[stevebrot]

sensor reflects light onto the back of the lens which shows up as a ghost, sometmes green

This is true for many lenses, but not universally so. I only have one lens in my collection that does this (Auto-Rikenon 55/1.4 in M42) and it casts a golden ghost. As for PF...I have never seen it on a film image* and it is not really much of a problem with my vintage lenses on digital as either. Much depends on the subject and lighting. FWIW...just because a lens says DA on the front doesn't mean it will be PF free.


Steve


*I must qualify that statement a little. A combination of LoCA and poor field flatness can cause a purple edge glow on high contrast edges at the margins and corners of the frame that is very similar to PF. This I have seen on film.

[Just1MoreDave]

Aside from coatings and auto-focus... Is there really much difference between new lenses and old? Many primes have kept the same optical formula for decades - only changing construction materials. Even some 30yr old zooms hold up by todays standards. (i'm subconsciously trying to convince myself into a purchasing spree)

The coatings are a double problem with older zooms, with a larger number of coated surfaces.

A lot of the focal length ranges of older zooms are just wrong for me, more of an issue than how good or bad they are.

Wide angle. say less than 28mm, you might as well only look at new lenses. The old lenses that actually work well are in high demand and they cost about the same as new lenses. The only advantage is possible compatibility with a larger sensor.

In 2006 I got a Takumar 35/2 and a Pentax-M 35/2 really cheap, but never really liked them. Later I realized that both lenses were in high demand, and I could trade up to the FA 35/2 for very little extra cost. The FA is way better than those older lenses.

When the DA* 55/1.4 came out, it wasn't a whole lot different than the FA 50/1.4, which is the same optical formula as the A 50/1.4. This range is probably toughest for new designs, once coatings and AF are ruled out.

As someone else mentioned, lots of focal lengths are unavailable new, like a lot of telephoto primes. I'm price-sensitive (cheap) so I'm not going to get the 100mm macro, *200 and *300 just for something in this range.

[monochrome]

This is true for many lenses, but not universally so

I really need to remember to write "some" in these posts. I had several Tamron AD-2 SP lenses that were really nice on film that were nearly unusable on my K10D whenever there was sky in the background and the subject was in the foreground. That also happened with some Takumars. I encounter PF less often with my K-mount Pentax lenses.

[jkomp316]

Most of my comparison has been limited to the 28-50mm range. Probably the hardest area to notice a substantial difference. There was more consumer grade in the 35mm days - most of the Pentax brand has held up well though. I've seen Canon guys running old Pentax lenses. Is it an accurate assumption that "factory seconds" were rebranded and sold under different names?

[calsan]

Interesting, you said disregarding coatings, but I guess that's a bit like trying to disregard height when picking basketballers.

Coatings are probably the most important factor upon which all other considerations follow. Also, better coatings on each glass surface within the lens, not just front and rear elements. This mostly so in lenses with many elements - such as zooms, which are noticeably better in recent years.

[stevebrot]

Coatings are probably the most important factor upon which all other considerations follow.

That is an interesting statement that many might dispute, but the point is well taken. At the end of the second world war, the Russians had negotiated for and were very keen to take possession of the Zeiss optical works. Yes, the lens designs were valuable assets, but more important were the Zeiss coating technologies to be applied to things like bomb sights, periscopes, binoculars, and rifle/spotting scopes. A happy spin-off was that all post-war Soviet camera lenses sported nicely coated optics.


Steve

[bdery]

Even some 30yr old zooms hold up by todays standards. (i'm subconsciously trying to convince myself into a purchasing spree

Not true for CA, generally. Older high-quality zooms (Vivitar series 1 70-210 comes to mind) are indeed very sharp and reliable. Regarding sharpness however, the entry-level FA100-300 f4,7 was as shar as the pro-level Series 1. With less CA.

Aside from coatings and auto-focus... Is there really much difference between new lenses and old? Many primes have kept the same optical formula for decades - only changing construction materials.

Coatings by themselves are a super-big improvement. The 50s and 28s have kept the same formula, but apart from that in the Pentax lineup I doubt there is still a lens with the same design as an olderr equivalent lens.

[kaipa]

Computer aided design / manufacturing has resulted in Here's a non-zoom example. To get 1:1 magnification thirty years ago, you'd either have had to fork out for an enormous, pant-wettingly expensive 200mm device or reach for the bellows. Today, you can get 1:1 with lenses in the 30-35mm range.

Macro Takumar 50/4 1:1, years of production 1964-1966
Pentax A 100/2.8 Macro 1:1, 1985-1989

Another example. Minimum focus distance for the M/A* 300mm is 4m. F/FA* 300mm is 2m. DA *300mm is 1.4m.

In old days tele-photo was designed best for tele Now lenses are more versatile, but it comes at compromise of something else. Anybody really uses F/FA* 300 for butterflies?

[dboeren]

I have little to offer to the thread, but wanted to say that I find it very interesting. I'm just starting out and have purchased two Pentax-A lenses (50mm f/1.7 and 28mm f/2.8) to supplement my regular 18-135mm zoom lens. If I find myself using the primes a lot or favoring the quality of their images over the zooms then I may eventually "upgrade" to the F, FA, or DA series later on down the road. I can't say exactly what's better about these, I've only been going by the ratings in the lens database, but this thread helps clarify what some of the differences might be to account for the higher ratings.

[Kerrowdown]

I can't say exactly what's better about these

I find for me, that there is a greater satisfaction to be gained, when using Pentax manual class glass.

[stevebrot]

Here's a non-zoom example. To get 1:1 magnification thirty years ago, you'd either have had to fork out for an enormous, pant-wettingly expensive 200mm device or reach for the bellows. Today, you can get 1:1 with lenses in the 30-35mm range.

Huh? In 1983 (30 years ago) there were a number of prime lens options for 1:1 macro, though 1:2 (1:1 with matched converter) was more the norm. The aim at the time was compactness and the full extension required at 1:1 was counter to that aim. As for focal length and macro...it is all about working distance, not challenges of lens design. I have a 50mm macro and have absolutely no desire to go shorter.


Steve

[Digitalis]

can reflects light onto the back of the lens which shows up as a ghost, sometmes green.

my SMCP-K 50mm f/1.2 produces red ghosting - which is actually rather handy because it can be subtracted from the other channels, and you can reduce its impact.

[Allison]

I think you have to look at your application to determine if they hold up. When I am on a paid shoot I need the speed and efficiency of newer glass. When it is personal work, I like the concept of having a modern camera with an old lens. It is just a neat exercise.

The the end the coatings (and auto focus too) make a difference, so you can't exclude them.

[whojammyflip]

take a look at the following:
Camera Eccentric: Info

You have to figure that there are many factors determining the quality of a lens, with age being only one. In fact, its not so much age as manufacturing technology, which is connected to age, which determines a lens quality. But looking at the efforts in the Zeiss article, it seems clear that the quality of the glass employed is significant: I can imagine there is a push towards smaller lenses due to reduced likelihood of flaws in a smaller lens element. In turn, I can imagine that the top lenses of the past 30 years will still be competitive with the best today. Certainly, my Bronica 75mm PE is incredibly sharp...and putting that resolution down on a 6cm sensor (film) outperforms anything available on the high street.

Note the discussion in the Zeiss document about using wavefront interference patterns...they were machining them down to within 1/2 wavelength accuracy vs the design template shape. I also like the bit about checking for the polarisation effects. And that was all a very long time ago, I dont know how old that doc is, but it must be something like 50 years old. Makes you realise that even if a lens diagram looks similar between two manufacturers, the glass used will have a determining impact on the lens quality. Hence, I guess, the price of Leica and Zeiss lenses.

[John Poirier]

Computer aided design / manufacturing has resulted in enormous advances in all forms of precision engineering, optics included. Factor in technological improvements in materials and now you have complex formulae with aspherical elements and extra-low dispersion glass that wouldn't have been achievable twenty years ago, let alone forty.

Here's a non-zoom example. To get 1:1 magnification thirty years ago, you'd either have had to fork out for an enormous, pant-wettingly expensive 200mm device or reach for the bellows. Today, you can get 1:1 with lenses in the 30-35mm range.

Another example. Minimum focus distance for the M/A* 300mm is 4m. F/FA* 300mm is 2m. DA *300mm is 1.4m.

Makro-Kilar D, ca 1955, 40mm f/3.5. 1:1 macro. I have the slightly later 2.8 version.