Great Lenses to not so great?

Antoine · Joined: 08 Jan 2016 Posts: 298 Location: London

Sony/Rangefinders
What I understand from the Kolarivision is that they address a specific issue: rangefinder lenses with their specific nodal issue on Sony A7 series cameras.
This is useful for wealthy amateurs and pros as this allows the use of Leica and other expensive rangefinder lenses.
I am not aware that a similar problem/solution exists for "mirror/reflex" camera vintage lenses.

Canon nFD 24 f 2.8
When I started buying manual lenses for my Sony A6000 (I already had old Minolta MDs), I bought a Canon nFD 24 f 2.8 (cost me about 50£ plus an adaptor) following reports this was a high performance lens.
I have been disappointed for 2 reasons:
- The bayonet system is a bit fiddly but I got used to it
- More importantly, the lens does not look very high mechanical standards while the focusing ring has some play in it which does not help for focusing. Sure, this is not worse than modern lenses but it much worse than the Minoltas and the Vivitar 17mm f 3.5 (Tokina) I further bought. While I accept this may be due to the specific lens, I have read other reports of such looseness in the focusing ring
- The optical peformance was excellent
I don't know whether the loose focusing ring can be remediated.

Modern versus vintage lenses
I understand posts stating modern lenses have better performance than vintage lenses...but there is a big caveat: tolerance, solidity and manufacturing standards. I have read many reports stating that some lenses don't perform because they are decentered, fragile... which leads them not to deliver the supposed design performance (in some reviews, the reporter mentions he sent back the lens to get a better one...)
Some websites (artaphot.ch for example) also show that vintage lenses do perform versus modern lenses.
Some other reviews show that many modern zoom lenses don't perform on high pixel cameras.
Of course, Autofocus requires modern lenses.

Other
I have given an example of a disappointing lens to get started as I believe we should not be too politically correct and not talk about this. Of course, this may be due to all sorts of reasons (camera-lens...).

I obviously accept that others may have a different experience/opinion with the lens that disappointed me.

dnas · Joined: 14 Nov 2008 Posts: 488 Location: Japan

There is another point not mentioned yet: Telecentricity.

Lenses for mirrorless cameras are usually telecentric. The light passes through the aperture and exits parallel to the optical axis, and not at an angle like more conventional (older legacy) lenses. This means that they are better suited to the narrow entry angle of a lot of image sensors. The angle on older legacy lenses are greater away from the optical axis, so some lenses (retrofocal wide angle lenses, for example) sometimes have poor performance on cameras like the A7.

Here's an example I did a few years back:
Legacy:

Modern lens with some Telecentric design (same focal length):

Basilisk · Joined: 21 Mar 2013 Posts: 356 Location: UK

My view is that I have a pretty good kit lens (Nikkor 24-85mm f3.5-4.5 G) on my D600, which covers quite a lot of needs - fast, AF, OK for landscapes, sharp enough for stopped down shots. Modern primes are a) quite expensive for fast ones and b) not very compact, so I have MF primes for the following reasons.

1) fast, with good bokeh
2) compact (if not very lightweight)
3) nice and sharp in the area of interest (central 2/3 of frame)
4) close focus is nice (always have one lens in the bag that can do close focus)

You will notice that sharpness across the frame and stopped down performance don't really rate highly in my calculation; as I say, modern zooms are much better than they used to be, and rendering of many lenses at f8 is much of a muchness.

My current selection is the following Nikkors - 28mm f2 AIS, 50mm f1.2 AI and 105 f2.5 AI - which all satisfy at least 3 of my conditions.

Nordentro · Expire: 2015-01-29

Well it is not really true that Sony uses thick filters infront of the A7 series sensors. They use regular or avarage thickness compared to the bunch of system cameras. It is the other way around, Leica use very thin filters to their sensors to match up with their symmetrical wideangle rangefinder lenses.

If you like small rangfinder wideangle lenses, a Kolari upgrade would be great indeed. Wink

(I will do my upgrade of A7 II too as I`m quite a big fan of rangefinder lenses my self, as soon as Youth Olympic Games is finished here in Lillehammer).

Basilisk · Joined: 21 Mar 2013 Posts: 356 Location: UK

Nordentro · Expire: 2015-01-29

Yes indeed, it is pretty selfexplaining and logical. Some people would even claim there is a difference on retro focal SLR lenses too, and this is perhaps true, but depends on how big of a pixel peeper you are Wink

I am even satisfied with many of my RF wides without a mod, so this is a very subjective topic and depends on your shooting style.

memetph · Joined: 01 Dec 2013 Posts: 942 Location: Poland

When I read the Kolari site , i understand that the modification consists also in removing the AA filter. This has an impact on crispness with any lens.

Nordentro · Expire: 2015-01-29

davidblue1984 · Joined: 29 Dec 2013 Posts: 68

This is exactly what i was trying to get at. I think a lot of people are under the impression if it adapts it works, but the optic designs are different .

calvin83 · Joined: 12 Apr 2009 Posts: 7553 Location: Hong Kong

How about the reverse? Some lens does not receive very good comments in the film days. However, they shines now thanks to with the aid of focus peaking/focus enlargement or even AF adapter? Wink

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

I can think of two specific lenses that have great reputations but that basically suck on an APS-C digital. These are the Tokina 17mm f/3.5 (Vivitar brand in this case) and the Tamron 17mm f/3.5. I have tried these two lenses on both my Sony NEX 7 and my Canon XS DSLR. Neither camera sensor could handle the angles in which light rays approach them, near as I can tell. Resolution is muddy -- the images look like they were taken with $10 optics made in China. In the old days. Yet when I use either one of these lenses on one of my 35mm cameras -- whew, look out!

The jury's still out as to whether or not a Lens Turbo (II) or Metabones would do any good with my NEX. And I don't believe I've seen definitive evidence yet -- although I might have missed it -- showing how the various FF cameras handle this ultra-wide focal length, be they Canon, Nikon, or Sony. A focal length designed for 35mm cameras and not digitals, I guess I need to point out.

Gerald · Joined: 25 Mar 2014 Posts: 1196 Location: Brazil

I think there is some confusion between focal length and exit pupil distance (the distance between the exit pupil and the focal plane). For a given sensor, the focal length determines the angular coverage and the inclination of the entrance rays. However, the inclination of the exit rays, which is what interests from the point of view of the sensor operation, is given ONLY by the exit pupil distance. In a retrofocus lens, exit pupil distance is always larger than the focal length (in a telephoto lens, it is the opposite). The retrofocus construction is especially suited for use with digital sensors justly because of the increased exit pupil distance.

An indirect way to measure the exit pupil distance is to multiply the effective diameter of the exit pupil by the F-number. The photo below shows the exit pupils of four lenses, three retrofocus and one almost symmetrical Double Gauss. Note that ALL the lenses are with apertures set to same F5.6.

Rather surprisingly, the lens with largest exit pupil diameter is the Tamron 17mm, which is precisely the lens with shortest focal length. This means that among the four lenses, the Tamron 17mm is the lens with largest exit pupil distance, so it is the lens that in principle best fits a digital sensor. The Tamron even beats Helios 44-M, which has focal length more than three times greater than the Tamron.

In my opinion, there is no technical limitation on the use of legacy retrofocus wide-angle lenses with FF digital cameras. The Tamron 17mm, as well as ALL ultra wide-angle lenses work very well with FF digital cameras, but they are not good choices for use with APS-C or m43.

Rigel · Joined: 26 Nov 2015 Posts: 121 Location: Belgium

I thought that this "usability" was only a matter of Flange focal distance ... and actually nothing else ?

https://en.wikipedia.org/wiki/Flange_focal_distance[img][/img]

paulhofseth · Expire: 2018-06-28

As an extreme example, consider the old Nikon 21mm f 4 for the F. It certainly had the same flange distance that your wikipedia reference explains, but the rear element almost touch the film. The angle of the light going towards the corners must be extreme.

p.