Close up filters

Sir SR

Sir SR

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Shaheed
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So I've taken a punt on a +2 achromatic screw in filter.

Anybody have any experience of using such things?

Will use it for up close portraits/ "arty" pics to put up round the house

Any change to DOF with them or is it just focussing distance?

I suspect shallower DOF but not sure.

Ta

Shaheed
 
If it's a +2, that would be the strength in dioptres (the reciprocal of the focal length in metres, which sounds an odd way of expressing it, but it's done for a reason). That means that when the lens is focused on infinity, objects half a metre away are in focus. Normal depth of field "rules" apply, so, yes, it will be shallower.

The reason for using dioptres is to make the effect of stacking close up lenses easy to see - you just add the values, and the focus distance is the reciprocal of the answer in meters (e.g. +2 and +3 = +5, so the focus distance is 1/5 meter).
 
StephenM said:
If it's a +2, that would be the strength in dioptres (the reciprocal of the focal length in metres, which sounds an odd way of expressing it, but it's done for a reason). That means that when the lens is focused on infinity, objects half a metre away are in focus. Normal depth of field "rules" apply, so, yes, it will be shallower.

The reason for using dioptres is to make the effect of stacking close up lenses easy to see - you just add the values, and the focus distance is the reciprocal of the answer in meters (e.g. +2 and +3 = +5, so the focus distance is 1/5 meter).
Click to expand...

Thank you

That was a perfectly concise, easy to follow explanation [emoji106]

It should arrive in the next couple of days so I'll use it on a digital camera to get used to it then have a play with the Bronica!
 
IME, extension tubes are a higher quality way of reducing the minimum focus distance.
 
I've used hoya +1 & +2 filters. My mamiya 645 kit came with a mamiya no. 3 extension tube which has been great. Took the minimum focus distance of my 150 f2.8 down from 1.5m to about 70cm. With a long extension you'd probably need to factor in some exposure compensation if you use a handheld meter rather than ttl.
 
I've found that close up tubes are better than close up "filters" too. Any extra glass between the object and the sensor/film can (and usually does!) cause some degradation in IQ but even Chinese air is fairly optically clear... Close up supplementary lenses are usually a lot cheaper than tubes (and can of course be used cross system.)
 
Kei said:
I've used hoya +1 & +2 filters. My mamiya 645 kit came with a mamiya no. 3 extension tube which has been great. Took the minimum focus distance of my 150 f2.8 down from 1.5m to about 70cm. With a long extension you'd probably need to factor in some exposure compensation if you use a handheld meter rather than ttl.
Click to expand...

I did think about the extension tubes but the screw in marumai achromatic filter was available and seemed to be better quality than the Hoya - I'll give it a punt!

Also I liked the appeal of not losing stops of light compared to the extension tubes.

I'll have a play in the next couple of days
 
I think unless you are using stacked extensions, the light loss is no more than 1/3 of a stop, probably less. It's something I have to remember more often when using my 6x7 as the RZ uses bellows which allows for very close focus on any lens.
 
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To calculate the exposure increase necessary, add the focal length of the lens to the extension given by the tube and square the result. Then divide this figure by the square of the focal length. And for the pedantic, this assumes that the lens is focussed on infinity.

Alternatively, if you know the degree of magnification, you can calculate the effective aperture by adding 1 to the magnification and multiply the marked aperture to give the effective value in terms of light passed.
 
I've only used close up filters once, the effect was so weird I was never brave enough again! Centre in focus, edges not just soft but way out of focus... Extension tubes proved very versatile and no such issues emerged. I even used my extension tubes with a pinhole lens to get rid of vignetting. They are a lot bigger than a close-up lens, of course.
 
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