[jeryst]

I have an old Asashi Pentax 49mm 1.4 lens and I tried to use it on
the K-5iis I just got, but the camera wont do anything. The display
keeps flashing "F--" and neither the shutter button nor flash respond.
I've set the camera to manual focus and manual exposure. Is it even possible
to use an old manyal lens like this?

[interested_observer]

There are menu setting you must change (just once and then leave them for all eternity). Adam has a link / sticky somewhere on the site that addresses this. I can't find it right now....

• Shooting manual lenses on Pentax DSLRs « robertsdonovan.com

You need to set Using Aperture ring to permitted and I think that there is another one too.

[tim60]

It is possible. Someone else here will direct you to the instructions.


In the meantime - is the lens you are using an early version of the K mount or the older M42 screw mount? Both can be used on the modern camera, but the method is different.


The lens you have is probably a 50mm f1.4, with 49mm filter mount. And if it is branded Asahi Pentax is most likely the original version of K mount. The lens may be the K50 or the M50, and dates from roughly the decade 1975 to 1985. Good lenses in those days that are well worth the effort to use.

[pathdoc]

Instructions:

Using Manual Lenses (M42 Screwmount, M , K) on Pentax DSLRs F-- - PentaxForums.com

[Adam]

I have an old Asashi Pentax 49mm 1.4 lens and I tried to use it on
the K-5iis I just got, but the camera wont do anything. The display
keeps flashing "F--" and neither the shutter button nor flash respond.
I've set the camera to manual focus and manual exposure. Is it even possible
to use an old manyal lens like this?

Here's the most complete guide:

How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com

[jeryst]

That worked. Thank you.

[heinamj]

Enjoy your old glass... Once you get used to the stopped down metering (which is basically like exposure lock), it's great having shake reduction with your old lenses.

[jddwoods]

Here's the most complete guide:

How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com

This is a really good guide and it got me using my M 50mm f1.7 on my K-3. I am interested in possible ways of making the manual usage a little more automated. Has anyone tried the following:
1. Using aperture priority mode with the lens set at maximum aperture. I realize this limitation that only max aperture can be used, but that is when I would use this fast lens anyway. Will the camera set shutter speed automatically?
2. Using catch in focus so the camera will fire the shot automatically when the subject comes into focus while manual focusing?
I really like the M lens but have gotten too used to automation to go back to fully manual operation except for photography of still subjects.

[sibyrnes]

This is a really good guide and it got me using my M 50mm f1.7 on my K-3. I am interested in possible ways of making the manual usage a little more automated. Has anyone tried the following:
1. Using aperture priority mode with the lens set at maximum aperture. I realize this limitation that only max aperture can be used, but that is when I would use this fast lens anyway. Will the camera set shutter speed automatically?
2. Using catch in focus so the camera will fire the shot automatically when the subject comes into focus while manual focusing?
I really like the M lens but have gotten too used to automation to go back to fully manual operation except for photography of still subjects.

1. You already have aperture priority at all f stops - it's called the green button. When you press the green button the proper shutter speed is automatically selected.


2. I know that focus conformation works with manual lens but I have never used catch in focus - why not just try it?

[Adam]

1. Using aperture priority mode with the lens set at maximum aperture. I realize this limitation that only max aperture can be used, but that is when I would use this fast lens anyway. Will the camera set shutter speed automatically?

1. You already have aperture priority at all f stops - it's called the green button. When you press the green button the proper shutter speed is automatically selected.

But to answer your question directly, if you keep the lens wide open, then yes, you can leave the mode dial in Av.

2. Using catch in focus so the camera will fire the shot automatically when the subject comes into focus while manual focusing?

Should work fine.

Catch-in-Focus Tutorial - Articles and Tips | PentaxForums.com

[sibyrnes]

But to answer your question directly, if you keep the lens wide open, then yes, you can leave the mode dial in Av.

But why? Why would anyone purposely limit themselves to shooting wide open?

[Adam]

But why? Why would anyone purposely limit themselves to shooting wide open?

So they don't have to push the green button before every exposure. Obviously very restrictive, but that's the question that was asked

[jddwoods]

But why? Why would anyone purposely limit themselves to shooting wide open?

Because I bought that lens only for its f1.7 aperture. If I am out shooting in daylight or any situation where I do not need maximum aperture of f 1.7 I will have either the HD DA 40 Limited or DA 16-85 on my camera. For $10 at a charity sale, it was worth it since I wanted an inexpensive fast lens for dedicated low light situations.

---------- Post added 11-12-17 at 08:38 PM ----------

So they don't have to push the green button before every exposure. Obviously very restrictive, but that's the question that was asked

Thanks Adam you answered it perfectly.