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05-27-2016, 09:41 PM   #46
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QuoteOriginally posted by asharpe Quote
As I have said before, it is likely the internal calculations that Pentax is doing that produce faulty readings; they assume that they have all the data about the lens, and with M42 they don't. So, instead of falling back to simply metering the light that comes through the lens, they alter that metering with a faulty algorithm.
You keep saying this, do you have some source that indicates how this is done? Seems counter intuitive. Why would they be making any assumptions about a lens that cannot be detected?

05-27-2016, 09:48 PM   #47
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QuoteOriginally posted by howieb101 Quote
Is manual exposure that hard with manual lenses? A test exposure using green mode then adjust to taste. This isn't film after all. If you are fussy with exposure, manual is always best.
Yes, manual exposure with manual lenses is hard. In fact, digital is worse than film; it is closer to slide film for the dynamic range. Of course I can take multiple photos and chimp. But I don't like blown highlights, and to really do it right, you need a spotmeter and some judgement about whether to put the highlights on 6 or 7. I'd like to use my M42 lenses not only for slow, careful, still life photography (or in my case, cacti), but I can't because of the exposure problems. I have three of the best light meters ever made, a Gossen Luna Pro-F, a Sekonic L-398A, and a Pentax Digital Spotmeter. They are all large, but work well. But I also have a modern, excellent, combination spot, center and multisegment meter in my camera, so I'd like to use it, and be able to trust it as much as I do these other meters.

---------- Post added May 27th, 2016 at 10:10 PM ----------

QuoteOriginally posted by jatrax Quote
You keep saying this, do you have some source that indicates how this is done? Seems counter intuitive. Why would they be making any assumptions about a lens that cannot be detected?
A very good question. I don't know. However, a meter is a meter is a meter. Why would metering behave this way, being dependent on the aperture of the lens, when it simply needs to report an exposure that produces middle gray? I'm making an assumption, of course, but really, it's just a hypothesis.
05-27-2016, 11:21 PM   #48
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QuoteOriginally posted by jatrax Quote
Got it, thank you. That actually makes a lot of sense, and might explain the OP's issue as well as the inconsistent metering I have seen with M42.
With older K mounts, I wouldn't be surprised if metering inconsistency is somewhat caused by the lens being a bit slow to hit the aperture being metered. The camera cycles the aperture control lever pretty fast. If the lens lags a bit, the lens will not be at the shooting aperture when metering is done. There is also the matter of aperture inconsistency to consider. These older lenses are not necessarily working as they did when they were new, and the aperture may be off from shot to shot by a significant amount.
I'm pretty sure that in green button manual, there is no fancy calculations going on. You have basic center weighted metering with no intervention from the computer beyond dumb light measurement.
05-28-2016, 08:24 AM   #49
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QuoteOriginally posted by Wheatfield Quote
I'm pretty sure that in green button manual, there is no fancy calculations going on. You have basic center weighted metering with no intervention from the computer beyond dumb light measurement.
That is what I assumed as well. But that leaves M42 inconsistent exposure a mystery.

05-29-2016, 09:22 AM   #50
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I think that the centre-weighted metering may be using a smaller area of measurement than previous cameras. Not as small as spot, but close.

If I want a correct exposure that won't blow the highlights with an M42 or K/M lens, I now find myself metering for a section of the scene that contains at least some of the highlight information I want to keep, hitting the AE lock button, than recomposing and focusing for the composition I intend for. If some shadow areas are underexposed I'll pull them up from the RAW file.

Didn't really have to use this method on the K-5, at least not as often as I do it now.
05-29-2016, 02:29 PM   #51
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QuoteOriginally posted by Mock Quote
I think that the centre-weighted metering may be using a smaller area of measurement than previous cameras. Not as small as spot, but close
That's a very interesting observation. I've also always wondered why they have to turn off multi segment metering for manual lenses. Light is still light, and it doesn't make any sense that the meter wouldn't be able to average properly over the whole scene regardless of the lens attached.
05-30-2016, 09:08 PM   #52
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QuoteOriginally posted by asharpe Quote
That's a very interesting observation. I've also always wondered why they have to turn off multi segment metering for manual lenses. Light is still light, and it doesn't make any sense that the meter wouldn't be able to average properly over the whole scene regardless of the lens attached.
Sometimes these things are done to encourage the sale of new lenses.
05-30-2016, 09:45 PM   #53
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QuoteOriginally posted by Wheatfield Quote
Sometimes these things are done to encourage the sale of new lenses.
If this is the case, then it's a real pity that a company that knows it has a strong old glass pedigree would do this. It's a major differentiator for Pentax, and the bodies they produce seem to spurn the manual lens user at (nearly) every turn, be it the crippled mount, the incorrect metering, and the limiting to center weight. The only thing going for them is that they haven't changed the mount, except for crippling it. This forum is a very large population of Pentax users, and a lot of us use manual lenses, if the signatures are any indication. I'm sure someone has asked them in the past why they they are so determined to ignore the manual lens users, but I can't find any such interview.

05-30-2016, 10:23 PM   #54
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Just a thought: are you using the stock focusing screen? And not letting light in through the viewfinder?
05-31-2016, 03:15 AM   #55
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QuoteOriginally posted by John Shriver Quote
I upgraded a lot of my Pentax-M lenses to the Pentax-A equivalents when I realized that the "full frame" wasn't going to have an aperture sensor lever. Still hoping that I can put in a focusing screen that will make manual focus work well, as there are a lot of interesting Pentax-A lenses that don't have Pentax-FA equivalents.

I'm like monochrome at this point, close to 50 K-mount lenses, but lots of redundancy.
I don't think that the K1 is able to change screens but the current screen is wonderful for legacy lenses.
05-31-2016, 03:20 AM   #56
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QuoteOriginally posted by felixkh Quote
I don't think that the K1 is able to change screens but the current screen is wonderful for legacy lenses.
I found out the K1 focusing screen is not interchangeable - bummer
05-31-2016, 09:31 AM   #57
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QuoteOriginally posted by Wild Mark Quote
I found out the K1 focusing screen is not interchangeable - bummer
Indeed. That's a real surprise to me. However, might it be because the K1 has so much more going on in the viewfinder now? So much now, that there is a dark and blurry image if there is no battery?

---------- Post added May 31st, 2016 at 09:36 AM ----------

QuoteOriginally posted by narual Quote
Just a thought: are you using the stock focusing screen? And not letting light in through the viewfinder?
No, and yes. I've been using Katzeye screens for a long time. And I always cover the viewfinder, whether with my eye, or my hand. But if it was the viewfinder, I would expect errors from all lenses, not just ones that didn't short out the contacts. It is a well-known fact that if you do short out the contacts on the mount, the lenses meter more accurately. That tells me that there is some electronic trickery going on that shouldn't need to be going on with manual lenses.
05-31-2016, 10:57 AM   #58
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QuoteOriginally posted by asharpe Quote
However, might it be because the K1 has so much more going on in the viewfinder now? So much now, that there is a dark and blurry image if there is no battery?
Best guesses so far have to do with the LCD overlay, which it is thought might be bonded to the focusing screen, or otherwise not suitable for user servicing.
05-31-2016, 09:02 PM   #59
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QuoteOriginally posted by asharpe Quote
If this is the case, then it's a real pity that a company that knows it has a strong old glass pedigree would do this. It's a major differentiator for Pentax, and the bodies they produce seem to spurn the manual lens user at (nearly) every turn, be it the crippled mount, the incorrect metering, and the limiting to center weight. The only thing going for them is that they haven't changed the mount, except for crippling it. This forum is a very large population of Pentax users, and a lot of us use manual lenses, if the signatures are any indication. I'm sure someone has asked them in the past why they they are so determined to ignore the manual lens users, but I can't find any such interview.
From a meter pattern perspective, they haven't changed anything. Pattern metering has never been usable with pre A series lenses. I didn't think removing the aperture simulator lever was a good move, and I would like to see it put back into at least one body. Perhaps if they do something higher end than the K1.
One can always dream.
Consider yourself lucky that your collection is K mount rather than FD mount. I know I do.

---------- Post added 05-31-16 at 10:04 PM ----------

QuoteOriginally posted by felixkh Quote
I don't think that the K1 is able to change screens but the current screen is wonderful for legacy lenses.
The screen is really good and the in focus indicators are excellent.
05-31-2016, 09:19 PM   #60
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QuoteOriginally posted by Wheatfield Quote
From a meter pattern perspective, they haven't changed anything. Pattern metering has never been usable with pre A series lenses. I didn't think removing the aperture simulator lever was a good move, and I would like to see it put back into at least one body.
Right. I don't understand that, though. Why can't they simply do pattern metering with stopped down aperture? I guess you'd have to tell it somehow that you are stopped down, and I think that that is precisely what metering with the green button is supposed to do. So, why can't they do full segment metering with the green button? I don't want to sound ungrateful, and yes, I am glad this isn't an FD mount. But to make enough of a statement to keep the mount (largely) intact, you would think that they, of all companies, would understand that the small details like this would help a lot.
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