In-camera focus bracketing with Olympus OMD M1 part 2

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g4lab
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Post by g4lab »

The close focusing distance for the Olympus 60mm macro is 0.19meter or just under eight inches.

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Post by rjlittlefield »

g4lab wrote:The close focusing distance for the Olympus 60mm macro is 0.19meter or just under eight inches.
Measured from where?

That number looks like the manufacturer's spec, for example from the Specs tab at http://www.getolympus.com/us/en/m-zuiko ... macro.html.

Most likely that's measured from sensor plane to subject, so to get working distance you have to subtract off the flange focal distance of the body and the entire length of the lens.

--Rik

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Post by ChrisR »

ChrisR wrote:Putting the converter at the camera end of the tubes isn't something I've done for years but remember it as giving an effect about the same as multiplying the extension by the converter factor. I expect it depends on the spacings/thicknesses of the specific components.
I suspect that ChrisR wrote something a little different from what he intended, but to set this matter straight...

When the converter is mounted directly on the camera, its effect is simple: it just multiplies the magnification by the TC's rated value, compared to what the rest of the optics would give without the TC. This is using the TC exactly as it's designed to be used, and in this configuration it just makes the image bigger.
What I remember, is that what I got wasn't exactly anything I could work out, so I assumed there was some extra factor. Maybe was trying to be too precise or missed something.
Chris R

g4lab
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Post by g4lab »

Most likely that's measured from sensor plane to subject, so to get working distance you have to subtract off the flange focal distance of the body and the entire length of the lens.

Quite right. The actual distance from the front element is more like one to one and a half inches.

wayupnorth
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Post by wayupnorth »

Back again,

Tubes arrived the other day, very cheap from Amazon, plastic but feel ok. Would probably invest in a ally/steel set in the future.

The 1.4x converter will NOT fit the tubes. The spigot on the converter will locate partially into the tube recess but gets very tight so not worth trying. Possible that another make may work.

Spent a while looking for a suitable subject and found a few cactii that work well.

All images processed as Dmap in ZS. Minimal editing in CS.

General image, not full magnification, no tube

Image

Max magnification, no tubes, 250 stack, differential = 1 (smallest focus step)

Image

Max magnification, 26mm - both tubes. Flower is approx 5mm diameter. 800 pic stack, 1/30 sec @ f2.8. Continuous light. Distance from front of lens (filter) 65mm to top of flower.

Image

Max mag, both tubes, different cactus. White area is approx 1.5mm dia at base of spines.

Image

g4lab
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Post by g4lab »

Beautiful!

ChrisR
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Post by ChrisR »

Interesting.
Have you got an idea now what "1 step" means?

In the last pic, what's going on with the dust which I assume is pollen?
It appears to be suspended in mid air.
Chris R

wayupnorth
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Post by wayupnorth »

Still confused regarding the differential (step) setting and have not found a definitive answer online. If I do a 100 shot stack at "1" using both tubes only a small section of the image is recorded. If I do the same without tubes from a distance then I would capture the whole plant depth and probably more.

If the differential is related to dof then this appears to change with magnification, I kept the aperture constant at f2.8 for all the images. If this is the case then it may explain why only 3 lenses are available with this feature, perhaps each has to be mapped to provide a table of magnification and step size.

The above could be a load of rubbish....

The "dust" is actually reflections from the cactus body but the stack stopped just short of showing more detail. You can see the reflection from the vertical thorn on the body, lower left. Also thorn at 7 o'clock needs editing as it has merged with the surface.

Overall I am pleased with the results but feel that the lens/sensor may be being pushed to capture this sort of detail. What did impress me was the thorn detail on pic 3 which suggests a picture of a critter may work well. Perhaps somebody can send me something they have already photographed by way of comparison.

wayupnorth
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Post by wayupnorth »

Some images were lit using an IKEA anglepoise lamp and a Godox panel.

http://www.amazon.co.uk/gp/product/B016 ... ge_o05_s00

Godox make a range of panels and this is the cheapest. 36 led's, dimmable and close to daylight temperature. The light is diffused and could easily take another diffuser to soften even further. 2x AA batteries seem to be lasting well. Another feature is the ability to couple additional panels together and has a tripod mount.

I seem to be achieving good stability with this very simple rig. The camera on tripod, subject on table. Concrete floor in living room so also on carpet.

The lens is very quiet during capture but there are probably micro movements as the lens moves. The 5 axis stabilisation built into the camera is excellent and I think this may be compensating for any lens vibration. Will test at some point but it certainly simplifies the setup.

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Post by ChrisR »

Just a guess, but it may well work out the DOF from the lens fitted. I've been using CHDK which can do that.
Your camera woudn't know it had tubes on, though, so getting a small range makes sense.
How do you set start/end focus positions?
Chris R

wayupnorth
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Post by wayupnorth »

Camera is connected to W10 tablet for live view. Start point is manually set by focussing on closest point and then backing off a little. At end of stack lens remains in end position, so useful to check coverage. Capture stops if lens reaches infinity before "number of shots" number is reached.

Without knowing the relationship between "differential" and dof the number of shots is a bit trial and error. However as the capture process is very quick, over-estimating the number does no real harm and I can strip away obviously dead images in Lightroom.

g4lab
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Post by g4lab »

The camera is definitely not expecting the extention tubes to be there. Nor would it know if you put a close-up lens.

Did you just choose 800 frames in the other picture "because you could"?
Have you tried letting the camera process the stack?

wayupnorth
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Post by wayupnorth »

800 was used after trialling 300, 500 etc. to get the coverage I wanted. Even without tubes there is no way of calculating how many frames are needed but this is just a question of experience, not really a problem.

The camera has an internal facility (Focus Stack) to record and process 8 shots automatically and produce a stacked jpg. The Focus Bracket option can capture up to 999 images for external processing.

Either option allows the selection of a "differential" number (1-10) which ultimately determines the "gap " between focus steps. If Olympus would publish a chart showing the realtionship between this and dof it would be a whole lot easier to determine which differential number to use.

The larger the differential the fewer frames needed - possibly. I am staying with "1" until I have time to experiment. The same applies to aperture, staying with f2.8 (min) for now. Cant get my head around changing 3 variables !.

g4lab
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Post by g4lab »

800 was used after trialling 300, 500 etc. to get the coverage I wanted. Even without tubes there is no way of calculating how many frames are needed but this is just a question of experience, not really a problem.
Did your trials not yield nice results?

The camera has an internal facility (Focus Stack) to record and process 8 shots automatically and produce a stacked jpg. The Focus Bracket option can capture up to 999 images for external processing.

I forgot that the stacking feature only does eight shots. My camera doesn't even do that but it does have the focus bracketing.

The larger the differential the fewer frames needed - possibly. I am staying with "1" until I have time to experiment. The same applies to aperture, staying with f2.8 (min) for now. Cant get my head around changing 3 variables !.
Always smart to only change one thing at a time :D

wayupnorth
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Post by wayupnorth »

I needed 800 images to produce the stack depth, 500 were not enough and the stack cut off too early. You need the M1 to get the Focus Bracket feature. However the focus stack will be very useful in the field.

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