40mm f2.8 STM or new 50mm f1.8 STM?

[Marsu42]

As 50mm on a crop pretty much matches the age-old advice of 85mm on full-frame being The Studio Lens

... for full/half body portraiture, for anything nearer 85mm is considered to have to much optical distortion and a longer focal length up to ~135mm is the way to go. Furthermore, I don't think such a (still) crappy lens as the 50 stm is a good pairing with a good crop camera body like the 7d as the af system isn't optimized for it and the lens' lack of sharpness will be magnified.

That's why I'd +1 the 60mm macro advice from above, a macro lens always is the most fun lens on the planet and you can dual-use it for portraiture just fine.

 

[mb66energy]

And here a comparison to the 40 STM:
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=810&Sample=0&FLI=0&API=0&LensComp=989&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=2

At f2.8 the 50 STM is looking even better in the center with just a little drop to the corners.

moushu, IMHO now it is clear which one to choose.

Tell us about your daughters reaction and maybe post some of her pictures here if she likes to.

It might be a good idea to wait for the 60D test images before making the decision ... APS-C sensors discriminate between so so lenses and the really good ones! (5Ds(R) will do the same)

 

[NancyP]

I think that the The-Digital-Picture comparison is of one copy of the old with one copy of the new Nifty Fifty. The optical design of the NF II and the NF STM is the same. It is possible that the manufacturing process could have been improved with the STM lens. But it is also possible that the difference is merely unit-to-unit variance.

 

[ajfotofilmagem]

I think that the The-Digital-Picture comparison is of one copy of the old with one copy of the new Nifty Fifty. The optical design of the NF II and the NF STM is the same. It is possible that the manufacturing process could have been improved with the STM lens. But it is also possible that the difference is merely unit-to-unit variance.

I remember reading in LensRental.com to copy variation visibly affects the image corners. There had to be something seriously wrong with a lens copy, to realize (the naked eye) variations in the center.

I also remember reading another article in LensRental.com which states that lens coatings are "the most important part" of the optical design.

Some people do not want to believe that Canon has made improvements in sharpness, contrast and bokeh, changing "only" optical coatings and aperture blades, and maintaining the sales price unchanged ...

 

[Sporgon]

I think that the The-Digital-Picture comparison is of one copy of the old with one copy of the new Nifty Fifty. The optical design of the NF II and the NF STM is the same. It is possible that the manufacturing process could have been improved with the STM lens. But it is also possible that the difference is merely unit-to-unit variance.

I remember reading in LensRental.com to copy variation visibly affects the image corners. There had to be something seriously wrong with a lens copy, to realize (the naked eye) variations in the center.

I also remember reading another article in LensRental.com which states that lens coatings are "the most important part" of the optical design.

Some people do not want to believe that Canon has made improvements in sharpness, contrast and bokeh, changing "only" optical coatings and aperture blades, and maintaining the sales price unchanged ...

Also Photozone's results support TDP between new and old, making 'copy variation' very unlikely.

In their pre release press blurb Canon stated 'improved optical alignment' (or something like that) as well as improved coatings, and it looks like they weren't kidding.

In answer to the OP, I'd suggest the 50 over the 40 in your case due to the fov and dof on crop.

 

[SpuTTer]

Dustin Abbotts video review shows improved optics also. Very unlikely that there is this much 'copy variation'. It looks like it's sharper than the II wide open, or better contrast, etc.

 

[SpuTTer]

Another review popped out which seems to support the improved sharpness (wide open). http://petapixel.com/2015/05/30/battle-of-the-nifty-fifties-canons-50mm-f1-8-lenses/

 

[bholliman]

And here a comparison to the 40 STM:
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=810&Sample=0&FLI=0&API=0&LensComp=989&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=2

At f2.8 the 50 STM is looking even better in the center with just a little drop to the corners.

I'm pleasantly surprised by the sharpness of the new 50 STM. Very sharp in the center at wide apertures, but sharp across the frame stepped down. In these comparisons with the 40 STM, the 50 is slightly sharper in the center at f/2.8, but when stepped down to f/5.6 and smaller, the 50 appears sharper across the frame.

This might make a good small/light lens for hiking. Its sharpness stepped down would make it a good for panoramas. At f/8 and f/11 it actually compares well with the 24-70 f/2.8 II! Not bad for a $125 lens!

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=787&Camera=453&Sample=0&FLI=3&API=4&LensComp=989&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=5

My 50 STM is on order, expected to arrive tomorrow. Looking forward to its arrival.

 

[Hjalmarg1]

Thanks all, it looks like most are coming down in favour of the 50 on a crop.
Now all I need to need is convince her highness that a prime isn't a limiting factor, as really she's angling for a 18-135 of her own..

Best selling factor for fast apperture lenses is the ability to gather bigger amount of light and this aspect is very important at weddings because some times flash isn't allowed at churches.
I owned the 40mm STM and now I own the new 50mm STM and the sharpness of both at f2.8 is quite similar with a slight edge to the 50mm STM but remember that you can still shot at f1.8 and have good center frame sharpness which is good in particular to portraits.

 

[Hector1970]

The 40mm is very sharp and a lovely tiny size.
I've always found 50mm on a crop very inflexible. Fine for portraits but almost nothing else.
The 40mm allows you do a little bit more.
On a full frame 40mm is neither here not there.
I like 50mm on full frames for some reason.
I don't use the 40mm much but I do rate it's sharpness highly.