Will an extension tube (spacer ring) work with the XA10?

[Nick Mirro]

I'm trying to decrease working distance when using a teleconverter (Canon TL-H58 1.5x). The minimum is 47"

Does anyone know if adding a spacer ring (58mm/58mm) has the same effect as an extension tube for SLR, that is reducing the minimum focusing distance? The object is to enable the teleconverter to produce macro images, but further out than with a diopter.

btw, the Raynox 2.2x teleconverter is actually a good match for the XA10. Optically, it surprisingly sharp - for the price - and does not produce lousy images like other 3rd party lenses.

[Alastair Traill]

Hi Nick,
Do you want to fit the spacer ring between the XA10’s lens and the teleconverter? If that is the case my guess is that it would do nothing significant to the working distance and could cause vignetting and other problems. Extension tubes are placed between the camera lens and camera body and make normal zooming impossible. Also you obviously have to be able to remove the camera lens to use an extension tube.

If you have a non-removable lens and want to reduce the working distance the easiest way to do this is to use a close up lens. Their strength is usually measured in diopters which is the reciprocal of the focal length in metres. A 1 diopter lens has a focal length of 1 metre and in use gives you 1 metre between subject and sensor when the camera lens is set to infinity. Likewise a 2 diopter lens gives you ½ a metre between subject and sensor. A 3 diopter gives you 1/3 metre and so on. If you want to estimate the minimum distance a given close up lens will give you add its power in diopters to the to the to the cameras minimum focusing distance (measured in diopters). So if your camera will focus to 1 meter it has 1 diopter of focusing power. If you use a 1 diopter close up lens and the camera lens is set to 1 metre the powers are added together viz, 1+1=2d or ½ a metre. Thus in this case a 1 diopter lens will give you a range from 1 metre to ½ a metre from the sensor.

[Nick Mirro]

Hi Alistair. Thanks for helping. The teleconverter is removable. Vignetting is already an issue with the Canon add-on lens. Since it is for telephoto, it is almost always used near full zoom, which solves that. I expect that extension will create a bit more but no problem there.

I'm trying to decrease working distance when the telephoto is attached. It is 4 feet. I already use diopters but do not need them in this case. Their working distance is too close for some work.

Question is will extending a telephoto lens on a camcorder (via spacer) decrease working distance?

[Don Palomaki]

You can do a simple test if you aleady have the tele converter, Use some black craft paper to simulate the extension tube and block out stray light. Place it between the camcorder lens and the teleconverter.

I would be sutprised if the results are satisfactory. I think a close-up attachment is a better approach, but keep in mind that quality (and price) varies greatly among brands.

The combination of teleconverter and extension tube (for close-up) on a camcorder with a 10x zoom range sounds a like a rather unusual requirement.

[Nick Mirro]

Thanks for the input! I'll try the construction paper, but without a tripod collar on the teleconverter, I expect all sorts of movement and light leak. Maybe it will be a good test :-)

I own both the 250 and 500D. The working distance of even the 500D is too close at 19". I'm aiming for around 2-3 feet. Teleconverter alone is 49".

The requirement is unusual to be sure, but in principle basic. That is unless the extension tube concept does not translate from SLR to camcorder. Guess that is the question.

[Nick Mirro]

Firstly, you were exactly right about the construction paper. Worked perfectly for the test. Thanks!

The result was completely unexpected. I added 5 mm of extra space between the camcorder lens and the teleconverters.

There was no difference in minimum focusing distance at all. Not even slight. Optically it even looked identical. I set up on an NBS test chart to be sure. What the heck?

Why does it change the focusing distance for SLR and not for a camcorder? Does it have something to do with the small sensor size?

[Nick Mirro]

I erred in not understanding the teleside converter concept, forgetting that the camcorder's primary lens is not removable like it is with an SLR.

[Alastair Traill]

Hi Nick,
As I said I did not expect putting an extension between camera lens and televerter would do anything useful. If you know what working distance you want you can select a close-up lens to suit. Your 500D lens has a 500 mm focal length so the maximum distance you can focus to is about 500 mm or ~ 19” as you indicated.

If you want to work in the 2 – 3 foot range you need a 1 diopter close-up lens (1000 mm) which will give you a maximum focusing distance of about 40”. The minimum focussing distance will depend on the XA10 lens minimum object distance but is likely to be ~20”.

[Don Palomaki]

FWIW: the minimum focusing distance of the XA10 at full zoom is spec-ed at 60 CM (about 2 feet).

[Alastair Traill]

Thanks Don,

A 60 cm minimum focusing distance represents a focusing power of 1/0.6 = 1.7 diopter. If you now add a 1 diopter close-up lens you get 1.7 + 1 = 2.7 diopter and the minimum focusing distance becomes 1 /2.7 metres or ~ 37 cm. In other words a 1 diopter close-up lens should give Nick an even better range than he requires. Furthermore he will still be able to use his zoom which he would not have been able to do had he been able to add an extension tube between lens and camera.

I use close-up lenses a lot and consider it worthwhile to get an oversize one to prevent vignetting. This of course necessitates the use of a step up ring. This can have the advantage of using the same close-up lens on several lenses by using suitable step up rings.