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10-10-2011, 12:42 AM   #1
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Contax Mount Kiron 28-70mm macro on a K100D = possible or pipedream?

Hi All,

I absolutely love this forum. I've found an absolute wealth of information here! And everyone seems so helpful and friendly!

Now I've searched the forum and scoured the webs and ebay and wondered if you helpful people could give me some advice.

I had a sudden black out and went and bought a Kiron 28-70MM Macro 1:4 SLR Camera Lens with Hoya 62MM Skylight filter off etsy. It was only after I'd purchased it that I'd realised that it might not be a Pentax mount... I think all I saw was the name 'kiron' and the $15 price tag....

After looking closer at the pictures of the mount and scouring some ebay listings I'm pretty sure I've purchased a Contax/Yashica mount.
Pic 4 is the mount: Etsy Transaction - Kiron 28-70MM Macro 1:4 SLR Camera Lens with Hoya 62MM Skylight filter
Here is the ebay listing I'm comparing to. Yashica Kiron 80-200mm f4.5 lens Contax macro zoom | eBay

They look pretty similar to me?

Looking through the posts here it sounds like there's lots of technical ways to turn the Contax mount Pentax friendly but all looks a bit intimidating to me. Everything ranging from taking the lens apart to drilling holes for new screws?!

I've scoured ebay and come across another possibility and wanted to run it past you experts before I shell out even more cashies.

What would happen if I bought two adapters? One Contax/Yashica (C/Y) to Nikon adapter, and then a Nikon to Pentax adapter. Screw them back to back and then put them in my camera. Would that work? What kind of compromises would I have to deal with? Would the range of the lens reduce? Would the pictures be too dark/range of zoom reduce because of the added length to the lens? The adapters reckon they will allow for focus to inifinity to still work. but even if it isn't, I bought this lens mainly because I wanted to try the 'macro' setting. I've got a Pentax k100d. I've had my camera for around 5 years and am now finally ready to play around more with the manual settings.

The adapters together will cost about $50-$60 depending on which vendor I go to. Postage to Australia for my $15 lens has made it a total of $30. So if the adapter idea works this bitty lens will have cost me around $80-$90. Is this lens worth it? Or should I just suck it up and try and resell it and be happy if I recoup my costs?

The lens review database (Kiron 28-70mm f/3.5-4.5 Macro 1:4 Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database) says that this lens gets a rating of 8 (albeit with only one review) but the pictures looked pretty spectacular! I wanna take photos like that!

I'd appreciate any advice you guys could give me.

TIA!

10-10-2011, 06:39 AM   #2
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Forget optical adapters. They make sense ONLY if 1) they're the highest-grade adapter, 2) used with a high-grade lens, and 3) you don't mind losing some of the lens' optical quality and focal length and aperture -- such adapters function as short teleconverters.

I have adapted several C/Y-mount lenses to fit on PK-mount cameras. It's easy and almost free and non-destructive in that they can still be used on C/Y-mount cameras. It requires a few minutes work with a Dremel with metal-cutting disc. No great skill is necessary, just a steady hand. I don't recommend such a modification with a heavy|long lens, but your Kiron zoom is under 400g so it should be OK.

Let me know if you're interested.
10-10-2011, 07:44 AM   #3
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As Rico (and his Forum famous Dremel) has indicated, the C/Y mount is physically and mechanically very close and similar to the PK mount. There is no C/Y to PK adapter, essentially there is no physically room for one. The registration distance (distance from the sensor to the mount) is essentially the same on the Contax and the Pentax (that is why Rico's technique works). There is a company over in Spain that makes a replacement mount for the Contax (only) lenses, and only Primes (Leitax.com) - so there is no option there.

Your only option is the path Rico suggests - or sell it to a Canon shooter - since they do have a C/Y to EOS adapter (and since their registration distance is shorter, there is physical room for the adapter - it does not work on Nikon, since they have the longest registration distance).

Get the procedure from Rico, get a Dremel with metal-cutting disc, do some surgery, and then go shooting with your new lens.....

You essentially have nothing - or very little to loose.

10-10-2011, 03:34 PM   #4
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thanks for all your help guys!

a dremel? metal cutting disc?! that sounds so hard core to me!

QuoteOriginally posted by RioRico Quote
Forget optical adapters. They make sense ONLY if 1) they're the highest-grade adapter, 2) used with a high-grade lens, and 3) you don't mind losing some of the lens' optical quality and focal length and aperture -- such adapters function as short teleconverters.

I have adapted several C/Y-mount lenses to fit on PK-mount cameras. It's easy and almost free and non-destructive in that they can still be used on C/Y-mount cameras. It requires a few minutes work with a Dremel with metal-cutting disc. No great skill is necessary, just a steady hand. I don't recommend such a modification with a heavy|long lens, but your Kiron zoom is under 400g so it should be OK.
Hi Rico,

When you say only make sens with a high grade lens and losing optical quality and focal length etc. What about my lens? Does that fall into high grade territory? Would a lens need to be rated a 10 in the lens database order to qualify?

I've seen short teleconverters online but I've wondered if they were worth the $30 odd some places wanted to charge?



Interested Observer -

QuoteQuote:
As Rico (and his Forum famous Dremel) has indicated, the C/Y mount is physically and mechanically very close and similar to the PK mount. There is no C/Y to PK adapter, essentially there is no physically room for one. The registration distance (distance from the sensor to the mount) is essentially the same on the Contax and the Pentax (that is why Rico's technique works). There is a company over in Spain that makes a replacement mount for the Contax (only) lenses, and only Primes (Leitax.com) - so there is no option there.
Ok... "registration distance" I'm a total newbie to proper photography terms. I've been *gasp* using my k100d as a point and shoot for five years!

Are you essentially saying the pictures would turn out weird and disappointing if there was in fact a converter out there? Would the pics turn out super small because there'd be more distance between the lens and the camera body?

QuoteQuote:
Your only option is the path Rico suggests - or sell it to a Canon shooter - since they do have a C/Y to EOS adapter (and since their registration distance is shorter, there is physical room for the adapter - it does not work on Nikon, since they have the longest registration distance).
When you say the lens won't work on a Nikon - what about the adapter I found? (eBay Australia: Buy new & used fashion, electronics & home d?r)

What would happen if a Nikon shooter used it?

Sorry for all the questions! I just want to better understand why my options won't work and what would happen if I went ahead and did them. That and I'm terrified of power tools!

10-10-2011, 06:42 PM   #5
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Good Evening Wolfie,

Registration distance is the distance from the sensor out to the front of the camera where the lens mounts. Take a look at the first diagram on this link. Down at the bottom, you see the distance marked "L". That is the distance between the sensor (film) and where the lens attaches to the camera.This distance varies based on the brand of camera.
  • Nikon - 46.5mm
  • Pentax - 45.46mm
  • Contax - 45.5mm
  • Canon - 44mm
Here is a list of all the registration distances for the various camera makes across the years...The problem that this causes is that a lens built for a different registration distance will not be able to focus the image properly on the sensor. The sensor will be too close or too far away. All the measurements are relatively close, but sufficiently different to make things not work. That is why Rico said that some times additional glass is needed in the adapter to adjust the focus properly.

However, you will note that the distance for the Pentax K mount, and the C/Y mount are nearly identical - close enough so that it will work.

There is a slight mechanical difference between the C/Y mount and K mount that needs to be shaved off slightly, so that the lens will be able to mount on the Pentax body and not fall off while you are taking a picture.

From the reputation of the Kiron lens, I would say that it would be well worth the effort. You really have absolutely nothing to loose and a very good lens to gain.

On your other questions - The lens would not be able to focus on a Nikon. For a Canon, the knowledgeable Canon folks seek out these lenses (along with the Pentax M42 lenses) because there is an adapter available that will hold the lens at the correct registration distance. For the Nikon, the lens would need to be pulled inside the body a bit for it to focus correctly.

10-10-2011, 06:44 PM   #6
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Dremel (brand name) makes a small motorized tool about the size of an old electric toothbrush. The basic kit includes small drill bits, and discs and such for sanding, buffing, cutting, etc. They're much used by crafters, jewelers, and lens-choppers like me. The modification I make to C/Y and other lens bases *could* be done with a small file, but that's tedious. My metal-working skills are not great; the dremel is the most advanced tool I use.

Teleconverters (TCs) in general, suck. High-quality (and costly) TCs matched to specific high-end (and costly) long lenses are worthwhile. Most others, aren't. They inevitably degrade image quality (IQ). (My IQ is degraded enough already, but that's another story.) An optical adapter, which is a short TC, can be useful with a superior (and costly) lens IF you absolutely MUST use that lens on a foreign camera AND you don't care about IQ loss. Such adapters are especially bad with short lenses like your very nice Kiron -- it will emerge a bit slower and longer and distorted, dropping it from VERY NICE to JUST OK.

Registration distance aka flange-focal distance aka registry is the distance from the lens base to the frame (film or sensor). Each camera mount has its own registry, decided-upon by engineers who smoke and drink too much. Longer-register lenses on shorter-register cameras can focus to infinity. Shorter-register lenses on longer-register cameras can't, and can only be used for macro or close-up work. Nikon is slightly longer than Pentax, which is very close to Olympus OM and Contax-Yashica C/Y and Petri, which are longer than Sony-Minolta Alpha and Canon and Leica. Which means that those longer lenses can be chopped to fit Pentax, and can use non-optical adapters to fit to the shorter-register cameras. Confused yet? Good, so am I. But it's true.

When we say that a lens won't work on another camera, we usually mean that it can't focus to infinity -- can't reach infinity focus, or NIF (no infinity focus), those are our muttered curses. They're NIF without a sucky optical adapter, that is. Yes, any lens CAN be made to work on any camera -- it just won't deliver the best images. Same with TCs. TCs are OK if IQ doesn't matter, where content is more important than quality, such as surveillance, blackmail, crime planning, etc.

Your Kiron *IS* very nice, but not exceptional, and not especially rare in any lens mount. Kiron (Kino Industries) made the same lenses for various mounts, sold under many brand names. interested_observer had a good suggestion -- sell the lens to a Canon shooter and look for a copy in a Pentax-compatible mount, either PK (Pentax bayonet) or M42 (screwmount). It might be branded as Kiron or Vivitar or Sears or Lentar or whatever -- if the serial number starts with 22, it's likely Kiron.

I think I covered your questions there. Feel free to ask more. Gotta go cook dinner now. Let's see, maybe deep-fried squirrel...
10-10-2011, 10:49 PM   #7
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wow, what a lot to take in! i feel like i've gone to a uni lecture on photography!!! absolutely fascinating!!!

interested observer:
thanks for the links on the registration distances. i think i'm going to need some time to read through it a few times to digest.

interesting about the differences between nikon and pentax, and yet these adapters are still available for purchase!

Rico

I went out to town today to look at dremel tools. The place I went to had the parts but not the tool itself. He was selling the tool/drill bits for $25 and warned me a proper dremel tool would cost around $99 (!!!!). I seem to recall you saying you got yours just at a cheapy bargain store. So I might keep shopping around and seeing what other stores have to offer.

Thanks for your lengthy explanation about what will happen if I get the converter/adapter lens. Interesting. I'd been wondering what IQ meant. But I hadn't gotten around to finding out. Now I know! Image Quality. Of course! So obvious!

Thanks also for your advice re the lens itself.

Too funny that interested observer started off telling me to bite the bullet and sell it, and you Rico wanting me to cut the lens to fit. And now you two have flipped with Interested Observer reassuring me it's worth the surgery and you, Rico telling me to find another buyer.

Def. lots of food for thought. I might hold off until the lens arrives and see if I can make a more informed decision then. Do you have a tutorial Rico of your Dremel cut down? I did a quick search last night but only found threads with you saying you'd done it. Not how you did it. I've seen a few examples online in general but a lot of them look quite complicated. Something about taking rings off lenses, losing bearing balls, etc etc.
10-11-2011, 12:36 AM   #8
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Options: I think i.o and I agree that you could go either way. Yes, the lens can be easily chopped; and yes, it's better NOT to chop if you can find a replacement. So if you see an actual PK version of the lens, buy that and sell the C/Y version. And if you decide to chop, here are the directions: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/144162-c-y-mou...ml#post1506028

I just searched eBay for DREMEL and I find some knock-offs for under US$10 , such as a basic unit meant to trim dogs' toenails! The metal-cutting blades are Dremel #426; a 5-pack cost me US$12 at a local non-discount store. I've chopped over a dozen lenses and have still not quite used-up two of the blades.

I keep promising to do a proper tutorial of this lens-chopping. If I can just concentrate long enough...

10-11-2011, 12:46 AM   #9
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Thanks for the linky Rico. A proper tut would be great! I'm a visual person, surprise surprise. But I will try and read slowly and see if the directions sound easy to do or not.

It's fascinating listening to what people have to say about photography. Every one I speak to has a different opinion. The dremel guy was all like 'buy the real stuff' coz the cheap after market stuff won't last long. And here you go saying you've chopped up dozen of lenses and the kit is still going strong! Go figure...

Thanks for all your help guys. Off to do some reading and browsing of more lens sales...

No, I do not have an addiction..
10-11-2011, 01:17 PM   #10
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Neither of those lenses are worth going to the trouble of converting to K mount, imho. Only reason you might convert these lenses might be if you had a T* Contax lens and want to practice on a "throw away" C/Y mount lens before tackling the "high end" lens.
10-11-2011, 02:33 PM   #11
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Hi excanonfd,

Thanks for your opinion! Is the T* Contax lens one of that mount/brand out there?
10-11-2011, 06:41 PM   #12
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QuoteOriginally posted by wolfiegirl Quote
Hi excanonfd,

Thanks for your opinion! Is the T* Contax lens one of that mount/brand out there?
I am talking about something along the lines like these: Contax 50mm f1.4 Planar T* Manual Focus Lens | eBay or SUPERB! CARL ZEISS SONNAR 135mm f2.8 *T CONTAX C/Y FOR CANON 40D,50D,7D | eBay

If you could get lenses like these and successfully convert them, you will have completely manual focus/exposure lenses with superb optics that will hold their value in perpetuity. The lenses you've shown in your initial post are Kiron brand (highly regarded third party lens maker) lenses made for the Contax/Yashica cameras. Within Contax/Yashica lens lineup, they had the Yashica lenses which could be seen as an equivalent to Pentax kit lenses and the highly sought after (now) Zeiss T* lenses which could be seen as an equivalent to our own star lenses.

I would advice that you sell the C/Y mount Kiron zoom lens(es) and look for similar lenses in the PK mount (no need to waste time and effort converting the mount, just shoot). However, if you find one of those Zeiss T* lens for a song and a dance, buy, convert and enjoy it for it's superb optics or sell it and get some serious coin in return.
10-11-2011, 06:42 PM   #13
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Gotcha! Thanks for the thorough explanation. Totally get what you're saying!
10-12-2011, 02:57 AM   #14
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Here's a site that might be of use.
Zeiss Contax lens for Pentax cameras
10-12-2011, 03:37 AM   #15
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thanks!!
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