dhessel

Thanks for the advice, I am aware that it requires dual focus but I would like to have the option. I have been using a Kowa for some time now so I am used to it. Thanks for the pics, is I will look them over again one the lens arrives.

I have an 50mm square front and original lens, oct18 version, that I will be mounting on my BMCC. I am thinking I may want to use it on my Nikon 50mm and speed booster for a wider FOV when needed so would like a way to mount it for non LOMO lenses. I don't have the lens yet, it is on it's way. Eventually I will want to pick up a LOMO 75mm lens for it as well. I already purchased the oct18 to m43 from ceilo7 so I am all set on that front.

Any idea how to mount just the anamorphic block of a LOMO to a regular taking lens? I just got one of these with it's own lens but may want to mount it on others so I can use with my nikon glass for faster/wider options. Any advice would be appreciated. Thanks.

That is what I suspected but wanted confirmation, thanks.

How are focal lengths reported on a OCT mount lens, are they relative to 35mm still or 35mm film? Thanks.

Thanks I didn't know that. I imagine I could overcome that limitation if needed. Can the taking lens be swapped out since these are not monoblock with other lenses?

I am toying around with getting a LOMO, OCT18 since they are cheaper, for use on my BMCC. I am not familiar with the mounts for these and am not sure what kind of mounting options there are. I would prefer to use it on a nikon mount for my speed booster but m43 is an option as well. Any information you can offer would be great. Thanks.

I had one of these a while back, most internal reflections i have ever seen.

I just got a RJ MFT to M42 reducer and I cannot even get it to seat in the lens mount on my BMCC. It almost seems like the adapter mount is a little to large in diameter. Any ideas?

I got a RJ MFT to M42 focal reducer for my BMCC, it doesn't seem to fit. I cannot even get all 3 bayonette's to go fully into the mount. It looks like the MFT mount is a tiny bit to large in diameter or something so I can only get 2 of the metal flanges into the mount at the same time. Any one else get this and have any issues? I see some dremel tool work in my future...

I have seen that the min focal on FF is about 75mm. That is somewhat rough based off a zoom lens I used to have. Since 85mm primes are more commonly used on FF many may say that the min focal is 85mm on FF. You can go much lower and still have a usable image when shooting wide open. I have used a Helios 44 which is 58mm on a FF 5DmkII. Wide open there is vignetting but it is a very soft darkening on the outsides, kind of nice actually. When stopped down you can clearly see the adapter on the edges and the edges must be cropped. Since a 2x gives you a 3.56 aspect ratio when shooting HD you can crop that down to a more normal 2.67 or 2.35 and remove most of the vignetting. This crop is may not enough to remove the vignette completely on the Helios at 58mm however. Since you have the MKII and III be sure to use the ML hack and shoot raw with a more square ratio, 1.175:1, 1.2:1, 4:3. I shoot 1472 x 1250 on my MKII which is continuous with MLV and audio at a 2.35 aspect when unsqueezed. I am hoping that at some point BM will add a 4:3 mode, I would be very happy with a 2048 x 1556 option for my BMCC. Considering their track record on updating their cameras, I am not optimistic that that will happen any time soon.

m43 is roughly a crop factor of 2, I believe. So take the focal lengths for the 5D and divide by the m43 crop factor. 29mm wide open and 42mm stopped down.

I would recommend the Kowa Prominar 16h. It is small, can handle wider taking lenses and is one of the best optical performers out there. Price ranges can vary but you can get a good deal if you keep an eye on ebay. It is dual focus but that will be the case with any lens unless you go high end. The SLR Magic is also an option that is not dual focus but it is on the expensive side and the 1.33x eliminates it for me.

So I have come to the conclusion that while it is mathematically possible to convert 4k 8bit to HD 10bit this 10bit is artificial and therefor doesn't offer the same grading benefits as true 10bit would. I will try to explain why. 8bit has 256 possible values 10bit has 1024 values, 4 times more. Going from 4k to 2k you are reducing the number of pixels by 4 hence 4 pixels are merged to make 1. If you take 4 8bit values and average them in floating point then multiply that value by 4 to transform it into a 10 bit range you will get the same result as if you just add all 4 values together. (p1+p2+p3+p4)/4 * 4 = p1+p2+p3+p4. Example. If I had a perfectly evenly lit scene and filmed it to true 10 bit it may end up with a 10bit value of 801. Convert 10bit 801 to 8bit: 801/4 = 200.25 this becomes 200 since values must be integers. Take 4 8bit values and make 1 10bit: 200+200+200+200 = 800. So by down sampling and converting to 10bit I would be getting a value of 800 when that value would have been 801 if it was originally recorded to 10bit. This means that there is an error when performing this down sampling and my initial impression is that this error is equal to the gained precision you get from going 8bit to 10 bit, +- 3. My conclusion is that while there is an increased numerical precision there is not a increased color accuracy therefore there is no real benefit for color grading. The resulting 10bit image does not more accurately represent what was recorded than the original 8bit did, same amount of error. 4:4:4 is the only benefit I can see.

Yes it did result in 10bit, 1024 potential values. I am a CG artist and TD so I actually did this in animation software, 3DS Max. It has a scripting language that supports per pixel image manipulation and I find it is the fastest way for me to whip something up for testing, slow to process though. It looks to me like the footage grades well as is and the conversion just artificially increases color precision, but since it doesn't add any more dynamic range it doesn't make a very large difference. My initial impressions, could still be proven wrong.

Tested it my self a while back and found no benefit to grading so far. Although I haven't tested anything from this particular app since I am on windows. It was done using floating point pixel summing though.

Thanks! I am fairly new to anything other than full frame lenses. I assume that this will work fine on a BMCC with the BMCC speedbooster since it is roughly APS-C after boosted?

I believe the Isco 54 I had a while back was pretty good at its widest. If you happen to be using Adobe CC you can use the optics compensation filter to reduce or remove it. I have used it in AE but I am not sure if it is available in any other adobe app.

Thanks I will give it a look.

I am looking for a wide angle zoom lens in a Nikon mount for a BMCC + Speedbooster. Something with a focal range around 18mm - 50mm. I am just moving over from Canon EF and am not really familiar with Nikon. Looking to spend a couple hundred, any suggestions would be appreciated. Thanks in advance.

Yeah I have seen that effect, it is similar to extreme barrel distortion and is worse on wide angle taking lenses. I have found it needs to be corrected for panning shots or else they look funky.

If you have it just test it, shoot a round object and see how much you have to stretch it to make it round again. These lenses are almost never what they say the are, usually a little less. The Isco's say they are 1.5 but are actually ~1.41.

I took my 54 apart and that is exactly what is inside, no more no less. I was able to repeat the design on a Kowa and it worked as expected in that I could focus just by moving the plano-concave lens. Getting a high quality result that works flawlessly is the tricky part that may or may not require some customization. The elements look like regular plano-concave and plano-convex lenses but that doesn't mean that they aren't in some way a custom design by Isco.

Not posting any images yet but in my testing so far I am seeing very little difference when I grade the 8bit 4k as apposed to the quasi 10 bit 2k footage. They both have banding when pushed too far at about the same point. Honestly the resolution loss is the most noticeable difference I see. I even programmed my own method for doing the down sampling to insure that the pixels were being combined in floating point format to get 10 bits of data. What I am seeing is that having 10bit doesn't have near as much of an impact if there is no increase in dynamic range. Down sampling may give something similar to 10bit color but it doesn't increase the dynamic range captured in the scene in any way so it is not a noticeable improvement in what I have seen so far. Also it is not anywhere near the Alexa with 10bit log encoding, the amount you can push the footage is insane because the 10bit log encoding is being efficiently filled with more dynamic range rather than just higher precision colors. The 4K footage looks great but that is about it.

I have done it a lot with a dual focus Kowa so it is possible. It's not something you want to jump into, I would suggest having 1 lens and the adapter that you use at first. Practice a lot getting comfortable with the process and learn how the lenses focus relate to each other and good at estimating focus distance. Eventually you get the point where you can quickly estimate your focus distance and know exactly where you need to set focus on your taking lens and adapter, some times this is not obvious, and then make some quick micro adjustments to the focus on the taking lens. You will also have to modify your shooting style to maintain the same distance from subject at all times while shooting and then stop and do a quick refocus for a new distance. It is also worth stating that the more stopped down you are the more forgiving the focusing gets. If you are stopped down enough on some lenses you can focus the adapter to the approximate distance and adjust focus with the taking lens. Sometimes you can even do some rack focus this way. Of course if you are on a FF camera it is less forgiving.