Thanks to all those who replied about my request for a lens cap. I sorted it out by using a very cheap set of extension tubes (£7 for the set - no contacts inbuilt!) I used the fitting and the thinnest tube to protect the contacts on my 24 - 105. Why? I had it reversed onto a 70 - 200 to do some extreme macro work. Here is a solitary granule of brown sugar.
This is a 27 (that's twenty seven) stack shot. The granule is only one millimetre or so in width, but at the magnifications I was using depth of field is less than one tenth of that. The major problem is refocussing. Even the slightest movement of the lens can vary the centre of the image by as much as one half of one millimetre. This is useless at these magnifications. I considered using focussing rails, but they will move the lens too. The problem is that the length and weight of the lens combo makes any movement at all induce lens movement.
I had to find some way of refocussing without touching the lens or camera at all. I resorted to tethered shooting, and the smallest adjustment in EOS Utility was just enough to change the point of focus. Unfortunately there is still some slight ghosting which I think may be due to focus breathing and focus is changed.
Not sure if I can improve this with the equipment available, and I've no wish to start spending silly money. So this remains as an interesting exercise, all for the price of a coupling ring.
This is a 27 (that's twenty seven) stack shot. The granule is only one millimetre or so in width, but at the magnifications I was using depth of field is less than one tenth of that. The major problem is refocussing. Even the slightest movement of the lens can vary the centre of the image by as much as one half of one millimetre. This is useless at these magnifications. I considered using focussing rails, but they will move the lens too. The problem is that the length and weight of the lens combo makes any movement at all induce lens movement.
I had to find some way of refocussing without touching the lens or camera at all. I resorted to tethered shooting, and the smallest adjustment in EOS Utility was just enough to change the point of focus. Unfortunately there is still some slight ghosting which I think may be due to focus breathing and focus is changed.
Not sure if I can improve this with the equipment available, and I've no wish to start spending silly money. So this remains as an interesting exercise, all for the price of a coupling ring.
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