Quick macro lens query

When I use my 2x macro teleconverter with my 50mm lens I can adjust the magnification in small increments from 1:3 to 1:1. I find this particularly useful if using a tripod so I can make minor focusing adjustments by altering the magnification, rather than shifting the tripod a few mm each way.

When I use the extension tubes with the 50mm I'm stuck with a fixed 1:1 magnification with a tiny focus throw which inevitably means difficulty placing the tripod exactly.

Does a dedicated macro lens allow slight adjustment to the magnification as well or is a 1:2 lens fixed at 1:2 when the macro facility is used?

Whilst the teleconverter is easier to use the image quality does suffer a little compared with the tubes and I wondered if a proper macro lens would give me the best of both?

A true macro lens simply focuses closer than a standard prime. Having set the camera up on a tripod in approximately the right position you focus as usual. If you want a greater or lesser magnification you then have to move the camera and refocus. Alternatively, if you want a specific magnification you set the lens to that and move the whole camera to focus. A focus rail can be a great help in this.

As far as I am aware, there aren't any true macro (i.e., 1:1) zoom lenses. Although some zooms have a "macro" setting, often they only go down to 1:2 or 1:4.

Hope this helps. Kris.

For very close work, rather than focusing the lens, the final adjustments can be made with a focusing rack. This mounts on the tripod and via very precise gearing moves the whole camera to and fro.

A macro lens focuses just like any other lens, but obviously much closer.

The best onverters are OK but generally not brilliant optically and the same goes for macro converters.

I played with manual extension tubes on an old FA film zoom for a while. Not very good but useful for learning.

My recent cheap Sigma F2.8 50mm macro (£213 from Microglobe)goes from 1:5 at around 350mm to 1:1 at 18.8mm which is of course very close. A longer lens in the series would allow further away (and cost more)

Even the dedicated lens loses a lot of light in this macro process. In any case you need F16 to get any usable depth of field.Manual focus advised.

I'm having fun with it when out. Drives my wife mad though when it interrupts the dog walk!

Thanks.

Bill, if you can't focus at 1:1 because you are slightly too far away can you adjust the magnification to say 1:1.5 rather than move the whole setup. The earlier replies imply not, but yours seems to suggest you can. That's what I can do with the teleconverter which is very useful, but at a cost optically.

I had considered a focusing rail, but the ability to alter the magnification on the teleconverter had done away with that need temporarily. Looks like I might need to start looking again.

I can't afford a new macro lens so am looking at older manual ones. Probably a choice between the Pentax M f4 or a Tamron SP90 2.5 adaptall. Any thoughts between the two or other suggestions for around the £120 mark?

On my Sigma the front element tube extends out as you move from infinity to closest and has a scale engraved on it from !:5 to 1:1 to give you a rough idea of object to image on sensor ratio.

I haven't bags of money either so I went for the Sigma as the cheapest new (grey import though to save another £50)macro on the market. If I'd had another hundred quid to spare I'd have gone for the 70mm model which gives you a bit more distance to work from.

I'd also like a ring flash (don't see many of thopse cheap second hand) but my Sigma with its low power 7 degree down action and a cheap 7 day shop diffuser will have to do for now.

Any cheap manual lenses would be fine if on a budget and 70mm to 90mm seems ideal as I think John has indicated on here before. Am I alone in thinking most second hand prices steep?