Infinity objective on low-end zoom telephoto works fine

marceppy · Post by **marceppy** » Sat Mar 15, 2014 1:00 pm

Rik,

A couple of questions:

My current sensor is the APS-H 29.7mm x 18.6mm. I have an EF-100mm f2.8 macro lens also. Do you think the Nikon CFI Plan Achromat 10x NA 0.25 WD 10.5mm (part number MRL00102) or the Nikon CFI BE Plan Achromat 10X NA 0.25 WD 6.7 (part number MRN70100) would work for this sensor?

Would the field of view at the sensor for the 100mm macro focused at infinity be equal to sensor size divided by the magnification of the objective? For the wide view of the APS-H that would be 2.97mm?

In a FAQ thread, you were explaining that the infinity objectives deliver actual magnification in proportion to the length of the lens, such like a 10x objective with a 100mm lens would provide a 5x magnification. I have the MPE-65 which can give 5x magnification. So, it sounds like I would have to go to a 200mm lens to reach 10x magnification. Sorry for the dumb questions, Im just trying to sort this out in my mind.

Marc

rjlittlefield · Post by **rjlittlefield** » Sat Mar 15, 2014 2:07 pm

marceppy wrote:My current sensor is the APS-H 29.7mm x 18.6mm. I have an EF-100mm f2.8 macro lens also. Do you think the Nikon CFI Plan Achromat 10x NA 0.25 WD 10.5mm (part number MRL00102) or the Nikon CFI BE Plan Achromat 10X NA 0.25 WD 6.7 (part number MRN70100) would work for this sensor?

I'm pretty sure the edges and corners would go bad. You might even get hard vignetting (completely black corners), but I don't know for sure about that. The high quality circle of the MRL00102 is a little over 5 mm on subject . It comfortably covers full frame at 10X and barely covers APS-C (26mm diagonal) at 5X. At 5X on your sensor at 35 mm diagonal, you would be asking the objective to cover 7 mm on subject.

Would the field of view at the sensor for the 100mm macro focused at infinity be equal to sensor size divided by the magnification of the objective? For the wide view of the APS-H that would be 2.97mm?

I think you mean field of view at the subject. That is equal to sensor size divided by the magnification of all the optics taken together. If all the optics taken together are 10X, then yes, your field width at the subject would be 29.7 mm divided by 10 = 2.97 mm. However, with the 100mm focused at infinity, your optics taken together would give only 5X, and that would mean a 5.94 mm field width.

In a FAQ thread, you were explaining that the infinity objectives deliver actual magnification in proportion to the length of the lens, such like a 10x objective with a 100mm lens would provide a 5x magnification. I have the MPE-65 which can give 5x magnification. So, it sounds like I would have to go to a 200mm lens to reach 10x magnification.

That is correct.

As a side note... For shooting a 5 mm field, using the objective makes sense because it is sharper than the MP-E. On APS-C (26mm diagonal), this happens at 5X. See the images linked from HERE. The objective would have the same advantage on APS-H if you ran the comparison at 7X, using the objective on 140 mm tube lens against the MP-E on a 1.4X teleconverter. But for shooting a field much larger than 5 mm, using the MRL00102 does not make sense because the corners will go bad.

--Rik

marceppy · Post by **marceppy** » Sun Mar 16, 2014 1:37 pm

Ok. Thank you for helping, Rik. Yes, I see what you mean about the field of view over the subject area.

The part I am missing is how to determine if the image covers the sensor without the edges and corners getting bad with a given lens and objective combination.

Let me ask the question a little differently. In you estimation, for the APS-H
sensor, what lens & objective combinations would deliver a magnification between 7x-10x (or both) without degradation of the image at the edges and corners?

I would like to consider using greater magnifications but need to understand
what gear it would take. Great information in this thread. Thanks!

Blame · Post by **Blame** » Sun Mar 16, 2014 3:32 pm

If you have the cash the mitutoyo 10x 0.28NA is going to be tough to beat with that camera at 7-10x.

Not sure about the best tube lens. About 180mm at 9x and f/16. Probably closer the 200mm and 10x for no loss of corner sharpness but it is a trade between corners and extra sharpness over the bulk of the area.

marceppy · Post by **marceppy** » Sun Mar 16, 2014 6:47 pm

The mitutoyo is a little out of my range but I like the thought of it. There is no issue with some cropping. The idea of getting sharp images at that magnification is compelling.

rjlittlefield · Post by **rjlittlefield** » Sun Mar 16, 2014 10:52 pm

marceppy wrote:Let me ask the question a little differently. In you estimation, for the APS-H sensor, what lens & objective combinations would deliver a magnification between 7x-10x (or both) without degradation of the image at the edges and corners?

At 10X, it's easy. Use a 200 mm tube lens and any of the following objectives: Nikon CFI BE Plan Achromat 10X NA 0.25 (MRN70100); Nikon CFI Plan Achromat 10X NA 0.25 (MRL00102); Mitutoyo M Plan Apo 10X NA 0.28. Those are listed in order by price for a new lens, today ranging from $102 for the CFI BE (from Optics Planet, HERE), through $226 for the MRL00102 (from SEO Enterprises, HERE), up to $865 for the Mitutoyo M Plan Apo (from Edmund Optics, HERE).

The Mitutoyo 10X is much loved for its lack of false color and its excellent sharpness. But in addition to its higher cost, all tests to date have shown that it has a smaller high quality field than the Nikon MRL00102 does. The tradeoffs mean that there's no absolute answer to the question of which is "better". A lot depends on what you care about. For many subjects I will still reach for my MRL00102 because it's a better match to the size of the subject, but for others I'll reach for my Mitutoyo because of the color issues.

--Rik

Blame · Post by **Blame** » Mon Mar 17, 2014 3:57 am

Um. Sharp is a relative term. The Mitutoyo is not going to stretch to the corners till you are up to f/16. like Rik says there are cheaper alternatives but that is roughly what you can hope for with decent corners. F /16 is significantly diffraction limited with a lot of cameras.

There is a lot to be said for dropping the magnification a little and taking a hit on the corners for the improved aperture.

marceppy · Post by **marceppy** » Mon Mar 17, 2014 3:20 pm

Thanks for the suggestions. Great information. Your feedback is appreciated.

There is a lot to be said for dropping the magnification a little and taking a hit on the corners for the improved aperture

Sounds reasonable, Blame. For the APS-H sensor, what were you thinking? I have a ME-P65, so I'm good to 5x.

Thanks,
Marc

Blame · Post by **Blame** » Mon Mar 17, 2014 5:10 pm

Well the top quality field of view is a circle of diameter of about 3.2mm. After that resolution slowly tapers off. So 9x at f/16 with a 180mm lens will stretch to the sides with just a trace of softening in the extreme corners.

You can drop to as low as 6x with a 120mm lens. That would give you a top quality circle that covered about 50% of the sensors area with a circle that would just touch top and bottom of the sensor but not to the sides. Believe it or not it won't vignette with the right tube lens. If you can move you eye back 3cm and still see enough then an excellent chance.

If I were you I would get a 135mm enlarger lens as a 6.5x wide and a 180mm prime for a more even coverage. I don't think I can recommend an enlarger lens at 180mm. They are not very sharp. Perhaps an old M42 camera lens if you can find one that doesn't vignette. You don't have to have exactly the correct focal length.

A quick test for a camera lens. Set to infinity and wide open. Hold a transparent ruler about 4cm from the opening at the camera side and look down the front of the lens with one eye pressed against the glass. wave the ruler back and forward a bit till it comes into focus. Now, without moving your eye, how much of the ruler can you see? If it is more than the diagonal of your sensor you have some chance of it not vignetting as a tube lens.

Worth pointing out that the MPE-65 has an effective aperture of f/16.8 wide open at 5x. I have some slight doubts as to whether it is diffraction limited like that given that some have reported their copies are sharper stopped down a tad. Maybe a good copy is.

If you are happy with your's at 5x then there are lenses as good up to 10x.

marceppy · Post by **marceppy** » Mon Mar 17, 2014 6:07 pm

Appreciate your thoughts on this. I will look around at some lenses and see what's available. I recently sold my EF 180mm macro to get the new 100mm IS. There was a nagging thought telling me to store it but ... with the thought of Canon upgrading the 180mm, the price may soon fall for the former http://egami.blog.so-net.ne.jp/2014-03-12

Rik's thoughts about the Nikon CFI BE Plan Achromat 10X NA 0.25 (MRN70100); Nikon CFI Plan Achromat 10X NA 0.25 (MRL00102) are well taken.

The ME-P65 has worked great and I am getting better at magnifications to 5x. My present rig is not stationary which induces vibration. I noticed that even a slight air current will cause some movement. Information gathered from the collective knowledge of this community, however, is very illuminating!

Thanks!

Blame · Post by **Blame** » Tue Mar 18, 2014 2:19 am

Selling your canon 180mm was not that bad a decision. If you need that focal length back the tamron 180/3.5 is every bit as good for far less while the Sigma 150/2.8 OS and 180/2.8 OS offer sharpness and stabilization at a price that canon is not going to match. Heavy though.

marceppy · Post by **marceppy** » Tue Mar 18, 2014 5:11 pm

Thanks again, Blame. Sigma and Tamron both have a 180mm f3.5 w/ a 72mm filter.

Finding a decent tube lens is certainly worth a look. Appreciate your thoughts.

marceppy · Post by **marceppy** » Sun Mar 23, 2014 7:23 am

Rik,

Above you mentioned

For many subjects I will still reach for my MRL00102 because it's a better match to the size of the subject, but for others I'll reach for my Mitutoyo because of the color issues.

Can you describe the color issues with the Nikon objective or an example showing the difference? Are the color issues with the Nikon correctable in post processing?

Thanks for the information. I am looking at the Canon EF 70-200mm f4 L non-IS as a good tube lens. Others have mentioned it also.

Marc

marisano · Post by **marisano** » Sun Mar 23, 2014 10:50 am

I'm very new to this. I'm setting up a rig to focus stack insects on the order of 1.7-2mm. I've got a Canon T3i and a Canon 100mm 2.8 macro. I'm wondering if it would be good to pick up a Nikon 135mm 2.8 AI and use it as the tube lens for infinity objectives as opposed to using the 100mm at infinity. I'm trying to avoid buying a 200mm lens (at least a Canon) - I'd rather put that expense better objectives.

Does anyone have advice on this? This 135mm seems to sell cheap in good condition on eBay.

Thank you,
Marisano

rjlittlefield · Post by **rjlittlefield** » Sun Mar 23, 2014 1:07 pm

marceppy wrote:Can you describe the color issues with the Nikon objective or an example showing the difference?

See http://www.photomacrography.net/forum/v ... 973#124973 for an example by abpho (faceted tungsten filament from a halogen lamp).

Are the color issues with the Nikon correctable in post processing?

In general, no. Once the colored light has gotten spread into places where it should not be, there's no practical way to get it out. The problem is most severe in image areas where there is no strong detail to force selection of just the in-focus information. The case shown by abpho is exactly what I would shoot to highlight the problem: it's a shiny subject with lots of dark OOF regions, illuminated by a light source that's not very diffuse and thus produces very bright highlights, and whose spectrum has a strong peak in an area where the lens has strong dispersion. That's a "perfect storm", and it renders in quite unnatural colors.

--Rik

Infinity objective on low-end zoom telephoto works fine

Nikon 135 f/2.8 vs Canon 100 mm f/2.8