topic Re: Working distance of EF 100mm f/2.8L in EF & RF Lenses

Working distance of EF 100mm f/2.8L

RobertCampiin — Tue, 20 Aug 2024 15:07:04 GMT

I would greatly appreciate it if someone could tell me the working distance to the front of the lens of the 'L' version of the Canon 100mm EF macro lens, i.e. 100mm f/2.8L when at maximum magnification of 1:1. Unfortunately, various on-line reviews of this lens list its working distance at 1:1 as 13.2 cm, 13.3 cm, 14.0 cm, 14.6 cm, and 14.9 cm. It turns out, I only have 13.9 cm to work with, so the precise working distance at 1:1 matters. Yes, I'm aware of the Canon 180mm macro, but its nearly 30-year-old design has lower resolution than the 100mm 'L' that was designed more than a decade later. Thanks in advance for your help.

Re: Working distance of EF 100mm f/2.8L

kvbarkley — Tue, 20 Aug 2024 15:13:44 GMT

Ken Rockwell says 133 mm

https://kenrockwell.com/canon/lenses/100mm-f28-is.htm

Re: Working distance of EF 100mm f/2.8L

RobertCampiin — Tue, 20 Aug 2024 15:38:11 GMT

Thanks for that, but the problem is on-line reviews, including Ken Rockwell's, differ from each other. Because of this, none are to be trusted to be accurate prior to me spending the better part of $1000 to buy the lens. If someone reading this, who owns this lens, could set it for maximum magnification and measure the distance, I would greatly appreciate it.

To contribute a measurement of my own to this discussion, I own the older 100mm macro, designed about a decade before the 'L' version. Setting the camera on the table with a ruler lined up with the end of the lens, it took less than 2 minutes to sneak up on the lens with the lid of a box. It would focus at 14.8 cm, but not at 14.7 cm, so that's its working distance. That distance would be great if it were the case for the newer lens, but it's of a different design, for which on-line reviews differ.

Re: Working distance of EF 100mm f/2.8L

p4pictures — Tue, 20 Aug 2024 17:01:51 GMT

Hi Robert,

I have the EF 100mm f/2.8L Macro IS USM lens. The lens does not change its overall external length as it uses an internal focus design. 1:1 magnification is achieved at the minimum focus distance of 30cm. This distance is measured from the film plane on the camera. The flange distance for EF lenses is 44mm. The EF 100mm f/2.8L Macro IS USM lens is 122mm from the front to the lens mount. This added to the 44mm to the sensor means that the distance in front of the lens is 134mm, or 13.4cm.

I then also carried out your test with a subject in front of the lens, and with the lens at minimum focus the subject was sharp when it was 134mm from the front of the lens.

For my test I used a Canon EOS R6 with Canon EF to EOS R mount adapter, though this only provides the necessary spacing so that EF lenses are 44mm from the sensor when fitted to mirrorless cameras.

Re: Working distance of EF 100mm f/2.8L

RobertCampiin — Tue, 20 Aug 2024 17:15:45 GMT

>at minimum focus the subject was sharp when it was 134mm from the front of the lens.

Darn. That means the lens won't work for my purposes. Well, at least it saves me ~$1000...

Thanks very much for conducting the actual test. I sincerely appreciate it.

Re: Working distance of EF 100mm f/2.8L

kvbarkley — Tue, 20 Aug 2024 17:26:15 GMT

Some of this could be sample to sample variation.

You can always rent one to check it out.

Of course, if you can live with 0.95 magnification - or whatever - you can set a longer focal distance.

I don't know about macros, but I doubt that the focal length for any given lens is better than 5% anyway

Re: Working distance of EF 100mm f/2.8L

RobertCampiin — Tue, 20 Aug 2024 17:39:17 GMT

>Some of this could be sample to sample variation.

>You can always rent one to check it out.

Renting one wouldn't be a solution. Even if the working distances varied by that much, which is unlikely, and the rental company happened to have a "long" production version, the one I then spent my money to buy easily could be a "short" version. No, Brian had the correct answer. Sadly, though, he didn't provide the solution, i.e. the name of an aftermarket macro lens having 140+mm working distance and at least the lp/mm resolution of the Canon 2.8L.

Re: Working distance of EF 100mm f/2.8L

spencerselvidge — Fri, 30 Aug 2024 03:19:12 GMT

Stumbled onto this forum post looking for similar info. Are you looking for less than 13.9cm or more than 13.9cm? I am unclear.

I need >152mm or 5.9in (of minimum working distance) to achieve 1:1 reproduction on a full frame camera for an automatic slide scanning machine I built out of a Kodak Carousel projector. Works great but I need a longer Min. Working Distance (MWD) unless I want to do some serious and irreversible Dremel damage to the front of the projector.

Of course as you pointed out there are discrepancies on various websites. This site incorrectly does the math for the MWD on the 100mm L , claiming 5.9inches is 146mm when it is actually 149.86mm. But I personally know 5.9" is still not close to the 1:1 on that lens. So I am inclined to believe the "Accepted Solution" above as accurate. If it fits your use care, you are good to go. I would be confident. Also, many camera shops would let you test on the spot and should carry this lens in stock. Camera and lens makers are notorious for rounding their numbers. You can verify here by choosing scenario 3 of 3 on any lens (on the top right), though its very, very technical. This site uses the lenses actual measurements rather than the claimed values: https://www.photonstophotos.net/GeneralTopics/Lenses/OpticalBench/OpticalBench.htm#Data/US007864451_Example01P.txt

If you are looking for < 13.9cm MWD, the Sigma 70mm Macro ART is an INCREDIBLE value. It's MWD is 82.25mm. I use it for all my 1:1 needs except my special use case of the projector. Dollar for dollar (<$500) it blows away the competition and still has autofocus: https://www.closeuphotography.com/1x-test-2020/2019/12/13/1x-magnification-test-2020

If looking for > 13.9cm MWD, the Sigma 150mm Macro may work well. This one has a MWD of 186mm. It is the one I am getting for my Kodak "scanner" needs:
https://www.the-digital-picture.com/Reviews/Sigma-150mm-f-2.8-EX-DG-OS-HSM-Macro-Lens-Review.aspx

My EF 100mm L is nice but leaves me with a lot of unused sensor on my R5 in my case. The closest I can get it before the front plastic hits the Kodak machine is 5.9" which cuts off a lot of the sensor. Thought I use the sharpest, center part of the lens at about 1.35:1 - AKA 0.73x reproduction - I lose a lot of potential resolution getting only 33MP instead of 45MP. Though I don't know where the lens is most optimized for sharpness, I suspect it is not at 1:1... though it is a specialized lens to get there.

Re: Working distance of EF 100mm f/2.8L

Tronhard — Fri, 30 Aug 2024 04:26:24 GMT

Hi Spenser and welcome:
Please, to avoid confusion between two posts for similar but quite different and detailed issues, please start your own thread, so we won't get mixed up with whom we are engaging.

Re: Working distance of EF 100mm f/2.8L

spencerselvidge — Fri, 30 Aug 2024 04:35:35 GMT

Thanks for the welcome!

No confusion intended. I replied with the intention of helping the original poster, Robert. I clearly gave him more information than he had before with multiple options for his use case of >, =, and < his MWD needs. I was describing my own experience, which was perhaps excessive, but I was simply trying to relate to his issues finding exactly what he needs.

Re: Working distance of EF 100mm f/2.8L

RobertCampiin — Sat, 31 Aug 2024 20:14:44 GMT

Thanks for taking the time to respond, but working distance is only part of the problem. The other is the resolution of the lens. Unless it is at least as great as that of the camera's sensor, information is lost. Unfortunately, the sites you link to for the Sigma lenses use statements like "great image quality," rather than something that's actually meaningful like MTF or lp/mm. And a lens doesn't seem like "incredible value" when the buyer has to send it back at least twice because of functional issues, which was the case at one of the sites you linked to. For your use copying slides, a lens with acceptable working distance and 1:1 magnification are necessary, but so is resolution at least as good as the film or camera, whichever is lower.

Re: Working distance of EF 100mm f/2.8L

spencerselvidge — Tue, 03 Sep 2024 21:00:57 GMT

My sidebyside tests have been stellar on my R5 with the 70mm Sigma ART vs Canon EF 100L, especially into the corners at full 1:1. The 70mm is far superior. Closer to my Nikkor-Scanner lens than the Canon. I have not tested the RF mount version, though I have read its very similar to the EF.

I am not only doing 35mm slides, was just an example. I usually image flat objects at 1:1 though. Lots of people have tested many lenses on silicon chips, showing fantastic performance.

If you want to create your own data, you could buy 35mm/120 resolution targets to test your lens resolving power on your sensor as well. If interested, I can link you to some. I use them in various sizes. Regardless of your use case, this could be useful data for you if it is of serious concern.

Newer lenses will be designed with modern sensors in mind compared to old ones. Personally I will opt that direction when given the chance but there are even more amazing performers in old and modern copy and reproduction lenses. It is quite the rabbit hole initially but there is a wealth of info out there.

On the Sigma that was returned... as best I can tell it was because of the OS system they use. Seems it requires the OS to be "off" when installing and removing the lens. Plus for me, it would never be on because it is used on a tripod or in a well-fixed position.

Happy to chat more and hope you find what you're looking for! Good luck

Re: Working distance of EF 100mm f/2.8L

spencerselvidge — Tue, 03 Sep 2024 20:57:23 GMT

https://www.sigma-global.com/en/lenses/a018_70_28/specification.html

Found a chart. No lp/mm but MTF.

Re: Working distance of EF 100mm f/2.8L

RobertCampiin — Tue, 03 Sep 2024 22:25:30 GMT

Thanks for taking the time to write. However, it may (or may not) have "fantastic performance," but Sigma only shows the MTF at 10 and 30 lp/mm, the latter being approximately equivalent to a 7 Mpixel sensor. For the camera's sensor to be the limitation, the lens has to resolve over 100 lp/mm. I need all the resolution the camera has to offer, so the only recommendation that I can rely on is the performance of a lens as measured by a reliable source.

Re: Working distance of EF 100mm f/2.8L

RobertCampiin — Tue, 03 Sep 2024 22:47:48 GMT

When I wrote "the only recommendation that I can rely on," I should have added "for purchasing a lens." I am able to measure the resolution myself, but I'd like not to spend the money to buy a lens that someone says has "amazing performance," only to find it actually is somewhat lacking in amazingness.

Re: Working distance of EF 100mm f/2.8L

spencerselvidge — Wed, 04 Sep 2024 15:30:17 GMT

Understood. Data is king, but its is hard to acquire! Haha! As I understand it, and I could be wrong, most MTF tests are usually done at infinity. Macro lenses are not optimized for infinity but unfortunately commercial producers rarely change their tests to account for this and measure them at infinity anyways. So test targets (Vlad's Test targets on Adox 20 film or specialty targets from Edmund Optics, for example) and info from other enthusiasts who dig deep into this will show us more than manufacturer marketing typically will ... unless the manufacturer provides 1:1 MTF data.

So I will leave it here with this advice because I recently spent months similarly researching as well:

Definitely look into the lp/mm of lenses optimized for 1:1 rather than lenses with the ability to get to 1:1. Lenses like a Printing-Nikkor 105mm 2.8 (Rayfact still produces similar), a Schenider Macro-Varon 80/4.5 (now called Pyrite), or one of the Rodenstock Rodagon 75mm f/4 printing/duplication lenses. They all have variations/options and there are more specialty lenses from various makers from there. They are, in my anecdotal experience with them borrowing from friends, a measureable notch above anything from the major full frame camera makers.

Some data can be found from their makers (due to their optimization use case) and on some specialist forums having to do with macro and micro photography. Which is how I found the link below. It has some independent data collected at 1:1 for many lenses (including MTFs and working distances). Though outdated in web design, it has useful features like building comparison charts. https://coinimaging.com/macro_lens_tests.html

Personally I am adapting my Coolscan 8000 Scanner-Nikkor lens for now until I can afford/justify a Printing-Nikkor 105 or 150 or a Macro-Varon 80.

Good luck to you on your project!

Re: Working distance of EF 100mm f/2.8L

spencerselvidge — Wed, 04 Sep 2024 16:36:26 GMT

https://medium.com/on-film-scanning/vibration-proof-scanning-setup-is-your-rig-up-to-the-task-ffa4f5cfe100 I remembered this post, with test targets and lp/mm conversation. There are test images with the USAF Test Target info for the Sigma 70mm and APO Rodagon 75/4 across many apertures and shutter speeds. Might become useful for you. Thats all, cheers.

Re: Working distance of EF 100mm f/2.8L

RobertCampiin — Sun, 08 Dec 2024 22:25:15 GMT

I bought a 100 mm f/2.8L to replace my non-L macro (which will be passed along to on of my granddaughters), and made my own measurements. When the lens is manually adjusted to the closest focus distance, I measured the distance from the filter mount to the object to be 132 mm, rather than the 134 mm reported by Brian. Also, if someone needs the very last micron of distance, the lens itself is recessed by 3.1 mm behind the filter mount. For the non-L lens, I repeated the measurement I reported a few months ago and got the same result; the distance from the filter mount to the object is 148 mm.