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Forum: Photographic Technique 06-19-2017, 02:31 PM  
Macro Auto teleconverter not passing aperture control.
Posted By joshuamcateer
Replies: 18
Views: 2,275
Thanks, Steve. Yes, I think it is a fault in the pass through wiring. A fairly subtle one. Whilst the pins on the lens side of the TC are connected to the pins on the bottom of the TC, it seems that the A pin is slightly too short. None of them is sprung, all of them being solid bars which are fixed fast in place. I made a small attempt at extending the A pin by wrapping it in aluminium foil and then reassembling it. But, alas, it did not fix it.

The whole teleconverter seems to be pretty poorly made. When I took apart I noticed that many of the screw holes were tapped in another location, about 20 degrees from where the screws were. I somewhat doubt that "Ranger" is a reputable maker. Perhaps I'll find a way to extend the bar or lengthen it, but I doubt I'll be able to. Oh well.

---------- Post added 06-19-17 at 02:42 PM ----------

Imgur: The most awesome images on the Internet This image shows the top half of the contact bars. They extend the whole way through the TC. There are no springs or anything, the only things holding them in place are nylon spacers at either end.




I'm still not sure what you mean by checking the continuity of then lens. Surely, you need to put one lead of the multimeter on one contact on the male side, and one on the corresponding contact on the female side. But in the lens you can only access one side? I'm sure the lens is working perfectly, it works on my camera, so it's not a big deal, but am I just being daft?
Forum: Photographic Technique 06-19-2017, 09:42 AM  
Macro Auto teleconverter not passing aperture control.
Posted By joshuamcateer
Replies: 18
Views: 2,275
I tried your aluminium foil suggestion, but I couldn't get the foil to stay in place. The TC fits too snugly with the camera mount and it just rips or drags the foil.

*Breaking news* tried to tape the aluminium foil into the pin hole. It didn't look like it was going to work, as the tape got dragged around as the lens mounted, but it did. I got aperture control and metering - perfect.

However, when I took the lens off the foil got dragged back and I'm not sure exactly where it was. I *think* that a tiny fleck of foil remained on the A pin, and that's what caused it. The only problem is that it's not really a permanent solution. I might try glueing some aluminium foil to the TC, although I'm not sure how best to do that.

Thanks so much. You've all been so helpful, I don't think I would have thought of any of those suggestions.
Forum: Photographic Technique 06-19-2017, 09:10 AM  
Macro Auto teleconverter not passing aperture control.
Posted By joshuamcateer
Replies: 18
Views: 2,275
I only make it four pins which are in the same location in each picture. I tried roughing up the surface with a nail file, trying to make the smallest possible difference to the teleconverter so that it wouldn't scratch then lens mount. I continued until there were faint scratches covering more than half of both the top and bottom of the teleconverter. I then cleaned it with isopropyl alcohol and tried it on the camera - it didn't work either. I then cleaned the lens mount of the camera and tried again, but to no avail.
Forum: Photographic Technique 06-19-2017, 08:07 AM  
Macro Auto teleconverter not passing aperture control.
Posted By joshuamcateer
Replies: 18
Views: 2,275
Yes, the top picture is the mount of the lens. I have read that the 7th pin does this. The f-number is not registering on either of the screens, displaying the "f - -" just like Steve said. I've checked all of the pins on the teleconverter with a multimeter and they all conduct all of the way through the teleconverter.

However, I'm not sure how to test the contact in the camera, although it's quite new and looks clean. The lens I tested it with is a D-series lens, the DFA 100mm macro, which doesn't have an aperture ring. However, I tested it on an F-series lens (a 70-200), which does have an aperture ring. The camera still doesn't recognise the lens even with it set to "A", displaying "F - -" on the screen. I'm not sure how to test my lens. I don't have an A-series lent to test it with.

---------- Post added 06-19-17 at 08:19 AM ----------



To answer your questions:
1) yes
2) no, it is bare metal
3) yes, perfectly, bought new in a shop and it has never been an issue
4) Some of the pins match. I've tried to align the images and flick between them Imgur: The most awesome images on the Internet and several of the pins are in different places.

to expand on 2) I believe that the metal lens mount is the ground for the electrical contacts. I checked the continuity between the two sides of it and it seems pretty dodgy but still makes contact. I thought that since the surface area is quite large the contact would be good enough. There is definitely continuity between then, as I also checked the polished metal screws. The screws on the opposite sides of the mount (lens and camera sides) make very good contact, so I thought that they should also make good contact with the surrounding metal mount. I could try polishing the mount.
Forum: Photographic Technique 06-19-2017, 06:45 AM  
Macro Auto teleconverter not passing aperture control.
Posted By joshuamcateer
Replies: 18
Views: 2,275
I tried as many of those fixes as possible, such as cleaning the contacts and checking continuity. But none of those things fixed this issue. It behaves in exactly the same way as it did before, like a manual lens.

I think the problem might be Imgur: The most awesome images on the Internet related to the location of the pins and the number of them. When I bought the teleconverter I bought the one which had the most contacts (6), although they don't match up with all of the pins on the lens. Although, I thought that it should still work, as it would be like connecting the lens to an older camera, or the camera to an older lens. This article The Evolution of the Pentax K-mount - Articles and Tips | PentaxForums.com suggests that the teleconverter is a KA mount, but also suggests that it should meter.

I'm not sure quite what you mean . The lens doesn't have an aperture ring.
Forum: Photographic Technique 06-19-2017, 04:36 AM  
Macro Auto teleconverter not passing aperture control.
Posted By joshuamcateer
Replies: 18
Views: 2,275
I quickly tried it in P and in Manual. It didn't work in either. The stop down metering was with the green button. It did stop down, but it would only stop down to the minimum aperture.
Forum: Photographic Technique 06-19-2017, 04:15 AM  
Macro Auto teleconverter not passing aperture control.
Posted By joshuamcateer
Replies: 18
Views: 2,275
Sorry if this is in the wrong place. I was looking for a set of extension tubes for macro work, but couldn't find any with auto aperture. I found a forum post which suggested that the best way to get around this is to gut an auto teleconverter with the contacts, to leave a single extension tube, with no optics in it. So, I bought a "Ranger auto 2x teleconverter (PKA)". It has the apature lever, for stop down metering, and six electrical contacts. These contacts pass straight through and, I believe, have no electronics in the way.

When I connected the teleconverter to my K-1 it asked for the focal length of the lens - which made sense I suppose - but then continued to not register the aperture, just like if you connect a lens without the contacts. On pressing the metering button, it stops down to the minimum F-number, and it also only takes photos at the minimum F-number. I believe this is the expected behaviour of a lens without the electrical contacts to the camera, but with the lever.

The lens I tested this with was the 100mm macro (I just wanted to get a little bit closer), and I didn't do anything to the teleconverter.

There are only three things I can think of as to why it doesn't work, that the contacts are in a slightly different place/missing one contact or something - I now realise that the converter has some of the contacts in slightly different places, but most of them line up. That the contacts might not be making good electrical contact with either the camera or the lens. Or that there is some option in the menus which needs to be enabled.

I don't know if anyone else has had this problem. I'll try to find the original thread which suggested this. If someone has any other ideas for how to get auto aperture extension tubes or any teleconverters that are known to work that would be great. The ones that people suggest (I think the Vivitar AT-23 seem to be very hard to find).

Thanks
Forum: Pentax SLR Lens Discussion 11-28-2016, 10:46 AM  
What's so special about the limited lenses?
Posted By joshuamcateer
Replies: 31
Views: 3,461
Thanks. Everyone on here seems to vouch for them.

I *was* a little apprehensive about the k-1, but it's an excellent body. I got the two lenses that I really put as the minimum requirements with it, the 24-70 f/2.8 and the 100 f/2.8 macro. But I was thinking of getting a few primes at some point as I really like the 50mm fov and something a bit faster than f/2.8 would be nice.

My main reason for calling them "awkward, old-fashioned" (which I now feel might not be completely fair, and reads in a somewhat antagonistic way) was based on the slow af speed (which I understand they tend to have) and I found slightly annoying with the 100mm macro (I know macros are normally slow, but even in cases it doesn't need to hunt it is much slower than the 24-70).

Thanks for you answer
Forum: Pentax SLR Lens Discussion 11-28-2016, 10:26 AM  
What's so special about the limited lenses?
Posted By joshuamcateer
Replies: 31
Views: 3,461
I agree. I love using old lenses, and old cameras. Sometimes they have a wonderful look or feel (I think ebay is also extremely happy that I like them, I'm sure I keep their site open). Although, I use them less than I did after I got the m42-kmount adapter stuck in my k-1 (the horror).

But sometimes you need sharp, fast, work-horse lenses to get the photos you need.
Forum: Pentax SLR Lens Discussion 11-28-2016, 10:16 AM  
What's so special about the limited lenses?
Posted By joshuamcateer
Replies: 31
Views: 3,461
It's a valid criticism of the system. For a modern full frame camera, there should be plenty of full frame autofocus primes and zooms. I have a hand full of m42 mount lenses, and they're great, but you can't do anything quickly with them. Hell, I mounted lenses off of my pentacon six onto a m4/3 camera, it doesn't mean that it's practical to do for all types of photography.
Forum: Pentax SLR Lens Discussion 11-28-2016, 10:11 AM  
What's so special about the limited lenses?
Posted By joshuamcateer
Replies: 31
Views: 3,461
The digital rev reviews seemed pretty scathing. Although, I just looked, the review on here for the 43mm do seem very good. However, there seem to be several comments like

"Sharpness:
I gave this a 5 because when it focuses, it's pretty good, especially at screen size. But a pixel peep reveals that the lens lacks the resolution of its FA31 and FA77 sisters. Perhaps the biggest problem with this lens is its poor contrast, even stopped down until you hit f/5.6 or so. Using flash helps a bit but compared to what other lenses can do on the K-1, the FA43 is a huge disappointment.

I'm not even commenting on wide open performance. I'm trying to shoot this at f/3.2 to f/4 and not seeing acceptable results. Flash helps a bit but the off-center performance is quite poor even stopped down a bit. A normal lens like this should really be accomplishing a lot more." from MadMathMind

And none of them are *that* fast. I have a 50mm 1.4 (8 element) takumar that you could say similar things about (although without af, somewhat less sharp, and a stop faster), and it cost about a fifth as much.

Maybe I'll just have to try one and see
Forum: Pentax SLR Lens Discussion 11-28-2016, 09:41 AM  
What's so special about the limited lenses?
Posted By joshuamcateer
Replies: 31
Views: 3,461
Lots of people on here, and on other sites seem to rave about them. But in reading the reviews, they generally seem mediocre, awkward, old-fashioned, and extremely expensive. From my understanding, they were designed in Pentax's early digital days, for crop sensor cameras with fairly low pixel densities (but many of the do cover ff), and so you might expect them to be a little soft and not have the best autofocus. Both of which seem to be common complaints.

I recently got my first Pentax, a K-1, and I do like it, but there still aren't very many lenses for it, and it seems that people suggest these extremely expensive limited lenses as the saviour of the system.

Am I wrong, am I missing something about the system? Is it their nostalgic charm? Do they capture that quintessentially Pentax light that each epitomises what it is to shoot Pentax (just like the creamy Leica-look. Or that Hasselblad feel)?

Thanks awfully,

Josh
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