8-16mm Sigma with Scarlet ?

[Kalani Prince]

Any input on how you think this thing might work with the crop factor on Scarlet 2/3 ? If so, would it be a 50ish to 100ish in focal length ?..

http://www.sigmaphoto.com/shop/8-16mm-f45-56-dc-hsm-sigma?gclid=CIW9gdvZnaECFQQTawodBn6RwA

Peace-



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[John Caballero]

With the 2/3 is useless.

 

[Kalani Prince]

With the 2/3 is useless.

why ?

 

[Pietro Impagliazzo]

I'm not familiar with this glass and never used 35mm glass in 2/3" systems, common knowledge says it'll look soft because of the resolution of the glass itself.

If that's a rectilinear wide angle and doesn't distort and you the resolution is good enough for you... Why not?

8mm will give you the field of view of 20mm in S35. So it's a pretty good lens, considering only focal length range.

 

[Kalani Prince]

I'm not familiar with this glass and never used 35mm glass in 2/3" systems, common knowledge says it'll look soft because of the resolution of the glass itself.

If that's a rectilinear wide angle and doesn't distort and you the resolution is good enough for you... Why not?

8mm will give you the field of view of 20mm in S35. So it's a pretty good lens, considering only focal length range.

Isn't it designed to resolve still images on the latest camera's pushing 20mp + .. I thought 3k was like 5mp or summn' like that.. I don't know, maybe my mushy brain isn't getting something.

 

[Terry VerHaar]

Any input on how you think this thing might work with the crop factor on Scarlet 2/3 ? If so, would it be a 50ish to 100ish in focal length ?..

Isn't the "crop factor" for a 35mm lens more like 3 - 3.5 on a 2/3" sensor? Turning this into about a 30-60 equivalent.

 

[Kyle Presley]

It's about a 2.2 crop, so about 18mm. I can't remember exactly... but somewhere close to that. It would probably be soft because Scarlet's pixels are smaller than those on an APS-C sensor. Pixel density is key here, not megapixel count.

 

[Alex Mack]

the 35 zoom to get for 2/3s is the tokina 11-16. nff sd

 

[Kenneth Elkington]

It's about a 2.2 crop, so about 18mm. I can't remember exactly... but somewhere close to that. It would probably be soft because Scarlet's pixels are smaller than those on an APS-C sensor. Pixel density is key here, not megapixel count.

2.5x crop factor for S35 and 3.7x for FF35.

 

[Terry VerHaar]

It's about a 2.2 crop, so about 18mm. I can't remember exactly... but somewhere close to that. It would probably be soft because Scarlet's pixels are smaller than those on an APS-C sensor. Pixel density is key here, not megapixel count.

I strongly suggest you check your math before you run out and buy any lenses. :smile5:

When using a full frame 35mm film camera (36 x 24 mm) as the standard for comparison, an APS-C digital SLR such as the Canon 7D has about a 1.6 "crop factor." By the time you shrink things down to the 2/3" Scarlet sensor (about 10mm wide), the so-called "crop factor" is more like 3.5. Really!

So this 8-16 does come in at an comparative equivalent of about 28-56when it comes to FOV.

 

[Jacek Zakowicz]

Diagonal or horizontal?

Diagonal or horizontal?

Just to add to this messy confusion are we talking about horizontal or diagonal crop? Red official policy seems to point at horizontal convention....

 

[Kenneth Elkington]

Just to add to this messy confusion are we talking about horizontal or diagonal crop? Red official policy seems to point at horizontal convention....

Horizontal is pretty much the only way to do it, because most formats change aspect ratio and the diagonal is not a consistent measure across them.

 

[J Davis]

if you got a red pro zoom 17-50 and put it on 20mm and stuck it on an s35

IT WOULD BE THE SAME FIELD OF VIEW

as this sigma at 8mm on a 2/3

2.5 crop factor

 

[Kyle Presley]

I strongly suggest you check your math before you run out and buy any lenses. :smile5:

When using a full frame 35mm film camera (36 x 24 mm) as the standard for comparison, an APS-C digital SLR such as the Canon 7D has about a 1.6 "crop factor." By the time you shrink things down to the 2/3" Scarlet sensor (about 10mm wide), the so-called "crop factor" is more like 3.5. Really!

So this 8-16 does come in at an comparative equivalent of about 28-56when it comes to FOV.

Yes, 3.5 (more like 3.6) compared to FF35, but not super35.

 

[Terry VerHaar]

if you got a red pro zoom 17-50 and put it on 20mm and stuck it on an s35

IT WOULD BE THE SAME FIELD OF VIEW

as this sigma at 8mm on a 2/3

2.5 crop factor

But an S35 is not what is "normally" used as the standard - FF35 is the 36 x 24 mm sensor and is comparable to the 35mm film cameras where this all got started. S35 is more like an APS-C sensor size and much smaller.

Scarlet 2/3" still translates to a 3.5 "crop factor" (I am growing to hate that term) in comparison to the "baseline" of the 35mm film camera.

 

[J Davis]

But an S35 is not what is "normally" used as the standard - FF35 is the 36 x 24 mm sensor and is comparable to the 35mm film cameras where this all got started. S35 is more like an APS-C sensor size and much smaller.

Scarlet 2/3" still translates to a 3.5 "crop factor" (I am growing to hate that term) in comparison to the "baseline" of the 35mm film camera.

Thats where you're missinformed Terry

Still Photography Film
Full Frame Still Film is 36mm x 24mm

Movies Film
Three Perf Academy 35mm is 22mm x 12mm
Four Perf Academy 35mm is 22mm x 16mm
Three Perf Super 35mm is 24.89mm x 14mm
Four Perf Super 35mm is 24.89 x 18.66mm

RED's s35
24.4mm x 13.7mm

Digital Full Frame DSLR (5DM2)
36mm x 24mm

7d and t2i
22.3mm x 14.9mm

 

[Terry VerHaar]

Thats where you're missinformed Terry

Still Photography Film
Full Frame Still Film is 36mm x 24mm

Movies Film
Three Perf Academy 35mm is 22mm x 12mm
Four Perf Academy 35mm is 22mm x 16mm
Three Perf Super 35mm is 24.89mm x 14mm
Four Perf Super 35mm is 24.89 x 18.66mm

RED's s35
24.4mm x 13.7mm

Digital Full Frame DSLR (5DM2)
36mm x 24mm

7d and t2i
22.3mm x 14.9mm

Well, I hate to make this a pissing contest but I assure you neither of us is misinformed - at least about sensor sizes. But one of us is wrong about so called "crop factors" (and I don't think it is me). :laugh:

All the information you listed is nicely placed into a graphic here:

http://reduser.net/forum/showthread.php?t=23192&page=8

It agrees completely with everything you listed (and I suspect you might have even taken it from there). But you will notice that, on the chart, next to the APS-C size sensor of the DSLR, it says "1.6x crop..." That figure is relative to the FF35 still film camera size of 36 x 24mm. And you will notice that (APS-C) sensor size is very close to the Four-Perf Academy 35mm film size. So Four-Perf will also be roughly a "1.6 crop."

To my knowledge - and I do believe this is accurate - the crop factors discussed in this forum, and generally in the world of digital cinema, are all relative to this still film standard - not any of the smaller motion film ("35mm") sizes.

From this we can determine that "regular" 35mm lenses behave like "regular " 35mm lenses in cameras like the 5D and will do so in the FF35 Epics and Scarlets (some day). However, as indicated, they "crop" the picture on the APS-C sized sensors like the 7D or Scarlet S35 - effectively acting like a telephoto adaptor making the FOV of a 50mm lens act more like an 80. Of course, we agree that they further "crop" the pictures on smaller sensors like the 2/3" Scarlet but can't seem to agree on how much - at least from what standard we are comparing.

My contention, and I stand by this, is that the "usual" standard, as indicated in the sensor chart, is the still film based full frame size of 36 x 24 mm. Thus, the listed crop of 1.6x for the 22.3 mm x 14.9 mm (APS-C) sensor. Taking this math further down the line, the Scarlet 2/3" is roughly a 3.5x "crop" as compared to the FF sensor. If you are comparing it to the APS-C sensor (or the S35), then yes, the crop is closer to 2.5, but only compared to that, and I think that is not the usual reference.

I am guessing we agree on dimensions and relative "crops" but disagree on what the reference point is? And of course, this is all very approximate since the sensors are of slightly different proportions.

To all those reading this about "crops" and rolling your eyes, I agree. But I think the usage has evolved as a short-hand method of comparing how lenses behave when moved from the "base line" of the 35 mm camera, which many of us grew familiar with back in "the day." Clearly, given these discussions, maybe the days of its usefulness as short-hand are at an end. :blink:

 

[Michael Hastings]

The problem with using the sigma 8-16 on 2/3" is that it is essentially a waste.

All of the design energy and cost went into correcting distortions and aberrations at the edge of a much larger APS-C/S35 frame - that you will never see on a 2/3" sensor. Plus as has been mentioned it is designed for a larger pixel pitch so probably not as sharp as a lens designed for a 2/3 sensor. Because of those factors you would probably do as well with very inexpensive c-mount lenses designed for S16 or 2/3". And performance might be significantly better from some of the higher resolution lenses made for 2/3".

With that said, if you already have an APS-C dslr so that the 8-16 would be a dual purpose lens - then it is probably not a bad investment for occasional use as a mid wide zoom on scarlet 2/3" if you plan to buy the RED Canon or Nikon mount anyway for use with the telephoto lenses which is where the big advantage comes in using SLR lenses.

 

[Lee Saxon]

...essentially a waste...All of the design energy and cost went into correcting distortions and aberrations at the edge of a much larger APS-C/S35 frame - that you will never see on a 2/3" sensor...you would probably do as well with very inexpensive c-mount lenses

Probably not true. Remember that stills glass costs half a zillionth as much as cinema glass. A brand new Sigma is probably similarly priced or cheaper than a 30 year old S16 lens.

And performance might be significantly better from some of the higher resolution lenses made for 2/3".

This is probably true primarily in the corners (where sharpness drops way off on most stills glass, thus the aforementioned lower price). But as you pointed out you never see that on a 2/3" sensor, you're just gonna be using the center "sweet spot" of a stills lens.

 

[Jason Murphy]

Not to mention that this lens is f4.5/5.6. Really slow, without a constant f/t-stop through the zoom range.

As Michael mentioned above, if you're only interested in shooting 2/3", you'd be much better off with an inexpensive c-mount lens designed for 16mm. A lens designed for that size would be most likely be faster, lighter, smaller, and very possibly sharper as well.

EDIT: For example, it's not going to be quite as wide, but you could probably get a decent Angenieux 9.5-57mm HEC T1.9 lens for about $1500. Great lens, incredibly versatile, and pretty sharp through the range. And in terms of construction, it's going to be much better suited to shooting motion than the aforementioned Sigma.

Lee's right that you probably won't find a good 16mm zoom lens for much cheaper than the Sigma, but the slightly more expensive ones you do find will be much better for shooting 2/3, if that's all you're after. If, of course, you also need a superwide for your APS-C sensor camera, that's something else entirely.