg and 3 m away as the result can be seen immediately in the viewfinder.

From recent experience when adding a 1.4TX to my Nikon 80-400mm at 400mm I had serious front focusing when used on both my cameras.

Yes, I understand the implications of fine tuning a zoom lens, but, I specifically wanted it as good as possible at 400mm.

[William W]

I would recommend that you also undertake a test to check for near/back focusing Richard if you intend primarily using AF. Very easily done wide open at f/8 and targeting the markings on a steel rule placed at around 45 deg and 3 m away as the result can be seen immediately in the viewfinder. . .

I wonder if that would be good to do at (for example) a distance of 20m? If there is front/back focusing issue, does it always remain the same across the range of focussing distances. I don't know, I have never investigated that particular aspect of AF.

???

WW

[Stagecoach]

I wonder if that would be good to do at (for example) a distance of 20m? If there is front/back focusing issue, does it always remain the same across the range of focussing distances. I don't know, I have never investigated that particular aspect of AF.

???

WW

Ok Bill, the full story.

I was obsessed with shooting small crabs on the rocks using the 80-400 mm always at max or near max FL and these subjects had excellent AF targets, eyes on antennas and I achieved good sharp results on the eye I AFd on. Shooting distance around 3 to 4m as they are so skittish.

I then started using a 1.4TX with the 80-400mm at max or near max FL and immediately noticed the eye I had AFd on was not as sharp as it could be BUT the image was sharper at a plane forward to this.

A quick 45 deg ruler check (at rough distance I would be using for the crabs) very clearly showed, without even the need to take a shot, far more was in focus in front of my AF target point. I then undertook more extensive testing, confirmation and fine tune adjustment (+18 of -20,0,+20 available adjustment).

I have also confirmed using kite surfers at mega shooting distance it's spot on at max FL.

As for the shorter FL basic tests have shown that it's acceptable BUT to be honest I rarely use this lens plus TX at other than long FLs. If I had not been forced to shoot the crabs so often wide open at f/8 with such limited DoF chances are I would have never noticed the problem.

As to tuning AF I would suggest when, what and how you do it should take account of your own personal priorities and it can also be very quickly turned on or off.

[rpcrowe]

I have not had the chance to play with the lens + TC (doggie priorities) however, I am want the lens to focus perfectly (which it seems to do) without the TC. If there is a bit of a problem with the TC, that will not bother me that much since I don't see myself using the lens wit the TC very often, if at all...

[Stagecoach]

I am want the lens to focus perfectly (which it seems to do) without the TC. If there is a bit of a problem with the TC, that will not bother me that much since I don't see myself using the lens wit the TC very often, if at all...

This is overcome with the lens/TC/Camera combo I have fortunately by the cameras automatically recognising when the TC is fitted and only applying the AF fine tune biased setting when it sees the TC on.

With the TC not fitted I have no AF fine tune adjustment set for the AF focusing on the 80-400 as I have found no problem with it.