Seeking some hints and tips for my bellows

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VR8
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Joined: Wed Mar 20, 2013 6:51 am
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Seeking some hints and tips for my bellows

Post by VR8 »

I have acquired a Sb-6 bellows and 50mm 2.8 Companon-S lens. I have been scouring this website looking for hints. I have some lighting solutions both flash and LED. I have a Kirk focusing rail and Photoshop. I would like to see what can be done with this. kit before investing further. My subjects to start will be simple things around the house, moss. lichen. I am interested in knowing

1. if I should reverse the lens from the start.
2. What fstops to experiment with or best with the combination.
3. Ideas on a focusing stage I can place my subjects on.
4. The Sb-6 has a focusing rail, should I use the kirk as cross axis, or for the focus stage.

Thanks for any help, much appreciated.
Victor Rakmil

ChrisR
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Post by ChrisR »

I see your kit 'o bits is growing Victor!
1.) Yes reverse it, for 1:1 and greater magnifications. You may need a tube of black paper or similar on its exposed rear end, to act as a lens hood.
2) the higher the magnification the larger the aperture you need, to avoid diffraction blur, BUT:
- you probably need to stop the lens down to f/5.6 or so for its best aperture
- it depends how critical you are, in terms of final image or "print" size
- towards 1:1 you may well find that there's little to be gained going larger than perhaps f/11, and of course you need fewer steps in your stack.

3) One thing a few of us used is a spare lens stood on end, for up/down adjustment. A macro lens is best of course for height variation. (As long as it's not "internal focusing"!)
Spare small tripod heads and cheap Chinese x-y rails are also handy. Something heavy and ferrous, with the subject on a magnet, is also popular.
A "Helping Hand" thingy is crude, but versatile and cheap.
There's a bunch of contraptions available from microscope suppliers with swinging needles, and the like.

4) Is it a Nikon PB-6?. As we mentioned in a previous answer, the steps you need to make are getting tricky on a standard bellows focus rail. If you do the sums, you find that coarser steps can be used on the rear "standard" of a bellows to achieve fine focus-plane movements. If you don't fancy the sums, eyeball it and take excess frames!

I'd suggest you start with flash, because movement is such a bogey. A large sheet of ordinary or tissue paper, near/around the subject, is fine as a simple diffuser.

I think the biggest problem you'll have, for now, is making fine-enough focus steps. I don't know what the rail you have can do, but its surprising how much can be achieved with care, and a clothes-peg on a focus knob to give more precision.

Photoshop isn't the ultimate stacker, but I think for lichens and the like you'll be fine.
Have fun!

VR8
Posts: 16
Joined: Wed Mar 20, 2013 6:51 am
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Post by VR8 »

Thanks. Yes its a Pb-6.
Thanks for the suggestions!
For diffusion I have some Lee filter material I have been using with the Nikon R1C1. Those flashes should well with this, and the LEDs should help me set up my shot.
I have a helping hand and I will try that for some of the material, or an old ball head and pins.
Can you point me somewhere where I can look at the math on coarse bellow movements?

Thanks
Victor Rakmil

ChrisR
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Post by ChrisR »

The maths - it's been a while...
Pick an aperture and look up/work out the depth of field you'll get from that. (I have a much-altered spreadsheet for that.)
Then make another spreadsheet and the basic (simple) lens formula
1/v + 1/u = 1/f
to give you a set of bellows-draw measurements, or step increments.
Or a single calculation to give you an idea.
I did it a couple of times, then found it was OK to judge focus bands by eye and "underdo" the steps, then got a better stage.

The "5x" table is here somewhere, I'll try to find it.

ChrisR
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Post by ChrisR »

That took a while to find :)
http://photomacrography.net/forum/viewt ... 3299#43299
If you look at the leftmost part of the table, you'd be moving the sensor ~about~ 5mm instead of moving the subject, or lens + sensor, 0.2mm. A lot easier.
Disadvantages - the magnification changes as you go, which gives the stacking program more work to do, and wastes the edges of your sensor at one end of the travel.

VR8
Posts: 16
Joined: Wed Mar 20, 2013 6:51 am
Contact:

Post by VR8 »

I am very grateful.
While I can use a spreadsheet, this s higher math for me. So it will take some time for me to worth through.
Great to have this as a project, it will make the winter go faster!
I am going to start with some very simple flat plan things, before stacking, just to make sure I have the framing, focusing, lighting, stability etc. right.
Then I will do a simple stack and see how it goes.
Much appreciated.
Victor Rakmil

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