Testing C-Mount lenses on NEX

Started Aug 23, 2011 | Discussions
Sixela New Member • Posts: 6
Testing C-Mount lenses on NEX

Hi, I have a NEX-5 since Dec' 10 and enjoyed using it with the kit lenses until now and have just started using manual lenses (or am about to start as the adapters just arrived this morning).

I also happen to work in Machine Vision for a large industrial camera manufacturer. As these cameras mostly uses a C-Mount I have tens of C-mount lenses lying around in the office that I plan on testing with the NEX. I expect most of them to be crap (and not covering the full sensor) but I may have a few gems in the lot like some 25mm f1.4 made for 2/3" 5Mp sensor (3.45 x 3.45µm pixels) which should be plenty sharp on the NEX or an old Fujinon TV zoom 12.5-75mm with a constant aperture of f1.2.

I just received the C-Mount adapter this morning (the cheapest one on eBay) and I have a few question before starting to test some of the lenses.

  • What's the position of the NEX shutter relative to the e-mount? Some C-Mount lenses have a protruding rear element that extend beyond the C-Mount and I'd like to avoid the shutter getting damaged by hitting the rear of lens. The C-Mount registering distance is already shorter than the e-mount and I'm affraid that with some lenses the rear element may be sitting too close to the shutter.

  • Any kind of recommendation for testing the relative quality of the lenses? What should I look for when testing the lenses? I'll check the size of the image circle of course and how it covers the APS-C sensor and if there is any vignetting/light fall-off. I have a few test charts and pattern boxes in the office that I can shoot to test the sharpness. Any other things I should look for?

Thanks,
Six

mynakedsoda Contributing Member • Posts: 701
Re: Testing C-Mount lenses on NEX

For me any full size samples are great. It makes it easier to judge the big issue (resolution) for me with these lenses. As far as what will hit the mirror I am not sure. After that is the amount of vignetting.

Jamesch Forum Member • Posts: 92
Re: Testing C-Mount lenses on NEX

I can't really contribute, but looking forward to your tests.

BTW do all those CCTV lenses have the same registration distance? I don't think any would hit the shutter though.

zoranT Contributing Member • Posts: 919
Re: Testing C-Mount lenses on NEX
  • Any kind of recommendation for testing the relative quality of the lenses? What should I look for when testing the lenses? I'll check the size of the image circle of course and how it covers the APS-C sensor and if there is any vignetting/light fall-off. I have a few test charts and pattern boxes in the office that I can shoot to test the sharpness. Any other things I should look for?

Thanks,
Six

really, don t bother with charts etc. real life is what counts,

One indoor shot with each lens, one outdoor (may be panorama with lots of fine detail to capture).
Fix ISO, shutter, then shoot one position wide open, and the other at around F10

that should give us an idea, thanks in advance for testing, looking forward

youngG Regular Member • Posts: 191
Re: Testing C-Mount lenses on NEX

I'm looking forward to your results as well. If the any of the lenses you test turn out to be useful, I'd be pretty interested. The size of c-mount lenses alone is worth the consideration.

I've been under the impression that lenses shorter than 35mm would heavily vignette on the NEX's sensor, but is seems the c-mount sensor size can factor into this as well? I wasn't aware there were varying sizes of c-mount sensors. Can you to shed some light on this?

This is slightly OT, but on the topic of testing c-mount lenses, I figure this would be the most appropriate place to bring this lens up (and perhaps you'll be testing it?):

http://www.ebay.com/itm/f-1-4-50mm-C-Mount-CCTV-Lens-GF1-GH1-G1-EP1-EP2-EPL-/260739008853?pt=Camera_Lenses&hash=item3cb5418955#ht_2775wt_952

Have you (or anyone) tried this lens out? Not too much info on this lens, but I think it has potential.

Vadimka Regular Member • Posts: 422
Re: Testing C-Mount lenses on NEX

I started buying C-mount lenses back in 09, as soon as I got my Panasonic G1 and since then I've tried great deal of them. At one point I was going to do some testing and write my findings about everyone of them, but pretty soon I got overwhelmed by the quantity and never really posted anything. (although I did and still do enjoy using them, I dont really have time for review)

But to summarize:

1. not all C-mounts are created equal, I like the results I get from Cine lenses vs CCTV (although some people claimed that there are some good CCTV lenses, I just never bought any of them)

2. On m4/3 body most 35mm and up will cover sensor completely. On NEX body, most 50mm and up will cover sensor completely.

3. I like Old Cine glass like Kern, Angenieux, Cooke, Kodak etc. They were made with good care and most were assembled by hand. CCTV lenses on other hand considered to be a commodity, with low quality control and specs, afterall most CCTV monitors feed only required less than 1mp resolution.

4. Cine lenses control aberation very well. So well in fact I sold all of my Voigtlander lenses, incluidng 25, 28, 40, 50/1.1 and 90. (Lanthar 90 was not bad though, but I do have Leica APO 135mm that performs a bit better and longer, in fact I like my long lenses to be APO, because sharpness does matter for those, while cine glass I like in 25-75mm range)

Yes most Cine lenses are very expensive, but I have yet to loose money on any of them, I wish I could say the same about those Voigtlanders.

GarageBoy Contributing Member • Posts: 924
Re: Testing C-Mount lenses on NEX

Cine lenses are generally the cream of the crop
Too bad most barely cover MFT
The longer ones might cover APS-C

fermy Veteran Member • Posts: 3,168
Re: Testing C-Mount lenses on NEX

Before people rush to buy cine lenses, I suggest they search m4/3 forum for $2000 Schneider samples or getdpi forum for some more samples and tests. IMHO, objectively cine lenses are just as bad on m4/3 sensor as CCTV lenses, obviously on NEX sensor they will be worse, most won't cover it. However, CCTV lenses are cheap and so one might experiment with them just like with Holga, while most cine lenses carry ridiculous price tag. There is no denying that many cine lenses look beautiful and are well made.

Btw, here's a bunch of samples with 50mm/2.8 Cosmicar (Pentax) CCTV lens.

mynakedsoda Contributing Member • Posts: 701
Re: Testing C-Mount lenses on NEX

youngG wrote:

I'm looking forward to your results as well. If the any of the lenses you test turn out to be useful, I'd be pretty interested. The size of c-mount lenses alone is worth the consideration.

I've been under the impression that lenses shorter than 35mm would heavily vignette on the NEX's sensor, but is seems the c-mount sensor size can factor into this as well? I wasn't aware there were varying sizes of c-mount sensors. Can you to shed some light on this?

This is slightly OT, but on the topic of testing c-mount lenses, I figure this would be the most appropriate place to bring this lens up (and perhaps you'll be testing it?):

http://www.ebay.com/itm/f-1-4-50mm-C-Mount-CCTV-Lens-GF1-GH1-G1-EP1-EP2-EPL-/260739008853?pt=Camera_Lenses&hash=item3cb5418955#ht_2775wt_952

Have you (or anyone) tried this lens out? Not too much info on this lens, but I think it has potential.

I've been talking with someone about some C mount lenses. Various ones are designed to cover various size sensors.

Jamesch Forum Member • Posts: 92
Re: Testing C-Mount lenses on NEX

Has anyone tried this:

http://www.ebay.com/itm/CCTV-25mm-f-1-2-C-mount-Lens-NEX-3-NEX-5-/260837301759?pt=Camera_Lenses&hash=item3cbb1d5dff#ht_3854wt_1110

It would be really great for shooting at parties and things like that with the f number being 1.2. I don't care that the aperture is triangular stopped down, I would mostly shoot wide open.

I can't really figure out where the focusing ring is, assuming the blue one is for aperture

I have the 35mm 1.7 CCTV, and I like that, if this is any similar I would buy it.

fermy Veteran Member • Posts: 3,168
Re: Testing C-Mount lenses on NEX

Didn't try it, but the fact that it's 1/2" inch means that it likely won't cover even m4/3 sensor.

mynakedsoda Contributing Member • Posts: 701
Re: Testing C-Mount lenses on NEX

fermy wrote:

Didn't try it, but the fact that it's 1/2" inch means that it likely won't cover even m4/3 sensor.

I haven't either but asked about it here some time ago. I was told by a user that had tried it that it doesn't come close to covering the Nex sensor. I also found an M4/3 user that had examples. Even with their smaller sensor it vignettes badly.

OP Sixela New Member • Posts: 6
Re: Testing C-Mount lenses on NEX (long post)

Hi,

First of all, the C-mount can accomate sensor up to 1" of diagonal. Most c-mount machine vision cameras use sensor ranging in size from 1/4" to 2/3" (1" sensor are quite rare, no idea for c-mount cine camera). Therefore, lenses are designed to cover a specific sensor size and are specified as 1/3", 1/2", 2/3"... lenses.

I've been able to try out a few of the C-mount lenses I have available and here's what I could gather so far.

  • Most lense below 2/3" and 25mm focal length will not provide enough coverage for the APS-C sensor heigth. Even if the sensor is somehow illuminated up to its border the sharpness will fall off quickly out of the center and there will be lots of smearing on the outside.

  • Machine vision lenses are quite sharp as expected (at least in the center) as they're mostly used for metrology/measurement image processing in industrial processes. Because most machine vision systems use B&W cameras in a controlled lighting environment the coatings on machine vision lenses do not seem to be well suited to general photography and they flare heavily as soon as there's some bright light outside the frame

  • The intriging Fujinon TV zoom 12.5-75mm f1.2 is utter crap with tons of flare and internal reflexions

  • The barrel on "5Mp" lenses I have is too large to fit within the recessed portion of the NEX-> C-Mount adapter. Meh.

Below are a few test shots with some 2/3" lenses designed for 3Mp cameras (roughly 4.5µm pixels - NEX-5 pixel size is 5.08µm).

  • Spacecom JHF25M: 25mm, f1.4

  • Spacecom JHF35m: 35mm, f2

  • Spacecom JHF50M: 50mm, f2.8

These lenses made by Spacecom ( http://www.spacecom.co.jp/ ) cost somewhere around 300€ each - I have no affiliation with this company, those 3 lenses just happened to be lying around in the office

Group shot: C-Mount adapter, 25mm, 25mm, 50mm, NEX kit zoom

Quick test shots from my balcony on a cloudy day in Paris. Sorry for the bad quality I just a had a crappy flexible tripod and tried to make it stand still one of my balcony planter without falling down on the street... ISO 200, straight export from LR3, no sharpness or NR applied. These lenses are quite soft wide open but start getting better once closed down to f2.8.

  • 25mm f1.4

  • 25mm f2.8

  • 25mm f8

  • 35mm f2

  • 35mm f2.8

  • 35mm f8

  • 50mm f2.8

  • 50mm f4

  • 50mm f8

Six

Vadimka Regular Member • Posts: 422
Re: Testing C-Mount lenses on NEX

Great samples, I like #1 and #2 the most. Cosmicar is of the of the better CCTV lenses, as well as Fujinon. (because their ties to photo and video industry) Some modern Fujinon cine lenses are considered the sharpest in the industry.

But I have to agree with some people, that cine lenses are not going to be an all in one solution and by no means we all should run and get one at any cost. Majority of people judge lenses strictly by how much resolution they produce and how much vignetting and distortion it has. (these people should not consider most of the C-mount cine lenses)

But for some other people who look at photography as art, and pay more attention to tones, colors, draw, aberrations, bokeh and overall uniqueness of the whole image, for those it might worth a try.

I don't know how to really explain it, but I did own one of the sharpest lenses ever made (zuiko digital 50/2 macro) and it made me yawn everytime I took it for a spin.

But for those who want the best of both worlds with no compromise should consider 35mm cine lenses (arri mount, etc) they will cover aps-c and will have no problem with vignetting.

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