[LeDave]

Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.

---

For Jinfinance, you might want to ask him if it's in stock, scroll down on that link and you'll see a lot of questions asking if it's in stock as well as his updates. I believe a lot of people on this forum including myself have bought cheap split-focus focusing screens from him before and never had a problem.

Here was his last update on Q&A

Nov-24-09
Q: Are these in stock?
A: thanks for the message... none for now, but should be coming very soon... estimated 6~8 days.. if you buy it now, you'll be the first in line, and we ship this item at first in / first out basis... best...

---

Last edited by LeDave; 01-02-2010 at 03:22 PM.

[stanleyk]

For Jinfinance, you might want to ask him if it's in stock, scroll down on that link and you'll see a lot of questions asking if it's in stock as well as his updates. I believe a lot of people on this forum including myself have bought cheap split-focus focusing screens from him before and never had a problem.

Here was his last update on Q&A

I just ordered one from him (Jinfinance). He's out of stock. He's supposed to email me tonight to let me know when he will have more. I'll post his reply.

[snostorm]

Here's a question I thought of while I was sleeping

Since the 1.7x TC is AF, does that mean that Catch-In Focus (aka Focus Trap) would not work? I thought Catch-In Focus required a manual focus lens (or a lens/TC with its own MF switch).

Hi Frank,

Focus trap will not work as defined, but with tele lenses, where the AFA will not focus the entire range of distances, you can actuate the AF and full press the shutter button with the lens focus outside the AFA's range, then rotate the focus collar until you enter the distance range where the AFA will work. When you reach this point, the AFA will fine tune the focus and the shutter will fire once it's locked. This isn't an ideal way to shoot since it's a crapshoot when the shutter will fire.

I'd rather just actuate the AF, manually get within the AFA's range, then make any last second adjustments to focus, frame, and fire away.

Scott

[snostorm]

Scott,
First, your photos are stunning.
So, please stop posting them here because I am becoming rather jealous!

Seriously: I see that you have "stacked" two TC's for some of your pics. Granted, you have some fast glass and I would assume this "stacking" would only be possible with fast lenses, right? ... but I wonder if that there is a remote possibility to achieve similar (if not quite as good as those you have) results with slower lenses, i.e.: F4 such as the DA*300.
I am soon getting this Tamron 70-200 f2.8 and I already have a Tamron 1.5x TC. Do you think stacking another TC (such as your 1.7X) on top of it would work with?

Cheers.

JP

Hi Jacques,

Thank you!

I've had success in getting an AF lock with the K-7, FA*300/4.5 + Sigma EX 1.4x APO AF TC, and the 1.7x AFA, but not with the K20, K10, K100DS, or DS.
The difference is the added AF sensitivity of the K-7 AF system. The DA* is 1/3 stop faster than the FA*, so it would probably work with a K-7, and maybe with a Kx. f9.52 (f4 x 1.4 x 1.7) is really pushing it though, and for me, at least, it would only be a last resort type of thing, with cropping possibly being the better alternative. The AF was slow to lock, but it was pretty accurate. If I want/need the longer reach than 510mm, then I'll drag along one of the 300/2.8s. I'd think that stacking 2 1.4x TCs would give better results at 600/8. Some might say that a 2x TC would outperform 2 stacked 1.4xs, but I've yet to use an AF 2x TC that gives better results than the stacked 1.4xs, -- YMMV, of course.

Scott

I forgot to comment about the 70-200. I think that you might be able to stack converters with this lens, but it's always dicey predicting how well it might work. The resultant 476mm f6.7 will probably AF fine, but I've found that pushing the reach of zooms is a possible problem (possibly because of optical design compromises that might have been made to give good zoom performance). I have an SP 80-200/2.8 Adaptall 2 that is and outstanding lens, but though it's great with the AFA, it's not given me results that I like with stacked converters. It's worth a try though. . .

---

Last edited by snostorm; 01-02-2010 at 05:02 PM. Reason: added some text

[frank]

This is a wonderful TC. Actually it's still available new from Japan. You can buy it directly from amazon.co.jp:

HOYA F AFアダプター1.7X F AFアダプター1.7X

About 300usd ...

[snostorm]

So, I have browsed the Net and found a couple of places selling this TC:
$480 USD in "auction 1"
$529 USD in "auction 2" ... that was two days ago.
Went back to retrieve the info this afternoon: GONE! I mean, the ads have simply disappeared!
Anyway, the prices are way too steep for my present and nearly empty budget.

JP

Hi again Jacques,

I recently (about 6 weeks ago) found one at KEH in EX condition for $228 USD shipped. Within the last 2 years, I found one at a little shop in MN on the web for $75 shipped! The 4 I've owned have averaged under $150 each. Ebayers have apparently caught on to the huge demand, and are asking some bizarre prices. I'd think that local listings like newspaper want ads and Craig's List might be the best places to look, where people might list something that they just inherited and know nothing about it, or the current market.

Before the big rush for Adaptall lenses by Pentaxians, I went around to all the ma and pop camera shops in the Chicago area and bought up PK/A adapters -- got 6 total, and they were glad to get rid of them because they had been sitting on the shelf for years. Average price paid was about $20 USD.

Ebay used to be a good place to find unaware sellers of rare Pentax gear, but now, I'd say it's only really good to find dealers looking to dump inventory at closeout prices.

Scott

[snostorm]

I've done biz with Rong Jin a.k.a. "Jinfinance" over the past few years.

I've never bought a 1.7x Pentax mf>af from him but it looks like he's sold (((74))) of them.

Looks like $379 plus delivery from Shanghi China.

I too like mine, earlier Japan made model I bought years ago.

If you love Pentax its certainly an innovative adapter any fan should own.

However I find it can be a chromatic aberations monster with certain lenses I own.

With my 300mm 2.8 Adaptall 2 its a GEM.

1.7x, 300mm 2.8 and K20D abnd seven other lenses keep me owning my Pentax.

According to my pentax instructions sheet it costs you only one f stop,

so my 300mm 2.8 becomes a 510mm f4.

and then you aps-c croppers get added reach I suppose.

Handy item and smart of Pentax to re-make them once more.


SMC PENTAX F AF 1.7X ADAPTER K20D K200D K100D K10D K110 - eBay (item 200284488123 end time Jan-29-10 01:15:07 PST)

Hi Samsungian,

You said that the AFA is a CA monster, but that's being a bit unfair, since it's only with "some" of your lenses -- I'd say that a fairer statement is that it just makes a lens with CA/PF worse by a factor of 1.7x.

You are absolutely incorrect about the light loss, despite what you might have read, and who might have written it. The light loss is a physics thing, and there are no exceptions. The formula for Aperture value (Av, or f number) is N = f/D where N=f number, f= focal length, and D= diameter of the entrance pupil (dia of the front lens element). When you add a TC, you're magnifying the image (increasing the focal length (f), while the entrance pupil remains constant (D), so if you increase the focal length by a factor of 1.7, then you must also multiply the aperture value by the same factor (N). Multiplying the Av by 1.7 gives you a 1.5 stop difference (remember that each stop is a result of multiplying the previous stop's value by @ 1.4). I would imagine that you might have questioned this because your AFA automatically converts the Av for both display in the VF and in the exif info imbedded in the pic, and if anything, rounds the value up.

Scott

[Stringmike]

I've had my 1.7 AF converter for a couple of years and wouldn't part with it. I've used it primarily with my older MF lenses (particularly my Tamron Adaptall 300mm f 2.8).

I hadn't though of using it with shorter lenses, but after this thread will certainly give it a shot for macros.

I also recently acquired a Sigma 120-400mm and will test it with the converter to see if I can answer a recent question posted on this.

Mike

[eziodoc]

I would like a new one of those. If It's not toooo expensive...

I bought one two months ago from a very reliable chinese seller (a lot of items bought from him: always correct guy):
SMC PENTAX F AF 1.7X ADAPTER K20D K200D K100D K10D K110 su eBay.it Lenses, Lenses Filters, Cameras Photo
Item perfect, new.
I've also the old one: looks really similar items in all details, only boxes are different. The last, grey, says: "Assembled in Vietnam".

Happy new year.
Ezio

[GoremanX]

Here's a question I thought of while I was sleeping

Since the 1.7x TC is AF, does that mean that Catch-In Focus (aka Focus Trap) would not work? I thought Catch-In Focus required a manual focus lens (or a lens/TC with its own MF switch).

Goreman,
You are suffering from PRSS , "Pentax-related-sleeplessness-syndrome"
Remedy: get one of those TC's!

lol! Actually, I did dream of nothing but lenses last night, in anticipation of the arrival of my first new lens (besides the kit lens); the DA* 50-135mm.

However, I'd still like an answer to the question. Would the Pentax 1.7x TC prevent Catch-In Focus from functioning? I think the Focus Trap is brilliant for catching birds coming and going to the bird feeder while the camera is unattended, and a TC would be a great way to setup the camera far from the bird feeder.

[Fototim]

lol! Actually, I did dream of nothing but lenses last night, in anticipation of the arrival of my first new lens (besides the kit lens); the DA* 50-135mm.

However, I'd still like an answer to the question. Would the Pentax 1.7x TC prevent Catch-In Focus from functioning? I think the Focus Trap is brilliant for catching birds coming and going to the bird feeder while the camera is unattended, and a TC would be a great way to setup the camera far from the bird feeder.

I don't believe a set up like that would work. But I honestly don't see the point.

If you set up the camera next to a bird feeder to do trap focus, what do you need the TC for? You can set the camera as close to the feeder as you like. Just leave the camaera there and let the birds get used to it.

[snostorm]

However, I'd still like an answer to the question. Would the Pentax 1.7x TC prevent Catch-In Focus from functioning? I think the Focus Trap is brilliant for catching birds coming and going to the bird feeder while the camera is unattended, and a TC would be a great way to setup the camera far from the bird feeder.

Hi Frank,

I just tried it, and yes it would work, but as I said in the previous post answering this, the AFA will adjust focus when the subject gets within it's focusing range, so the result might not be quite the same. For example, if the bird is flying towards the camera, with a straight manual lens, the shutter will only fire when the bird enters the prefixed focusing plane. With the AFA, I think the shutter will fire when the bird enters the focusing range of the AFA -- the AFA will attempt to focus, then will allow the shutter to fire if it finds a lock. Realize I haven't tried this for real, with birds, but I'm thinking that you would get more predictable results with a straight MF TC.

Scott

[jpzk]

lol! Actually, I did dream of nothing but lenses last night, in anticipation of the arrival of my first new lens (besides the kit lens); the DA* 50-135mm.

That's a very good reason to be dreaming as long as you don't neglect other important reasons!
So, I am sure you'll be pleased with this lens .... read/heard a lot of good stuff about it.

JP

[GoremanX]

That's a very good reason to be dreaming as long as you don't neglect other important reasons!
So, I am sure you'll be pleased with this lens .... read/heard a lot of good stuff about it.

Oh it's everything I hoped for. I received it today, and despite the fact that it was near-blizzard conditions out, I still went outside to try it (yay for weather sealing!)

The shooting conditions were horrible, but I managed to salvage a few interesting shots:
https://www.pentaxforums.com/forums/866528-post22.html

[Samsungian]

I'll look into it again. I found previously lenses that I own that do not exhibit chomatic aberations alone that when paired with 1.7x mf>af then they do have excessive chromatic aberations. Whereas my 300mm 2.8 is pretty much CA free with or without the Pentax 1.7x mf>af teleconverter. I remember how disappointed I was with my 105mm macro and 1.7x combo. But that was when I only owned one brand of gear a few years ago. I have not revisited my prior observation since adding other brands of gear to my kit.

As far as pricing goes, these originally sold for what, under $100 new in 1992? I remember I could still order it new in 2002 when I bought my first Pentax body new but passed on ordering it. It was like $139 plus tax back then. I just couldn't understand how it functioned and neither could the sales clerk when I asked for help deciding, so I passed. Manual focus lens to autofocus lens function teleconveter, What a concept. Seems simple now, the teleconverter's elements group that moves in or out to dial in & fine tune focus. Very Nice Item Indeed.

Thats good to know you're locking autofocus with K-7 and 1.7x mf>af whereas with K20D and earlier bodies do not lock af with same lenses. You've now given me a reason to buy the K-7 inspite of the fact I had completely decided against it due to its smaller size. I usually wait till pentax dslrs shed close to half of their issue price to buy their cameras and in April 2010 or so when K-7 is a cent under $700 I'll give it serious considerations now. Thanks

Oh yeah one more observation, I think I can better your PK-A adaptall aquisitions story of 6 at $20 a pop?

I have 3 PK-A mounts and they came with my three adaptall 2 lenses, 300mm 2.8, 200-500mm 5.6, 500mm f8 Mirror. I actually paid less for each lens locally because they each had PK-A adaptalls mounted on them, all like new & perfect. Considering adaptall-2 mounts cost $34.95 a pop brand new when they were brand new back in the day I enjoyed paying less for my three lenses due to the PK-A mounts included for essentially less than free.

Hi Samsungian,

You said that the AFA is a CA monster, but that's being a bit unfair, since it's only with "some" of your lenses -- I'd say that a fairer statement is that it just makes a lens with CA/PF worse by a factor of 1.7x.

You are absolutely incorrect about the light loss, despite what you might have read, and who might have written it. The light loss is a physics thing, and there are no exceptions. The formula for Aperture value (Av, or f number) is N = f/D where N=f number, f= focal length, and D= diameter of the entrance pupil (dia of the front lens element). When you add a TC, you're magnifying the image (increasing the focal length (f), while the entrance pupil remains constant (D), so if you increase the focal length by a factor of 1.7, then you must also multiply the aperture value by the same factor (N). Multiplying the Av by 1.7 gives you a 1.5 stop difference (remember that each stop is a result of multiplying the previous stop's value by @ 1.4). I would imagine that you might have questioned this because your AFA automatically converts the Av for both display in the VF and in the exif info imbedded in the pic, and if anything, rounds the value up.

Scott

Hi Jacques,

Thank you!

I've had success in getting an AF lock with the K-7, FA*300/4.5 + Sigma EX 1.4x APO AF TC, and the 1.7x AFA, but not with the K20, K10, K100DS, or DS.
The difference is the added AF sensitivity of the K-7 AF system. The DA* is 1/3 stop faster than the FA*, so it would probably work with a K-7, and maybe with a Kx. f9.52 (f4 x 1.4 x 1.7) is really pushing it though, and for me, at least, it would only be a last resort type of thing, with cropping possibly being the better alternative. The AF was slow to lock, but it was pretty accurate. If I want/need the longer reach than 510mm, then I'll drag along one of the 300/2.8s. I'd think that stacking 2 1.4x TCs would give better results at 600/8. Some might say that a 2x TC would outperform 2 stacked 1.4xs, but I've yet to use an AF 2x TC that gives better results than the stacked 1.4xs, -- YMMV, of course.

Scott

I forgot to comment about the 70-200. I think that you might be able to stack converters with this lens, but it's always dicey predicting how well it might work. The resultant 476mm f6.7 will probably AF fine, but I've found that pushing the reach of zooms is a possible problem (possibly because of optical design compromises that might have been made to give good zoom performance). I have an SP 80-200/2.8 Adaptall 2 that is and outstanding lens, but though it's great with the AFA, it's not given me results that I like with stacked converters. It's worth a try though. . .

Hi again Jacques,

I recently (about 6 weeks ago) found one at KEH in EX condition for $228 USD shipped. Within the last 2 years, I found one at a little shop in MN on the web for $75 shipped! The 4 I've owned have averaged under $150 each. Ebayers have apparently caught on to the huge demand, and are asking some bizarre prices. I'd think that local listings like newspaper want ads and Craig's List might be the best places to look, where people might list something that they just inherited and know nothing about it, or the current market.

Before the big rush for Adaptall lenses by Pentaxians, I went around to all the ma and pop camera shops in the Chicago area and bought up PK/A adapters -- got 6 total, and they were glad to get rid of them because they had been sitting on the shelf for years. Average price paid was about $20 USD.

Ebay used to be a good place to find unaware sellers of rare Pentax gear, but now, I'd say it's only really good to find dealers looking to dump inventory at closeout prices.

Scott