OlyMinCan-28

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

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Charles Krebs
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OlyMinCan-28

Post by Charles Krebs »

Here are three shots of the gear used for the stacked close-up/landscape shots like the ones posted here.

It consists of the optics from an older Olympus 28/3.5 lens mounted to the inside of the rear standard of an old Minolta bellows. This standard does not move. (The Minolta mount was removed and the bellows standard was machined flat and the hole machined to the proper size in order to do this). A male EOS lens mount was attached to (what was previously) the front standard of the bellows. This moves in and out on the rails via the geared knob. The pleated bellows material was shortened in order to allow them to be compressed enough to reach “infinity” focus.

They key considerations when doing this were:

- The requirement that the lens remain in exactly the same position when the series of shots -- from near to far -- is taken. This is extremely important, and is the reason that focus is changed by moving only the camera body.

- A wide angle lens. I would probably prefer something even wider than 28mm (on a 24x36mm frame body). I’ve thought of also looking at a 24mm Olympus lens.

- The need to focus continuously from very close (at least 1:1) to "infinity”. The “infinity” focus is actually the trickier part. You need sufficient bellows (or some other focus mount) to allow enough extension for very close focus, and yet it all needs to compress sufficiently to get infinity focus as well. Care must be taken that the lens used, when focused at “infinity”, does not interfere with the SLR mirror mechanism as it swings up and down. (This is a bigger issue with the Canon 5D than Canon’s other full frame DSLR bodies. The mirror swings slightly closer to the lens mount in this model).

- The lens must perform well when extended for the close subjects. Many “conventional” wide-angle lenses give really horrible image quality, especially toward the corners of the frame, when extended in this way. This Olympus lens performs quite impressively!

Operationally the trickiest part is positioning this in the proper shooting location. Most foreground subjects are at, or near ground level. I have found that it is often easiest to hang this upside down suspended under a large tripod.

Image

Image

Image

rjlittlefield
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Post by rjlittlefield »

Lovely! This answers all the questions I had. :D

--Rik

rjlittlefield
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Post by rjlittlefield »

Linking in another approach to the same goal...

See also "Macro landscape stack using compact digital camera".

--Rik

Charles Krebs
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Post by Charles Krebs »

Irwin,

In response to your questions over in the "Image Galleries"...
First, putting aside the question of infinity focus for a second, would it possible to use a set of bellows that has a movable back standard and focus by moving the back standard, thus keeping your lens position identical.
Yes, this is exactly what I did.
I assume that the lens used has to have a registration distance greater than the registration distance of the camera...

...Lastly, do you have a stop or some mechanism where the back of the lens won't crash into the mirror if you collapse the bellows too much.
Yes, I have incorporated an "infinity stop" in my setup. (You can actually see the infinity-stop tab in the lower picture sticking out at the bottom of the lens standard). Having a wide angle lens and obtaining "infinity focus" down to extreme close focus is really the tricky part. My Canon EOS has a 44mm "flange-to-sensor" ("register") distance, the Olympus (OM) optics I used are from a lens with a 46mm "flange-to-sensor" distance. This made it all feasible. But it still took some work to get the lens back far enough to reach infinity focus while still incorporating some bellows in order to get down to the close focus distance I wanted.

Charlie

cactuspic
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Post by cactuspic »

Thanks Charlie. My first attempt at making a similar rig ended when the initial bellows I purchased did not have sufficient clearance for the fat body of my 1Ds Mark II. Your wonderful images are inspiring me to get off my keister.

Irwin

Charles Krebs
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Post by Charles Krebs »

Irwin,
As you mention it's much more difficult to accommodate a body with a large battery pack. Except for the 5D there are no "full frame" DSLR's without this lower protrusion. I've looked around for bellows that could work with these taller cameras. One possibility would be to have the rails over the top of the body (it seems I wind up using this one "up-side down" much of the time anyway), but it would still require a bellows with very tall standards. A Nikon PB-6 with a pair of "Nikon PB-6D standard extensions" is a possibility. But you don't want too much bellows (or anything else) sticking out in front of the lens since the nearest subject matter will be so close.

If I wanted to use a larger camera like a 1D or 1DS I would explore the possibility of mounting the lens in a large sturdy "L" bracket, with the bottom of the "L" running under the DSLR. The body itself could be attached to the rail via a small sliding linear stage (smooth, "ball-bearing" movement like the ones Newport and others make). I think with a little thought this could be made to work quite nicely. If I ever try a 24mm lens (or wider) I might go that route.

cactuspic
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Post by cactuspic »

Thanks Charlie, I am running to catch a plane to visit my Dad , who is ill. I think your suggestions are a great approach. I'll be back in a week or so to start cobbling my rig.

Irwin

lhhansen
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Dis-assembling lens

Post by lhhansen »

Dear Charles, I like this idea very much and love the "bugs view of the world" and would like to try it out too. Regarding the dis-assembly of the lens. Did the whole lens assembly come out as one unit? and what is the purpose of the black tape around the lens assembly in the first photo of the setup? As you also mention, I think it would be great to go even wider and will look for 24mm or even 21mm options. I guess Zuikos will be most suited due to their size and aperture ring location near the front. Best regards, Lars

Charles Krebs
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Post by Charles Krebs »

Lars,

The lens disassembled quite easily. The optics came out as a single unit. Having the aperture ring at the front does make a setup like this easier.

The tape you see only serves to hold a small "lever" so that the aperture can be closed down manually...normally the aperture is sprung "open". (This could be done more elegantly than with a piece of tape :wink: , but it works fine so I just left it.)

Keep in mind that if the ability to focus out to "infinity" is desired, things get a little tricky and the camera flange focal distance ("register") distance comes into play. Canon EOS is 44mm, Olympus OM is 46mm, and Nikon is 46.5mm. So I have about 2mm of extra distance to make use of with an EOS to Olympus lens "surgery", but putting an Olympus lens on a Nikon body means that the lens actually need to be set into the body a small amount... I have no idea if this would present mirror clearance problems or not. A micro 4/3 body would give you plenty of room to work with since it has a a 20mm flange focal distance, but that format would mean that you would want a much wider focal length than you might use with a 24x36mm sensor. (You would need a 14mm lens to get the same effect as the 28mm on 24x36mm sensor).

Charlie

rjlittlefield
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Post by rjlittlefield »

Charles Krebs wrote:The tape you see only serves to hold a small "lever" so that the aperture can be closed down manually
Aha -- this explains a great deal!

In the year that I've been looking at this picture I have never seen a piece of tape. What I "saw" instead was a rough piece of black metal that appeared to have been abused somehow. I actually thought it was a bit remarkable that the optics were intact, considering what the mechanics had probably gone through.

Now that Charlie say "tape" I can see tape, but it's still a bit of effort. I have been interpreting those pixels as black metal for so long that it takes conscious effort to see them differently. I suppose by tomorrow I'll see tape, and wonder how I could possibly have gotten it wrong in the first place.

Brains are such interesting beasts...

--Rik

Charles Krebs
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Post by Charles Krebs »

Rik,

Faked out old eagle-eye! :wink:

I'd need to take it off to check, but I think it was left there because it not only held the lever as mentioned, but it also effectively sealed off the slot in which the lever rotated. This prevents dust from getting into the lens. (And again, it could be "prettier", but it does the job).

lhhansen
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mirror clearance

Post by lhhansen »

Thank you Charles,
I have been thinking about mirror clearance but as I mentioned in an answer on my own thread @ http://photo.net/nikon-camera-forum/00VSNM I was delighted to find http://www.leitax.com/OlympusOM-lens-fo ... meras.html where it looks like there will not be a problem with the Zuiko 21/3.5. I would really prefer doing this with the cameras I already have. Finding a nice used and not too expensive Zuiko 21/3.5 will probably be a challenge...

ChrisR
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Post by ChrisR »

The Leitax mount must be very thin between the front of the Nikon mount and the rear of the Olympus lens, under half a millimeter.
That mount wouldn't allow closer focusing than the original Olympus lens will go to, so you may as well use a Nikon lens.
To focus from infinity to something close then, the rear standard of a bellows would have to be the same thickness, less than half a millimeter. Too thin!

It would be possible to use the Leitax mount with the screws missing, to give some strength and something to hold on to. I think you'd have to drill a big hole in the rear standard of a cheap bellows and glue it to the Leitax mount, and fix the front standard to the filter thread. But then you could do the same with a Nikon lens.

One way to win a little might be to find and remove the "end stop" on the focus helicoid, at the close-focus end. The lens would obviously come apart if you overdid it, but I expect you could get a few millimeters extra movement.
Many 28mm Nikkors focus to 0.3m, one to 0.2m.
I'm not sure if that measurement is from the focal plane or the lens, to subject.
Assuming that it's the lens, the extyensions you'd need for a 28mm lens are approximately (for a simple lens):

Code: Select all


Lens - subject        extn      field of view 
______________        ____      _____________ 

Infinity               0              inf 
 300                   2.88           350 
 200                   4.56           221 
 150                   6.4            157 
 100                  10.8             93 
So for dramatic stuff, you do need a bellows I think.
Last edited by ChrisR on Thu Jan 14, 2010 12:36 am, edited 1 time in total.

lhhansen
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not using LEITAX

Post by lhhansen »

Hi Chris,
I did not plan to use the LEITAX mount at all (which should be 0.5mm thinner than the original OM mount) but just took the fact that this lens can be converted as an insurance that it will not hit the mirror of an FX Nikon when focused at infinity. I still want to attach the lens like Charles did - inside a bellows.

ChrisR
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Post by ChrisR »

What I'm trying to say is that you almost certainly won't be able to do it "like Charles did ", unless you can figure out a bellows with a rear standard half a millimeter thick. Charles had a total of 3mm or so to play with.

Be careful about trusting 3rd part measurements too. With a D700 the clearance between the Oly 28 3.5 and the mirror is under half a millimeter. Other bodies may be different.

Edit
It turns out I was remembering the focus ring being left in place. Then you'd have very little room.
Last edited by ChrisR on Wed Jan 20, 2010 8:24 am, edited 1 time in total.

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