Upgrade to Nokton 50mm from Cron?

[Huck Finn]

Huck - I am sure you are right, but really, in practice, film is not so exact a medium (and most users' practices are not so precise) that a 1/3 stop difference in rated lens speed will change the outcome of a picture. Keep in mind that there is also some real mechanical variation in actual shutter speed, manufacturing variation in film stock, differing film age and storage conditions, processing chemicals that are of varying ages, paper of varying ages, enlarging lenses with their own actual variation in focal length and speed . . . I would judge mainly on the results that you get -- that is, the actual pictures -- and if you are unhappy with the quality, tweak the process in a way that makes sense.

Or put another way, if you were able to measure the inaccuracies in the system you use and the result was that you were habitually underexposing by 0.2 of a stop, what would you do? In my case, if I decided to do anything, I'd probably lengthen my film development time by a few seconds. Because I really don't have control over the other aspects of the process. But the real point is that even if you could measure a difference that small, you would probably not be able to spot the effect of that difference in your finished product.

Now, I need to find my Leica M 50/1.9 and go make some pictures . . .

Ben

Ben,

I was just responding to a question from Avotius. I posted the list of lens speeds that I happened to have saved when I read the reviews because he wanted to know if there were any other lenses that varied from their listed specs. As I said in my post, it's no big deal. It occasionally becomes significant as in the case of ywenz. He was considering "trading up" from his summicron to a Nokton so that he could gain a full stop with a wider maximum aperture. He won't; he'll only gain a half stop. Only he can determine if this is a significant issue.

In regard to my bashing of Cosina - good naturedly, I hope 🙂 - my issue isn't that their lenses vary from the specs in almost every case of a lens that I've seen tested, but that they so often artificially inflate the speed of the lens by picking a number like f/2.5 out of the blue to represent a lens that is really f/2.7. If they stuck with standard apertures, I would have no problem with approximations that are a little bit off.

I have seen posters express an interest in a CV lens with the comment that not only do they like the lens but they will gain almost half a stop over Brand X at f/2.8. The fact is that they won't gain this half stop & it is misleading for Cosina to give the impression that they will.

Cheers,
Huck

 

[Benjamin Marks]

Huck - of course you are quite right about the half-stop upgrade scenario. It is a different ball game when you are talking about what induces a consumer to spend $$ for some perceived benefit.

Ben