Jonesy Jones

Thanks guys for your help. I have decided to exchange my Sigma for a new one. Partially because of the light transmission issue, which may be identical on all copies, and partially because something doesn't look right with the aperture blades when I stop all the way down. It turns into a strange oval hexagon shape. When I get my new copy I will test it again and post the results.

So once again I've done another test, against both my Leica and Nikon prime 2.8. This time the test was with all the lights off and just a candle on a table, and once again the results are the same. Again, the difference of light transmission from the Sigma 1.8 and the prime's is minimal. If I were to guess t-stop, it would be 2.6 or 2.7 at best for the Sigma. Do you think there is something wrong with my copy of this lens? Or do you think this is consistent across all copies?

"The same clarity needs to be applied to aperture (f-stop) in relation to brightness (t-stop). The Canon 24-70mm F2.8L I (original version) and EF-S 17-55mm F2.8 for instance DXOMark rates at T3.6! The difference is highly noticeable in the real world with my Tamron 24-70mm F2.8 VC a T3.0 and far brighter than my Canon wide open. Showing the T-stop of the lens on the box next to F-stop would help allow the consumer to make a more informed choice especially if they need to shoot in low light." Everyone's getting pretty worked about the megapixel thing, but the T-stop idea is great. For instance, I've been testing the Sigma 18-35, and it's no where near 1.8. Probably more like T2.5.

​That's good to know. Thank you for sharing. Keep in mind that you are comparing the Sigma to another zoom... while using a speedster. Compared to a prime the Sigma is only slightly better than a 2.8. I'm guessing 2.5-2.6.

​Yes, in the first set. In the next two sets of images the Sigma is the 2nd image.

Added some more examples. There is just no way this Sigma is even close to a 1.8. ​This is a great idea. I am going to try this next.

​CheckCheckCheckShooting ProRes Lt (same settings on single frame export)

​Leica 19mm 2.8 Sigma 18-35 (@19) 1.8 (or wide open using metabones adapter) Will try and post another test later today.

Hey guys, thanks for your help. I just uploaded some sample pics to illustrate what I am talking about. Yes, you can sort of see a difference. But no where near the difference a stop + should represent.

I'm trying to figure out how to upload sample pics but EOSHD seems to have a super low data allowance. Any ideas?

So, I just got a hold of the Sigma 18-35 for the first time. Lovely lens. I'm trying to do some tests to make sure I want to keep it. Decided to compare it with another lens that I own which is a Leica 19mm 2.8. I thought I'd run them both through a few tests. Just fiddling around I shot the keyboard on my desk with both lenses wide open... and to be honest I don't see too much of a difference. Granted the 1.8 is slightly brighter, but not by much. Definitely not a stop +, at least to my eyes. Both lenses are using adapters to get them on my BMPCC. The Sigma lens is using the Metabones (non speedbooster). I've looked at the aperture blades of the Sigma/adapter and they appear to be opening up all the way. The Leica is using a cheap (non speedbooster) adapter. You guys are smarter than me. What am I doing wrong? Thoughts? EDIT: Just added the sample photos. Can you tell which is which? EDIT #2: Added a couple more examples. I also compared the Sigma to an old 24mm 2.8 Nikon I have (this is the 3 pair of photos), with the same results. I am going to try a couple more tests, the suggestion of shooting a candle seems like a great idea. However, at this point, it is becoming obvious that the Sigma 18-35 is, regarding exposure, closer to a 2.5 than 1.8.

Definitely has that era grade feel.

I'm ok with either, separate apps for individualized tasks, or 'one app to rule them all' approach. I'm just glad we all have these tools available to us in any form. But I definitely prefer the latter. Why wouldn't I want to do all my work from the same place.

Updated. See original post for a list of edits.

​I just researched this some more and you are correct. It's late. Will get these changes in tomorrow.

​Only with external recorder.

​Is the Red designed for the same thing as the FS7, or vice versa? I would say the FS7 is way better at some things, and the Red at others. And the Red, Alexa, and yes Blackmagic are designed for similar applications, as opposed to the FS7 and C300.

​Didn't say they are on the same level. I said they were designed for similar purposes, which is accurate.

​After doing some research I'm quite certain they will work. My concern, is it worth the trouble? I'm planning on buying the URSA mini, EF mount. Currently I have the BMPCC and an A6000. I don't have the Sigma 18-35 yet, but I would prefer the Nikon version as it works on other cameras so easily. However I'd need to buy an expensive Metabones to get a Canon mount Sigma on my other cameras. I wish the URSA mini just had a Nikon version. That would solve all my problems. Sage wisdom please.

​I don't know what G linkage is, but it is a very modern lens. Are there adapters that allow you to change the iris electronically?

​Yes. I've used Nikon lenses on a Canon too. But not a lens without a manual aperture like the Sigma 18-35.

Yes. Blackmagic cameras are more or less designed for similar purposes as an Alexa or Red.

Updated chart.

I'm looking to use the Nikon version of the Sigma 18-35 on a Canon mount camera. Anyone tried that? What were your experiences? Is it too big of a hassle? Any experiences with the following or similar adapters? http://www.bhphotovideo.com/c/product/724050-REG/Novoflex_EOSNIK_NT_EOS_NIK_NT_Lens_Adapter_for.html http://www.bhphotovideo.com/bnh/controller/home?O=&sku=995261&gclid=Cj0KEQjw6tepBRDLqLnxouaY_pkBEiQAPIOiBuQPPviNGidWVabw6sQUZQVUOaDVKZSxmBCsgREas48aAj_m8P8HAQ&Q=&is=REG&A=details

I'm not exactly sure what you're looking for regarding the rain scenario. Your GH4 should be pretty weather resistant so you shouldn't have to worry about a little rain, but personally I would use that camera cover in an all out down pour just to be safe. It is my understanding that you should definitely use Auto (no flash) mode for time-lapse. But why not try a few time-lapses before June? Put 'er in auto and film the sunrise and set from your current location. You'll be a pro by the time you take your trip.