Help needed please

[Jody Melanson]

I am going to purchase a Mitutoyo M Plan APO 10x/0.28na 33.5mm Working Distance Objective.

I use a Canon 1DMK3 for my camera. Would someone be so kind as to tell me what else I need to purchase to make this work?

Thanks much!

[Chris S.]

Jody,

Optically, the basics are that you need a lens to converge the rays from that objective (a converging lens or "tube lens"), and an adapter to fix the objective in front of it.

Given your non-macro work, I'll bet you already have some lenses that would work well as converging lenses. Top contenders would be any prime lens of around 200mm, or any zoom on which the longest focal length is around 200mm.

If so, then you need a simple adapter that screws into the filter threads on that lens, and has a threaded hole in the center to accept the objective. The objective's threading is 26mm x 36 threads per inch (0.706mm). Two possible candidate adapters--from a good eBay vendor:

140436592235 Mitutoyo to 52mm
200619047550 Mitutoyo to M42

You of course might need a step down ring to go from either 52mm or M42 to the filter thread size of your converging lens.

Then, just mount the converging lens on the camera as you would for normal use, then add the adapters on the front of it and screw in the objective. Set the converging lens to infinity and you're ready for action. You can use the converging lens wide open, or try stopping it down a bit to see if you gain any quality (if so, it would likely be due to reduction in internal flare, rather than any stopping down of the objective). Just don't stop the lens down to the point that you get vignetting.

Does that answer your question, or did you also want to discuss any mechanical implications for stacking with a 10x objective?

Best,

--Chris

[Jody Melanson]

Jody,

Optically, the basics are that you need a lens to converge the rays from that objective (a converging lens or "tube lens"), and an adapter to fix the objective in front of it.

Given your non-macro work, I'll bet you already have some lenses that would work well as converging lenses. Top contenders would be any prime lens of around 200mm, or any zoom on which the longest focal length is around 200mm.

If so, then you need a simple adapter that screws into the filter threads on that lens, and has a threaded hole in the center to accept the objective. The objective's threading is 26mm x 36 threads per inch (0.706mm). Two possible candidate adapters--from a good eBay vendor:

140436592235 Mitutoyo to 52mm
200619047550 Mitutoyo to M42

You of course might need a step down ring to go from one of these to your converging lens.

Does that answer your question, or did you also want to discuss any mechanical implications for stacking with a 10x objective?

Best,

--Chris

Thanks Chris for the fast reply! I have a Sigma 150 Macro lens. Would this work? Would a extension tube help?

re: the mechanical implications, any help you want to provide would be awesome.

[Chris S.]

I have a Sigma 150 Macro lens. Would this work? Would a extension tube help?

Before I saw your reply, I edited my post to add that you'll want to set your converging lens to infinity. Some other focus distances may work, but infinity is the place to start. I can't think of a scenario, though, in which an extension tube would help.

I have no personal experience on whether the Sigma 150 macro works well with the Mitutoyo 10x. Perhaps someone has tried this combination and can say.

If the combination does work, it will give you about 7.5x magnification, rather than 10x. Magnification = 10(f/200), where f is the focal length of the converging lens.

The potential pitfalls are that some models of microscope objective are more tolerant than others of being used on a shorter converging lens than they were designed for. Mitutoyo objectives are designed for use on a 200mm converging lens. Having never tried my Mitty 10x on anything like a 150mm converging lens, I have no idea what the results would be.

Also, shorter converging lenses work on a case-by-case basis, depending, among other things, on the location of their entrance pupil, which can cause vignetting if too far forward. Prime lenses tend to be OK in this regard, while most zoom lenses used much shorter than their long end seem to vignette. But I have no experience with the Sigma 150.

If your Sigma 150mm doesn't deliver what you are looking for, and you have to buy a converging lens, this becomes a longer discussion. You could go with a prime lens of about 200mm, or use a lens intentionally made by a microscope manufacturer for use in the tube of a microscope (an official "tube lens.") Good candidates include Mitutoyo, Nikon, Thorlabs, and Olympus tube lenses--and when it comes to these, the key factor may well be mechanical integration, more than optical differences. Others have made good use of Raynox diopters and other things for converging a microscope objective.

--Chris

[Chris S.]

re: the mechanical implications, any help you want to provide would be awesome.

I've edited my prior post a little bit since having a chance to check the equipment used in some of your recent posts. I'd recalled that you use an MP-E 65mm lens, but not whether you are using a StackShot. The placeholder for you in my head includes images like your iconic great gray owl and northern hawk owl, which crowd out trivialities such as whether or not you use a StackShot for macro.

Your StackShot should work fine with the 10x lens. You are already accustomed to working at 5x, and you have a ton of experience with high-magnification telephoto lenses. My guess is that you won't find this next step all that mechanically challenging.

--Chris

[Charles Krebs]

Jody,

I've used the Mitutoyo on a 150mm lens (as the "tube lens") and it worked fine. However I was using a an APS-C sized Canon body...sensor size 22.3x14.9mm with a 26.8mm diagonal. Your camera has a an APS-H sized sensor... 28.7x18.7mm with a diagonal of 34mm. This is a close call as far as having sharp coverage to the corners of the frame even when using a 200mm tube lens (the sensor is actually larger than the maximum specified image circle). If you use a shorter than 200mm focal length for a tube lens, the magnification will be slightly less, but perhaps more importantly, the "quality" image circle gets smaller as well. As I say... it is a close call... may work out fine. But I would be inclined to try to find a 200mm lens to be used as the tube lens.

[ChrisR]

Hi Jody
another other thing you'll have read about is the separation between the objective and the camera lens.
Mitty talk about it being 100mm, with their tube lens.

There have been a few reports about IQ differences on changing that distance. My coalesced recollection, combined with my own rather ad-hoc trials, is that some separation helps, perhaps 50mm. The improvements are usually reported as being to do with CA at image edge. Any improvement (at all) does seem to depend which particular optic you're using as the "tube" lens.

For widest field coverage, - yours is going to be marginal - you may want to reduce the lens/objective distance as much as possible.
If the distance is very short then you have more measures to take about reflections between the objective and lens.
If you use the conical adapters, watch out, some are very shiny black inside. (Though their shape is nice).

Mechanics, then.
The conical adaper gives separation, excluding the "very short" option. So you'd need a flat adapter, and tubes for playing with. Perhaps M42 of course, but if 52mm is convenient then the Nikon K rings work well.
K rings come two ways - pristine, in leather case, "collectable" and overpriced; or obviously used, with a few irrelevant scratches, at a few bucks.
The K rings also mean you can have a (Nikon!) bayonet-fit magnification change to a different objective.

[Jody Melanson]

re: the mechanical implications, any help you want to provide would be awesome.

I've edited my prior post a little bit since having a chance to check the equipment used in some of your recent posts. I'd recalled that you use an MP-E 65mm lens, but not whether you are using a StackShot. The placeholder for you in my head includes images like your iconic great gray owl and northern hawk owl, which crowd out trivialities such as whether or not you use a StackShot for macro.

Your StackShot should work fine with the 10x lens. You are already accustomed to working at 5x, and you have a ton of experience with high-magnification telephoto lenses. My guess is that you won't find this next step all that mechanically challenging.

--Chris

Thanks for the info Chris! I do have a stackshot. I will try the Sigma 150 and if it gives me 7.5x that'll do until I purchase a 200mm. (give me a good excuse to buy a Canon 200/2 )

[Jody Melanson]

Jody,

I've used the Mitutoyo on a 150mm lens (as the "tube lens") and it worked fine. However I was using a an APS-C sized Canon body...sensor size 22.3x14.9mm with a 26.8mm diagonal. Your camera has a an APS-H sized sensor... 28.7x18.7mm with a diagonal of 34mm. This is a close call as far as having sharp coverage to the corners of the frame even when using a 200mm tube lens (the sensor is actually larger than the maximum specified image circle). If you use a shorter than 200mm focal length for a tube lens, the magnification will be slightly less, but perhaps more importantly, the "quality" image circle gets smaller as well. As I say... it is a close call... may work out fine. But I would be inclined to try to find a 200mm lens to be used as the tube lens.

Thank you Charles for the info. I will give it a shot and purchase a used Canon 200/2.8 in a few months.

Edit: I guess a 70-200 lens would work as well?

[Chris S.]

I guess a 70-200 lens would work as well?

It should work very well, Jody, as long as you keep it close to 200mm. At some point shorter than that, it will almost certainly vignette.

However, I suspect--perhaps unfairly--that a good prime might deliver a bit more quality than a good zoom. For someone who cares about getting every last scintilla from his optics--which I'm pretty sure describes you--it's probably a good idea to check any zoom against a prime lens or two before settling on it.

--Chris

[Jody Melanson]

I guess a 70-200 lens would work as well?

It should work very well, Jody, as long as you keep it close to 200mm. At some point shorter than that, it will almost certainly vignette.

However, I suspect--perhaps unfairly--that a good prime might deliver a bit more quality than a good zoom. For someone who cares about getting every last scintilla from his optics--which I'm pretty sure describes you--it's probably a good idea to check any zoom against a prime lens or two before settling on it.

--Chris

Thanks Chris! Canon's 70-200 is extremely sharp and I have wanted one for awhile now. I found a used one without IS for $550cdn. I may just grab that and give it a shot. If it isn't up to par, I'll sell it and grab a prime.

I just ordered the Mitutoyo.

Thanks again Chris and Charles.

[nielsgeode]

I guess a 70-200 lens would work as well?

It should work very well, Jody, as long as you keep it close to 200mm. At some point shorter than that, it will almost certainly vignette.

However, I suspect--perhaps unfairly--that a good prime might deliver a bit more quality than a good zoom. For someone who cares about getting every last scintilla from his optics--which I'm pretty sure describes you--it's probably a good idea to check any zoom against a prime lens or two before settling on it.

--Chris

Thanks Chris! Canon's 70-200 is extremely sharp and I have wanted one for awhile now. I found a used one without IS for $550cdn. I may just grab that and give it a shot. If it isn't up to par, I'll sell it and grab a prime.

I just ordered the Mitutoyo.

Thanks again Chris and Charles.

I compared the Canon 200 f/2.8 with the Canon 70-300 f4-5.6 and I do see better image quality with the 200 prime. Zoom lenses are simply not as sharp as primes...

[Pau]

IMO the tube lens is much less important than the objective.

I have a 70-200 IS USM L and like it very much both as tele lens and as tube lens with the Nikon CFI 10 0.25 paired with my 7d. With APSC it is good as tube lens down to 140mm were vignette begins to appear.