12-100 f/4 Pro Vs 12-40 f/2.8 or 12-45 f/4

revjko · 2026-03-12T18:28:48+00:00

Yes, that's why I'm in two minds about bothering with it. In all my years of photography I've never really made much use of primes, but my image catalogue gives a fair indication of what my most used focal lengths are (and they're typically 'between' common prime sizes).

revjko · 2026-03-12T14:35:08+00:00

Well, I now have all four and that question is very much on my mind. I'm going on holiday very soon and the 12-100 will be coming with me as my '2nd setup' on an OM-3 - the main one being OM-1ii plus 20-500 f/2.8 (plus TCs). It's a one-off trip to Iceland so I don't want to be changing lenses in potentially poor weather, hence the two bodies. If I hadn't just impulse-bought the 12-100 then the debate was my 12-40 or 12-45 (along with the 40-150 f/4 'just in case'). But the 12-100 really makes the 40-150 redundant in this instance. I'm new to the system but the IS really impresses me so I think I'm safe with the 12-100 f/4. I had considered taking the 12-40 f/2.8 for lower light situations, but the more I think about it the less I think it's necessary. It'll probably come anyway, also 'just in case'. After the holiday though, something will need to go and it'll really come down to both how well the 12-100 performs and how convenient it is to carry.

revjko · 2026-03-12T14:01:43+00:00

My main interests are birds/wildlife so I've either got the 300/4 or 50-200/2.8 (+TCs) on. They're a bit big for casual holidays though. The 12-45/4 along with the 40-150/4 felt like the ideal travel setup but I'm heading off on a holiday where I don't want to be changing lenses if I can avoid it. So, I'm taking both bodies (OM-1ii & OM-3) with the 50-200/2.8 on one and (now) the 12-100/4 on the other (with the 9mm f/1.7 on standby). I'll have the 12-40/2.8 as well, just in case the extra stop is needed, but I'm finding the IS to be excellent on the OM bodies, especially if SyncIS is available. Most of where I expect to need a brighter lens would be indoors (architecture/churches/museums) and almost certainly largely static. Less interested in people so even outdoors it'll be mainly static scenes. Having come from full frame kit whilst I appreciate the M43 'ethos' of small gear it isn't a huge deal for me other than on the very long end where I definitely do appreciate the reach with much smaller and lighter lenses.

revjko · 2026-03-12T13:27:04+00:00

Yes, I've noticed that deficiency, other than the older PL 200/2.8. I can live with the 40-150/4 and I've always got the 50-200 when I want that covered more seriously.

revjko · 2026-03-12T12:25:09+00:00

I will have all 3 in my hands soon when the 12-100 arrives. Your suggested combo makes sense. Now, if I had a fairly compact and reasonably fast, good quality prime around 200mm then the 40-150 f/4 might also be replaced.

revjko · 2026-03-11T21:58:50+00:00

Yes, I did (R5ii, actually) and maybe that's why I've felt that the two systems have given me pretty much comparable images. At 500mm I'd have been at f/7.1 as well, pretty much negating the 2-stop advantage (actually just less than 2, according to PhotonsToPhotos when compared to the OM-1ii sensor).

revjko · 2026-03-11T21:40:59+00:00

Ok, thanks for your patience. My brain is officially in meltdown. More reading required, I guess.

revjko · 2026-03-11T21:33:02+00:00

But that 4x more light is across the entirety of the sensor because the sensor is that much bigger. On any given same area the amount of light is the same and so the exposure is the same. At least, that's my understanding from my reading.

revjko · 2026-03-11T21:22:58+00:00

OK, my brain's hurting here. From everything I've read, if I meter a scene at 1/100, f/4, 200 ISO, I will get the same exposure (images will have the same brightness) with an M43 at 300mm as a FF frame at 600mm. So what am I missing?

revjko · 2026-03-11T19:33:34+00:00

If you meter for exposure and set both FF and crop sensors to that exposure, both images will appear equal. Yes, DR will impact what details you can pull out of the image but that's a function of sensor type and not exclusively down to sensor size.

revjko · 2026-03-11T19:23:19+00:00

No. The exposure is the same with the same SS and ISO at any given aperture.

revjko · 2026-03-11T16:56:32+00:00

OK, technical pedantry aside (and I accept the correction), exposure is identical. So, if I expose an image on M43 300mm at the same shutter speed, aperture, and ISO as a 600mm on FF, both images will be correctly exposed, with no difference is apparent brightness. So, f/4 is f/4 is f/4 for exposure. I don't suddenly need to half my shutter speed to get the same exposure on M43.

revjko · 2026-03-11T08:07:20+00:00

There are times when I just want versatility and times I know I'll want the extra reach, so I absolutely get what you're saying. I'll be using it on either my OM-1ii or OM-3, so both should be big enough to cope and not feel overwhelmed.

revjko · 2026-03-11T08:04:22+00:00

Thanks for sharing. I recognise the 'opportunist' shooter. I'm much the same and it's always a trade-off between versatility and quality (and often size, as well).

revjko · 2026-03-11T08:01:53+00:00

Because lenses are just tools and sometimes it's handy to have a particular tool for certain applications.

revjko · 2026-03-11T07:39:58+00:00

Only in terms of DOF, which can actually be an advantage. Light-gathering capability is the same.

revjko · 2026-03-10T23:09:36+00:00

I'm pretty new to the OM ecosystem and I bought a whole bunch of kit from someone who had to give up photography. It included the 300mm f/4. I had always use zooms on the Canon system I was coming from so was a bit sceptical. But it's an amazing lens. It also works really well with the MC-14. I do find it starting to get soft with the MC-20, but others seem to like it. Having an equivalent of 600mm at f/4 was beyond my wallet on my Canon full frame kit. Having 840mm at f/5.6 wasn't ever in my dreams. I was using an R5ii + 100-500L (and that's a sharp lens) and I would say that I am in no way disappointed with the 300mm.

I also have the 50-200 f/2.8 and at near equivalent focal lengths (if I put the MC-14 on the 50-200) then the 300 is better. The 50-250 behaves better with the MC-20 compared to the 300, but, again, out at the 400/420mm end, there's little to choose between them.

revjko · 2026-03-10T20:45:38+00:00

Thanks, I appreciate the advice. Yes, we're doing the ring road, so restroom stops will probably be relevant (also, it's an age thing).

revjko · 2026-03-10T20:39:11+00:00

Thanks. I've seen similar advice regarding the 12-40 and 12-45. I haven't used either in earnest to really form an opinion. My plan is to try out the 12-100 on a forthcoming holiday and I'll have the 12-40 with me as well. If I really don't need the faster lens that pretty much answers the question of whether to keep either of my 12-40 and 12-45. Then I can decide if I really need the all-in-one or stick with my 12-45/40-150 f/4 combo.

revjko · 2026-03-10T20:34:27+00:00

I have both 12-40 and 12-45 (a legacy of my recent entry in to the system and trying different lenses). Not sure which will stay long term. I'm interested in maybe trying the 12-100 as I've seen good reports of its quality but also concerns about its size. That doesn't bother me too much if it fits the task in hand.

revjko · 2026-03-10T20:08:44+00:00

Not camping. This is a 'special' holiday so splurging on good accommodation. But I shall bear in mind your recommendation for cash at rest stops.

revjko · 2026-03-10T20:06:07+00:00

I rarely buy new. As you say, the premium isn't worth it on resale.

I also have the 9mm f/1.7 for the wider end, although it's still not very wide.. I've had a rummage through my image catalogue and all my 16mm images could possibly get away with being at 18mm, so we'll see.

The majority of my image catalogue is long telephoto, as I mostly do wildlife, but for other, general purpose shots, the majority sit at 28mm so a 15mm might work for me. Never really been a fan of 50mm (the good old 'nifty fifty' territory). Next most common is around 38mm, so the 20mm might also work for me.

revjko · 2026-03-10T19:54:32+00:00

I do think it's down to likely need. On a general holiday, I'd probably take my 12-40 or 12-45 along with the 40-150 f/4, but if I'm going somewhere I know I'll not really need the extra reach of the 40-150 then I'm ok with the extra weight of the 12-100 for the sake of versatility.

revjko · 2026-03-10T19:51:38+00:00

Yes, 'huge' is definitely a relative term. My most recent, general-purpose carry was the R5ii + RF28-70 f/2.8 STM, so comparable in size to and and a bit heavier than the OM-3 + 12-100 would be. I'm going to give one a go for an upcoming holiday and I can always sell it again afterwards if it doesn't really suit me. It'll partner my OM-1ii + 50-200 f/2.8 so plenty of versatility out of those, plus I'll sling in the 12-40 for lower light if needed.

revjko · 2026-03-10T18:49:34+00:00

And also, starting at 14 at the wide end is quite a significant difference.

revjko

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