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12-05-2015, 07:55 AM - 2 Likes   #2881
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Shot my first roll of film last week (ME Super with Ultramax 400).

01BB:







40A:








Last edited by tonezime; 12-05-2015 at 08:25 AM.
12-05-2015, 11:30 PM   #2882
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QuoteOriginally posted by Jean Poitiers Quote
Agreed ... thanks for the repair info. J
Ditto!

Btw, I got a Nikon mount bundled in with a recent 60-300mm Adaptall zoom lens purchase. I had a test done with the Tamron 60B on a friend's Nikon D750. A colleague of mine saw the result and took the same picure with his Canon 5D MkIII and Canon 100-400mm zoom @300mm focal length setting. Results below. Other than cropping and exporting to jpeg, no other post processing done.

Nikon 750D & Tamron (top) and Canon 100-400 (bottom). The Canon shot was made 2 days later and with an hour's difference between the time of day.
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12-09-2015, 10:05 AM   #2883
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Sp 26a

This has been a hole in my collection for a long time but now filled. A decent example, some external wear, ding or two, optically good.

First pics have impressed, seems to have strong contrast. And the detail (lichen, brickwork) in the 100% crop (f8, 210mm) is good. OtC (well just levels adjusted in faststone) jpg, samsung NX20.
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Last edited by marcusBMG; 12-09-2015 at 10:34 AM.
12-11-2015, 02:32 PM - 2 Likes   #2884
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QuoteOriginally posted by stevebrot Quote
Here are a few from this last weekend's short excursion to Yosemite...






Both with the Tamron 70-150/3.5 (20A) mounted with the K10D.


Steve
Due to a little shuffling on Flickr, one of the photos in the previous post was no longer visible. Fortunately, I am a little compulsive and offer to you again, Bridal Veil Falls in Yosemite Valley taken with the Tamron 70-150/3.5 (20A)




Steve


Last edited by stevebrot; 12-24-2015 at 10:50 PM.
01-08-2016, 12:05 PM   #2885
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Beautiful shot and lighting, Steve.
01-20-2016, 01:23 PM   #2886
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Mounting 31A (x post with 300mm lens club)

I spent some time during the xmas monsoon rethinking the mounting of my adaptall 31A 200-500mm on my large old Slik tripod.
Mk I. Aluminium plate drilled and tapped for 3/8" to 1/4" tripod adapters to provide several mounting positions so that the lens can be balanced. And I kept the second support point I was using with the macro rail.



Mk II


I initially tried to set the 1/4" tripod adapters into the hardwood with the Mk II, but a quick stress test ripped one out, hence the aluminium plate. The end support is lined with a "sorbothane" type shock absorber material from a cannibalised insole, the idea being this will reduce vibration.
Both are good, is there really any advantage to the MkII, it's certainly less convenient? Time will tell.

PS cost was negligible: Al plate off ebay a fiver; TM adapters x 10 3.

Last edited by marcusBMG; 01-20-2016 at 03:41 PM.
01-20-2016, 03:15 PM   #2887
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Nice work!
01-29-2016, 01:41 PM - 1 Like   #2888
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PKA mount tests - part 1

I have been testing my adaptall PKA mounts.

I was slightly surprised, once I had rooted out the ones clandestinely lurking on a lens or put absent-mindedly to one side, to see that I have 9 of them. I had previously marked 4 as iffy or faulty. My test was pretty straightforward; test/check mechanical function by inspection, then function, and exposure results in Av, on camera. I used a 52B f2.5 90mm macro, and a 01B f2.5 24mm. I was using the whitewashed wall in the conservatory as a relatively uniform exposure board, although the 24mm was including the windows in the edge of the shot. The results were as follows (pentax K5, centre weighted metering, 2M jpg's):
  • All except two functioned fully. One didn't get the camera to display f numbers, no matter how much wiggling of the lens on the camera (usual fix) I did, and then I realised it was the one with the iffy bent aperture lever that I got stuck on the camera previously and posted about - took that off the camera quick!! In fact the small auto button on the side of the mount didn't click when setting the mount to f32/AE - the usual reason for that is that one of the "tabs" that engage with the aperture ring on the lens is out of position and I have noticed before that in this case Av doesn't function. The other wouldn't show f numbers below f4 - I think this is the one I had to disassemble and tlc on acquisition because it was completely seized up. I have to admit I was not perfectly diligent in making sure the delicate contacts that move over the circuit board (see pic here) didn't get nudged/tweaked.
  • All registered f2.4 with these f2.5 lenses. One or two stuck at f2.8 initially, corrected with a varying amount of wiggling.
  • All showed a significant underexposure (no compensation on camera) wide open. This was consistently around 0.5-1 stop.
  • Then stopping down exposures would tend to brighten. At f11-ish exposures were typically good, or even tending to overexpose a little.
  • However some mounts showed considerably more variation than others. A couple were almost consistent, with only slight change.
  • And I felt I was seeing more exposure change with the 24mm.


These "filmstrips" illustrate one of the most consistent result sets (top) with the 52B, and one of the least (below) with both the 52B and 01B.

Mount 1 - 52B



Mount 2 - 52B



01B. You can see there is a shift in the histogram from f2.8 to f16 to the right of at least a stop.



For me the most annoying thing to occur when using these is pronounced exposure inconsistency. One twiddles the dial to stop down one or two stops, fires a shot and the image is overexposed. Is it the mount? Is it the camera? Is it the lighting situation?

I think the inherent underexposure, and a certain trend for that to alleviate with higher f stops, can be attributable to the camera. It is observable with other non-chipped PKA mount lenses, this filmstrip shows the results I got with my SMC-A 50mm f1.7 for comparison.




An element of underexposure is there but otherwise pretty consistent actually. T-mount and M42 lenses show both underexposure and a trend to higher exposure with higher f stops. But with those lenses the camera is stop-down-metering ie measuring the exposure to produce the shutter speed at the actual f-stop. My understanding is that with PKA lenses the camera calculates the shutter speed from the wide open aperture reading. It is noticeable that the shutter speeds mostly change correctly with the f-stops, halving each time. It is also interesting that the most noticeable inconsistencies are through f2.4-5.6. I was contemplating the possibility that there could be a mechanical issue, that some mounts are not fully effective at allowing the aperture to stop down fully (see my post #2843 ). But in that case I would expect the deviation from consistent exposure to be most noticeable at the higher f numbers (is that what we are seeing in the case of the 01B filmstrip - the shutter speeds are consistent but the exposure still moves - by more than a stop, look at the histogram?), and that the exposure might not correlate with the shutter speed. It's as if the actual stop the lens goes to is not the same as what the camera calculates. This might imply that the initial discrepancy in the f stop, f2.4 registered, f2.5 actual, is a factor. But my understanding of that is that this shouldn't be a problem. The initial f stop is slightly out, and so are all the rest by the same amount, it's a consistent error. Am I wrong?

I think I should identify the ones that showed the most exposure variation and check them out some more.


Last edited by marcusBMG; 02-01-2016 at 11:06 AM.
01-30-2016, 01:06 PM - 1 Like   #2889
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I am pretty sure now that these shots were taken with Tamron Adaptall-2 80-210mm f/3.8-4 (103A) in June 2013. Personally I like the soft bokeh, it is very pleasing! Both of them were cropped a little, no remarkable other PP done.

Pentax K-r, ISO200, f/5.0, 1/1250 s


Pentax K-r, ISO200, f/7.1, 1/200s
01-30-2016, 04:04 PM   #2890
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QuoteOriginally posted by Andep Quote
I like the soft bokeh, it is very pleasing!
Totally agree!
02-02-2016, 03:48 PM - 1 Like   #2891
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Part 2 PKA mount with adaptall-1 lenses.

PART ONE - Post 2888

Is there any issue with the earlier lenses?

Let's recap that when Pentax moved from the PKM to the PKA mount, they changed the mechanics of the iris closure. With "M" and "K" lenses the closure of the iris was linear with the movement of the aperture lever, but with the KA mount it was the area of the iris that changed in linear proportion to the movement of the aperture lever. That's why if you try to add PKA contacts to a K or M lens the exposures are not consistent as the aperture is changed, as this thread illustrates:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/63878-how-c...s-ka-lens.html

I used the following lenses to check things out ( I also tried a PFH-28 1st gen 28mm but this proved to have a mechanical fault invalidating any results):

and I selected three of the mounts, one which showed the most exposure variance with the 01B and 52B (#3), one the least (#8 - newly acquired) and one middling one (#7). I used my tripod this time, positioned so that the whitewashed wall comprised just about all of the shot, giving a histogram with one pronounced peak. In the event the mounts all behaved pretty similarly so I am just showing one result.

Results - CT105 105mm f2.5



Results 689 135mm f2.8



Results CT200 200mm f3.5



Results Z250 80-250mm f3.8. The PKA mount can't register f3.8 - shows f4.


My at a glance assessment is that there is no significant difference between the behaviour of the Adaptall 1 lenses and the Adaptall-2/SP lenses with the PKA mounts. This seems to me to be logical. The adaptall lenses all have the same aperture mechanics, that didn't change, couldn't change otherwise there would be backwards compatibility issues with older mounts. Any differences in mechanical behaviour must be incorporated in the mount. The PKA mount is designed to work with the aperture closure mechanism of a Pentax camera and so must be congruent with a SMC-A lens.
But overall we haven't moved forward. The question is still: how about the observed exposure inconsistencies?? > part 3.

Last edited by marcusBMG; 02-02-2016 at 03:57 PM.
02-07-2016, 11:33 AM   #2892
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06A tech

Today I noticed something unexpected about my recently acquired 200-500mm 06A. There aren't many of these around, I have only seen 3 or 4 come up for auction. So I couldn't resist chipping in a bid to satisfy my curiosity.
Well, first I noticed I couldn't seem to get into Av, using a PKA mount. Then when I looked at things later, the 06A's mount, it turns out, has only one space for the ears/tabs on the PK mounts. It has a space for the ear that connects to the mechanical aperture connection, that's on the left side as you are looking at the mount on the lens, but not for the other one on the right side, that just slides freely. And the aperture numbers go to F32 but no AE.

So the upshot is: M only, no Av.
Any others like this eg the adaptall-1 Z500/CZ500?
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02-07-2016, 12:05 PM   #2893
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QuoteOriginally posted by marcusBMG Quote
Today I noticed something unexpected about my recently acquired 200-500mm 06A. There aren't many of these around, I have only seen 3 or 4 come up for auction. So I couldn't resist chipping in a bid to satisfy my curiosity.
Well, first I noticed I couldn't seem to get into Av, using a PKA mount. Then when I looked at things later, the 06A's mount, it turns out, has only one space for the ears/tabs on the PK mounts. It has a space for the ear that connects to the mechanical aperture connection, that's on the left side as you are looking at the mount on the lens, but not for the other one on the right side, that just slides freely. And the aperture numbers go to F32 but no AE.

So the upshot is: M only, no Av.
Any others like this eg the adaptall-1 Z500/CZ500?
The PKA adapters only understand f/4 or faster, so it wouldn't read right anyway. (It does work on the f/5.6 lenses of the SP line, but the numbers are off.)
02-07-2016, 12:15 PM   #2894
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QuoteOriginally posted by vonBaloney Quote
The PKA adapters only understand f/4 or faster, so it wouldn't read right anyway. (It does work on the f/5.6 lenses of the SP line, but the numbers are off.)
Yes I'm perfectly aware of that, my point is that the 06A is the only adaptall lens I've seen that is designed in the manner I've described. There is no click into AE and no possibility of using Av with a PKA mount, numbers off or not.

In any case, the f numbers being off doesn't negate the utility of having/using Av - works just the same!!
02-07-2016, 12:23 PM   #2895
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QuoteOriginally posted by marcusBMG Quote
In any case, the f numbers being off doesn't negate the utility of having/using Av - works just the same!!
Well, sort of, but better than being stuck in M mode, yes. No doubt the slow f/6.9 max aperture is the reason -- probably none of the brands could deal with that as an automatic setting. (Isn't it just bending your mount if the ear has no where to go?)
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