Just for fun..
Moderators: rjlittlefield, ChrisR, Chris S., Pau
Just for fun..
.. I tried using a 10X objective from an old lab microscope I have (Baker) by mounting the lens in an expanded polystyrene disc and hand holding it on the end of an old set of pentax fit ext tubes which I cobbled onto a canon T mount ages ago, The length of the tubes is about 75mm. Much to my suprise I seemed to get a reasonable image on a 1.6 crop camera body (just looking in the viewfinder). The image seemed to be approx 10:1. Is it worth doing a slightly more permanent fixing (probably using a pentax body cap on the end of the tubes) for the lens or am I barking up the wrong tree ?
Brian V.
Brian V.
www.flickr.com/photos/lordv
canon20D,350D,40D,5Dmk2, sigma 105mm EX, Tamron 90mm, canon MPE-65
canon20D,350D,40D,5Dmk2, sigma 105mm EX, Tamron 90mm, canon MPE-65
- Planapo
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Brian, I don't think that you're barking up the wrong tree, otherwise we would be quite a pack barking up there.
I would expect that your 10x objective has an RMS thread, so in case photographs would show that it needs its matched eyepiece for better correction of distortions like CA in the final image, and you would hence want a fully corrected objective that can be used without correcting eyepiece, you could still use that pentax body cap adapter with tubes or bellows with that, given that you can position the hole in the cap adequately centered.
I have experienced that distortions are more prone to show up in later photographs than when first looking through the objective "live" by eye alone.
--Betty
I would expect that your 10x objective has an RMS thread, so in case photographs would show that it needs its matched eyepiece for better correction of distortions like CA in the final image, and you would hence want a fully corrected objective that can be used without correcting eyepiece, you could still use that pentax body cap adapter with tubes or bellows with that, given that you can position the hole in the cap adequately centered.
I have experienced that distortions are more prone to show up in later photographs than when first looking through the objective "live" by eye alone.
--Betty
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There may be something here:
http://www.srb-griturn.com/t-mounts-and ... -331-c.asp
They made me an adapter to use my Canon 20mm macro lens, with its RMS thread on Olympus OM via a T-mount.
Harold
http://www.srb-griturn.com/t-mounts-and ... -331-c.asp
They made me an adapter to use my Canon 20mm macro lens, with its RMS thread on Olympus OM via a T-mount.
Harold
My images are a medium for sharing some of my experiences: they are not me.
Thanks for the comments and info
As it's slightly inclement weather outside (gales and rain), I went ahead and tried a slightly more permanent fitting using the objective attached to a body cap on the end of the tubes.
Image seems not too bad- couple of test shots (with a bit of hand stacking on the pollen) of some hibiscus bits just taken resting the camera on a table.
Brian v.
As it's slightly inclement weather outside (gales and rain), I went ahead and tried a slightly more permanent fitting using the objective attached to a body cap on the end of the tubes.
Image seems not too bad- couple of test shots (with a bit of hand stacking on the pollen) of some hibiscus bits just taken resting the camera on a table.
Brian v.
www.flickr.com/photos/lordv
canon20D,350D,40D,5Dmk2, sigma 105mm EX, Tamron 90mm, canon MPE-65
canon20D,350D,40D,5Dmk2, sigma 105mm EX, Tamron 90mm, canon MPE-65
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Brian,
Recent thread with links to a variety of RMS to T2 adaptors
http://www.photomacrography.net/forum/v ... ght=#50197
Your lens looks not to be producing much CA. Would be interesting to see the edge of a small black spot on a pure white background to see if there is a colour fringe.If not, then you have discovered a much cheaper alternative objective to the Nikon CF series.
Peter
Recent thread with links to a variety of RMS to T2 adaptors
http://www.photomacrography.net/forum/v ... ght=#50197
Your lens looks not to be producing much CA. Would be interesting to see the edge of a small black spot on a pure white background to see if there is a colour fringe.If not, then you have discovered a much cheaper alternative objective to the Nikon CF series.
Peter
Not sure if this will do - hard to find a good full stop when you are looking for one . I took a shot with my MPE-65 of the same thing (a lot easier to focus) and cropped it to the same print magnification for comparison.Peter M. Macdonald wrote:Brian,
Recent thread with links to a variety of RMS to T2 adaptors
http://www.photomacrography.net/forum/v ... ght=#50197
Your lens looks not to be producing much CA. Would be interesting to see the edge of a small black spot on a pure white background to see if there is a colour fringe.If not, then you have discovered a much cheaper alternative objective to the Nikon CF series.
Peter
Ignore any white balance diffs - that's down to me
Brian V.
MPE-65 cropped to same print mag on 5Dmk2
10X objective on 40D
www.flickr.com/photos/lordv
canon20D,350D,40D,5Dmk2, sigma 105mm EX, Tamron 90mm, canon MPE-65
canon20D,350D,40D,5Dmk2, sigma 105mm EX, Tamron 90mm, canon MPE-65
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Brian,
Seems that there is some lateral chromatoc aberation from the Baker objective. I took it into Photoshop and examined it at 600% in order to look for any sign of colour fringing. There is a quite obvious blue fringe on the right ende of the full stop and the letter. Just to check that it was not in the printing ink, I did the same with the MPE image. It is black and white with no colour fringe.
That said, the two images which you posted of short stacks suggest that the Baker lens performs well in a more real world test than the pixel peeping which I was doing, at least when shooting a stack which is going to be used at web resolution.
Guess this just demonstrates why we are prepared to pay more than the price of a Baker of London 10x onjective for a Nikon CF 10x.
Cheers,
Peter
Seems that there is some lateral chromatoc aberation from the Baker objective. I took it into Photoshop and examined it at 600% in order to look for any sign of colour fringing. There is a quite obvious blue fringe on the right ende of the full stop and the letter. Just to check that it was not in the printing ink, I did the same with the MPE image. It is black and white with no colour fringe.
That said, the two images which you posted of short stacks suggest that the Baker lens performs well in a more real world test than the pixel peeping which I was doing, at least when shooting a stack which is going to be used at web resolution.
Guess this just demonstrates why we are prepared to pay more than the price of a Baker of London 10x onjective for a Nikon CF 10x.
Cheers,
Peter
Thanks for the analysis Peter. I'll probably try it properly soon if i can find a suitable subject. Been meaning to try one of the objectives for a while but only just figured out how to DIY mount it
Brian v.
Brian v.
www.flickr.com/photos/lordv
canon20D,350D,40D,5Dmk2, sigma 105mm EX, Tamron 90mm, canon MPE-65
canon20D,350D,40D,5Dmk2, sigma 105mm EX, Tamron 90mm, canon MPE-65
- rjlittlefield
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I used an old non-CF objective for a long time, pretty happily. The visible color fringing due to CA can mostly be removed in post-processing. Even a cheap objective will give lots more resolution than traditional macro lenses, see for example the comparisons HERE, third panel.LordV wrote:Been meaning to try one of the objectives for a while but only just figured out how to DIY mount it
--Rik
Specs for mounting a microscope objective on a DSLR
I have somehow acquired an understanding that it is exceptionally critical to mount lenses accurately, especially for high-quality micro and macro work. That is, I thought that very high-precision optical equipment would be needed to construct a lens mount and to verify that the microscope objective is perpendicular to the sensor plane, etc, etc.
Yet I occasionally see reasonable image quality from hand-mounted lenses using DIY components, for example a body cap with a hole drilled and tapped for a microscope objective.
Should I abandon my DIY anxieties regarding lens mounts with respect to this specific forum topic and examples?
Thanks to everyone who posted T-mount adapters for microscope objectives, etc.
Yet I occasionally see reasonable image quality from hand-mounted lenses using DIY components, for example a body cap with a hole drilled and tapped for a microscope objective.
Should I abandon my DIY anxieties regarding lens mounts with respect to this specific forum topic and examples?
Thanks to everyone who posted T-mount adapters for microscope objectives, etc.
-Phil
"Diffraction never sleeps"
"Diffraction never sleeps"
I don't think it's the end of the earth if you do this in a slightly sloppy way - I mean if you end up slightly off perpendicular then you just have a slight tilt lens, which shouldn't do any harm. You need to make sure it's pretty well centered though, otherwise it quite possibly will vignette on one corner unless well extended. (Particularly as I know Brian now uses a full frame 5DII).
- rjlittlefield
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DQE, your concerns are too strong in this case.
Step back and think about the big picture.
If the objective is mounted parallel to the sensor but is off center, then nothing happens except that the image circle shifts on the sensor. Even if the decentering is as bad as a full mm, this is still only a small fraction of the sensor size, so the high quality central portion is still available for cropping.
It is unlikely that the sensor will be tilted with respect to the extension axis, but even if it were, all this does is to tilt the focus plane and introduce a tiny change in "tube length" across the sensor width. Neither effect is important for the sort of subjects that Brian is shooting, or for typical focus stacks.
The biggest problem is if the objective gets tilted, since this not only tilts the focus plane but also shifts the objective's optical axis by a surprisingly large amount at the sensor. Fortunately, objectives have mounting shoulders, and many body caps have flat fronts. In this case, the objective will naturally snug up perpendicular even if the threads are not perfect.
Come to think of it, I'm not sure I've ever heard anybody say "Be sure the front of the body cap is flat." But that is important. Choosing a cap that would leave one side of the objective propped up on an embossed logo would be a Really Bad Idea.
--Rik
Step back and think about the big picture.
If the objective is mounted parallel to the sensor but is off center, then nothing happens except that the image circle shifts on the sensor. Even if the decentering is as bad as a full mm, this is still only a small fraction of the sensor size, so the high quality central portion is still available for cropping.
It is unlikely that the sensor will be tilted with respect to the extension axis, but even if it were, all this does is to tilt the focus plane and introduce a tiny change in "tube length" across the sensor width. Neither effect is important for the sort of subjects that Brian is shooting, or for typical focus stacks.
The biggest problem is if the objective gets tilted, since this not only tilts the focus plane but also shifts the objective's optical axis by a surprisingly large amount at the sensor. Fortunately, objectives have mounting shoulders, and many body caps have flat fronts. In this case, the objective will naturally snug up perpendicular even if the threads are not perfect.
Come to think of it, I'm not sure I've ever heard anybody say "Be sure the front of the body cap is flat." But that is important. Choosing a cap that would leave one side of the objective propped up on an embossed logo would be a Really Bad Idea.
--Rik
Rik,rjlittlefield wrote:DQE, your concerns are too strong in this case.
Step back and think about the big picture.
If the objective is mounted parallel to the sensor but is off center, then nothing happens except that the image circle shifts on the sensor. Even if the decentering is as bad as a full mm, this is still only a small fraction of the sensor size, so the high quality central portion is still available for cropping.
It is unlikely that the sensor will be tilted with respect to the extension axis, but even if it were, all this does is to tilt the focus plane and introduce a tiny change in "tube length" across the sensor width. Neither effect is important for the sort of subjects that Brian is shooting, or for typical focus stacks.
The biggest problem is if the objective gets tilted, since this not only tilts the focus plane but also shifts the objective's optical axis by a surprisingly large amount at the sensor. Fortunately, objectives have mounting shoulders, and many body caps have flat fronts. In this case, the objective will naturally snug up perpendicular even if the threads are not perfect.
Come to think of it, I'm not sure I've ever heard anybody say "Be sure the front of the body cap is flat." But that is important. Choosing a cap that would leave one side of the objective propped up on an embossed logo would be a Really Bad Idea.
--Rik
Thanks for the very helpful explanation.
While reflecting on the possible source(s) of my lens mounting anxieties, I recalled that I became conditioned to the need for extreme precision in making and assembling optical devices during learning the basics of making one's own reflector astronomical telescope. There, interferometric techniques were sometimes used for testing component quality (e.g., finishing and polishing the primary mirror. Also, and more to the point, I only have a limited understanding of lens design and optics - my total education in these domains consists of a two-week summer course by the legendary Rudolph Kingslake a few decades ago at the University of Rochester.
-Phil
"Diffraction never sleeps"
"Diffraction never sleeps"
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Unlikely for recent cameras I suppose but I obtained a metal body cap for a similar project I had in mind for my OM sytem. (This was for a non-RMS lens).rjlittlefield wrote:many body caps have flat fronts. In this case, the objective will naturally snug up perpendicular even if the threads are not perfect.
Harold
My images are a medium for sharing some of my experiences: they are not me.