And here's a stack of 7 using coker's pointer and rotating protractor method for adjusting focus. Q-S1 with 30mm and reversed 35mm macro, as above. The pointer is a bit of wire attached to the knob on the 300's tripod collar. Protractor is thin cardboard, fixed by elastic band to the focus ring (thank goodness it's a big one on the 300).




They're getting better. Next steps are to adjust lighting to reduce highlights, improve the wire pointer and do something a bit better for positioning specimens. And perhaps add a tube or two between lens and camera.

Of course, what I'd really like (wouldn't we all...) is the Novoflex stepping motor controlled rack, repeatable steps as small as 0.2 micron (i.e. 1/5,000 mm). But at getting on for £2K (:shock, it's really far too much of an extravagance...

Steve

Words first, then a picture.

The Novoflex rack is of the rack and pinion type. It has a scale marked out in cm and mm. The mount is moved along the rack by rotating a smallish knob on the mount. Unaided and with a steady hand, 2 steps per mm are possible. However, Novoflex provide (at a price!) a 'fine adjustment handle' which can be fixed to the knob and allows finer control - same principle as your pointer and protractor. It's attached in the picture below. Rotating the handle by 4 marks on its scale moves the mount by 1mm, so that's 1/4mm per mark. 3 steps per mark are just about possible, so that's 1/12mm per step. The rest is just a matter of being careful and patient. And, of course, it's only possible because of superb engineering by Novoflex - not cheap, but you really do get what you pay for here.




Steve

That's why I'm EXTREMELY careful !!. First step is to add the reversing and step down rings to the front of the 300, it gives a bit of protection to the front element. Just as big a concern was keeping the aperture of the reversed DA35 macro open. A bit of plastic coated wire bent into a hook at each end does the job, but the rear element is very close and the thought a bent aperture lever is always on the mind...

The reason for putting the coin on a sideways moving rack is because I found sideways alignment was difficult without it. It should be easier now I've realised that shining a light through the lens from the camera end (camera not attached, of course) gives a small dot of light where the subject should be. Position the coin so the dot is over the tiny letters and you're ready to go.

For and aft movement of the camera/lens is actually very smooth, accurate and not at all unwieldy. The Novoflex rack is well engineered, holds the camera/lens very firmly and allows precise movement (steps of about 1/12 mm achieved yesterday). The camera/lens is attached via the tripod mount on the lens, so is well balanced. The only ad-hoc hack was to add a foot under the font end of the rack to eliminate slight up/down movement due to there being a thin rubber 'grippy' mat on the top of the clamp that attaches to the worktop - perfectly OK for 1:1 macro, but not quite good enough at these magnifications. The foot was assembled from a couple of bits with 1/4 in threads, screwed into a hole in the focusing rack. I wouldn't want to try doing all of this with a less robust rack and clamp though!!

More to come using coker's needle and rotating protractor focussing method...

Steve

OK, here we go...

All with DA*300mm + reversed DA35mm f2.8 macro. JPG straight from camera.

This set uses linear focus. Steps of about 1/12mm. One step is enough to take focus from surface of letters to surface of coin, so the letters must be about 0.1mm thick.

1. K3




2. K3 + 1.4TC




3. Q-S1




4. Q-S1 + 1.4TC




And here's the kit.




The needle and rotating protractor method comes next... perhaps a stack or two.

Steve

Sun ???

Rain and wind down here. Perfect weather for stopping people coming from half way across the country to do silly things at Durdle Door during half-term week. Hope it stops for an hour or so tomorrow late afternoon/early evening so I can walk to get The Jab without getting soaked.

Steve

What matters most is how much of the sRGB colour space the monitor covers. An uncalibrated monitor can always be calibrated. But if a monitor doesn't cover the whole space, calibration can only take it so far, the lack of complete coverage will mean that compromises have to be made. I have 2 monitors, one full sRGB and factory calibrated 'for photographers', one general purpose, not full sRGB and calibrated by me. There is a difference after calibration, although it isn't huge. It was a bigger difference before calibration.

As for ultrasharp monitors, I wish I had ultrasharp eyesight...

Steve

Just printed and cut out a protractor, fitted it on the nice, big focus ring of the DA300, found some fine wire and a way of holding it in place... Now need the kitchen to be clear of people and cooking. Perhaps have a go this evening when the haze has cleared after pancakes have been cooked and eaten (the smell won't clear for days...).

Steve

Aha, I now understand how you're getting the fine control. A brilliant bit of creative improvisation.

Does the fine focus work because the 200 f4 is changing its point of focus or because the attached reversed lens moves back/forwards as the focus ring of the 200 f4 is rotated? Or to put it another way, would it work if an internal focus lens (like the DA300 f4) were used instead of the 200?

You ought to patent your 'device' before a bloke in a shed in Shanghai makes a cheap, plastic copy and starts selling it on e-bay!

Steve

Any idea of the distance between each shot in the stack? And how far those letters protrude from the surface? (So I know what to aim for...:wink

Steve

Found time to have a break from doing other things, so here as requested is a PP'd version of my first shot (F50mm f1.7 @ f11 reversed on DA*300mm).




Steve