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I’m considering getting rf 100mm f2.8L macro but..


For crop sensor,r10 this lens seems bit too long for portraits , not long for sport or wildlife . I’m mainly interested in its 1.4 macro but that money would need to be utilised more than just for that . I already have 35 mm 1.8 but 0.5 macro, and 100-400mm .


What are the best uses for 100mm on crop? 



For Macro, obviously. 100mm provides a lot more "working distance" than the 35mm. But horses for courses as they say. If the 35 mm meets your needs there is no reason to get the 100mm. No one says - except Canon, maybe, - that you have to get *every* lens.

Note that the 100mm has Hybrid IS, which can come in *very* handy for handheld macro shots, and can do things that IBIS cannot.



We can only comment on function, the choice to buy is ultimately yours.  The most popular FL's for portrait photography is 85-135mm.  Some enjoy using a 70-200mm for portrait work.  The the RF 100 f2.8 like its EF predecessor is an exceptional lens for macro.  About as good as it gets. 

Coupled to a R10, you'll need to use your legs for composition and framing of distant subjects.  While it has a 10in MFD, you will probably use it for macro at greater distance too.  I would expect it to be more functional for macro work over portraits on a APS-C based camera.

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Thank you, why do you think I’ll use greater distance for macro despite 10in?


I think I’ll use my 100-400 first to see how I feel shooting at 100mm but even if I don’t like it, 1.4 on crop remains tempting.

Because you might not be at 1:1.

Could you please elaborate? What the photographer needs to do to be at 1:1?


isnt 1.4 on crop like 2.2 magnification?

@thetoxicmud wrote:

Thank you, why do you think I’ll use greater distance for macro despite 10in?

I think I’ll use my 100-400 first to see how I feel shooting at 100mm but even if I don’t like it, 1.4 on crop remains tempting.

First off, you've already received some great info, but I'll add a few things. I shoot a lot of macro on both FF and croppers.

You might want or need greater than Minimum Focus Distance (MFD) to get shots like this. Please keep in mind that this example is extremely reduced from the original crop.

Ruby-throated Hummingbird MAL-0001Sb.jpg

I was shooting a lizard on the feeder support at MFD when this hummingbird came to the feeder. I was probably 2 feet away but was able to crop in post to get a greater than life size capture.

As for using your 100-400 at 100mm, please keep in mind that macro lenses are designed differently. I won't go into the details of the differences, but they [macro lenses] are designed to account for all the difficulties that arise when shooting up close  You can get a good "closeup" using the 100-400, but they are by no means the quality you would get from a true macro lens. TIP: I've shot closeups using the EF 100-400mm II L, RF 100-400mm, and the RF 100-500mm L with good results, but at the max FL, never 100mm. All of these lenses are designed to focus closely, compared to other telephoto lenses, at their max FL.

If I'm shooting macro, I strictly use the EF or RF 100mm f/2.8L Macro lens (I still use my DSLR's). Outdoors I mostly shoot hand help and increase my shutter and ISO. While indoors under controlled  or posed subjects, I use a tripod with macro rail, and I use the rail even when focus stacking so I can at least start at 1.4 or 1 to 1.


EOS R5, R6, R6II. RF 15-35 f/2.8L, 50mm f/1.2L, 85mm f/1.2L, 100mm f/2.8L Macro, 100-400mm, 100-500mm L, 1.4X.


Crop factor does not come into it. 1:1 means that the image on the sensor is the same size as the object. So a subject that is 25mm by 16mm will fill the sensor.

You only get that at one focus distance. For a macro lens that maxes out at 1:1 it will be the minimum focus distance. As you move further away, you must refocus and at some point, the image on the sensor will be half the size of the object, so at that focus distance, the 25x16mm object will be 12.5 x 8 mm on the sensor. And so on.

So for a macro lens with a max 1:1 ratio, you need to set the lens to the minimum focus distance. In fact, my EF-S 60mm macro has a scale that shows the focus distance as well as the magnification ratio so you can set the magnification and the move the camera to get the object in focus. This is exactly what a macro rail is for.


It is hard to see, but the little yellow "1:" above the distance scale shows where the magnification shows up.

Thanks , still if I’ll be capturing subjects 1:1 is entirely up to me, all you have to do is to manually adjust focus at minimum range and then get camera as close as possible, then you always get 1.1 or 1.4 in this case, is that correct? 

Yes, you get the maximum magnification at the minimum focus distance. But note that I think that you need to be at 400 mm to get the 1:1.4.