Thanks for these images, inglis, the lens seems better at the short end from the MTF, but very tidy at longer FLs.
'What I find really hard to understand is how to translate what the three lpmm measurements means in an image.'
Yes it is, and indeed different people look for different things in the data. Mike Johnston of the Online Photographer and others feel that the 20 lpmm is the pair you want high measures for, whereas as I think we are moving towards the time when users will be looking for higher resolution to match their higher density sensors. Yes, 50 or 60 lpmm would sort out the pecking order in quick time, for 35mm coverage lenses anyway!
High 5 and 10 lpmm are associated with image 'brilliance', as seen in many Leica images, they clearly use it as a design goal, especially wide open. It's not what I think of as contrast, which is a subject characteristic, but I can understand people saying that.
While I'm at it, a great intro paper on the subject is 'The Quality Criteria of Lenses' available as a PDF from Schneider Optics (the people who make the finest large format lenses), here is the URL:
The following crops from a CY 35-70 image help to put the Contax G 35-70 in a context on the Nex 5n.
The edge of the CY 35-70 at 35mm wide open does not suffer from the same issues as the G 35-70 at 35:
Really appreciate the images and effort inglis - very helpful.
And thanks AhamB, ahh there's the relationship between lpmm-measurments and the sensor('s pixel density). Very helpful too philips with further interpretation of the measurments, seem that there's no easy "truth" around - although a lot of indications..
I'd say that the G zoom is quite impressive at 50 and 70 mm, already at F3.5. There has to be quite a lot of atmospheric haze contaminating those shots too, which you have to mind when judging the detail contrast.
Paul FWIW, I use a single cheapo Chinese for all my G's. Either my lenses have become smoother with usage, or I am just used to the behavior. I always magnify x 2 for focusing, and what takes time for me is to interpret the current tolerance span for focus peeking - not to set focus where I want.
I also have the EVF, but it changes nothing.
Due to primitive gearing - even in expensive adapters such as Metabones (with the large ring) - you will always have a stochastic variable resistance for a G-lens. Sometimes it will be far away from where you want to set focus, sometimes it will disturb exactly where you want to put it.
But there is a better way. Just a few more gears and some grease. But we're not there yet, alt-photo needs to marry with some elementary mechanics first. The gearing in a 5$ servo for a remotely controlled 3D helicopter is rocket science compared to the hunter-gatherer technology found in current G-adapters :-)
Wilhelm,
Is the EVF worth having for G lenses? I use a hoodman in bright light at times and wonder if the EVF would help. If I understand correctly, you suggest that it does not help with peaking.
Not for me. I'm sure others find it more useful. One good point with it though, is that it provides some additional stability when shooting. Perhaps it's also better in harsh sunlight (compared to the more exposed screen), but we seldom have that kind of light here this time a year so I dont know yet.
I just got my copy of the 35-70G today and I need to figure out if it in normal or not.
I have a Kipon adapter and a G 90mm that I use on Nex 5N. That combination is as smooth as silk.
I just put the "Demo Quality" 35-70G on that same Kipon adapter. There are now several "sticky" spots in the rotation of the focus wheel. Some areas smooth, but some spots where the resistance jumps way up. sometimes binds very badly. Is this normal for this lens? Or do I have a bad copy that I should send back while I still can?
Any experience and thoughts would be greatly appreciated.
My experience is the same with a Kipon. Makes focusing difficult at times. Sometimes it jumps every so slightly making focus more difficult. This especially happens (for me) when moving to a new focal length. Often if I turn it a few times after moving to a new focal length, it gets much easier.
I dont think it's the lens. It's the adapters. Cheapo chinese, Kipon or Metabones does not matter much. The gearing is the culprit. None of my G's (I have four of them) feel smooth allover.
I bet the required torque for the focusing screw on the lenses themselves are as constant as any real focusing ring.
wfrank wrote:
I dont think it's the lens. It's the adapters. Cheapo chinese, Kipon or Metabones does not matter much. The gearing is the culprit. None of my G's (I have four of them) feel smooth allover.
I bet the required torque for the focusing screw on the lenses themselves are as constant as any real focusing ring.
I think tht's right and I recall reading ona foru somewhere of a person who had a very sticky lens and had it taken apart and cleaned. Worked very smoothly after that with the same adapter.
I'm using one Kipon and one Metabones and I have the 28/45/90s and just got a 35-70. The 45 was a little sticky for a while on the Metabones but has noe freed up nicely, the 90 is also very good, the 35-70 is just great on my Kipon and the 28 has been very good on both.
