Best lens for a large group shot (crop camera)

I am pretty happy about the lens lineup I have converged to over the years, with one obvious exception: regularly (though rarely - 1-2 times a year) I need to take a large group (20 ... 80 people) photo at my work, and my only lens suitable for these occasions (Sigma 17-50mm f2.8 OS) produces poor corner sharpness (I'm using 30...35mm, f5.6-f8), so I end up doing selective corner sharpening, and even then the result is far from ideal.

So basically I'm now looking for a new lens for my 50D, around 30...50mm, which would have very good sharpness across the entire frame. Given that this would be used rarely, I want a cheap solution, so lenses like Sigma 35mm Art are not an option (though it does look very nice). Between the-digital-picture.com and photozone.de I quickly converged to the two following candidates:

- Canon 40mm f2.8
- Canon 35 f2 (non-IS)

The first one can be found very cheaply (~150$) second hand. The 35mm f2 IS does look slightly better than non-IS at f5.6, but at 2x higher price that would be not justifiable (I only plan to use it with a tripod, so IS is useless).

What bugs me is that according to the-digital-picture.com both above options are much sharper at the corner at f5.6 than my Sigma 17-50mm at 35mm f5.6, whereas photozone.de numbers show the opposite - the Sigma is quite noticeably sharper. I think the photozone.de corner numbers look way better than my personal experience with the 17-50mm lens (but not sure if my lens is as bad as the-digital-picture.com would let you believe).

Anyone here with first-hand experience with either of the primes listed above and the Sigma 17-50mm f2.8 OS lens? What is your experience?

Any other lenses to consider which would be sharp across the frame around 35mm and f5.6 and wouldn't cost a kidney?

E.g. I looked into the new Tamron 35mm f1.8, but it didn't look much better than the two primes I listed above, and it's 2x more than the Canon. Also, Samyang 35mm f1.4 looks interesting, but I don't really need f1.4, and MF lens can be challenging when you shoot a large group.

pulsar123 wrote in post #18031002
Any other lenses to consider which would be sharp across the frame around 35mm and f5.6 and wouldn't cost a kidney?

Tamron 17-50 non-VC

I don't notice issues with mine at 5.6 in the corners so much. You could stop down to f8 for more sharpness though. another option would be to sell the 17-50 and buy the 18-35 where you wouldn't have issues with corner sharpness even at f2.

No experience with the 40 pancake but it's supposed to be very sharp. Still for 80 people with a 40mm on crop you may want a megaphone too

pulsar123 wrote in post #18031002
I am pretty happy about the lens lineup I have converged to over the years, with one obvious exception: regularly (though rarely - 1-2 times a year) I need to take a large group (20 ... 80 people) photo at my work, and my only lens suitable for these occasions (Sigma 17-50mm f2.8 OS) produces poor corner sharpness (I'm using 30...35mm, f5.6-f8), so I end up doing selective corner sharpening, and even then the result is far from ideal.

So basically I'm now looking for a new lens for my 50D, around 30...50mm, which would have very good sharpness across the entire frame. Given that this would be used rarely, I want a cheap solution, so lenses like Sigma 35mm Art are not an option (though it does look very nice). Between the-digital-picture.com and photozone.de I quickly converged to the two following candidates:

- Canon 40mm f2.8
- Canon 35 f2 (non-IS)

The first one can be found very cheaply (~150$) second hand. The 35mm f2 IS does look slightly better than non-IS at f5.6, but at 2x higher price that would be not justifiable (I only plan to use it with a tripod, so IS is useless).

What bugs me is that according to the-digital-picture.com both above options are much sharper at the corner at f5.6 than my Sigma 17-50mm at 35mm f5.6, whereas photozone.de numbers show the opposite - the Sigma is quite noticeably sharper. I think the photozone.de corner numbers look way better than my personal experience with the 17-50mm lens (but not sure if my lens is as bad as the-digital-picture.com would let you believe).

Anyone here with first-hand experience with either of the primes listed above and the Sigma 17-50mm f2.8 OS lens? What is your experience?

Any other lenses to consider which would be sharp across the frame around 35mm and f5.6 and wouldn't cost a kidney?

E.g. I looked into the new Tamron 35mm f1.8, but it didn't look much better than the two primes I listed above, and it's 2x more than the Canon. Also, Samyang 35mm f1.4 looks interesting, but I don't really need f1.4, and MF lens can be challenging when you shoot a large group.

Heya,

EF-S 18-55 STM - Very sharp, very good lens, super cheap $80 often.
EF-S 24 STM - Very sharp, wide, great lens for groups, also only about $100 often.
Yongnuo 35mm F2 - Sharp, wide, cheap, $99.

Very best,

Thanks for the suggestions, but not sure they'd do better than what I already have. I had the 17-50mm Tamron in the past, wasn't impressed with its AF consistency. And 24mm is too wide for group photos I'm afraid.

I think I found another interesting option - the new Canon 50mm f1.8 STM; a bit too long for group photos on a crop but still manageable. Both the-digital-picture.com and photozone show it as quite a bit sharper in the corners than the 40mm pancake, and I kind of miss a 50mm prime (I had the old 50mm f1.8 couple of times) - can be very good for full height portraits in studio when stepped down to f5.6-f8. I just missed a super good sale for the lens in a local store (staples; no longer in stock): only 130$ CAD.

pulsar123 wrote in post #18031099
And 24mm is too wide for group photos I'm afraid.

I think I found another interesting option - the new Canon 50mm f1.8 STM; a bit too long for group photos on a crop but still manageable.

So 80 people into 3 rows giving an average of 22" per person is like 48 feet across. Divide them into 4 rows and you are down to 36 feet across. With a 50 on crop you are talking about standing 80 feet away. Is this your plan? Last group picture I was in with 80 people was at a wedding and the photog used 16mm on full frame.

FEChariot wrote in post #18031143
So 80 people into 3 rows giving an average of 22" per person is like 48 feet across. Divide them into 4 rows and you are down to 36 feet across. With a 50 on crop you are talking about standing 80 feet away. Is this your plan? Last group picture I was in with 80 people was at a wedding and the photog used 16mm on full frame.

Yeah I know - it's always a compromise. Sharpness vs. convenience, at a given price point.

Here is a specific example, taken a few days ago using 28mm f5.6 of Sigma 17-50mm (corners extra sharpened):

http://www.physics.mcm​aster.ca/~syam/SS2016a​.jpg

You can already see faces in the corners stretched by perspective effects, so something like 35-40mm would be better. 50mm means being further, and I usually need to be in the photo as well, but I have a decent RF remote (Yongnuo RF603, works for 100 feet), so probably okay.

Also, people in the back look quite a bit smaller than in front (another issue due to short FL). A 50mm on a crop would result in a much nicer perspective compression, with faces sizes more comparable.

Anyway, I can see the 50mm STM sold by amazon.ca for only 130 CAD (100 US), and I can always return it if it doesn't work for me, so I'll give it a try.

pulsar123 wrote in post #18031159
Yeah I know - it's always a compromise. Sharpness vs. convenience, at a given price point.

Here is a specific example, taken a few days ago using 28mm f5.6 of Sigma 17-50mm (corners extra sharpened):

http://www.physics.mcm​aster.ca/~syam/SS2016a​.jpg

You can already see faces in the corners stretched by perspective effects, so something like 35-40mm would be better. 50mm means being further, and I usually need to be in the photo as well, but I have a decent RF remote (Yongnuo RF603, works for 100 feet), so probably okay.

Also, people in the back look quite a bit smaller than in front (another issue due to short FL). A 50mm on a crop would result in a much nicer perspective compression, with faces sizes more comparable.

Anyway, I can see the 50mm STM sold by amazon.ca for only 130 CAD (100 US), and I can always return it if it doesn't work for me, so I'll give it a try.

have you considered a software solution like dxo viewpoint? it does solve that somewhat, but front aisle will certainly remain bigger.

Another solution from a self admitted FF junkie would be to use the 5Dc and 70-200, a blistering sharp combo, sharper than anything you have IMO.

Charlie wrote in post #18031178
have you considered a software solution like dxo viewpoint? it does solve that somewhat, but front aisle will certainly remain bigger.

That effect actually doesn't bother me too much; stretched faces is the more ugly manifestation of perspective distortion.

pulsar123 wrote in post #18031183
That effect actually doesn't bother me too much; stretched faces is the more ugly manifestation of perspective distortion.

yes, and dxo viewpoint is designed to fix perspective distortion. Sometimes, you simply dont have the space for group shots, dxo to the rescue. If I have space, I'll do 100mm no problems.

Charlie wrote in post #18031187
yes, and dxo viewpoint is designed to fix perspective distortion. Sometimes, you simply dont have the space for group shots, dxo to the rescue. If I have space, I'll do 100mm no problems.

I'll look into that. Is it any different from the ACR perspective correction module?

pulsar123 wrote in post #18031193
I'll look into that. Is it any different from the ACR perspective correction module?

similar, but more comprehensive.

I have a 17-40 but I really dont' like the 17mm side for a group, for the distortion, as noted.

So I pan the group and stitch together. Less distortion, but you need to watch what ratio you end up with for a print.

pulsar123 wrote in post #18031183
That effect actually doesn't bother me too much; stretched faces is the more ugly manifestation of perspective distortion.

You lost me there. In the photo you linked to I am guessing you are about 32 feet away from the front row. It would give the same perspective distortion as shooting a single person portrait with a 300mm lens: See below.

http://stepheneastwood​.com …ials_Lens_Persp​ective.htm

I think you got it wrong. There are so many confusing and conflicting descriptions of the perspective distortion out there, it's mind boggling. For me it is simple geometry: perspective distortion occurs when you are trying to project the spherical world surrounding us onto a plane (camera's sensor). As we know this cannot be done perfectly (think a world map), and the projection error (called perspective distortion) depends only on one factor - angle of view of your lens. (Not on the distance, and not on the sensor size, as many would want you to believe; these are all derivatives.) That's why ultra wide angle lenses (rectilinear, not fisheyes) have very strong perspective distortion, especially near the edges. Your 300mm lens on a crop (or FF) camera has a very small angle of view, so perspective distortion will be negligible. My 28mm lens, on the other hand, has a pretty large angle of view, so the distortion shows quite a bit near the edges (that is, for points at a large angle from the frame center).

I just hope this won't trigger yet another great perspective distortion debate .