[JoepLX3]

Sorry, just bought an A 50 mm F1.4 for over 100 Euro's...

How attractive will the AF 1.7x TC 1.7 be for me:
M 28 mm F2.8 --> 48
DA 35 mm F2.4 --> 60
A 50 mm F1.4 --> 85
M 135 mm F3.5 --> 230
M 200 mm F4 --> 340

Should I try to get A iso M lenses?

[Lowell Goudge]

Sorry, just bought an A 50 mm F1.4 for over 100 Euro's...

How attractive will the AF 1.7x TC 1.7 be for me:
M 28 mm F2.8 --> 48
DA 35 mm F2.4 --> 60
A 50 mm F1.4 --> 85
M 135 mm F3.5 --> 230
M 200 mm F4 --> 340

Should I try to get A iso M lenses?

For me, the AF 1.7x resides almost perminantly on my 300F4, so I have 510mm F7 with AF. My other option is to use it with my Vivitar 85mmF1.4 so I have a 145F2.5. This allows me to not take anything longer when travelling only in cities, I take my Sigma 10-20, my tamron 28-75 and the 85 F1.4 plus the TC so I have portraits and medium tele and cover 10-~150mm with only 3 lenses.

you would find it somewhat interesting on the 50mm as well, but not on the 28 and 35mm lenses, After all, why would you want a 48mm F4.5 or 60mm F4 when you already have a 50mm F1.4? especially when a 50mm F1.4 is not much bigger than the TC?

Also on the M135F3.5 I can't see why you would bother, I would take a 200F4 over the resulting 230F5.6 any time. Now if it was a K135F2.5 that would be different, 230mm F4 plus the 135 on it's own would make some sense.

The whole thing with this TC, and it is a good one, is to couple it with really fast lenses, to get an equally long and fast benefit.

[JoepLX3]

For me, the AF 1.7x resides almost perminantly on my 300F4, so I have 510mm F7 with AF. My other option is to use it with my Vivitar 85mmF1.4 so I have a 145F2.5. This allows me to not take anything longer when travelling only in cities, I take my Sigma 10-20, my tamron 28-75 and the 85 F1.4 plus the TC so I have portraits and medium tele and cover 10-~150mm with only 3 lenses.
...
The whole thing with this TC, and it is a good one, is to couple it with really fast lenses, to get an equally long and fast benefit.

Thanks for feedback, that really makes sense!!!
- Using it on a 28 mm would only make sense to get an AF 50 mm prime, but not much faster than my 18-55 kit lens any more...

One question:
- Does this TC work correctly with aperture settings by camera on A-lens?
- Or in other words, does it make sense to go after A 200 rather than the M 200 I already own?

It might also make sense to combine with a fast tele zoom
- icw 50-150 mainly portability (compared to 55-200 kit lens)
- icw 70-200 next to portability also reach

[JoepLX3]

One more question, can you also attach the K-m42 ring onto the converter to use it with a m42 lens?
- Would AF then still work?

[JoepLX3]

Found some information myself:

SMC Pentax-F 1.7x AF Adapter Lens Reviews - Pentax Lens Review Database

[JoepLX3]

FYI: Just bought a K-x for 400 Euro (only have to wait about a week for delivery)