early pen f lenses and ttl meter numbers

[jagarch]

Hello,
I just got an early series Pen F 50-90 zoom. It doesn't have the ttl metering number ring and I plan on using it on a pen ft body.
What is the secret to translating the f stops to ttl numbers?
3.5 = 1?
16 = 6?
How does the camera recalibrate the scale for every lens? or does it?
Does anyone use this lens and is it any good?

 

[splitimageview]

I'll look at mine and give you the TTL numbers. The lens is a very good performer for a zoom of that time period.

 

[Disaster_Area]

When you say "good performer for that time period"... is it just the best of a whole lot of crap... or a lens that still hold it's own today? I've run two rolls through the Pen F I bought off you, Robert, and am loving every minute of it... now I need to expand my lens set for it. I'm used to primes and prime quality, but the Pen is becoming my "carry everywhere" camera so I thought a zoom might be convenient... will I be disappointed compared to the 38? (or the 40 f1.4 which is first on my shopping list)

 

[Doug]

I don't think the 50-90 can approach the optical quality of the 38mm f/1.8, which is one of the best lenses in the lineup. I have both, but I admit the zoom hasn't seen use in years. It is a pretty good way to get a variety of longer focal lengths... Another I've found is impressively crisp is the 20mm f/3.5, better than the 25mm f/2.8. They're all good, the 38 outperforms the 40, and the 70mm is excellent.

 

[Doug]

Oh, on the f-number vs exposure number... I was never able to figure any consistent relationship. But the exposure number click stops as I recall are evenly spaced whereas the click-stops for the f-numbers got closer together at the f/16 end of the scale. My Pen gear is packed up at the moment so I can't refer to it...

It was pretty tricky that lifting and rotating the aperture ring 180 degrees not only brought a different number scale to the top but changed the click positions too...

If your lens doesn't have the exposure number scale, in other words it's pre-FT, I'd suggest just use a separate meter. The exposure number system for TTL metering was a kluge anyway!

 

[splitimageview]

My favorite is the 38 Macro, but the 38/1.8, 40/1.4, 60 and 70 are all excellent. The 20 is great, but I like the 25/2.8 as well. I have not tried the 25/4. Doug, do you have experience with that?

TTL numbers on the zoom are 0.5, 1, 2, 3, 4

Speaking of FT meters, I pulled the meter out of mine and put a first surface mirror in place of the semi-silvered. It brightened the view by two full stops...and I like using an incident meter since the FT meter isn't coupled anyway.

 

[splitimageview]

When you say "good performer for that time period"... is it just the best of a whole lot of crap... or a lens that still hold it's own today? I've run two rolls through the Pen F I bought off you, Robert, and am loving every minute of it... now I need to expand my lens set for it. I'm used to primes and prime quality, but the Pen is becoming my "carry everywhere" camera so I thought a zoom might be convenient... will I be disappointed compared to the 38? (or the 40 f1.4 which is first on my shopping list)

Hi Jesse,

Glad you are liking the Pen F! They are such cool cameras, so small to carry everywhere.

I have two zooms, but haven't used them yet, as they need cleaning. One has a stuck aperture. I may have time to dive into them tomorrow. Once they are cleaned I'll post some shots.

Robert

 

[Doug]

Robert, I have not had experience with the 25 f/4, just the f/2.8. It's a good lens, and a handy focal length, but not as crisp as I'd hoped. Maybe it's just this sample... No experience with the 60 either, as it seems rare and expensive. Let's see, that should give about a 28-30° angle of view, a fast short tele. What do you think of it?

I've only recently found a 70mm f/2 so it's seen only one roll of film so far... but it looks fine.

Changing the FT mirror is a pretty tricky move! Makes sense if you can do it and get it calibrated and all. Essentially the equivalent, then, of the FV, though my FV doesn't seem all that much different from either FT, which each have different brightnesses. Age probably plays a role at this point some 40-45 years down the road!

 

[splitimageview]

Doug, I'd tend to agree, the 25 is very good, but not up to the level of the 20. The 60 is fantastic but a little big on the Pen, at least compared to the other lightweights like the 40/1.4. And pricey, although not nearly as much as say a Leica lens built in similar minimal quantities, which would be probably 3-4x as high.

The FT mirror is easy to remove, no calibration or anything, the trickiest part is sourcing a good first surface mirror and then cutting it to size. Comparing using a meter pointing thru the viewfinder, it is about 2 stops brighter than a mint condition FT, but if the FT semi silvered mirror is in poor shape (many are deteriorated) it will make that much more of a difference. Since there is a plentiful supply of FTs as compared to FVs this is a good conversion, and there are many FT meters that are inoperative anyway.

 

[jagarch]

TTL numbers on the zoom are 0.5, 1, 2, 3, 4

So
3.5 = 0.5
4 = 1
5.6 = 2
8 = 3
11 = 4
16 = 5

it only goes up to 5? The meter goes up to 7. Is that right?

 

[splitimageview]

The TTL numbers don't correspond exactly to the f stops, unfortunately...

If I choose the click stop on the TTL scale, the aperture scale will show the following:

0.5 = 3.5
1 = ~4.5
2 = ~6.3
3 = ~9
4 = ~13