Using an iris diaphragm with Bellows and a Mitutoyo objectiv

[MacroB]

Looks as if I'll have to use a tube lens to connect a 10x M Plan Apo to my Novoflex bellows.

Was just wondering if it would be worth making the connection with an iris diaphragm and from which supplier.

Has anyone tried it?

Bob

[rjlittlefield]

The usual approach is to use the M42 iris from jinfinance on eBay. Get the 26 mm x 36 tpi flat adapter to go with it.

http://www.ebay.com/itm/IRIS-DIAPHRAGM- ... 0547138653

http://www.ebay.com/itm/thin-M42-BD-Nik ... 0619040662

I've used this with various M42-to-filter-thread adapters on the front of telephoto lenses, and also I've mounted a Mitutoyo tube lens inside M42 extension tubes (setup shown HERE). What tube lens did you have in mind?

--Rik

[MacroB]

Hello Rik,

Many thanks for the info on Jinfinance on Ebay.

Was considering a MT-4 or MT-40 from Edmund Optics, but didn't know which was best for a Canon D50. I see the image circles are 30 and 24 mm respectively.

After seeing your result with Canon 55-200 and Vivitar 200, however, I think I may go for one of those. Could then venture out with camera, though I find fitting to and from macro rig makes for a lot of dust, which I generally end up taking to shop for cleaning.

Just spent an hour or so cleaning up latest shot in PS CS5!

Thanks for pointing me in the right direction,
Bob

[Chris S.]

Was considering a MT-4 or MT-40 from Edmund Optics, but didn't know which was best for a Canon D50. I see the image circles are 30 and 24 mm respectively.

Bob, among the various Mitutoyo tube lenses available at Edmund Optics, you would probably want to avoid the MT-4 and MT-40, and go with an MT-1, mounted inside an MT-1/MT-2 C-mount adapter. (You can see my implementation of this approach here.) According to Mitutoyo's literature, the MT-4 is for objectives below 20x, the MT-40 for objectives 20x and above. The MT-1 is recommended for all Mitutoyo visible light objectives. Why these recommended limits with the MT-4 and MT-40? I have no idea. But I can confirm that the MT-1 works fine with the whole range of Mitutoyo objectives from 2x through 100x. It does not vignette on an APS-C or DX sensor, although it does on a 24x36mm full-frame sensor.

Mitutoyo has more information than is available at the Edmund Optics site. You might want to download the pdf file here. The portions of interest to this discussion are on or about page 23.

That said, if you have the lenses you mention below, by all means try them! They will likely perform pretty well. A Mitutoyo tube lens (or Nikon or Olympus tube lens, or an apochromatic enlarging or large-format lens) is probably a bit better, but whether or not that incremental improvement is worth it to you is a choice that can be made later.

. . .though I find fitting to and from macro rig makes for a lot of dust. . .

This, and your mention in the first post about using a tube lens on your bellows, makes me wonder what mechanical assemblage you're using. With either the Canon or Vivitar lens you listed, you would not need a bellows to mount an infinite objective. So there would be no more dust introduced to the camera than with any other lens change--right?

Cheers,

--Chris

[MacroB]

Hello Chris,

Thanks for your advice on the MT-1 that's great.

I should explain that up to about 20x I use the optical system of a Leica Z-16. After 20x aberration rears its ugly head and images become unfocused.

Have got a Nikon M Plan 40x ELWD, which I've tried on the bellows, however, jumping straight in at 40x magnification I'm not able to navigate and find my way to some morphological feature of the fly. I though that if I used a 10x or 20x Mitutoyo that would allow me to line things up before I change to the Nikon 40x.

Just a pity that the Nikon finite objectives are in such short supply.

As you said there is not a lot of info with the Edmund Optics site, so I do appreciate your advice on the MT-1 and the photos of your rig.

Best wishes,
Bob