Are Mitu M and BD Plan optically identical?

Have questions about the equipment used for macro- or micro- photography? Post those questions in this forum.

Moderators: rjlittlefield, ChrisR, Chris S., Pau

Macrero
Posts: 1166
Joined: Thu Sep 01, 2011 8:17 am
Location: Valladolid , Spain

Are Mitu M and BD Plan optically identical?

Post by Macrero »

As far as I know they are, but I recently got a Mitu BD Plan 10 and from quick comparison I noticed the BD has slight edge over the M in terms of contrast and even resolution, which is rare, that is compraring it with 2 different Mitus M Plan 10.

The only difference I can see in the specifications is the WD - 33.5mm for the M and 34m for the BD.

Could anyone enlighten me on this?

Best,

- Macrero
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

ChrisR
Site Admin
Posts: 8668
Joined: Sat Mar 14, 2009 3:58 am
Location: Near London, UK

Post by ChrisR »

I don't know - it sounds like mechanical measurement differences only.

As for "slight differences" in performance, I'm not surprised - they ALL seem to vary noticeably when you look hard.
Chris R

Macrero
Posts: 1166
Joined: Thu Sep 01, 2011 8:17 am
Location: Valladolid , Spain

Post by Macrero »

The difference is far from significant, but it's there. Most likely it is just the usual difference between used (and even brand new) objectives, as you said.

But if they are optically identical, where the difference in WD comes from? :-k
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

Pau
Site Admin
Posts: 6052
Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Post by Pau »

Macrero wrote: But if they are optically identical, where the difference in WD comes from?
Maybe the outer shell that contains the illumination path is protruding a bit more than the outer ring of the non BD version, pretty usual with BD objectives, or the external ring protecting the front lens is a different. 0.5mm is a small difference
Pau

Macrero
Posts: 1166
Joined: Thu Sep 01, 2011 8:17 am
Location: Valladolid , Spain

Post by Macrero »

Pau wrote:
Macrero wrote: But if they are optically identical, where the difference in WD comes from?
Maybe the outer shell that contains the illumination path is protruding a bit more than the outer ring of the non BD version, pretty usual with BD objectives, or the external ring protecting the front lens is a different. 0.5mm is a small difference
Yep, maybe that's the explanation. Anyway I'll try to contact Mitutoyo to be 100% sure. Just curious about this.
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

Macrero
Posts: 1166
Joined: Thu Sep 01, 2011 8:17 am
Location: Valladolid , Spain

Post by Macrero »

Just for the record: I contacted Mitutoyo Spain and this is the answer I got , translated from spanish:

Thank you for your inquiry. We have discussed with Mitutoyo directly and this is the response we received.
 
In fact, the small difference in the working distance is not the main difference between the types of objectives. This difference is probably rather just a rounding of the data.
The main difference is the pipe ring surrounding the lens in the case of the BD lenses. This tube ring used to guide the light outside the lens instead of the inside.
This is essential for observing Darkfield therefore it is provided by BD Plan Apo lenses and not in the M Plan Apo.
The internal optical system of the inner lens is exactly the same, however, it's not possible to replace one objective for the other as fixing thread is completely different.


So yeah, the are optically identical, the only difference is obviously physical.

- Macrero
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light

Post Reply Previous topicNext topic