Confused about mft lenses

[Bytesmiths]

Wasn't long before I put it down thinking "**** this. This is mathematics. I didn't like it as a teenager and don't like it now".

I encourage you to "push the envelope" and move out of your comfort zone now and then, by considering the "mathematical" nature of photography.

I designed and taught an eight-week course I called "The Art and Science of Photography." It took pains to reconcile the two, presenting artistic material is a mathematical way for "left-brained" people, and presenting technical material with artistic explanations, for the "right-brained" people -- and I encouraged those who considered themselves to be in one or the other camp to "cross over" to whatever extent they felt able. It seemed to really click with people, and I got many positive comments (from both "artistic" and "technical" people) that they had learned a lot more than they had in other photography courses.

I don't really think people can learn, change, and improve without pushing their limits. So I hope you don't totally give up on math, Gary!

 

[Gerard]

In europ we went from the country currency to the Euro.
First we did the math for every (intended) purchase. In The Netherlands the factor was 2.21*****.
Later each of us had to establish a new standard of references, like what does a beer cost, or a 7 year old BMW four door 6 cylinder. All europeans did this conversion math and we all succeeded (, except the british of course).
So how hard can it be?

 

[Aperture Don]

In europ we went from the country currency to the Euro.
First we did the math for every (intended) purchase. In The Netherlands the factor was 2.21*****.
Later each of us had to establish a new standard of references, like what does a beer cost, or a 7 year old BMW four door 6 cylinder. All europeans did this conversion math and we all succeeded (, except the british of course).
So how hard can it be?

When in Europe, I do the math. For my wife, I installed a currency converter on her iPhone. Both work.

 

[Gerard]

When in Europe, I do the math. For my wife, I installed a currency converter on her iPhone. Both work.

So you are not British?

 

[pondball]

So my wife just got a new car today (Honda Civic) to replace her 10 year old hybrid (also a Honda Civic). Last year we replaced her snow tires and had them put on alloy rims (cuz the steel ones looked like crud).

So the new/old rims (from her Hybrid) had a focal length of 15" whereas the new ones have a focal length of 16". The 15" ones are about 10mm wider than the 16" ones but also have 8mm less profile than the 15" tires.

So, trying to save a few $$ so I'd still have some cash left over for my glass collection I naturally asked if I could put the old APS-C tires on her new FF Civic... and they replied that it could be done but that it was a good thing I wasn't looking to buy the Medium Format Honda Accord because with a focal length of 17" it just wouldn't be possible.

They did warn me though the the milekilomeratage she would be getting would not be totally accurate because some the sensor, sorry, rims were a different size. I started to ask for an explanation, but stopped and asked what I thought was a more important question... "Would she still get some pretty good handling and performance out of her car regardless of which focal length rubber she used?"

The dealer said it would depend on how often she used her vehicle.

Just couldn't help thinking this might somehow be relevant?

 

[demiro]

when my wife drives it's all about the circle of confusion...

 

[Aristophanes]

Funny how 35mm equivalence dominated the mindset. Must be since 135 became such an everyday layperson format back in the day. "Small format." I find my self using equivalence back to 35mm even for medium and large format lenses. Like you say, its a great way to reference what you are going to get in terms of view based on familiarity.

Focal Length is very difficult to calculate. So there has to be a normative benchmark. Once the 135 standard came to dominate sales, that became the common reference point. It’s actually easier to,understand aperture than focal length because aperture is just a constant. It the mm in focal length isn’t really a true distance measure in any case.

And no focal length is exact amongst designs. Different measures from different companies have variations, so they are all somewhat approximate. This is more apparent with very wide lenses.

 

[Petrochemist]

In europ we went from the country currency to the Euro.
First we did the math for every (intended) purchase. In The Netherlands the factor was 2.21*****.
Later each of us had to establish a new standard of references, like what does a beer cost, or a 7 year old BMW four door 6 cylinder. All europeans did this conversion math and we all succeeded (, except the british of course).
So how hard can it be?

The British did a similar exercise with distance/weight etc. when switching to SI units. (Something we've still not completed).
I'm reasonably fluent in both systems, typically thinking mainly SI for work & food and old units for driving & beer. I have been known to use a mixture in DIY (4 foot long 23mmx18mm). I do get a bit wound up by some odd combinations - my wife's car gives fuel consumption in 'litres/100 miles' over here the traditional unit has always been miles/gallon conversion is complicated enough that they may as well have just stuck with the continental version of litres/100km!

 

[SojiOkita]

When I first purchased my Mu-43 I needed to check this conversion factor myself.
To convince my self of this 2x crop factor I checked a full frame with 50mm beside my Mu-43 with the 25mm. View was the same as expected.

Worth doing then you will never wonder again.

It's always more convincing when you experience it yourself than when you just read the explanation...

If someone is lost in the focal length equivalence, just check the diagonal angle of view.
That's what really matters.

 

[lchien]

First off, hello everyone.
I'm coming across from Nikon of which I've been a user for over 10years. I've been shooting full frame for the last 3 years and am switching to an Olympus OMD E 5mk2 (it's arrived at the shop and I'm very excited).
I'm trading in my D750 body and a selection of lenses for a few MFT lenses.
The problem is, I'm a bit confused as to why all the reviews state "XX full frame equivalent".
I'm looking at the 60mm 1.8, 17mm 1.8, and 40-150mm 2.8 Pro.
Every time I read a review, the reviewer, for example for the 60mm 1.8, will state 120mm ff equivalent (I see the crop factor on the mft is x2).
Now. When I went to ff with my Nikon gear, I understood that I'd have to upgrade to ff lenses or I'd have vignetting using my DX (aps-c sensor) lenses. I also understood that going the other direction, ie. fitting an FX (ff) lens to a DX camera body would result in cropping, which I did quite a bit when using my old D80 and scouring eBay for older, non aps-c lenses.
In this case with the Nikon, I can see why someone would say that a 30mm prime full frame lense on an aps-c would have an effective length of 75mm due to the 1.5 crop factor. Simply because the full frame lens is designed for a full frame sensor and the DX lens is designed specifically for an aps-c camera ( I won't go in to the distances from sensor to lens etc etc).

So. After all that, if all the lenses I'm looking at are designed for the mft camera, why is everyone mentioning the X2 cropped ff equivalent?
If I buy the 17mm 1.8 and pop it on my M5, am I expecting to see a true 17mm field the same way I'd pop on a 17mm on my D750? Or should I be expecting a field of view that I'd expect if I'd put a 34mm on to my d750? Basically, should every lens length that I look at be multiplied by 2 or not? If I use a 50mm on my Nikon and want the same view on the Oly, do I buy a 50mm mft or do I have to buy a 25mm to achieve the same viewing angle?
Bit of a long post but the reviews have really messed me up a bit with these mft lenses.

Basically the full frame equivalent focal length (2X the actual FL) tells you the equivalent field of view you would have with a full frame camera (or 35 mm SLR) with a lens of the equivalence focal length.
When you have 17 mm lens mounted on your MFT camera, the field of view you will get is like having a 34 mm on your old D750 full frame DSLR. And if you have a 150 mm MFT lens it gives you the telephoto magnification of a 300 mm lens on your FF camera. That's really all it tells you. Don't overthink it.

 

[Gregory]

Thanks all. Looking forward to playing with this 4/3 system. I'll get myself to that we'll known camera shop and have a play with a few lenses and see what is what.

Consider the 12-40 Pro lens. It outperforms all primes residing in its focal length range. Naturally it's heavier than the primes. Also, you may know that m4/3 lenses have a two stop advantage if deep depth of field is what you need. An f/8 setting has the same depth of field as f/16 on a FF camera. When I bought into the m4/3 format in 2013, I took the smaller sensor size and the resulting light-gathering disadvantage of the format seriously. But I reasoned that for landscape (my interest) while the sensor size on a four-thirds sensor was about 4 times smaller than the sensor size on a FF camera at 24 mpx, the setting of f/8 gave me four times as much light on my smaller sites. That realization triggered my buy in to the format and the excellence of Olympus color cinched it for that system. Have fun!

 

[Gary Thompson]

Stop it! I can't pick it up until Sunday and you're getting me even more excited!

 

[TNcasual]

Consider the 12-40 Pro lens. It outperforms all primes residing in its focal length range.

Hyperbole much?

I think the PL12, O12, O17 1.8, PL15, P20, PL25, O25 1.2, Sigma 30 1.4, Voightlanders, PL42.5... all beg to differ.

 

[Bytesmiths]

For my wife... Both work.

It's especially important that the wife works.

 

[Bytesmiths]

It’s actually easier to, understand aperture than focal length because aperture is just a constant.

Wait… if by "aperture," you mean "ƒ-stop," then no, it is not "just a constant:" it is the ratio of focal width to focal length.

So, if "the mm in focal length isn’t really a true distance measure," how can the ƒ-stop be any more accurate than the focal length?

 

[Aperture Don]

Basically the full frame equivalent focal length (2X the actual FL) tells you the equivalent field of view you would have with a full frame camera (or 35 mm SLR) with a lens of the equivalence focal length.
When you have 17 mm lens mounted on your MFT camera, the field of view you will get is like having a 34 mm on your old D750 full frame DSLR. And if you have a 150 mm MFT lens it gives you the telephoto magnification of a 300 mm lens on your FF camera. That's really all it tells you. Don't overthink it.

Did you read the first ten or so replies?

 

[Gregory]

Hyperbole much?

I think the PL12, O12, O17 1.8, PL15, P20, PL25, O25 1.2, Sigma 30 1.4, Voightlanders, PL42.5... all beg to differ.

I should have qualified my assertion to be limited to Olympus lenses only. If the O12, O17, and the O25 beg to differ, they will be begging for a very long time. I refer you to Micro Four Thirds Lens Tests.

 

[ianpiper]

I've been shooting full frame for the last 3 years and am switching to an Olympus OMD E 5mk2 (it's arrived at the shop and I'm very excited).
I'm trading in my D750 body and a selection of lenses for a few MFT lenses.

You are setting the bar high - the D750 is a superb camera. That said, the OM-D e-M5 II is also superb (I have one) and I think you shouldn't be disappointed by the results you get. Your back will thank you after a day's shooting, if you have been carrying Nikon FF kit around. I can get two Olympus bodies and six lenses in a small Billingham bag.
I find it's not a good idea to dwell on this equivalence thing - it just bamboozles me. Just look through the viewfinder and see what your picture will look like. If you need a rule of thumb (and I honestly do not think about this now) just double the focal length of an MFT lens to get to what you would have used on the Nikon. My main walk-about lens is the Olympus 17mm f1.8. This corresponds to a 34 mm FF lens. My 60mm macro is like a 120 mm FF lens. And so on. But after a bit of acclimatisation you probably won't even think about the relative numbers.

The one thing I'd say to anyone coming to the MFT system is, look at the primes first (i.e. before going to zooms). Olympus do a number of outstanding prime lenses; the two above, plus the 12mm, 45mm portrait lens and the 75mm short telephoto. They are light, small and give excellent results.

 

[moonhawk]

Basically the full frame equivalent focal length (2X the actual FL) tells you the equivalent field of view you would have with a full frame camera (or 35 mm SLR) with a lens of the equivalence focal length.
When you have 17 mm lens mounted on your MFT camera, the field of view you will get is like having a 34 mm on your old D750 full frame DSLR. And if you have a 150 mm MFT lens it gives you the telephoto magnification of a 300 mm lens on your FF camera. That's really all it tells you. Don't overthink it.

One correction: A 150 mm MFT lens will NOT give you the same telephoto magnification that a 300mm FF lens would. It will give you the same field of view or angle of view.

An image of an apple, shot with both, from the same distance, would appear twice as close with the 300 mm FF, but would fill the same amount of the frame. But, the frame of the smaller MFT image would have to be enlarged to be the same size as the FF image for the apple to be the same size.

150=150, and 300=300.

 

[JonathanC]

One correction: A 150 mm MFT lens will NOT give you the same telephoto magnification that a 300mm FF lens would. It will give you the same field of view or angle of view.

An image of an apple, shot with both, from the same distance, would appear twice as close with the 300 mm FF, but would fill the same amount of the frame. But, the frame of the smaller MFT image would have to be enlarged to be the same size as the FF image for the apple to be the same size.

150=150, and 300=300.

Doesn't this have more to due with the number of pixels and size of the sensor (and thus the dimension of a full-size image)?

If both the FF and MFT cameras had 16MP, the full-size images of the apple through the 300mm FF and through the 150mm MFT would be the exact same size, correct?