May need to do some sizing down, advice needed.

sarge · 10-28-2016, 01:21 PM

Hello everyone,
Due to some significant back and neck issues I am thinking about selling my Sigma 17-50 2.8 and going with a Limited 20-40.
I have shot several weddings this year and used the Sigma as my main lens on my K-3II with the grip and flash on the camera.
This configuration shooting for 8+ hours has left me useless for days after. I have tried sling straps and cannot stand them.
I am thinking seriously of doing away with the grip and using a 20-40. I will loose a stop on the long end but have not found the Sigma to give much separation wide open anyway. My DA 70 Limited does a much better job.
What do you all think?

narual · 10-28-2016, 01:39 PM

Try one of these - takes the weight off your neck and puts it on your shoulders without putting the camera outside of the position you prefer to carry it in.
Bino/Cam Harness | OP/TECH USA

But ditching the grip and going with a lighter lens would certainly cut down on the weight.

You can also look at switching to lithium batteries for the flash. They recycle slower, but they weigh like half what normal batteries do.

**BigMackCam** · 10-28-2016, 01:40 PM

I wouldn't recommend the 20-40 in your situation. It's a lovely lens, but needs stopping down to perform really well (unlike the Sigma which is great wide open) - at least f/5.6 at any focal length, preferably smaller (it's excellent at f/7.1 or f/8).

How about the Tamron 17-50 f/2.8? That would save about 130g. Combined with removal of the grip, that would be a very noticeable saving...

Blacknight659 · 10-28-2016, 02:08 PM

I was in the same boat as you just this month.

> Owner of Sigma 17-50 2.8
> Tired of weight and lack of WR
> Looking for a better solution
> Purchased 20-40 Limited

Let me first say, the 20-40 makes wonderful photos. I will say it isn't as easy to use for portraits and create subject isolation / background blur. Also, max aperture of f4 can be a hindrance if you are a wedding guy.

My suggestion, Stop your Sigma down to f4 and shoot your common lighting scenario. Limit yourself to 20-40mm and see what you come up with. You may decide to go another route like a camera strap or a few primes.

I am very happy with my 20-40. I also complement it with a 15mm limited, DA 35mm, and DA 50mm. The 35 and 50 help if the light gets too low. I also keep my PTTL flash ready to go, and it often saves the day.

---------- Post added 10-28-16 at 04:10 PM ----------

One more thing, The flash will make it a bit top heavy and there isn't anything you can do about it really. This lens will keep you light, but if you need to go lighter, you won't find it in a slr system. Even if you go with M43, when you start carrying lenses you need, you might as well keep your Pentax system.

sarge · 10-28-2016, 02:14 PM

Originally posted by Blacknight659

I was in the same boat as you just this month.

> Owner of Sigma 17-50 2.8
> Tired of weight and lack of WR
> Looking for a better solution
> Purchased 20-40 Limited

Let me first say, the 20-40 makes wonderful photos. I will say it isn't as easy to use for portraits and create subject isolation / background blur. Also, max aperture of f4 can be a hindrance if you are a wedding guy.

My suggestion, Stop your Sigma down to f4 and shoot your common lighting scenario. Limit yourself to 20-40mm and see what you come up with. You may decide to go another route like a camera strap or a few primes.
This is a great idea! Thanks!
I am very happy with my 20-40. I also complement it with a 15mm limited, DA 35mm, and DA 50mm. The 35 and 50 help if the light gets too low. I also keep my PTTL flash ready to go, and it often saves the day.

---------- Post added 10-28-16 at 04:10 PM ----------

One more thing, The flash will make it a bit top heavy and there isn't anything you can do about it really. This lens will keep you light, but if you need to go lighter, you won't find it in a slr system. Even if you go with M43, when you start carrying lenses you need, you might as well keep your Pentax system.

I tried Olympus M43 and though they were light cameras I have sausage fingers and they were just to small.

---------- Post added 10-28-16 at 02:15 PM ----------

Originally posted by BigMackCam

I wouldn't recommend the 20-40 in your situation. It's a lovely lens, but needs stopping down to perform really well (unlike the Sigma which is great wide open) - at least f/5.6 at any focal length, preferably smaller (it's excellent at f/7.1 or f/8).

How about the Tamron 17-50 f/2.8? That would save about 130g. Combined with removal of the grip, that would be a very noticeable saving...

I did not realize the Tamron was that much lighter. I may look into that.

**BigMackCam** · 10-28-2016, 02:28 PM - **1 Like**

As Justin says, the 20-40 can take wonderful photos... My own experience with it pretty much mirrors the combined results from test sites, summarised in the attached table. You can see that borders are only "Fair" until f/5.6, where the lens starts to perform much better (although center performance is already excellent at f/3.5 in the middle of the focal length range). Peak performance at all focal lengths comes at f/8.

Of course, this is test data info, and whilst my own results closely reflect that data, real world photos are what count. It's perfectly possible to take great photos with the 20-40 at wider apertures - you just have to know what you're getting (very good centre resolution, so-so borders), and work with it.

I think Justin's idea is spot on... try your Sigma at f/4 (or better still, f/5.6) between 20 and 40mm and get a feel for it before deciding on the new lens. I actually find the 20-40mm range to be quite versatile, but it's definitely a little more limiting than 17-50mm, and the slower aperture requires a different approach on subject backgrounds...

sarge · 10-28-2016, 02:43 PM

Originally posted by BigMackCam

As Justin says, the 20-40 can take wonderful photos... My own experience with it pretty much mirrors the combined results from test sites, summarised in the attached table. You can see that borders are only "Fair" until f/5.6, where the lens starts to perform much better (although center performance is already excellent at f/3.5 in the middle of the focal length range). Peak performance at all focal lengths comes at f/8.

Of course, this is test data info, and whilst my own results closely reflect that data, real world photos are what count. It's perfectly possible to take great photos with the 20-40 at wider apertures - you just have to know what you're getting (very good centre resolution, so-so borders), and work with it.

I think Justin's idea is spot on... try your Sigma at f/4 (or better still, f/5.6) between 20 and 40mm and get a feel for it before deciding on the new lens. I actually find the 20-40mm range to be quite versatile, but it's definitely a little more limiting than 17-50mm, and the slower aperture requires a different approach on subject backgrounds...

I never got the separation I wanted with the 2.8 anyway. I am thinking of going with the 20-40 and have the DA 70 for when I need separation. I also have the DA 50 1.8, that weighs next to nothing so I could throw it in my belt pouch also.
BTW I have invested in the Think Tank modular belt system so this will hopefully help. I am shooting a senior portrait session and a family portrait session tomorrow with the belt system so I will know how well it works over a long period of time.

---------- Post added 10-28-16 at 03:13 PM ----------

Originally posted by narual

Try one of these - takes the weight off your neck and puts it on your shoulders without putting the camera outside of the position you prefer to carry it in.
Bino/Cam Harness | OP/TECH USA

But ditching the grip and going with a lighter lens would certainly cut down on the weight.

You can also look at switching to lithium batteries for the flash. They recycle slower, but they weigh like half what normal batteries do.

That Harness looks like it would help.
I use Panasonic Eneloop batteries in my flash units. I won't skimp on those.

**caliscouser** · 10-28-2016, 05:03 PM

Originally posted by BigMackCam

I wouldn't recommend the 20-40 in your situation. It's a lovely lens, but needs stopping down to perform really well (unlike the Sigma which is great wide open) - at least f/5.6 at any focal length, preferably smaller (it's excellent at f/7.1 or f/8).

Going to disagree with this. Maybe there is some sample variation here but my copy of the 20-40 is frankly spectacular at any focal length and aperture with the possible exception of the corners wide open at 20mm.
A fine lens for weddings I would think as long as you can live with F4.

Originally posted by sarge

I never got the separation I wanted with the 2.8 anyway. I am thinking of going with the 20-40 and have the DA 70 for when I need separation. I also have the DA 50 1.8, that weighs next to nothing so I could throw it in my belt pouch also.
BTW I have invested in the Think Tank modular belt system so this will hopefully help. I am shooting a senior portrait session and a family portrait session tomorrow with the belt system so I will know how well it works over a long period of time.

Love the DA70. Would be interested to hear your experiences whichever way you decide to go.

Blacknight659 · 10-28-2016, 05:09 PM

I can back your decision. I love my 50-135, but I have considered adding a 70mm limited to my kit to bring the weight and size down. I would like my portrait kit to be significantly lighter and the 20-40 was a major part in making that happen.

sarge · 10-28-2016, 05:45 PM

Originally posted by caliscouser

Going to disagree with this. Maybe there is some sample variation here but my copy of the 20-40 is frankly spectacular at any focal length and aperture with the possible exception of the corners wide open at 20mm.
A fine lens for weddings I would think as long as you can live with F4.

Love the DA70. Would be interested to hear your experiences whichever way you decide to go.

Will do!

---------- Post added 10-28-16 at 05:48 PM ----------

Originally posted by Blacknight659

I can back your decision. I love my 50-135, but I have considered adding a 70mm limited to my kit to bring the weight and size down. I would like my portrait kit to be significantly lighter and the 20-40 was a major part in making that happen.

I do like how the DA 70 renders. I have not used it much other than some portrait sessions. With weddings I have tended to use zooms. Going to have to change the way I do things a bit. I just can't work with these heavy fast zooms anymore.

Oldbayrunner · 10-29-2016, 06:04 AM

This what I use when I am using singely or both my K5lls and my K3ll even with my 150-500mm Sigma. I fractured my neck surfing years ago so I can't take much weight on it, this makes it a lot easier for me.. Dual Harness | OP/TECH USA

sarge · 10-29-2016, 06:51 AM

Originally posted by Oldbayrunner

This what I use when I am using singely or both my K5lls and my K3ll even with my 150-500mm Sigma. I fractured my neck surfing years ago so I can't take much weight on it, this makes it a lot easier for me.. Dual Harness | OP/TECH USA

Thanks for that link.

Nicolas06 · 10-30-2016, 05:51 AM

Originally posted by sarge

Hello everyone,
Due to some significant back and neck issues I am thinking about selling my Sigma 17-50 2.8 and going with a Limited 20-40.
I have shot several weddings this year and used the Sigma as my main lens on my K-3II with the grip and flash on the camera.
This configuration shooting for 8+ hours has left me useless for days after. I have tried sling straps and cannot stand them.
I am thinking seriously of doing away with the grip and using a 20-40. I will loose a stop on the long end but have not found the Sigma to give much separation wide open anyway. My DA 70 Limited does a much better job.
What do you all think?

I am not a wedding expert by far. Only shooted 2 with primes and it worked well even if of course it limited a bit reactivity. But I did them with DA21, DA35 f/2.8 ltd and FA77 just fine. For flash I used my Metz 44 AF1 in one hand wit a diffuser and the camera in the other hand.

My understanding is that the gear is heavy but the problem is also of course because you do that for hours.

To me there several things to investigate:
- Tamron 17-50 is smaller/lighter. It seems to be very good but has some field curvature.
- There very small prime available that do a nice job in low light/subject isolation and that are small/light. Like FA35 f/2, FA77, DA70...
- There small flashs too. The metz M400 go with 40 number guide, all advanced features you could want including HSS, is very small/light and weight 220g without batteries. My own 44AF1 is almost 100g heavier and also overall bigger.

To me, you could depending of the moment carry the tamron 17-50 or DA21/FA35/DA70. That cut the lens actual weight by more than a factor of 2. with proper carrying equipment the lenses are not currently using should not put any weight on the neck/back.

Added to that, you could check for a very small flash unit that does all the things you need and again take care to not carry it all the time.

Finally you can likely reduce your setup a bit futher with mirrorless.

Fuji 18-55 f/2.8-4 is f/3.2 at 24mm and f/3.6 at 35mm. Not perfect but not bad. More light gathering than DA20-40, not that much bigger 310g so you are saving more than 200g vs the sigma 17-50. And going 55mm f/4 mean more subject separation and reach than 40mm f/4.

The Fuji bodies are much lighter than than the K3. With batteries included Fuji XPro 2 or XT2 are 500g or less with batteries included. That 300g saved. You can combine that with 3 primes of their system and combined with the new metz flash, I think you can overall reduce the overall weight by a factor of 2. You can also get fast small WA if that important to you.

10-28-2016, 01:21 PM	#1
sarge Veteran Member Join Date: Feb 2016 Location: Illinois Photos: Gallery \| Albums Posts: 460	May need to do some sizing down, advice needed. Hello everyone, Due to some significant back and neck issues I am thinking about selling my Sigma 17-50 2.8 and going with a Limited 20-40. I have shot several weddings this year and used the Sigma as my main lens on my K-3II with the grip and flash on the camera. This configuration shooting for 8+ hours has left me useless for days after. I have tried sling straps and cannot stand them. I am thinking seriously of doing away with the grip and using a 20-40. I will loose a stop on the long end but have not found the Sigma to give much separation wide open anyway. My DA 70 Limited does a much better job. What do you all think?

10-28-2016, 02:28 PM - 1 Like	#6
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,670	As Justin says, the 20-40 can take wonderful photos... My own experience with it pretty much mirrors the combined results from test sites, summarised in the attached table. You can see that borders are only "Fair" until f/5.6, where the lens starts to perform much better (although center performance is already excellent at f/3.5 in the middle of the focal length range). Peak performance at all focal lengths comes at f/8. Of course, this is test data info, and whilst my own results closely reflect that data, real world photos are what count. It's perfectly possible to take great photos with the 20-40 at wider apertures - you just have to know what you're getting (very good centre resolution, so-so borders), and work with it. I think Justin's idea is spot on... try your Sigma at f/4 (or better still, f/5.6) between 20 and 40mm and get a feel for it before deciding on the new lens. I actually find the 20-40mm range to be quite versatile, but it's definitely a little more limiting than 17-50mm, and the slower aperture requires a different approach on subject backgrounds... Attached Images

10-28-2016, 05:45 PM	#10
sarge Veteran Member Join Date: Feb 2016 Location: Illinois Photos: Gallery \| Albums Posts: 460 Original Poster	Originally posted by caliscouser Going to disagree with this. Maybe there is some sample variation here but my copy of the 20-40 is frankly spectacular at any focal length and aperture with the possible exception of the corners wide open at 20mm. A fine lens for weddings I would think as long as you can live with F4. Love the DA70. Would be interested to hear your experiences whichever way you decide to go. Will do! ---------- Post added 10-28-16 at 05:48 PM ---------- Originally posted by Blacknight659 I can back your decision. I love my 50-135, but I have considered adding a 70mm limited to my kit to bring the weight and size down. I would like my portrait kit to be significantly lighter and the 20-40 was a major part in making that happen. I do like how the DA 70 renders. I have not used it much other than some portrait sessions. With weddings I have tended to use zooms. Going to have to change the way I do things a bit. I just can't work with these heavy fast zooms anymore. Last edited by sarge; 10-28-2016 at 06:21 PM.

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10-28-2016, 01:39 PM	#2
narual Veteran Member Join Date: Jun 2013 Location: South Bend (Notre Dame), Indiana Photos: Gallery \| Albums Posts: 1,988	Try one of these - takes the weight off your neck and puts it on your shoulders without putting the camera outside of the position you prefer to carry it in. Bino/Cam Harness \| OP/TECH USA But ditching the grip and going with a lighter lens would certainly cut down on the weight. You can also look at switching to lithium batteries for the flash. They recycle slower, but they weigh like half what normal batteries do.

10-28-2016, 01:40 PM	#3
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,670	I wouldn't recommend the 20-40 in your situation. It's a lovely lens, but needs stopping down to perform really well (unlike the Sigma which is great wide open) - at least f/5.6 at any focal length, preferably smaller (it's excellent at f/7.1 or f/8). How about the Tamron 17-50 f/2.8? That would save about 130g. Combined with removal of the grip, that would be a very noticeable saving...

10-28-2016, 02:08 PM	#4
Blacknight659 Veteran Member Join Date: Aug 2013 Photos: Gallery \| Albums Posts: 731	I was in the same boat as you just this month. > Owner of Sigma 17-50 2.8 > Tired of weight and lack of WR > Looking for a better solution > Purchased 20-40 Limited Let me first say, the 20-40 makes wonderful photos. I will say it isn't as easy to use for portraits and create subject isolation / background blur. Also, max aperture of f4 can be a hindrance if you are a wedding guy. My suggestion, Stop your Sigma down to f4 and shoot your common lighting scenario. Limit yourself to 20-40mm and see what you come up with. You may decide to go another route like a camera strap or a few primes. I am very happy with my 20-40. I also complement it with a 15mm limited, DA 35mm, and DA 50mm. The 35 and 50 help if the light gets too low. I also keep my PTTL flash ready to go, and it often saves the day. ---------- Post added 10-28-16 at 04:10 PM ---------- One more thing, The flash will make it a bit top heavy and there isn't anything you can do about it really. This lens will keep you light, but if you need to go lighter, you won't find it in a slr system. Even if you go with M43, when you start carrying lenses you need, you might as well keep your Pentax system.

10-28-2016, 02:14 PM	#5
sarge Veteran Member Join Date: Feb 2016 Location: Illinois Photos: Gallery \| Albums Posts: 460 Original Poster	Originally posted by Blacknight659 I was in the same boat as you just this month. > Owner of Sigma 17-50 2.8 > Tired of weight and lack of WR > Looking for a better solution > Purchased 20-40 Limited Let me first say, the 20-40 makes wonderful photos. I will say it isn't as easy to use for portraits and create subject isolation / background blur. Also, max aperture of f4 can be a hindrance if you are a wedding guy. My suggestion, Stop your Sigma down to f4 and shoot your common lighting scenario. Limit yourself to 20-40mm and see what you come up with. You may decide to go another route like a camera strap or a few primes. This is a great idea! Thanks! I am very happy with my 20-40. I also complement it with a 15mm limited, DA 35mm, and DA 50mm. The 35 and 50 help if the light gets too low. I also keep my PTTL flash ready to go, and it often saves the day. ---------- Post added 10-28-16 at 04:10 PM ---------- One more thing, The flash will make it a bit top heavy and there isn't anything you can do about it really. This lens will keep you light, but if you need to go lighter, you won't find it in a slr system. Even if you go with M43, when you start carrying lenses you need, you might as well keep your Pentax system. I tried Olympus M43 and though they were light cameras I have sausage fingers and they were just to small. ---------- Post added 10-28-16 at 02:15 PM ---------- Originally posted by BigMackCam I wouldn't recommend the 20-40 in your situation. It's a lovely lens, but needs stopping down to perform really well (unlike the Sigma which is great wide open) - at least f/5.6 at any focal length, preferably smaller (it's excellent at f/7.1 or f/8). How about the Tamron 17-50 f/2.8? That would save about 130g. Combined with removal of the grip, that would be a very noticeable saving... I did not realize the Tamron was that much lighter. I may look into that.

10-28-2016, 02:43 PM	#7
sarge Veteran Member Join Date: Feb 2016 Location: Illinois Photos: Gallery \| Albums Posts: 460 Original Poster	Originally posted by BigMackCam As Justin says, the 20-40 can take wonderful photos... My own experience with it pretty much mirrors the combined results from test sites, summarised in the attached table. You can see that borders are only "Fair" until f/5.6, where the lens starts to perform much better (although center performance is already excellent at f/3.5 in the middle of the focal length range). Peak performance at all focal lengths comes at f/8. Of course, this is test data info, and whilst my own results closely reflect that data, real world photos are what count. It's perfectly possible to take great photos with the 20-40 at wider apertures - you just have to know what you're getting (very good centre resolution, so-so borders), and work with it. I think Justin's idea is spot on... try your Sigma at f/4 (or better still, f/5.6) between 20 and 40mm and get a feel for it before deciding on the new lens. I actually find the 20-40mm range to be quite versatile, but it's definitely a little more limiting than 17-50mm, and the slower aperture requires a different approach on subject backgrounds... I never got the separation I wanted with the 2.8 anyway. I am thinking of going with the 20-40 and have the DA 70 for when I need separation. I also have the DA 50 1.8, that weighs next to nothing so I could throw it in my belt pouch also. BTW I have invested in the Think Tank modular belt system so this will hopefully help. I am shooting a senior portrait session and a family portrait session tomorrow with the belt system so I will know how well it works over a long period of time. ---------- Post added 10-28-16 at 03:13 PM ---------- Originally posted by narual Try one of these - takes the weight off your neck and puts it on your shoulders without putting the camera outside of the position you prefer to carry it in. Bino/Cam Harness \| OP/TECH USA But ditching the grip and going with a lighter lens would certainly cut down on the weight. You can also look at switching to lithium batteries for the flash. They recycle slower, but they weigh like half what normal batteries do. That Harness looks like it would help. I use Panasonic Eneloop batteries in my flash units. I won't skimp on those.

10-28-2016, 05:03 PM	#8
caliscouser Site Supporter Join Date: Sep 2014 Location: SF Bay Area, CA Photos: Albums Posts: 1,037	Originally posted by BigMackCam I wouldn't recommend the 20-40 in your situation. It's a lovely lens, but needs stopping down to perform really well (unlike the Sigma which is great wide open) - at least f/5.6 at any focal length, preferably smaller (it's excellent at f/7.1 or f/8). Going to disagree with this. Maybe there is some sample variation here but my copy of the 20-40 is frankly spectacular at any focal length and aperture with the possible exception of the corners wide open at 20mm. A fine lens for weddings I would think as long as you can live with F4. Originally posted by sarge I never got the separation I wanted with the 2.8 anyway. I am thinking of going with the 20-40 and have the DA 70 for when I need separation. I also have the DA 50 1.8, that weighs next to nothing so I could throw it in my belt pouch also. BTW I have invested in the Think Tank modular belt system so this will hopefully help. I am shooting a senior portrait session and a family portrait session tomorrow with the belt system so I will know how well it works over a long period of time. Love the DA70. Would be interested to hear your experiences whichever way you decide to go.

10-28-2016, 05:09 PM	#9
Blacknight659 Veteran Member Join Date: Aug 2013 Photos: Gallery \| Albums Posts: 731	I can back your decision. I love my 50-135, but I have considered adding a 70mm limited to my kit to bring the weight and size down. I would like my portrait kit to be significantly lighter and the 20-40 was a major part in making that happen.

10-29-2016, 06:04 AM	#11
Oldbayrunner Pentaxian Join Date: Mar 2013 Posts: 1,665	This what I use when I am using singely or both my K5lls and my K3ll even with my 150-500mm Sigma. I fractured my neck surfing years ago so I can't take much weight on it, this makes it a lot easier for me.. Dual Harness \| OP/TECH USA

10-29-2016, 06:51 AM	#12
sarge Veteran Member Join Date: Feb 2016 Location: Illinois Photos: Gallery \| Albums Posts: 460 Original Poster	Originally posted by Oldbayrunner This what I use when I am using singely or both my K5lls and my K3ll even with my 150-500mm Sigma. I fractured my neck surfing years ago so I can't take much weight on it, this makes it a lot easier for me.. Dual Harness \| OP/TECH USA Thanks for that link.

10-30-2016, 05:51 AM	#13
Nicolas06 Veteran Member Join Date: Nov 2013 Posts: 4,854	Originally posted by sarge Hello everyone, Due to some significant back and neck issues I am thinking about selling my Sigma 17-50 2.8 and going with a Limited 20-40. I have shot several weddings this year and used the Sigma as my main lens on my K-3II with the grip and flash on the camera. This configuration shooting for 8+ hours has left me useless for days after. I have tried sling straps and cannot stand them. I am thinking seriously of doing away with the grip and using a 20-40. I will loose a stop on the long end but have not found the Sigma to give much separation wide open anyway. My DA 70 Limited does a much better job. What do you all think? I am not a wedding expert by far. Only shooted 2 with primes and it worked well even if of course it limited a bit reactivity. But I did them with DA21, DA35 f/2.8 ltd and FA77 just fine. For flash I used my Metz 44 AF1 in one hand wit a diffuser and the camera in the other hand. My understanding is that the gear is heavy but the problem is also of course because you do that for hours. To me there several things to investigate: - Tamron 17-50 is smaller/lighter. It seems to be very good but has some field curvature. - There very small prime available that do a nice job in low light/subject isolation and that are small/light. Like FA35 f/2, FA77, DA70... - There small flashs too. The metz M400 go with 40 number guide, all advanced features you could want including HSS, is very small/light and weight 220g without batteries. My own 44AF1 is almost 100g heavier and also overall bigger. To me, you could depending of the moment carry the tamron 17-50 or DA21/FA35/DA70. That cut the lens actual weight by more than a factor of 2. with proper carrying equipment the lenses are not currently using should not put any weight on the neck/back. Added to that, you could check for a very small flash unit that does all the things you need and again take care to not carry it all the time. Finally you can likely reduce your setup a bit futher with mirrorless. Fuji 18-55 f/2.8-4 is f/3.2 at 24mm and f/3.6 at 35mm. Not perfect but not bad. More light gathering than DA20-40, not that much bigger 310g so you are saving more than 200g vs the sigma 17-50. And going 55mm f/4 mean more subject separation and reach than 40mm f/4. The Fuji bodies are much lighter than than the K3. With batteries included Fuji XPro 2 or XT2 are 500g or less with batteries included. That 300g saved. You can combine that with 3 primes of their system and combined with the new metz flash, I think you can overall reduce the overall weight by a factor of 2. You can also get fast small WA if that important to you.