[skamaraju]

Could some of you please post images taken with it and give your comments regarding image quality comparing that and Tamron 1.4X teleconverter? Thank you.

[stevenlin]

Pentax -F smc 1.7x AF ADAPTER

???: ???? Pentax - F smc 1.7x AF ADAPTER

1.可以搭配手動鏡,並有限度的AF.
2.中央成像中等以上,周圍太過鬆散.

May any person to help me to translate,tks.

[Lowell Goudge]

I can't give you tamron TCs as I don't own one.

See below for Pentax 300mm F4 with 1.7x AF TC and Sigma 70-200 F2.8 with 2x TC.

Note the 1.7x is an autoficusing TC which has moving elements, to provide AF for non AF lenses.

300F4 with 1.7x
https://www.pentaxforums.com/forums/106132-post4.html
70-200f2.8 with 2x
https://www.pentaxforums.com/forums/187646-post19.html

It is important to note the sigma TC only works on long fast sigma lenses and on sole very long older pentax lenses.

In my opinion the TC does not degrade the lens very much in either case

[frank]

Pentax -F smc 1.7x AF ADAPTER

???: ???? Pentax - F smc 1.7x AF ADAPTER

1.可以搭配手動鏡,並有限度的AF.
2.中央成像中等以上,周圍太過鬆散.

May any person to help me to translate,tks.

1. Can work w/ MF lenses and do AF in certain range
2. IQ at the center is above average, but not so good at the edges

For 1, means you can only do AF within a limited range around the current distance set on the lens. If you wanna focus out of the range, you need to turn the focus ring on the lens first.

[Piotr]

With Voigtlander 180/4 it is very good combination. It gives me very compact 300mm lens.

Pentax *ist DS ,Voigtlander 180/4 APO-Lanthar +AF1.7X, 1/750s f/6.7 iso200



With K 500/4.5 it is my 800mm lens which I used in 50% of birds shots here Ptaki z okolic Czarnowa Photo Gallery by Piotr Sobolewski at pbase.com

Pentax *ist DS ,Pentax smc 500mm f/4.5 +AF1.7X 1/350s iso400


In general I can confirm it does not reduce quality.

[Peter Zack]

I have both and consider them about equal other than the magnification. The Tamron is easier to use since the AF works without any manual focus adjusting.

2 very different shots but here's the FA*300mm with the Tamron 1.4

This is the Pentax AF1.7 TC with an FA50mm/1.4

And here are both together. Tamron attached to FA*300mm and the Pentax 1.7 added to that. Manual focus at this point with 714mm total focal length.

[dantuyhoa]

Taken with Vivitar Series One 105/2.5 + 1.7x F Adapter








Not bad for some "fresh meat" like me , eh ?

And thanks frank for setting me up with the 1.7x TC .

Tran

[k100d]

i'm a bit miffed as to why you would use the TC with the Macro? to get AF?

[frank]

i'm a bit miffed as to why you would use the TC with the Macro? to get AF?

W/ a TC, you can get even bigger mag ratio

[skamaraju]

Thank you for the opinions. I won an auction on Pentax 1.7X by chance for 310$. Now I am not sure whether I should keep it as these days the adapter is rare to find or spend the money on some good glass. If the image quality with the adapter is on par with the Tamron 1.4X, I might as well keep it.

[Peter Zack]

I'm with k100d on this question. dantuyhoa sorry to be blunt but your shots are very close and tight but the IQ is suffering. The red one has all sorts of colour shifts and appears soft. The other 2 are better but still lack the crispness we've seen from this lens.

I'm willing to bet that taking these same shots with the 105mm alone would look better and if you wanted to get closer, extension tubes would do a better job.

[dantuyhoa]

I'm not the first one or the last to add a TC to a macro lens . It has been done quite many times with a wonderful results . . Do a quick search then you will see .

The advantage of the TC is that it will not change the minimum focus distance of the said macro lens . Greater mag , too .

The Pentax 1.7X F TC does not magically turn any manual lens into an AF one . You still has to focus the lens first before the TC kicking in . The Vivitar 105/2.5 has a very long focus throw . TC won't help much at all .

In my humble experience , it helps to study the subject first before I shoot : Cactus , a dry harsh climate native resident , does have a waxy skin to protect against water evaporation . This skin will also reflect the incident light which could help to reduce the internal body temperature .

Anyway , with that waxy feature in mind , I knew that by using a flash I will create some unreal light + color effect at the macro level . So unreal that unless I tell you - or you happen to study it like I did - you won't be able to tell it is a cactus !

Hence I name it "Aliens" as I posted this on POTW thread .

But like any creative project , its merit is quite subjective.

Just think of shooting a mirror ball but in small "macro" mode .

PS Cactus - of spineless variety - was brought to Sonoma-Napa area as cattle feed . But they do need water as soon discovered . Another problem is slow growth due to small photosynthesis efficiency - internal instead of inside leaves .