[roosm]

Hi,

I or rather my girlfriend has a Pentax K5IIs. I bought her a new lens which I am planning on giving her this christmas and was just going to try it out so that it works alright before I gave it to her.
So I tried this lense once I got it yesterday and I couldn't really figure out the correct way of using it.

The lens is a Auto Chinon 50 mm f1.7 manual focus / manual aperture lens.
I switched the camera to Manual Focus and Manual Mode and tried to shoot some pictures.
First, of course, I had the error "F--" on the display. Some quick googling I found that I needed to permit aperture ring in the menu.
Then I could finally at least get the camera to operate. Though the pictures were very close to black.

I then figured out the "green button" to get the camera to set shutter-time (or something).
This got me to a point where I can take pictures with the camera. Though they are still dark.

If I set the lens to f1.7 on the aperture ring it is still considerably darker then her "standard" lens a Tamron 18-250 f3.5-6.3 lens.
This doesn't really seem right. I bought the lens after her father had displayed his Pentax 50 mm f.14 lens (though with auto-aperture) which gave fantastic bright pictures.

When you turn the camera on with this Auto Chinon lens attached and in manual mode the first thing it says is that I should select aperture setting.
I then get a range of values to choose from. Lowest being 8 and highest somewhere around 300. Can't figure out what this setting does.

Any help would be greatly appreciated.

Oh, and i don't know anything about the ISO-setting or any other settings that might be going on in the camera and screwing things up so I there is anything that I should check as far as those are concerned please let me know.

Thanks,
Mike

[Adam]

The manual lens instructions are found here:
https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...k-x-k-7-a.html

If you follow the bullet points step by step, your exposure should be correct To meter, you can use the DoF preview button instead of the green button on the K-5 IIs.

If that doesn't help, it's possible that something's wrong with your lens. Does the viewfinder appear darker than it should be?

[roosm]

I can't say I noticed anything like the viewfinder being darker, I will check once I get a chance.

Could the ISO settings be different between "m" mode and "user" mode making one picture appear brighter on the LCD than the other simply because it was another ISO-setting?

As I said, I am a beginner. I know how to shoot pictures with the camera but my girlfriend makes all adjustments.
Just want to make sure the lens works as it should before we end up getting to christmas and discover the lens is something wrong with.

I am not sure the picture is too dark, it is just darker then a picture taken with the tamron lens.

Picture 1: Auto chinon, Manual Focus, Manual Mode, f1.7 aperture ring setting, "green button", shoot.
Picture 2: Tamron, Auto Focus, User Mode, about the same focal length/zoom, shoot.

Both pictures are of the same object. The Auto Chinon one turned out darker.

Could this be because of the "User" mode settings.

Should I try both lenses in "manual" mode using the green button, or isn't that possible with the tamron?

Thank you,
Mike

[Not a Number]

Make sure your ISO is not set to "Auto". The green button should be set to Tv Shift for M and TAv mode (the default on most Pentax bodies is Program line). DOF preview should be set to optical in order to meter as Adam mentioned above.

Yes, the ISO could be set differently in the user mode.

Check the lens to make sure the aperture stop down lever hasn't been chopped off or moves smoothly. If a Canon user got their hands on the lens prior to you the lever often gets amputated.

FYI:
Chinon Auto MC 50mm f/1.7 Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

[Oldbayrunner]

The green button should be set to Tv Shift for M and TAv mode (the default on most Pentax bodies is Program line).

This step isn't needed for this camera, The set lens focal length for SR comes up even with P-line set in M and Tav with everything else functioning correctly with the changes to allow aperture and optical preview.

[othar]

When you turn the camera on with this Auto Chinon lens attached and in manual mode the first thing it says is that I should select aperture setting. I then get a range of values to choose from. Lowest being 8 and highest somewhere around 300. Can't figure out what this setting does.

when you use old lenses that don't transmit their focal length (for example K, M or A lenses) to the camera you have to enter the focal length manually when you start the camera. this is important for the shake reduction of the camera to work properly and also to have the correct value shown in the exif data.
this value has no influence on the exposure of the pictures you take.

[aleonx3]

This got me to a point where I can take pictures with the camera. Though they are still dark.

If I set the lens to f1.7 on the aperture ring it is still considerably darker then her "standard" lens a Tamron 18-250 f3.5-6.3 lens.
e

When you say the picture taken with the Auto Chinon lens is considerably darker than the one taken with the Tamron. Since the one taken with Chinon MF lens is taken in M mode, the other one taken with Tamron lens is in likely taken in P mode, the reason it is darker is likely because of either 'metering' option selected in each case or the ISO setting. Keeping in mind that Pentax M mode (unlike Nikon) is all manual setting including ISO.

If none of the above applies, I hope you sorted it out why it is darker.

[roosm]

When you say the picture taken with the Auto Chinon lens is considerably darker than the one taken with the Tamron. Since the one taken with Chinon MF lens is taken in M mode, the other one taken with Tamron lens is in likely taken in P mode, the reason it is darker is likely because of either 'metering' option selected in each case or the ISO setting. Keeping in mind that Pentax M mode (unlike Nikon) is all manual setting including ISO.

If none of the above applies, I hope you sorted it out why it is darker.

The Tamron shot was taken in "user" mode set on the dial. Could def be ISO setting.
What do you mean with "metering" option?

Thanks for your input!

I'll check when I get a chance.

Mike

[ChristianRock]

Metering can be set to spot, center-weighted or matrix.

If it is set to spot and you press the green button pointing it toward something white, it will meter very darkly. If you point it at something black, it will meter too bright.

I personally prefer matrix metering, that way I am usually sure I'm in the ballpark, and since I shoot raw I can always recover highlights or boost shadows if I need to, but they won't be too far off. And in manual, I always check the histogram every once in a while and adapt accordingly. After all, it's manual mode - you're supposed to make manual adjustments

[Oldbayrunner]

Using DOF Optical Preview will let you know the how the exposure is metering in the view finder.

[stevebrot]

Metering can be set to spot, center-weighted or matrix.

Not with lenses lacking the A contacts. For those matrix in unavailable.


Steve

---------- Post added 12-04-14 at 01:06 PM ----------

Could the ISO settings be different between "m" mode and "user" mode making one picture appear brighter on the LCD than the other simply because it was another ISO-setting?

In a word...yes.

Stop-down (green button) metering on the K-5 (and most other Pentax dSLR) uses a different set of exposure algorithms than open-aperture metering on the same camera with lenses having the A contacts. The two systems often indicate different exposure values (EV) for the same scene, though they are usually within a stop of each other. If the difference is greater, there are two common causes:

• The camera is in spot meter mode with the center metering area pointed at something lighter than the rest of the frame
• There amount of light reaching the light sensors is below the linear range for the meter.

The second point is fairly likely, can happen in moderately dim light, at moderate apertures, at ANY ISO, and is difficult to explain. The short explanation is that stopping down the lens (green button) decreases the amount of light available to the meter and if that falls below -3 EV, the meter will indicate higher shutter speed than is appropriate.


Steve

[roosm]

Sorry for the late response. You have all been very helpful and I have finally found the time and oppurtunity (a time when the girlfriend isn't around) to test the lens again.

I first started off taking som pictures in USER mode with the tamron. It jumped back and forth between 800 and 1600 ISO in the lighting we hade indoors at that time.
I then attached the Auto Chinon and switched to M mode which was set at 100 ISO.
This could obviously make some difference.

I took a couple of pictures. Switched to the Tamron with manual on and took a few pictures of the same objects. Still think the tamron pictures are brighter but only slightly so.
Though the shutter speed is longer for the tamron so it might be the metering.

If I on the other hand set the auto chinon to f2.8 meter and then open it up to f1.7 and shoot som pictures it is really bright.

I found some video on youtube where someone used an old manual lens on a Pentax K5IIs. When he pressed the green button the display on the camera showed something like f2.8.
I can't get this to happen when using the auto chinon. It just keeps showing f--.
Is this normal?

Thanks,
Mike

[Not a Number]

I found some video on youtube where someone used an old manual lens on a Pentax K5IIs. When he pressed the green button the display on the camera showed something like f2.8.
I can't get this to happen when using the auto chinon. It just keeps showing f--.

The only time a manual lens will show the f-stop in the viewfinder is if it is an "A" type lens or has been modified to simulate an "A" lens. These lenses have electrical contacts and the "A" pin must be connected/shorted by setting the lens to "A" or by physically shorting the pin on the camera side by other means.

[roosm]

Ah, ok. So it doesn't show this number but still works as it should.

You have all really been great. Thanks for all the help!

Mike

[emalvick]

I think that to truly compare you have to make sure that

1. You use the same mode for both lenses. This way they will both have the same ISO (if you aren't able to set it).

2. Use the same settings as much as possible. In other words, set both cameras to use the same f-stop, shutter speed, and focal length as well as you can. With the zoom lens, the focal length might be challenging since it is an 18-250 mm. If you don't hit 50 mm exactly, then the field of view would be a bit different and thus the exposure could end up slightly different.

If you are in other modes, you end up having the possibility that other ISO settings and exposure compensation might be set already. With M-Mode you have to set exposure compensation yourself by visually setting the exposure so that it slightly over- or under-exposes to your liking. Thus the suggestions to just test everything in M-mode if you're going to compare.