Not In In water but...

Not In In water but - it is still picture taking....

I have a small land picture job taking some shots of dental implants for a manufacturing company, ( if you think that is scary then next on the list are some needles that are used to inject stuff into eyeballs ).

Needless to say these are pretty small - sub 1mm diameter and maybe 3-4mm in length.

I have a pretty stable set-up and a focusing rack but am wondering how far I can go with extension tubes and a 105mm lens (crop camera).

Currently I have a stack of extension tubes 68mm long and would like a bit more. Also have a 2* Kenko but have not been there yet, should I?

So what are the limiting factors ? (DOF obviously) and is it worth me purchasing another set of extension tubes or is it all just going to get ugly ?

Thanks,

Paul C

My experience is that modern IF lenses do not work well with extension tubes because they are optimised for the range in which they work as they are. I have the 60mm EFS Canon which works well with the 12mm extension tube but softens noticeably with the 25mm - the same is true with the 100mm - it simply doesn't work so well with extension tubes. The best solution is an older none IF macro lens and extension tubes - the Nikon 60mm or 55mm are fine and because they work on none IF principles, they can be used at quite high magnifications with little loss of quality. You might also want to look at using stacking software such as Zerene Stacker and stitch several images together - to do so you will need several shots taken by moving the camera and lens on a focus rack to produce images with different parts of the subject in focus, the sharp areas can then be assembled as one final fully sharp image.

If you are really struggling then you can always talk to me about it on the 'phone!

Not struggling yet Paul but thanks for the offer!

Interesting - I am getting what I thought looked OK results with the 105 and the extensions - following your input I may try the 60mm - lighting may become an issue as I can see the lens getting darn close to the subject but I have IR triggers on a flash so can hand hold it.

Not been there with the focus stacking software - may go that way if I have to - sounds like a time bandit though.

Thanks again,

Paul C

The problem with modern IF lenses is that they shift focal length as they focus closer and in order to do this they seem to be optimised for best image quality at their normal rear flange to sensor distance. Move beyond this and the image softens and as I said before, in my experience this happens quite quickly. However you might want to work out your final output requirements because it isn't always necessary to shoot to the highest resolution possible (I often shoot to output requirements when undertaking commercial jobs) and if output requirements are lower than possible sensor resolution then you may be able to shoot accordingly. I had to take some images of some live, newly hatched and growing lobster larvae (~4mm-10mm) recently and to do so had to shoot whilst 'tracking' them in a petri dish. I had to use as small an aperture as possible to ensure as much was in focus as possible whilst accepting that the image would be diffraction limited, but this was not such an issue because whilst the final image size was quite big (A3+), the viewing distance will be across the lobster tanks and so any softness due to diffraction (and I can certainly see it) will not be evident by viewers. The overview impression of the shape of the various stages of the larvae is more important to show than the detail within each image.

Focus stacking is effective but very memory intensive and can be very slow indeed.

Hear what you say Paul - but it is tough to accept 'not the best I can do' or obtain from the gear that I have to hand.

To be fair without the focus rack I would be truly stuffed - it was worth the time in the machine shop knocking it up.

I tried the 60 and the output looks so similar to the 105 (to me anyhow), but the lighting was a bugger due the the lens to subject distance reduction.

The customer seems happy at the moment - it is just the bag of eyeball injection needles that are scaring me.......

Paul C

Hi Paul,

Is their no end to your talents Paul?? now you are in to dentistry, is that before you go out to dive for scallops??

mow the lawn, iron the washing, do the washing up, hoover the house, etc, etc how many hours are in your day??

Regards,

Andy

See that you too are avoiding the eyeball issue Andy. Just don't want to be involved in the live patient or 'testing' phase of that product.

That bag of eyeball needles scares the cr*p out of me.

To be fair these things are a work of art, all sorts of exotic metals and drilled holes that are so small you can barely see them, some of the surface finishing / detail on them is astounding. So much so that you have to be way more than 1:1 before you start to appreciate it.

The guys doing the machining are also quite interested - they know the story dimensionally but the litho magnification tools they have don't show detail & shadow etc.

Not been scalloping for a few days due to weather - probably why I am indoors playing with this stuff.

Paul C

You might find this site interesting:

http://www.photomacrography.net/forum/index.php

See that you too are avoiding the eyeball issue Andy. Just don't want to be involved in the live patient or 'testing' phase of that product.

 

That bag of eyeball needles scares the cr*p out of me.

 

To be fair these things are a work of art, all sorts of exotic metals and drilled holes that are so small you can barely see them, some of the surface finishing / detail on them is astounding. So much so that you have to be way more than 1:1 before you start to appreciate it.

 

The guys doing the machining are also quite interested - they know the story dimensionally but the litho magnification tools they have don't show detail & shadow etc.

 

Not been scalloping for a few days due to weather - probably why I am indoors playing with this stuff.

 

Paul C

Funny, I teach Intra Oral photograhy to dentist, must be something in our genes that attract us to this (I think it has to do with the fact that underwater photographer are known for their macro work al lot more than the earthly bound variety.

http://www.cognisys-inc.com/stackshot/stac...7d1f06c384fb779 , Try checking this out, its an automated stacking macro rail, I use some of there product for High speed images, they are wll made and reliable. (I never use the Stackshot myself, but the design looks sharp)

I use a PB-4 bellow with the older 105 (sometime inverted), alos for tiny stuff a old 50 Micro nikkor and ring flash as done well for me.

I also have resorted to mounting lens from my Microscope directly on extesion tube (via a drilled out body cap) their small profile make lighting much easier.

Some stunning images on that site Paul.

Some of the kit looks pretty sophisticated.

Thanks,

Paul C

I would relish the idea of doing close ups of these piercing the globe and sucking out the vitreous.....

I would ship you one for testing but don't think I could handle the resulting images.....

Paul C

I used to do eyeball injections (before I moved onto better things): can I help?

I quite like Paul Kay's digital solution: for a static set-up with controlled lighting focus stacking is probably as fast as setting up a demanding optical rig.

Tim