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10-17-2013, 08:58 PM   #1
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Anyone thinking of their M42 lenses here?

For those who are getting a K-3....

I know a lot of you have them! Those M42 lenses are quietly and patiently waiting in your bag or on your shelf to be mounted on your K-3. When you can you please tell us how well the lenses meter and render colors? Is 24MP enough to make these lenses look bad? I kind of doubt it but I wanna see pics!!

10-17-2013, 09:04 PM - 1 Like   #2
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QuoteOriginally posted by 6BQ5 Quote
For those who are getting a K-3....

I know a lot of you have them! Those M42 lenses are quietly and patiently waiting in your bag or on your shelf to be mounted on your K-3. When you can you please tell us how well the lenses meter and render colors? Is 24MP enough to make these lenses look bad? I kind of doubt it but I wanna see pics!!
Any particular reason why m42 lenses work better on the K-3? what about the K/M or A lenses? I will be checking the K-3 out when I go to Japan late this year... plan to add the K-5IIs but tempted to get K-3 instead....
10-18-2013, 12:15 PM   #3
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Since my 55mm f1.8 SMC lens is awesome on my K5 and K5-IIs, i think it should be even better on a K3. I like having the lens on my K5. It's like finding a long lost friend.
10-18-2013, 04:18 PM   #4
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Depends on the lens, I think some will be quite spectacular with the added resolution! But some might look worse than on the 16MP we have available atm
Some might be very useful for video, with quiet preset aperture ring and no AF, dreamy look but good detail.. and the K-3 apparently is a video machine

10-18-2013, 04:58 PM   #5
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In M42 I have a smooth 80-200 zoom, a 135mm 2.8, and a 50mm 4 macro. I will be curious about all of these on the K-3. Mostly the 135 though. It's nice on the K-01/K-5, so it'll make a good comparison IMO.
10-19-2013, 01:05 PM   #6
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My K-30 goes kind of nuts with manual lenses. The metering is very non-linear and I use my exposure compensation feature quite a bit at times. Will the K-3 be more linear?
10-19-2013, 03:49 PM   #7
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QuoteOriginally posted by 6BQ5 Quote
My K-30 goes kind of nuts with manual lenses. The metering is very non-linear and I use my exposure compensation feature quite a bit at times. Will the K-3 be more linear?
This is with stop-down metering?
10-19-2013, 04:29 PM   #8
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QuoteOriginally posted by 6BQ5 Quote
My K-30 goes kind of nuts with manual lenses. The metering is very non-linear and I use my exposure compensation feature quite a bit at times. Will the K-3 be more linear?
I doubt it. It is really the matte screen that is non linear. And since the exposure is measured from there, you have a problem. The non linear function i depending on the aperture, so the camera can compensate for it with modern lenses, but with old ones the camera do not know what aperture is being used, thus the measurement can not be corrected.

10-19-2013, 08:36 PM   #9
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QuoteOriginally posted by 6BQ5 Quote
My K-30 goes kind of nuts with manual lenses. The metering is very non-linear and I use my exposure compensation feature quite a bit at times. Will the K-3 be more linear?
Didn't we have this discussion a few times before? Use M mode, not Av mode, with your lenses lacking the "A" contacts all will be better.


Steve
10-20-2013, 02:00 AM   #10
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QuoteOriginally posted by stevebrot Quote
Didn't we have this discussion a few times before? Use M mode, not Av mode, with your lenses lacking the "A" contacts all will be better.


Steve
It does not change anything, the behaviour is still non linear, and the camera can not compensate. How big the problem is depends on what lens you are using, and what aperture you are shooting at. This is why some people see very little problem, while others have huge issues. Using M helps only in the perspective that when you have found a setting that works, you use that until light conditions change or you change the apertue or lens. This is one of the situations I wish there would be a way to lock the settings as it is so easy to accidentally move one of the wheels.

/PA
10-20-2013, 12:09 PM   #11
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QuoteOriginally posted by quarc Quote
It does not change anything, the behaviour is still non linear, and the camera can not compensate. How big the problem is depends on what lens you are using, and what aperture you are shooting at. This is why some people see very little problem, while others have huge issues. Using M helps only in the perspective that when you have found a setting that works, you use that until light conditions change or you change the apertue or lens. This is one of the situations I wish there would be a way to lock the settings as it is so easy to accidentally move one of the wheels.

/PA
My experience* with the newer generation bodies (K-7 on) is that M-mode stop-down exposure is pretty decent and linear within the sensitivity range for the meter**. Av mode with M42 lenses essentially sucks however, for the reasons you described. That is why modes other than M are annotated in the user manual as being likely to result in exposure error.

Anyone interested in testing the linearity of their camera's stop-down metering can PM me for detailed instructions.


Steve

*Not as owner, just as in-shop evaluation with my own flash card and lenses.

**Use of a narrow apertures in dim light for stop-down metering can easily overreach the linear range of the meter. This is true regardless of set ISO. In the old days the user manual would have a table indicating the limits, but now the user has to calculate it out manually.

Example: The K30 has a meter sensitivity range of 0-22 EV(100). A subject indicating an exposure of 1/15s @ f/8 for ISO 100 (e.g. dusk) would provide only -1 EV(100) to the meter at f/8 using stopped-down metering and would be outside the built-in meter's linear range.

Last edited by stevebrot; 10-20-2013 at 12:58 PM.
10-20-2013, 05:39 PM   #12
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Yes, but stop down metering is still not working properly on the K-30 (and yes, I know what the heck I'm doing!)

QuoteOriginally posted by Kozlok Quote
I've been shooting with my Super Takumar 55/2 as my single in July. First time using an M42 on my K-30, but used them quite a bit on my KX (The Tak and a Helios).

When I place my K-30 in M, the green button metering seems to default to whatever the sunny 16 shutter speed would be. The button is set on Tv Shift, and it does change the shutter speed, but no matter where I set my aperture on the lens, and no matter what the light, the shutter speed chosen is the inverse of the ISO setting (i.e. the correct shutter speed for sunny 16). If I go to Live View, the green button meters correctly and chooses the correct shutter speed. If I put an M lens on, it likewise meters correctly. If I switch to Av mode, it constantly meters (correctly).

I'm pretty sure I used the green button to meter on my KX with success, and I recall that it was a more reliable way to control my metering process, since I could use it to lock exposure on a specific point. It's possible, and perhaps more likely, that I'm crazy and it never worked that way, but man, I really think it did.

Is there a menu setting I missed somewhere?
And I confirmed with Pentax that all K-30's, at least with the latest firmware are behaving the same:

QuoteOriginally posted by Kozlok Quote
I finally successfully got Pentax to actually pay attention to my problem, instead of telling me to enable aperture ring in the menu, and their response is quoted below:

Dear Keith, Thank you for contacting RICOH. I sent your email to our technical support specialist in the corporate office and he tested the K-30 there and got the same results that you reported. It appears there is not a specific problem in your K-30. We do not have any information from Japan about what, if any firmware updates they have planned for the camera. If you are in need of further assistance, please respond to this email or call our technical support center at 800-877-0155. Sincerely, Randall S. RICOH IMAGING AMERICAS CORPORATION
10-21-2013, 12:03 AM   #13
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QuoteOriginally posted by Kozlok Quote
Yes, but stop down metering is still not working properly on the K-30 (and yes, I know what the heck I'm doing!)



And I confirmed with Pentax that all K-30's, at least with the latest firmware are behaving the same:
As i said above, as long as the camera does not know what lens is mounted it can not compensate fir the non linearity, it has to be done manually. I do not think pentax has published what they assume, maybe 2.8? Those who claim it work just happen to use lenses close to those assumptioms
10-21-2013, 04:37 PM   #14
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Kozlok
IIRC, this problem was limited to the Tv shift case, was it not?

quarc
Different issue.

Do a controlled exposure series using a gray card as the exposure target in bright constant light (say 10+ EV(100) and post the results (shutter speed by f/stop, not photos) on a new thread. If you have the software, you should be able to put it into Excel and generate appropriate graphs which should produce a compelling case.

There have been a couple of threads on this site with complaints regarding metering, but in each case, the information has been essentially anecdotal. I.e. "Sucks when I try xxxx", "severe over/under (take your pick) exposure when xxxx", "Everyone knows (choose your model) sucks for (choose your exposure mode). And then there are the solutions..."Do xxxxx to your lens", "cut off the aperture pin", etc..

I don't want to be mean, but I would really like to see the numbers. I suppose I could go into town and do an exposure series in the store with the cameras they have on the shelf, but I am not the one making claims that the feature sucks. You (quarc) have multiple bodies (K-5 IIs, K-5, K-7, K20D, K10D, and *ist DS according to your member profile) in your possession and are uniquely qualified to do a comprehensive comparison. I have only tested the K-7 and lost the data in a harddrive crash a few years back.

FWIW, you (quarc) are correct in regards to the correction factors being applied for the case where the camera controls the aperture. Where you are lacking is that Pentax changed the behavior in M mode with the K-7 such that it applies a different set of factors when the A-contacts are not detected*. This corrected most of the stop-down issues and was big news at the time, enough so that I almost upgraded just to get that feature. The difference is easily demonstrated if you have a Pentax-A or FA lens and run an exposure series both on and off the A position (body controlled vs. aperture ring controlled).

The modified M mode behavior has been incorporated into every body made since the K-7...at least they all have the same verbiage in the user manual.


Steve

*A-series and newer lenses are negative for the A-contact when off the A position on the aperture ring. K-series, M-series, and M42 glass are always detected as negative for the A-contact.

Last edited by stevebrot; 10-21-2013 at 04:42 PM.
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