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Lens focus The place to talk about your camera's glassware.

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  #16  
Old 18th January 2008
OlyFlyer
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Re: Bellows or lens reversal?

Quote:
Originally Posted by lauriek View Post
Bit late on this thread I know but I only just found this site!

Don't forget the 4x magnification stated on this page assumes a 35mm sensor size in an OM camera behind the bellows. As the 4/3 sensor is half the size, the magnification should be 8x (on a 4/3 sensor cam).
That is wrong. Magnification is independant of which sensor size you have.

I think I have discussed this over and over again on every place I have been. Magnification factor is the same as if you take an image of a ruler in landscape mode and then divide the sensor size with the number of millimeters you see in the image, whichever sensor you have. If you for example take an image of a 1 mm part of a ruler, than divide 17.3 with 1 gives you 17.3:1 magnification. If you would take the same 1 mm piece with a 35 mm film camera you must divide 35 with 1, which will give you 35:1 magnification. Magnification factor has nothing to do at all with the sensor size, it is a ratio between the life size image and the size of the image on your sensor.

It is a common misunderstanding that Olympus falsely try to spread on unfortunately. The ED50/f2 macro is capable of 0.5:1 nothing else.

1:1 magnification is 1:1 magnification on ANY sensor. Period.

The image below is a ~1 mm part of an aluminum ruler, which in my case is equal to a magnification factor of ~17x since the E-system uses 17.3x13 mm sensor image area.



Assuming the camera would be a 35 mm film camera, using the same setting would still give me ~17x magnification since the sensor would be further back and I would record about twice the image, ie. about 2 mm. Please don't mix magnification factor with the crop factor. Two different things and it will just create confusion.

Quote:
Originally Posted by lauriek View Post
Please see my gallery for some examples of what you can achieve with this combination... (using focus stacking for enhanced DOF).
I will have a look tomorrow, but you have to tell me where to find it. I love macro as well, and really like to have a look at other peoples images as well.
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  #17  
Old 18th January 2008
lauriek
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Re: Bellows or lens reversal?

I think I see what you are saying but will have to think about it a little further before I say anything else!!

I've just uploaded a couple of pictures to the gallery on this site,just click the gallery link up the top then I suppose you look for my username? (Or maybe look at recent files for some bug close ups? Not totally sure as I only just got here!)
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  #18  
Old 18th January 2008
PeterD
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Re: Bellows or lens reversal?

Quote:
Originally Posted by OlyFlyer View Post
That is wrong. Magnification is independant of which sensor size you have.

I think I have discussed this over and over again on every place I have been. Magnification factor is the same as if you take an image of a ruler in landscape mode and then divide the sensor size with the number of millimeters you see in the image, whichever sensor you have. If you for example take an image of a 1 mm part of a ruler, than divide 17.3 with 1 gives you 17.3:1 magnification. If you would take the same 1 mm piece with a 35 mm film camera you must divide 35 with 1, which will give you 35:1 magnification. Magnification factor has nothing to do at all with the sensor size, it is a ratio between the life size image and the size of the image on your sensor.

It is a common misunderstanding that Olympus falsely try to spread on unfortunately. The ED50/f2 macro is capable of 0.5:1 nothing else.

1:1 magnification is 1:1 magnification on ANY sensor. Period.

The image below is a ~1 mm part of an aluminum ruler, which in my case is equal to a magnification factor of ~17x since the E-system uses 17.3x13 mm sensor image area.



Assuming the camera would be a 35 mm film camera, using the same setting would still give me ~17x magnification since the sensor would be further back and I would record about twice the image, ie. about 2 mm. Please don't mix magnification factor with the crop factor. Two different things and it will just create confusion.

I will have a look tomorrow, but you have to tell me where to find it. I love macro as well, and really like to have a look at other peoples images as well.
Hi OlyFlyer

You will find LaurieK's images under L of the members gallery. Only one person under this letter. At least it was the last time I looked. Hope you don't mind me butting in but I know how precious your time is.

Kind regards

PeterD
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  #19  
Old 18th January 2008
OlyFlyer
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Re: Bellows or lens reversal?

Thanks for the clarification. I misunderstood, since I somehow assumed my gallery means outside this forum, like pbase or something similar.

I had a look and I must say I love the wasp image. Would love to know some details about the how to... and with what gear part.
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  #20  
Old 18th January 2008
OlyFlyer
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Re: Bellows or lens reversal?

Quote:
Originally Posted by lauriek View Post
I think I see what you are saying but will have to think about it a little further before I say anything else!!
Hi again,

I hope you don't mind that I continue. Since dpr is now up again (six days posts are gone due to a RAID 5 dual failure ), I looked up one of my last arguments about the magnification. This is an exact quote of my post over there:

Quote:
Originally Posted by OlyFlyer @ dpreview
" 'Macro' is a general term applied to lenses for close-up photography and low power photomicrography - conditions under which the image is larger than the subject. They are generally of short focus and corrected for close subject distances. Maximum field is usually of a diameter matching the focal length. When using these lenses care has to be taken to establish the effective - as opposed to engraved - f-number, as this will vary with subject distance."

The above is a word for word quote from one of my college books, Advanced Photography, written by M. J. Langford. Old book (printed in 1977), but still stands, light has not changed since, lenses are still used and calculated the same way.

Any other serious book I read, define macro similarily. Nowhere is the 36x24 mm mentioned, because as soon as you mention that, you commit an error. The error is than you *cannot* blend *any* size into a general definition, since it has absolutelly nothing to do with sensor, or film sizes. 36x24 mm is just *one* of many available sizes, there has been, there are, and there will be others as well. As soon as you mention 36x24 mm, you specialize the definition to one single format only. 36x24 mm is *not*, on the contrary to what many would like to believe, a reference measure to anything else than 36x24 film format. It is not meant to be used as anything else.

Macro image starts at 1:1, which is the same size (= life size = 1 mm in real life is equal to 1 mm on image sensor surface), regardless if you use an A4 size film or a tiny P&S sensor. The quality of that image is up to the lens quality. A macro lens can be used to take non-macro images, just as well a non-macro lens can be used to take macro images. Now, if you can come up with a better, but still a general definition I may agree and change my learned in definition, but as long as you mix sensor sizes into the definition, that definition is wrong. The day the 36x24 mm format dies you have to redefine your definition of macro. On the contrary to my old definition above, which still will be valid for *any* given image sensor format.

This is only an academic discussion, probably not nay are interested of. I don't think we must agree on anything. I personally don't care if people call their images macro, when in reality they are only close-up, that is up to them, but for me, macro starts at 1:1. That is the only way one can compare object size with image size.
This is the link to the whole thread including all the usual arguments there, in case you want to have a look. I also posted a few images myself over there.
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  #21  
Old 18th January 2008
OlyFlyer
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Re: Bellows or lens reversal?

Quote:
Originally Posted by PeterD View Post
Hi OlyFlyer

You will find LaurieK's images under L of the members gallery. Only one person under this letter. At least it was the last time I looked. Hope you don't mind me butting in but I know how precious your time is.

Kind regards

PeterD
Thanks Peter for the pointer. As for my time, don't worry, I always use time if I find something interesting.

Cheers
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  #22  
Old 19th January 2008
lauriek
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Re: Bellows or lens reversal?

Quote:
Originally Posted by OlyFlyer View Post
I had a look and I must say I love the wasp image. Would love to know some details about the how to... and with what gear part.
Equipment - E1, MF1, OM Auto Bellows, Reversed OM50/1.8, STF-22 twinflash. White card fairly close behind subject.

Method - Shot around 12 focus slices (well actually shot more but only used 12 in the stack). Used the OM auto bellows built in focus rail for repositioning the plane of focus through the bug... Stacked with Combine ZM. Bit of levels/curves work and a small amount of cloning 'bad' background!

My current rig uses a tripod/ball head for the camera and is far from optimal, I'm currently working out the next version, which will be a low level rig holding the camera setup and the subject holder...
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  #23  
Old 19th January 2008
PeterD
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Re: Bellows or lens reversal?

Quote:
Originally Posted by lauriek View Post
Equipment - E1, MF1, OM Auto Bellows, Reversed OM50/1.8, STF-22 twinflash. White card fairly close behind subject.

Method - Shot around 12 focus slices (well actually shot more but only used 12 in the stack). Used the OM auto bellows built in focus rail for repositioning the plane of focus through the bug... Stacked with Combine ZM. Bit of levels/curves work and a small amount of cloning 'bad' background!

My current rig uses a tripod/ball head for the camera and is far from optimal, I'm currently working out the next version, which will be a low level rig holding the camera setup and the subject holder...
Hi Lauriek/Olyflyer

Fascinating stuff. Can either of you point me to further information. Particularly of your mrthod description Lauriek?

Best regards

PeterD
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  #24  
Old 22nd January 2008
lauriek
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Re: Bellows or lens reversal?

Peter,

It's basically a case of;

Shooting:
Get the subject lined up in the viewfinder, get the magnification you want by setting the bellows extension, focus on the part of the bug closest to the lens. Stop the lens down (using the aperture ring on the lens and the aperture close switch on the bellows). Shoot. Adjust exposure if necessary, and possibly background. Reshoot. Move the plane of focus slightly forward 'into' the bug, using the focus rail on the bellows. Repeat until you have focused and shot the furthest part of the bug you wish to keep in focus.

PP: RAW:
Process the RAW files - if you do any adjustments, make sure you do exactly the same to all images in the set of slices. Save from RAW processing as TIFFs.

Do Stack:
Load the TIFFs into Combine ZM, tell it to do-stack, save the output.

PP:
Further curves/levels tweaks as required in your image editor of choice, trim off oddities which occur around the edge of the frame due to the camera movement. Resize for web and save out as JPG.

Notes:
There's a bit more finesse to it to get good results but that's the kind of stuff which is down to your specific setup and I can't really comment on unless you have any specific questions?

Cheers

Laurie
--
ps you can see my current rig for this work here;
http://www.photomacrography2.net/for...pic.php?t=4132

Last edited by lauriek; 22nd January 2008 at 07:03 PM. Reason: Added link to my setup
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  #25  
Old 22nd January 2008
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Graham_of_Rainham Graham_of_Rainham is offline
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Re: Bellows or lens reversal?

Hi,
I use the bellows and got over the problem of the lever interfereing with the Mirror box by using the 7mm extension tube. I also experimented with my 80 - 200 f2.8 zoom, before buying the OM 80mm Macro Lens. This combination gives me a good working range and acceptable magnifications

Hope this helps

Graham
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  #26  
Old 22nd January 2008
PeterD
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Re: Bellows or lens reversal?

Quote:
Originally Posted by lauriek View Post
Peter,

It's basically a case of;

Shooting:
Get the subject lined up in the viewfinder, get the magnification you want by setting the bellows extension, focus on the part of the bug closest to the lens. Stop the lens down (using the aperture ring on the lens and the aperture close switch on the bellows). Shoot. Adjust exposure if necessary, and possibly background. Reshoot. Move the plane of focus slightly forward 'into' the bug, using the focus rail on the bellows. Repeat until you have focused and shot the furthest part of the bug you wish to keep in focus.

PP: RAW:
Process the RAW files - if you do any adjustments, make sure you do exactly the same to all images in the set of slices. Save from RAW processing as TIFFs.

Do Stack:
Load the TIFFs into Combine ZM, tell it to do-stack, save the output.

PP:
Further curves/levels tweaks as required in your image editor of choice, trim off oddities which occur around the edge of the frame due to the camera movement. Resize for web and save out as JPG.

Notes:
There's a bit more finesse to it to get good results but that's the kind of stuff which is down to your specific setup and I can't really comment on unless you have any specific questions?

Cheers

Laurie
--
ps you can see my current rig for this work here;
http://www.photomacrography2.net/for...pic.php?t=4132

Hi Laurie

Thanks for your explanation above and also to your description. Fascinating stuff. I note that the subject unit and camera unit are two separate items. does this cause alignment difficulty when taking slices?

Did you make the x-y-z adjustment plates.

Kind regards

PeterD
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  #27  
Old 22nd January 2008
lauriek
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Re: Bellows or lens reversal?

If you move the camera on the focus rail then there's no problem with alignment. If you need higher magnification, then it becomes difficult to do small enough focus steps with the focus rail. That's where I'd like to use the fine movement on the subject mount. This does lead to some alignment issues which I'm currently working on!!

I got the X-Y-Z thing on eBay, it's called a micromanipulator. It's possible to put something like this together with individual linear stage plates, and right angle brackets, but that looks like an expensive route. Having said that these manipulators don't seem to come up very often...
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  #28  
Old 23rd January 2008
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Re: Bellows or lens reversal?

Hi,
I use a 7mm OM extension tube between 4/3rd adaptor and Bellows to get over the problem with the bellows release lever interfering with the Mirror Box.

I used zooms to find out which lens length gave me the best working distance and ended up buying an OM 80mm Macro. I havn't tried reversing a lens yet so would be very interested in seeing how you progress with this.
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  #29  
Old 23rd January 2008
OlyFlyer
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Re: Bellows or lens reversal?

The image in my post #16 above, and the ball point pen (top images) in this thread are both taken with a reversed OM 35 mm lens. Reversed lens gives better results than used normally, due to the fact that the image subject is almost where the film plane is whne used the 'right' way. The shallow DOF demands a flattened image area, which is best done that way. I am however convinced, that using any of the OM macro lenses, or (a dream) the OM bellows lenses would give even better results. The problem with using the 4/3 macro lenses is the actual physical sizes they have. Just too large and the working distance becomes minimal at arond ~7:1 magnification already when a macro adapter and some tubes are used, or like ~4-5:1 on bellows.

The OM bellows are designed for 49 mm filter thread lenses and are extremely easy and convenient to reverse, since you can select the aperture in advance and still focus wide open. The lever on the side, or a separate trigger wire can be used to close the aperture just before taking the image. If a wire is used camera shake is prevented as well.
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  #30  
Old 23rd January 2008
lauriek
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Re: Bellows or lens reversal?

Quote:
Originally Posted by OlyFlyer View Post
I am however convinced, that using any of the OM macro lenses, or (a dream) the OM bellows lenses would give even better results.
I just picked up a 20mm/3.5 OM bellows lens + the mount, will let you know how it goes!!
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