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Comment by ChrisA posted on A reply (sort of) to G's ICBM at 05/08/2007 - 23:03
Just thought that I would share this with you and ask for comments, don't be too cruel, but any help is always welcome.
About 800 pixels is a decent compromise between too small to see the detail properly, and too large to fit on the screen.
Comment by ChrisA posted on First K10D image? at 05/08/2007 - 19:47
how about one set up for one type of shooting and another set up for a different type of shooting...
ie during a wedding I might have one set up for inside the church, and the other set up for outside....
I was thinking more along the lines of a second one as a backup - but presumably not wanting to cart both of them around all the time.
Comment by ChrisA posted on Using two bodies at 05/08/2007 - 19:51
Do you use one exclusively, aiming to keep the other in 'new' condition, or do you use them about equally?
I can see pros and cons of each approach.
Comment by ChrisA posted on Using two bodies at 05/08/2007 - 19:34
Very Well Done Chris...what dedication a lot to digest, merci beaucoup, Lil
Comment by ChrisA posted on Reverse mounting for MACRO at 06/08/2007 - 20:38
28mm lens, normal orientation attached to 65mm tube: Magnification 2.4
28mm lens, reversed on to 65mm tube: Magnification 4.2 (5mm of ruler scale occupies almost the entire width of the frame).
And just to add a very modest, but I'd contend, more practical contribution to the amazing 'IRB test', this was taken with the "28mm reversed on to 65mm tube" configuration:

Not wanting to take anything away from Dan's amazing effort on the other thread, it remains the case, surely , that in any "mine's bigger than yours" macro competition, you have to divide the magnification by the price of the lenses, converters and tubes used, to obtain the true MCC (macro competition coefficient).
My lens was 6 quid, the reversing ring was 12, and the tubes were about 30. So that makes my MCC equal to 4.2/48 = 0.0875. Still probably way back in the also-rans
Comment by ChrisA posted on Reverse mounting for MACRO at 06/08/2007 - 19:42
Just stuck that on the reversing adaptor, and here's the result:

It's not at all sharp - I just hand-held it to get this, but as you can see, the magnification is much bigger than with the 50mm lens reversed.
It's about 1.9. So more than the 50mm and the tubes.
Comment by ChrisA posted on Reverse mounting for MACRO at 06/08/2007 - 11:39
I think I might just save up for that 100mm macro !

As you can see, the frame shows 4.55 cm of actual distance, so the magnification is only 24/45.5 = about 0.5, compared with 1.4 with the 50mm and the tubes.
Comment by ChrisA posted on Reverse mounting for MACRO at 06/08/2007 - 09:21
The width of the image shows about 17mm, so slightly under 1.5:1 magnification. Assuming you have similar sized tubes, either the spider was bigger than you remember (4mm body + legs?), or you have super long tubes, or you have a macro 50mm lens.
I photographed a ruler as you did, focused as close as I could; standard 50mm 1.7 lens, 65mm of tube.
Magnification 1.4, as you say.
I guess the spider was bigger than I thought. It was a money spider - tiny. I guess when I measured its size it must have had its legs much more curled into its body - it is quite stretched out in the photo.
Thanks for the correction. 3:1 did sound a bit unlikely, I must admit.
Comment by ChrisA posted on Reverse mounting for MACRO at 05/08/2007 - 22:19
A set of three extension tubes would give you approximately 1:1 magnification with a 50mm lens, but with the result that your subject will be about 25mm from the front of the lens.

It was about 4mm across including legs, and occupied half the original frame width. If the sensor is 24mm wide, that makes the image 12mm wide, so I think that's more like 3:1 than 1:1.
Or have I misunderstood how to calculate the magnification?
Comment by ChrisA posted on Reverse mounting for MACRO at 05/08/2007 - 14:51


I'm also wondering about the eyes. The whites look to have been whitened a bit, which is fair enough, but is it possible that in selecting the area for attention you've damaged the circular part at the bottom? Especially the one on the left as we look at it, they don't look quite the right shape to me.
Otherwise I can see why George approves.