[skid2964]

I do a lot of real estate photography(using K-30 and Sigma 10-20mm) and have been doing video but I am not completely happy with the results.
These environments are low light with movement(I'm doing walk-throughs)...

To solve this problem I am considering the Sony Alpha 7s, am I on the right track? If so, lens suggestions? Do I need a FF lens or will an adapted APSc lens be ok? I'd like to use my Sigma 10-20mm...

I'd prefer a Pentax solution but.... oh well....

Thanks....

[Deedee]

Seriously you are willing to change your system?

Why not go for Samyang 10mm f2.8 it is seriously wide and designed for low light. or Sigma 18-35 f1.8.

By the way if video is a challenge. A7S is seriously expensive and completely a new system. I would wait for bug being solved first.

Why not go for Panasonic GH4 or some other system just designed for great video technology?

Just my two cents.

Cheers!

[Digitalis]

The sigma 18-35mm f/1.8 ART is your best bet, I have reservations about recommending it due to AF inconsistencies I have experienced with the lens under low light*. But for manual focus video work on a tripod it should be fine.

* and seeing that the Sigma lens dock for K mount still isn't available in my country, so I have no way to correct any of these issues.

[Stavri]

Switching on a new system would be expensive, they are sensible solutions to your needs as suggested above by the previous members.

I second Digitalis suggestion, the 18-35mm f1.8 is a great choice for low-light video, also has quick-shift so you can correct those inconsistencies on the fly (or produce interesting effect when you want)

Samyang/Rokinon has some fast ultra-wide lenses for video shooting that work well in MF

The Sony a7s has excellent low light performance, but its expensive and has no AF support on your pentax lenses, unless you intend to buy some zeiss fast primes. (the base a7 model low-light performance is similarly to the K-3 at higher ISO, and the a7r should be between the 7 and 7s)

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Last edited by Stavri; 09-15-2014 at 09:19 AM.

[Digitalis]

also has quick-shift so you can correct those inconsistencies on the fly

The sigma 18-35mm f/1.8 it doesn't have quick shift - not the way pentax implements it. Manual focus is able to be used at any time, however the focus throw on this lens is very short and DOF at f/1.8 even at 18mm is very narrow. For use at f/1.8 with some subjects focus peaking will be an important feature*. For video work you might want to also invest in an appropriate follow focus rig - also as far as I can tell the Sigma 18-35mm f/1.8 ART isn't parfocal**.

My comparative review with the Pentax FA31mm f/1.8 Limited and the Sigma 18-35mm f/1.8 ART can be found here.

* Focus peaking on the Sony cameras is unreliable with extremely fast lenses.
** On the RED Cinematography forums this is a bit of a contentious issue, some users say it is parfocal, some say it isn't. A parfocal lens is a lens that maintains focus even when the zoom setting is changed.

[skid2964]

I am curious what a faster lens will offer, 18-35mm isn't wide enough, I need 10mm.
I think I will test some video using my 17-50 at 2.8 just to see if this setup offers enough low-light performance...
Then maybe I can try the Samyang 10mm 2.8.... I'm not sure just getting a faster lens is going to be enough though...

[Stavri]

The sigma 18-35mm f/1.8 it doesn't have quick shift - not the way pentax implements it. Manual focus is able to be used at any time.

my mistake on the quick-shift. Like most of the Sigma HSM lenses, you can apply MF at all times.

[Digitalis]

I need 10mm.

Or a Nikkor 14-24mm f/2.8G ED on FX format - though that lens has some pretty spectacular distortion that is difficult to hide, which is a problem all super wide angles have - especially fast ones. Lens designers intentionally leave distortion in the design to correct for astigmatism.

[skid2964]

Or a Nikkor 14-24mm f/2.8G ED on FX format - though that lens has some pretty spectacular distortion that is difficult to hide, which is a problem all super wide angles have - especially fast ones. Lens designers intentionally leave distortion in the design to correct for astigmatism.

Everything I am reading is confirming that high ISO performance is the solution to my problem. The camera that seems to have the best high ISO performance (for the money) is the Sony Alpha 7s.... I'm still curious if I will limit this system by adapting my Sigma 10-20mm to it... or will I need to buy a "Full Frame" lens...

[yygomez]

I do a lot of real estate photography(using K-30 and Sigma 10-20mm) and have been doing video but I am not completely happy with the results.
These environments are low light with movement(I'm doing walk-throughs)...

To solve this problem I am considering the Sony Alpha 7s, am I on the right track? If so, lens suggestions? Do I need a FF lens or will an adapted APSc lens be ok? I'd like to use my Sigma 10-20mm...

I'd prefer a Pentax solution but.... oh well....

Thanks....

Absolutely, you are on the right track the A7s will give you what no Pentax body can, specially considering that you will need some DOF so shooting wide open is not an option. The problem will be finding wide angle lenses for that Sony mount, there are not many right now but all manufacturers are focus on that mount

[Stavri]

Absolutely, you are on the right track the A7s will give you what no Pentax body can, specially considering that you will need some DOF so shooting wide open is not an option. The problem will be finding wide angle lenses for that Sony mount, there are not many right now but all manufacturers are focus on that mount

Of course he's on the right track, of wasting thousands of dollars. Since we're burning away cash, why recommend the Nikon D4s, or even better a proper camcorder Red ONE. The a7s is not cheap, neither are FE zeiss lenses, so we have to be sensible here. Samayang lenses and Sigma 18-35mm are two of the better options out there.

[johnmflores]

Everything I am reading is confirming that high ISO performance is the solution to my problem. The camera that seems to have the best high ISO performance (for the money) is the Sony Alpha 7s.... I'm still curious if I will limit this system by adapting my Sigma 10-20mm to it... or will I need to buy a "Full Frame" lens...

I think you will need a full-frame compatible lens to use, which I am not sure the Sigma 10-20mm is. I'll leave it up to you to decide whether the Sony is worth the purchase for your business, but perhaps another, cheaper alternative is a hacked Panasonic GH2:

Here's some footage shot at ISO1600 in Times Square at night. F2.8

Vimeo

Shadows are crushed but noise is well controlled. Olympus has a 12mm F2.0 for Micro Four Thirds (24mm EQ). If you need wider, I think there are options (i.e., Panasonic 7-14mm F4)

Best of luck!

[narual]

I suppose bringing a lamp in is out of the question? You can get a lovely football sized full-spectrum CFL bulb fairly cheap on Amazon.

[dborked]

Everything I am reading is confirming that high ISO performance is the solution to my problem. The camera that seems to have the best high ISO performance (for the money) is the Sony Alpha 7s.... I'm still curious if I will limit this system by adapting my Sigma 10-20mm to it... or will I need to buy a "Full Frame" lens...

All the cameras in the A7 line have an APS-C crop mode, just be mindful of the fact that because you are utilizing a smaller portion of the sensor your Megapixel count will decline. I believe on the A7 the crop mode reduced the megapixels to about 10MP, not sure about the A7S but it would probably be around 5-6MP. Now if you don't intend on blowing these photos up very large you should be fine (in fact you would get some excellent low light photos) just be mindful that if you plan on doing any cropping or blowing up the photos to large scale you may run into issues. But if you're only uploading them for online usage then 5-6MP is more than enough.

BTW, the Sony 10-18mm E mount lens is pretty stellar.

[btnapa]

I am curious what a faster lens will offer, 18-35mm isn't wide enough, I need 10mm.
I think I will test some video using my 17-50 at 2.8 just to see if this setup offers enough low-light performance...
Then maybe I can try the Samyang 10mm 2.8.... I'm not sure just getting a faster lens is going to be enough though...

I have not had first hand experience with the Sony offerings other than shooting with them at trade shows.

The camera that I know about that is a superior performer for low light is Canon 6D. I owned the camera just before switching to Pentax K5IIs then to K3. I love the Pentax images. I prefer the Pentax system over Canon but if I had to pick a camera for high ISO clean images, my choice hands down would be the Canon 6D. I shot with it many times at ISO 6400 or even 12800 without thinking about it twice. In comparison (my personal experience) the K3 image breaks down past ISO 1600. I would not shoot the K3 for a paid assignment past ISO 1600. I know people might disagree with me but that is my personal experience.

Now, switching systems is going to be costly. With my Canon, I had a host of lens but the one I used for RE interior images was the Sigma 15-30 which is a slow lens but I cranked up the ISO. I did use a flash to fill in some shadow areas. I don't think you are going to find a camera that can shoot with no flash at all. Some interiors are simply too dark for no flash. Video footage in dark rooms is going to be a lot trickier. I would be curious to know how you end up solving video in a dark room issue.