Crop Factor: Why you multiply the aperture by the crop factor when comparing lenses

face is better with full frame, why you are paying attention to background but not to sharpness of the face

Tony, shouldn’t the iso on the 4/3 camera be 400 instead of 200 on your example? If it is 200, how did you come with that so i can calculate it right. Thanks!

Really appreciate this explanation

Very much appreciated for the awesome information about Crop factor! I learnt a lot! God bless and good luck!

You explained it very well! I’m a m43 user. Some people think that m43 sensor can’t do any bokeh which is not true. And it is not “harder” as there are many tiny to mid size lenses with 1.2-1.8 aperture to compensate the small sensor size. So generally speaking the image quality is not worse on m43 it depends on the lens you use. When weight, size and price don’t matter, then yes full frame has better image quality.

F-stop remains the same...
Its the distance between sub and camera( u'll either have to zoom in or go closer ,in full frame camera for the same field of view as in apsc .leading more blurry background)...
Note- hence,exposers ,aprature remains the same in both the cameras but full frame sensor has advantage on low light performance

This is all fine but you don’t need to compare anything; you are just taking a photo. You have a camera, pick the lens opening you want, iso, shutter speed - take the photo. It is true though, camera sales/manufacturers are kinda misleading you; a 50 on a crop sensor does not give you a 50 mm frame.

If you adjust everything the same on a MFT and FF you will find the ISO will be lower on a MFT than a FF - therefore you don’t apply the crop factor to the aperture

This guy is the real shit! Good info

um so pretty much i don’t see the point of multiplying crop factor for aperture on high quality dslrs, especially if you shoot reasonably low iso images, unless you are obsessed with portraiture and a particular quality of bokeh

Time to sell my sl3

If depth of field depends on 3 things, focal length (this is a property of the lens), aperture (this is also a property of the lens) and distance to subject, then by zooming in from 10mm to 20mm you have changed the depth of field. This has nothing to do with the camera sensor. Where this video gets confusing is that it's missing a caveat.If you want to achieve the same depth of field AND THE SAME FIELD OF VIEW, then yes, you have to do some calculations. But if you don't care about achieving the same field of view, you can absolutely achieve the same look you get on a full frame camera with the same lens on both full frame and aps-c cameras. This is where people get confused. Aperture and focal length are properties of the lens not the sensor or the camera. It still lets in the same amount of light no matter what it is attached to. Things will only change if you're trying to achieve the same field of view as a full frame.

Amazing video
Wish i knew this sooner :)

I am glad you dropped the goatee. You look much better clean faced

And chelsea managed to stay still for 8 whole minutes lol

Great explanations ! Learned a lot from this !

So I should get a 25-28mm for my m4/3 to get the equivalent of a 50mm in a Full frame

Pretty sure that Fstoppers describes this and shows that the aperture's not affected... perhaps that's not the case?

On the M43, if there is a 2x crop, the 100mm lens is equivalent to 200mm. So is perspective stacking the same as ff 200mm crop 2x 100mm?

the best video on this subject EVER

If you take a photo with a full frame and a crop camera, if you don't mind the smaller field of view, you don't have to calculate the aperture by that factor. You only have to do it if you want to achieve the same picture, from the same distance, the same shutter speed, the same iso, the same field of view AND the same bokeh. But still if you change the aperture according to the multiplier you still have to compensate for the less incoming light by changing the other parameters. So, you only have to worry about all these things if you want to take same picture as a full frame and the opposite goes if you want to achieve the same photo from a crop camera to a full frame.

BTW how much change calculations do lens adapters require?

That full frame pic in the thumbnail looks a lil bit better

Thanks for this, great video. Since moving to digital with APS-C sensor I had always wondered about this - I understood the focal length difference. I'm a little puzzled however by the recommendation to multiply the aperture by crop factor to get the equivalent however. For simplicity in maths, I'll compare full frame with micro 4/3 due to the 2x factor. So f2 become f4 using the crop factor calculation you suggest however f2.8 allows twice the light that f2 does. Am I missing something?

AWESOME VIDEO AS USUAL ... YOU GUYS ROCK !!!! IM STILL NOT SURE HOW TO FIGURE OUT THE mm EQUIVELENT OF THE CANON SX HS 50 ... WHICH HAS A 50X OPTICAL ZOOM , IVE USED THIS CAMERA FOR YEARS BEFORE I GOT INTO DSLR .. BUT THE ZOOM ON IT WAS AMAZING AND I TOOK SOME AMAZING PHOTOS WITH IT ... CAN YOU EXPLAIN HOW TO FIGURE THAT ONE OUT ? I WOULD LOVE TO HAVE THE SAME REACH ON MY ...NOW 7D, BUT IM NO WHERE NEAR IT WITH EVEN A 600 MM PLUS A 2X TELECONVERTER ??? ANY HELP WOULD BE APPRECIATED THANKS AGAIN FOR ALL THESE GREAT INFORMATIVE VIDEOS !!!! KEEP UP THE GREAT WORK !!!!

80% of the m43 community can't comprehend this video

Use a crop lence for crop sensor its simple.

Make some wonder why manufacturers didn't just use the FF equivalent FL and aperture for APSC and MFT lenses. A Leica Nocticron 42.5mm F1.7 should be sold as an 85mm F3.4. That would spare people the guesswork. But perhaps they would be less inclined to spending top $ on non FF systems. (saying that: I am on MFT 😁😉)

Best explanation out there! Thank you 🙌🏽

Thanks for sharing great stuff... Love the good job you guys are doing. Such a nice, well-prepared and to-the-point way of explaining things :)
I have an a6300. Works just fine. Just struggles in low-light a little bit. Any full-frame camera recommendations which has an image stabilization like or near Gh5?

Good! I was just concerned about the bride wilting in the back there. Beautiful though.

It feels a bit shady that information is this way. I’ve always been very confused about this. Thank you for your your explanation.

She looks so uncomfortable standing there for 8 minutes as he babbles on.

Why Tony and his wife so similar

I always come back to this video. as of today sellers have been adding crop factors in terms of distance they havent done so for the f stop because i guess it makes the sell. but theyve added crop factors at least on BnH.

Does the same logic work for cinema? Lenses for cinema? BlackMagic with its crop factor?

Keep in mind that lots of background blur isn't always preferred, so a Micro 4/3 Sensor will have more light while achieving the same focal blur reduction (micro 4/3 also usually have less pixels but 20mp is still way more than 99% people need/use, so less light hitting each pixel of the sensor isn't really a thing as said here).Having the aperture set too low can cause undesirable blur on parts of your target it self (even with a smaller sensor). What is considered good or bad works both ways, bokeh is a little over emphasized as a good thing in most reviews. Also worth of note, is that f1.8 - f2.8 on a micro4/3 can be more than plenty, especially with bigger lenses, as they magnify the bokeh if that is something you need. It's 2 different systems with different use cases and mechanics to doing essentially very similar things.

Thank you for clearing this up 👍

Nice explanation.

So with the Fuji example (56mm f1.2) it's STILL a fast lens, right? At f1.2 I would think it's still sucking in a bunch of light, but the comparison with the 35mm sensor equivalent lens is a comparison in the thin depth of field achieved wide open and therefore the quality and/or quantity of the background blur, no?

Tony, Useful video. To add further complexity, is the use of focal reducers, (e.g. Metabones Speed booster). I use one on my Fuji X-H1 with full frame CONTAX Zeiss lenses. The 85mm F1.4 with speed booster, shooting wide open results in depth of field of about 1" with the subject at about 10' shooting distance . With what appears to me as razor sharp in focus images. As the speed booster is correcting both focal length and aperture.

A 100mm lens is always a 100mm lens no matter what camera you put it on. There is no equivalence to a lens. The lens is always 100mm. The field of view changes not the focal length of the lens. If you have a full-frame camera and you put a 100mm lens on it it has a field of view of some degrees. If you take the full-frame camera and make it a cropped sensor but cutting a paper with a smaller hole in it and put the paper in the full-frame camera you have cropped the field of view. It has in degrees a smaller field of view. The lens is still a 100mm lens. It is the same f/value. No matter how big or small the sensor is the lens is always the same. Focal length and value are fixed. Nothing can change that because it is a physical property of the lens. Please go take a physics class in optics.

I don’t understand how there’s less bokeh on a smaller sensor when you have the same exact lens and only switch camera bodies.. I understand the light gathering part, but bokeh is an effect of the out of focus light detracting inside the lens. If you have a lens mounted to a tripod and only switch camera bodies, would that not just make it a bit darker and crop in on the same image, not effecting the bokeh?

I don't see any differences, she still looks beautiful.

It is just tragic how many people have been mislead by this - FOV radius at any given working distance is not linear, while DOF with regard to working working distance is.

Anyone who has spent any time using a camera should intuitively realize this.

What this means in practice isfilm plane

This means that any compensation for depth of field will not necessarily double the projection of magnification, so moving in closer won't necessarily compensate depth of field for crop factor. This disparity naturally will decrease with focal length as FOV approaches zero degrees, and is why between 100mm and 200mm the difference in the two images is negligible. However, the same is not true of wider lenses as the FOV approaches 180 degrees (as it is applied to rectilinear lenses).

Hello! You get less light with the APS-C camera because of the pixel size ( 6,41 microns vs 4.29 microns) not because of the crop factor or sensor size and you have more blur in the background of the image taken with the full frame camera , because you used 200 mm focal length instead of 100 mm. The crop factor or using different size sensors will not change the focal length of the lens, will give different field of view, and usually different image scale. Cheers!