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02-12-2010, 10:13 PM   #16
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I never have inconsistent exposure with my K200D either...before or after I got my jinfinance split prism screen. I do have to wind the exposure compensation upto +1.7 for any M42 lens though

02-12-2010, 10:32 PM   #17
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QuoteQuote:
Steve Beswick: If you are looking for a reasonably fast (f2.8 or maybe faster) you might want to consider polishing up your hacking skills and nodding a medium format lens to fit. That's what I'm working on, in my case it's the Mamiya 80mm f1.9.
Now there is an interesting pairing. How much "hacking" are you talking. MF Pentax lenses easily mate up to their smaller brethren, DSLR bodies, so I'm curious what you are working on? Are you talking mount re-working?
02-12-2010, 10:35 PM   #18
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Lowell Goudge: I presently use a JinFinance split image in the K10D and while spot metering is worse (due to the darkening of the split image) average metering is reduced.
Nice to hear your findings with the screen. My Jinfinance screen added stability to my metering in the K20 as well, not to mention the boon it provides to my macro work.
02-12-2010, 10:54 PM   #19
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j9 issue

I have a J9 for LST. I have used it on my Canon 7. After cleaning and shimming I have been very impressed with the OOF, color saturation/contrast, and resolution. I like my Canon 85/2, 85/1.8, 85/1.2, and tak 85/1.8 more. It has more saturation and contrast than the Canon's, closer to to the tak.

I do not have any scanned images from that lens.

The problem with the LST version, is that as the lens is stopped down, light reflected off of the back of the iris causes a bright spot in the center of the frame. I've tried coloring the leaves with a sharpie pen, but it rubs off. I don't know if this problem exists with the M42 version, but I don't want to try.

02-12-2010, 11:57 PM   #20
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the Helios would probably be the best lens in terms of IQ, but the Polar/Samyang/Rokinon ain't that bad nor clearly loses in terms of IQ (resolution), as long as it's in the wider open aperture end (f1.4 to f4). it may run 2nd or 3rd fiddle to the Helios, but that is enough of a big accomplishment for such a 3rd party lens. I also disagree that the Rokinon 85/1.4 only has an average good or boring bokeh. in fact, it can produce a smooth and creamy bokeh. I dunno why or where some people got that idea of very average bokeh, eventhough they got the lens. because it clearly isn't as average nor even as ugly as that of other fast lenses that I had seen. also not to mention that I prefer it having an auto-aperture which is really helpful and useful in metering. the Helios though has better contrast and sharpness but the Samyang/Rokinon has a well-controlled CA. so it's more of a pros and cons thing. ultimately these are very good alternatives to those who can't afford to buy the FA77. otherwise, there's nothing wrong with shooting for the stars. if you got the money to spend, the FA77 is the way to go. AF, fast aperture, IQ and portability are it's main strength. so it's worth the investment.

Last edited by Pentaxor; 02-13-2010 at 02:59 AM.
02-13-2010, 02:53 AM   #21
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Being as it's a hobby, I really was shooting for a cheaper alternative TO the FA77.
02-13-2010, 06:34 AM   #22
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QuoteOriginally posted by Marc Sabatella Quote
I ran a complete series of tests with my M135/3.5 on my K200D, and found exposures completely consistent (within a quarter stop) at all apertures. So while it might be the same screen (wasn't aware of that - are you sure that's true?) something about the light path - whether the pentamirror or whatever - seems to render the K200D immune to this.
I thnk steve mis spoke (mis typed)

the KXXD, specifically the K10 and K20 are where the problem really is.

I think it is cameras with screens with "80" in the model.

the *istD is an LL60 screen and the K10D meters perfectly when you put this screen into it.

I did a survey at one point to work out the screen naming, and it seems the letters denote the camera and the numbers the surface type of the screen.
02-13-2010, 10:09 AM   #23
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Photozone did a review of the Samyang: Samyang 85mm f/1.4 Aspherical (full format) - Review / Test Report . Seems to be a good performer and would certainly be way easier to use than Jupiter 9 with the pre-set aperture. Good bokeh too. That said, the Jupiter does have its charm.

02-14-2010, 01:40 AM   #24
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QuoteOriginally posted by Lowell Goudge Quote
I thnk steve mis spoke (mis typed)

the KXXD, specifically the K10 and K20 are where the problem really is.

I think it is cameras with screens with "80" in the model.

the *istD is an LL60 screen and the K10D meters perfectly when you put this screen into it.

I did a survey at one point to work out the screen naming, and it seems the letters denote the camera and the numbers the surface type of the screen.
Mis-speak? Me? Me NEVER WRONG!!!

My understanding is that the KxxD and KxxxD all shipped with the LF-80 screen, though I have been wrong before. The K10D and K20D for sure. Stop-down metering with the K10D and K20D is uniformly poor at apertures wider than f/4. The KxxxD penta-mirror models situation is somewhat different due a different metering and exposure processing system. Simply put, some lenses work fine on those cameras and others don't. The camera manual basically says that your mileage may vary. It is enough to say that the KxxxD models are less problematic than their pentaprism brothers.

Lowell has had good luck using the LL-60 screen and has reported his findings before. I seem to remember reports of sub-par metering using the LL-60 on KxxD cameras for open-aperture metering, but could not find a reference. I have not used the LL-60 screen, but have done extensive exposure studies with both versions of the Katzeye product that replace the LF-80. The Katzeye screen's behavior is essentially the same as for the LF-80 except for spot metering. Translation...changing to that brand of screen did not help.

The viewfinder on the K-7 is a complete redesign. I did a quick exposure test with the Pentax-M 50/1.7 on the K-7 when the K-7 road show was in town. Exposures were essentially correct and linear at all apertures in relative bright light, though I would still expect a drop in sensitivity in dim light at narrow apertures. (The meter is not linear below 0 Ev (ISO 100) at the sensor...no light...)

Steve

(End of thread hijack...Yep the Samyang is a good value and yes the J-9 has its charms...)
02-14-2010, 02:54 AM   #25
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QuoteOriginally posted by Jewelltrail Quote
Now there is an interesting pairing. How much "hacking" are you talking. MF Pentax lenses easily mate up to their smaller brethren, DSLR bodies, so I'm curious what you are working on? Are you talking mount re-working?
No, noting crazy. Really all I'm doing is making a crude mount adapter using a Mamiya 645 rear lens cap and a k mount body cap. the Mamiya has a roughly 18mm longer registration distance than the K mount, so it's really not difficult at all. There is an adapter you can buy ready-made on eBay, but it is over $100, and I'm either cheap or poor depending on who you ask. The biggest issue I'm running into is that there is still space left after using the caps and I'm not sure how I'm going to fill the space and secure the caps to each other.

I was originally going to just stick with the Mamiya 80mm 2.8 and save up to get the Rokinon. Then one day I was digging through KEH's site and I found it completely by accident - 80mm Mamiya Sekor C f1.9 ugly condition - $63! Let me tell you, they could have marked it as EX and I don't think anyone would have complained. It was like Christmas in January! To stick with the vintage look I put an old metal slip on lens cap on it. (psst- don't tell anyone, but it's a Pentax cap. I know, it's a sin. but I needed a lens cap and the center pinch plastic affair didn't look right.) Is it getting warmer in here? My feet feel really hot!
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