[HermanLee]

My experience is not exactly the same lens+teleconveter combo, but I had FA 50mm f/1.4 + Tamron 1.4x Pz-AF MC4 combo producing images with "soft fuzzy glow" as Marc mentioned. I tried to stop down from F/1.4, F/2.8, F/4.5, but the fuzzy glow didn't go away and I stopped trying.

Until yesterday I met one of the Forum users in person, I had thought either 1) a TC in general does not work with wide~normal lenses or 2) my TC is a faulty one. But he said he had the same issue with FA 50mm and the Tamron TC. He also told me that he had a rare Pentax "macro" teleconverter which works wonderfully with his FA 50mm and FA* 24mm. I don't remember what this teleconverter was, but it was for sure not a macro extension tube.

So I assume you can use a teleconverter with A-50 f/1.7 and get decent results as long as you can identify a TC which works fine with it. Sorry, I am not really helping here. But wanted to share this FA 50mm + Tamron 1.4x experience from two users.

Hi Hide,

Nice to meet you last weekend!
It's me who PentaJP is referring to as the 2nd person with soft & hazy result from my FA50/1.4 & Tamron 1.4x TC combo.

The Macro TC that I told you is this one:

and you can read the short review here:
PENTAX DSLRs: New "Old Stock" ! Vivitar 2X Macro-Focusing Teleconverter.

For the OP, if you're interested in using this TC with A50/1.7, there was somebody who did a test with pretty good result here:
Vivitar 2x macro focussing teleconverter - Steve's Digicams Forums

I don't have Kenko 1.5x TC but I have the Tamron 1.4x TC & Pentax A50/1.7.
If you want to know the result, let me know. I can try to take some quick photos with it indoor. The weather is bad this week so probably I won't be able to do outdoor shots.

[FHPhotographer]

herman, I'd appreciate seeing any shots you can get with the A50+Tamron TC. As I read here, some combinations of lens/TC work better than others, and I found this comparo of an A50+Vivitar 2X and the D-FA 100 macro interesting,
Brian

[Marc Sabatella]

Did you take those pictures outside without a hood?

I did make that mistake once, but even indoors in pretty low light, same results - really soft "fuzzy glow" on any moderately high contrast edges.

[PentaJP]

Hi Hide,

Nice to meet you last weekend!
It's me who PentaJP is referring to as the 2nd person with soft & hazy result from my FA50/1.4 & Tamron 1.4x TC combo.

The Macro TC that I told you is this one:

Hi Herman,

It was quite nice meeting you.
Thanks a lot for following up on my comments regarding your Macro TC

[HermanLee]

herman, I'd appreciate seeing any shots you can get with the A50+Tamron TC. As I read here, some combinations of lens/TC work better than others, and I found this comparo of an A50+Vivitar 2X and the D-FA 100 macro interesting,
Brian

Hi Brian,
Sorry I just got a chance to take some snapshot tonight. Please forgive the crappy photo . I just shot whatever I can find that can show sharpness. The weather is bad here in CA so I can't take outdoor photo.

Here are some samples (below each photo is the link if you want to check the original file):

A50mm f/1.7

original file: Download K20D A50 JPG

A50mm f/1.7 + Tamron 1.4x TC

original file: Download K20D A50 Tamron 4xTC JPG

A50mm f/2.8

original file: Download K20D A50 JPG

A50mm f/2.8 + Tamron 1.4x TC

original file: Download K20D A50 Tamron 4xTC JPG

Good luck,

[HermanLee]

Hi Herman,

It was quite nice meeting you.
Thanks a lot for following up on my comments regarding your Macro TC

No problem

[FHPhotographer]

Herman, thanks for posting the TC shots. Since the Tamron TC is out of production I'll have to find a used one because feedback from Marc and others suggests the Kenko doesn't cut it,
Brian

[Marc Sabatella]

I've heard stories that a least one of the Kenko 1.5 and Tamron 1.4 TC's are actually optically identical, although I know there are different versions of each. Anyhow, shots like the above are what I meant in saying I could get good shots of my bookcase (by which I also mean, any other flatly lit still life), which is why at first I thought the combo had more promise than it proved to when I tried using it "for real". Unfortunately, I've deleted the test shots I had made at the time. Because you've got my curiosity up again, I may give this another look.

[HermanLee]

Hi Marc,

what kind of real shot that you did last time that shows the weakness of the TC?
The reason I'm asking is because I'm curious also as to how this combo performs outdoor.
I actually never used this combo, only did this for this test for the first time.
If you can give me more description, I'll try to take similar shot when weather permits.

However, no matter how good a TC is, it will never performs 100% the same as the lens by itself. I think we all already knew about this.
I've tried this Tamron 1.4xTC with Pentax FA 50mm/1.4 and F 50mm/1.4 and both showed soft & little haze when shot wide open.

[Marc Sabatella]

For some reason, I am always reluctant to post shots I don't like - I guess mostly because I know how often I am the one trying to convince someone else their poor shots are *not* the fault of their gear :-). And I admit this is *not* a controlled test. But FWIW, here's typical sample. Hopefully you've seen enough of my concert shots to know that I *am* capable to getting much better results in pretty much identical conditions (I shoot in this same jazz club all the time) and with pretty much the exact same ISO, shutter speed, etc. My empirical experience is that I am easily able to get better results with every lens I've ever tried - even my 500/8 mirror(!) - than I was able to muster when trying out the A50/1.7 + Kenko 1.5 TC. This was one of the only shots I kept from a night where I forced myself to use this lens exclusively, and it's about a 50% crop:



That's with the camera setting aperture to f/2, meaning the real aperture of the combo is f/2.8. I think I have a prett good handle on the things that can ruin an image for me - focus, camera shake, motion blur, flare. When I shoot other lenses, I might see those show up, but I basically never see a shot ruined that I can't attribute to something like that, and I still expect at least half my shots to succeed on a technical level. With the 50/TC combo, basically, *nothing* worked, and shots like the one above seemed to indicate to me that the lens really was the limiting factor.

As a point of reference, here's the most similar shot I can find from the DA70 - same location, same aperture, and also about a 50% crop, but actually a higher ISO and yet also a slower shutter speed, because the light was a bit lower:



This is in itself, needless to say, hardly the most impressive concert shot I've ever taken, but it's the one that seems to do the best job of matching the rest of the variables (even though it's still far from perfect.

Anyhow, you be the judge.

[FHPhotographer]

Marc, thanks and thanks to all for the input. These example show the TC issues you've described. The only remaining thing would be if you have a bad Kenko 1.5 (I'm assuming other shots with the 50 f/1.7 have been fine). Maybe the only thing I can do is spend the $95 at B&H for the Kenko, and if it doesn't work out send it back . I'll have to talk to the bookkeeper who, when last asked, had embargoed camera stuff for eternity, or at least until after April 15,
Brian

[Oggy]

One question here - why on earth would you want to use a 50 on a TC?

Most 50s are quite sharp and easy to take a picture with. There are plenty of 85s (1.7x50) around which will work much better than the TC.

[FHPhotographer]

Oggy, I'd love to find one in the 70-85mm range as fast as the 50 f/1.7+ Kenko that I could easily fit in a jacket pocket for less than $100. Suggestions?
Brian

[JohnBee]

I acquired a good condition A-50 f/1.7 in a Forum trade, and now I'm wondering if anybody has any experience with the Kenko 1.5x converter on this lens?

It's fast enough that losing a stop isn't an issue for me, but will the excellent center resolution hold up enough to justify the expense?

Brian

I use the 50/1.7 with a Vivitar MFTC and the results are very very good.
Though I never use as a 100mm tele(I have primes for that) but it does very very good as a 100mm macro equivalent.

PS. I have a 100mm macro as well but I prefer to use my MFTC and so it's more convenient to bring with me.

I also wanted to add(forgot) that I've used the Vivitar MFTC with an old 135mm 137AM lens and was dumbfounded to find it better/sharper than my 200mm Series-1 200mm Komine.