Jim
My Pictures
My Fbook Group
In reply to Whistling Joe:
Tony
https://www.flickr.com/photos/wherryman/
A question was asked elsewhere (on the R5 thread) about using an extender on the macro lens to get the subject larger in the frame, so I've had a little experiment. The Canon 1.4x extender won't fit directly on to the Canon 100mm f/2.8 lens as the extender has a pokey out bit (technical term) preventing it. However, you can add a small tube to the extender to allow it to be used, so I gave it a try. I also have a Sigma 1.4x extender (I normally use it with the Sigma 180mm f/2.8 macro) which doesn't have such a large pokey out bit, so I tried that too. This pic shows the two extenders so you can see the difference
I used my little wooden mouse subject for all these pics, all at minimum focus. The lens was wide open (f/2.8), but it was interesting to note that the pictures' exifs did not report the aperture OR the focal length correctly. All these images show 100mm f/2.8, when they should have been 140mm f/4 (you lose a stop of light when you gain the focal length by adding an extender). AF worked each time, so communication was established between camera and lens, I can only assume that bolting bits together that are not normal interrupts the regular reporting between camera and lens. One other thing to note on AF. Well, two actually. AF through the viewfinder (I was using the Canon 5D4) didn't work very well - it kept hunting - so I used Liveview instead (which was fine). Infinity focus was lost however, when using the Canon extender + tube. This is not surprising as you always lose infinity when using tubes, but worth considering should you want to use this method. The Sigma 1.4x extender focussed to infinity OK (as expected). So, some pics. These are in pairs - an image showing each setup, together with a ruler to give an idea of the working distance, and the actual image taken. The images were all taken with AF (which locked each time) but the depth of field is very thin, so don't expect brilliant pictures!. What we're really interested in is the size difference of our subject
First, this is the basic camera + lens
The unit on the front of the lens is an LED ring light (in case you'd forgotten!). Working distance around 13.5cm
This is with the lens and the Sigma 1.4x extender
Working distance around 12cm
Now the Canon 1.4x + 12mm tube
Working distance around 11cm
Now, finally, the lens on its own but with a stack of tubes attached
Working distance about 8.5cm
So, what have we learned from all this? It does make sense if you think about it. Adding the Sigma extender gives you a bigger image, but your working distance shrinks by about the same amount as the extender thickness (which is 20mm). That's because the extender isn't reducing the minimum focus distance (which is measured to the camera sensor). So, a useful gain in subject size (or, put another way, you could hang back a bit to get the same size image). The Canon gives you a bigger image again, but that's because we have a tube as well as the extender. Putting a whole bunch of tubes in place gets you closer still - but none of this helps with trying to hold back in order to avoid scaring your subject.
So, for this pair of pictures, I used the lens + Sigma 1.4x and moved my subject away until the framing approximated that of the bare lens, to see how much further away I could get for the same image
Working distance around 15.5mm. So I gained about 3.5cm - nearly an inch & a half for all the messing around. Not sure if it's worth it!
Finally, I thought I'd put my other suggestion to the test - the 100-400 Mk2. This is a great bug lens, with a 3ft minimum focus, but it definitely gives you a smaller image
You do get a 63cm working distance though - far more useful for twitchy insects. If you add some tubes - this is the full set - your working distance falls to 31cm, but the subject size is actually not that far off that of the standard macro lens. OK, you're going to need extra light (I should probably have added flash on these two pics) and, as with any tubes, Liveview focus seems more reliable than through the viewfinder, but.....
Final word - these are all taken with the Canon 5D4, which is a full frame body. Remember that using a cropped sensor camera will help pull the image closer as well. The little mouse is about 22mm from the tip of his nose to his bottom (in case you were wondering!
___
Find me on Flickr / All about your camera - The Getting off Auto Index
Interesting. I must admit, I was surprised the difference of a converter was that low - a 20% improvement. It should have been closer to 40%, shouldn't it? I suppose there might be a bit of difference due to the length of converter/tubes reducing working distance, so perhaps at longer distances, it will approach the 40% as the length of the converter will have less of an impact at longer distances. My interest is piqued and I'll try a few experiments myself.
I think you're losing the EXIF info because you need the extender between the lens and the converter. If I attach a 1.4 converter to the 105mm macro and put the extension tube between the camera and converter it does recognise it as a 150mm focal length in EXIF data.
Anyway, I generally find it easier to use a converter than an extension tube as you don't lose infinity focusing and it doesn't hunt as much. Extension tubes are fine in the studio but can be a pain in the wild. Just my preference!
__________
Nige Flickr
In reply to Nigel O: