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
Are Mitu M and BD Plan optically identical?
Moderators: rjlittlefield, ChrisR, Chris S., Pau
Are Mitu M and BD Plan optically identical?
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light
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?
But if they are optically identical, where the difference in WD comes from?
https://500px.com/macrero - Amateurs worry about equipment, Pros worry about money, Masters worry about Light
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 differenceMacrero wrote: But if they are optically identical, where the difference in WD comes from?
Pau
Yep, maybe that's the explanation. Anyway I'll try to contact Mitutoyo to be 100% sure. Just curious about this.Pau wrote: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 differenceMacrero wrote: But if they are optically identical, where the difference in WD comes from?
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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.
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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
Thank you for your inquiry. We have discussed with Mitutoyo directly and this is the response we received.
Â
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