Aperture control on reversing ring

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cavemanaston

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Hello all,

I have had a quick look for any mention of it and can't find anything.
So I was wondering if anyone has found something that allows manual control of aperture when using a reversing ring or extension tubes.

All my lenses are new and therefore don't have any manual controls and I do not want to buy more lenses.

I also do not want to spend excessive money on getting extension tubes with electrical connections if I can help it.

I have seen some kits to swap a Sony A (a77 my camera) or Nikon to a Sony nex that has aperture control but wondered if there was a specific one just for the aperture without the extra cost of electrical connections to mount it to another camera type?
 
What you're looking for is a Macro lens reverse AF cable. Not many people make them but there's a decent one for around £200. Basically it allows you to use full electronic control over the lens with aperture value, it can meter the shot and focus for you. Have a look on the ebay china website as there's a few on there. Alternatively I believe Amazon sell some :)
 
Thanks but I was really looking for a more professional version of a lens cap with the centre taken out and a pin or something that pushes the aperture blade and locks in place.
 
Possibly the easiest (and cheapest) way is to use old lenses, probably fully manual (focus and aperture) 42mm screw thread mount lenses and reversing rings. Some of them are completely manual and don't have the auto stop down pin. Might take some experimentation to get the right exposure (or careful reading of the manual to find out how to do stopped down metering).
 
If you're referring to modern lenses then you won't be able to manually move the aperture regardless as they're generally sealed units anyway?
Unless you go down the old school route and find some manual lenses with aperture adjustment on the lens ring etc...
 
Another possible method would be to use one of your existing lenses mounted normally on your camera, then one of the old ones Nod mentioned mounted reversed via a coupling ring. This connects the two lenses via their filter threads.
So if you have a 50mm prime for your Sony, then screw on (eg) a reversed Helios 58mm, you'd have a 108mm lens which would focus very, very close. The normally mounted lens would retain your aperture control and you'd be metering through the camera.
Naturally, if you set the Helios (manually, of course!) to f5.6 and the camera mounted lens to say f8, the camera would meter for the combined light loss.
I've used reversed old lenses, on and off tubes. I've had some decent results, too. However, at the sort of apertures often used in macro (f11 and above) I struggle to focus through such a dark viewfinder. With the combined lenses, I've been able to keep the viewfinder bright enough, as the camera mounted lens will be at it's most open until I take the shot :)
 
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Carter64 said:
So if you have a 50mm prime for your Sony, then screw on (eg) a reversed Helios 58mm, you'd have a 108mm lens
Click to expand...

It doesn't work like that. You have to convert the focal length to Dioptres, add them together then convert back to focal length.

One Dioptre is 1 divided by the focal length in metres.

So using your examples, 50mm is 0.05m which is 1/0.05 = 20D

The 58mm lens is 17.24D

Combined it is 37.24D which translates back to 0.02685m or 26.85mm

Adding extra power to a lens makes it a wider angle lens. This works for macro as in order for it to work at infinity, it would usually have to move closer to the film/sensor than the mechanics will allow. In it's fixed position it is too far away to focus at infinity but ideal for close subjects.

** It's not quite as simple as that as the equation is really for simple single elements close to each other, but it's close enough to show what goes on when two lenses are used together.


Steve.
 
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the evf on my a77 auto brightens (certainly if you have flash enabled), but fine detail can disapear in noise.

theres a tamron 90mm with sony mount in classifieds for 70quid, buy that, its a great lens, and a damn good price, if its in decent condition
 
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