Extension tubes

[Shadowman]

Good to have found this thread I managed to buy a Sigma 105mm f/2.8 rather cheap off my brothers friend, whilst I love this lens one to two things confuse me.

I've been told 1:1 is true macro but when I use this I don't always seem to be able to fit all the subject in the frame, do I need to use a different setting than 1:1 or would I fare better with some extension tubes, also if I use say 1:2 is this still classed as a macro photo . I tend to use it mostly for flower pictures and seed heads etc.

New to photography so everything is a challenge at the moment and sorry in advance for stupid questions.

KarenO.

What is the size of the object you are photographing? How close can you get to the object and remain in focus? Are you using auto or manual focus?

[KarenO]

I usually find it happens with flowers I don't always get all the flower head in the frame even it's a smallish flower, I am using manual focus and I seem to be able to get about 6 inches from the flower when using 1:1 magnification.

Do people still crop pictures when taking macro?

Thanks KarenO.

[Stagecoach]

Hi Karen,

The often used definition of macro is a 1:1 ratio where for instance if you have a 23.6mm width sensor a bug or flower which is 23.6mm wide fills the frame exactly from side to side.

The term macro and close-up are quite loosely used and in real world photograph perhaps not really important.

If you use tubes you will be able to get 'smaller' objects to fill the frame than without tubes. The downside of this is that the DoF reduces.

I crop at times when using high magnifications, there is of course a loss of image quality but it's just one of the many losses and balances we have to make in any image.

Grahame

[Nass]

Good to have found this thread I managed to buy a Sigma 105mm f/2.8 rather cheap off my brothers friend, whilst I love this lens one to two things confuse me.

I've been told 1:1 is true macro but when I use this I don't always seem to be able to fit all the subject in the frame, do I need to use a different setting than 1:1 or would I fare better with some extension tubes, also if I use say 1:2 is this still classed as a macro photo . I tend to use it mostly for flower pictures and seed heads etc.

New to photography so everything is a challenge at the moment and sorry in advance for stupid questions.

KarenO.

1:1 is the definition of true macro, yes. But many brands try and get away with selling closeup lenses as macro lenses, which does nothing to help consumers and is just really a marketing gimmick.

If it means your subjects are too big to fit then you can either use a camera with a bigger sensor (ie full frame) which is expensive, or you'll just have to shoot smaller subjects

have a look at my site at http://extreme-macro.co.uk, it's a learning site about macro, might clear up a few things here and there

[KarenO]

1:1 is the definition of true macro, yes. But many brands try and get away with selling closeup lenses as macro lenses, which does nothing to help consumers and is just really a marketing gimmick.

If it means your subjects are too big to fit then you can either use a camera with a bigger sensor (ie full frame) which is expensive, or you'll just have to shoot smaller subjects

have a look at my site at http://extreme-macro.co.uk, it's a learning site about macro, might clear up a few things here and there

Thank you both for your answers, think I've grasped it now will have a look at your site now, always keen on learning.

Karen.

[jcuknz]

Good to have found this thread I managed to buy a Sigma 105mm f/2.8 rather cheap off my brothers friend, whilst I love this lens one to two things confuse me.

I've been told 1:1 is true macro but when I use this I don't always seem to be able to fit all the subject in the frame, do I need to use a different setting than 1:1 or would I fare better with some extension tubes, also if I use say 1:2 is this still classed as a macro photo . I tend to use it mostly for flower pictures and seed heads etc.

New to photography so everything is a challenge at the moment and sorry in advance for stupid questions.

KarenO.

When you use a longish lens you do not have to come in so close to obtain 1:1 as if you were using a short lens. I;I with an APS-C camera is something about 23mm across filling the sensor.

Your lens has a minimum focusing distance of 12.31 inches so if you cannot get everything in you need to move back to included more of the subject from further away.
On the other hand if you cannot get a small enough area filling the sensor you have two options, first is to get a close-up lens to suit the lenswhich has a 72mm filter/close-up lens thread. If you were to get a two dioptre or 500mm CU lens this would enable you to come in to about 7.3inches and would give you a tighter framing on the subject.

The other option for you is as I gather Stagecoach uses and this in the extension tube[s] which fits between camera and lens and provide extra focusing /extension. Here it is worth repeating the advice about the cheap extension tubes which do not connect electrically the camera to the lens and as far as I can see the lens doesn't have a manual aperture ring to handle that problem, a kacky way of working anyway, so you must get 'auto' extension tubes.

That you have an f/2.8 lens means you will have a bright image for focusing and, if you set to use it, it has a f/22 aperture for maximum depth of field. Some will caution against using small apertures from which diffaction causes unsharpness but I think it is generally thought that it is better to risk some diffraction rather than loose DoF in using a larger aperture such as f/11.

A side note about my expression "working properly" used earlier. If the CU lens is the same size or smaller than the camera lens it will work as a sort of aperture and cause a loss of transmitted light. My experience of this comes from playing around with my telephoto adaptors purchased for use on my bridge cameras but becuase I have then offered up in front of my DSLR lens and MFT lens. Used on my bridge camera there is about a third of a stop of light but when added to my Tokina f/4 I lost two stops. Then on arrival of MFT and its 140mm f/5.8 lens I had a loss of about 1.6 stops.

On measuring the front lens diameter of the camera lens and that of the rear pupil of the adaptor there was a marked difference in diameters which leads me to think that for 'proper' or maximum light transmission the 'front lens' needs to be bigger than the camera lens. However good the Raynox is it did strike me as rather small for use on a larger DSLR lens and while it would take excellent photos there would be quite a bit of light loss, with for instance the large 105mm f/2.8 that Karen has though could work better with the small 'kit' short zoom DSLRs often come with. Usually f/5.6 at full zoom which is a compafritively small bit of glass compared to Karen's 105 or my Tokina 230mm f/4 used in my experiments. The range the Raynox will work on is I believe is the mounting diameter which appears to be bigger than the actual lens.

Another consideration is the angle of view of the camera lens. I first noticved this when I offered my 50mm SLR lens in front of my P&S camera with its 80mm lens at full zoom and I got a severe vignetting ... just a ring of image surrounded by black
Later with my two telephoto adaptors, a Raynox 2020 which starts to vignette almost immediately I try to zoom back whereas my OLympus TCON x1.7 permits me to zoom back to about x7 [ of the camera's x12 zoom ] before it starts to vignette.
One of the first things I learnt when using long lenses was the frustration of not being able to get a wider view. I bought the Raynox and then later the TCON.

[jcuknz]

There is a third option which I have just started to learn about after getting myself a x2 Telephoto converter [ my $15 gamble mentioned earlier ]. Used with the 230mm Tokina f/4 that gives me an f/8 lens ...marginal for a PDAF camera but my Olympus E-PL1 is CDAF so no problems.
My roses suffer considerably from wind damage so I have what I have rather than 'show blooms' but this one was taken from about five feet or so, is full frame with the 920mm angle of view rig.