Tamron 1.4x Pz-AF vs Pentax 1.4x TC

**zkarj** · 06-10-2022, 06:36 PM

Originally posted by clackers

The DA55-300 is a slow aperture lens, and the TC makes it even slower.

Originally posted by clackers

TCs are designed for fast lenses ... f2.8, f4 ...

What no-one seems to be mentioning in this thread is the OP's 55-300 PLM will not autofocus on the TC, as its maximum aperture is narrower than 4.

The only way to extend beyond 300mm with the TC and keep autofocus is to use the DA*300.

**MikeNArk** · 06-10-2022, 06:46 PM

Originally posted by zkarj

What no-one seems to be mentioning in this thread is the OP's 55-300 PLM will not autofocus on the TC, as its maximum aperture is narrower than 4.

The only way to extend beyond 300mm with the TC and keep autofocus is to use the DA*300.

I use the Pentax 1.4 HD teleconverter with my 55-300 PLM and KP without problems in good light.

**UncleVanya** · 06-10-2022, 08:47 PM

Originally posted by zkarj

What no-one seems to be mentioning in this thread is the OP's 55-300 PLM will not autofocus on the TC, as its maximum aperture is narrower than 4.

The only way to extend beyond 300mm with the TC and keep autofocus is to use the DA*300.

People do it all the time. The limits aren’t “hard and fast” the limits are “a guideline” to expectations. It may be less snappy but it’s likely to work if you have the light.

**clackers** · 06-11-2022, 05:23 PM

Originally posted by zkarj

What no-one seems to be mentioning in this thread is the OP's 55-300 PLM will not autofocus on the TC

That's not true, it does, I've used it, so have plenty of other people, doesn't seem like you have, Zkarj.

But it's operating outside of the spec, so there are no promises about its performance.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
K-5 vs MZ-S vs LX vs PZ-1p vs ist*D vs K10D vs K20D vs K-7 vs.......	Steelski	Pentax K-5 & K-5 II	2	06-28-2017 04:59 PM
Kenko Pz-AF SHQ TC 1.5X vs Tamron-F 1.4X Pz-AF MC4	SKwan	Pentax DSLR Discussion	14	01-26-2013 05:17 AM
Wanted - Acquired: Tamron 1.4X TC or Kenko Pz-AF 1.5X SHQ TC	kesong	Sold Items	2	08-22-2012 07:31 PM
For Sale - Sold: Tamron-F AF TC (1.4x Pz-AF MC4) Teleconverter - highest rated TC on this forum	Quazimoto	Sold Items	3	06-17-2012 04:15 AM
For Sale - Sold: Tamron-F AF Tele-Converters (1.4x Pz-AF MC4, 2X Pz-AF BBAR MC7)	dgaies	Sold Items	2	11-02-2010 08:22 AM

06-10-2022, 06:36 PM	#31
zkarj Site Supporter Join Date: Jan 2009 Location: Wellington Posts: 1,290	Originally posted by clackers The DA55-300 is a slow aperture lens, and the TC makes it even slower. Originally posted by clackers TCs are designed for fast lenses ... f2.8, f4 ... What no-one seems to be mentioning in this thread is the OP's 55-300 PLM will not autofocus on the TC, as its maximum aperture is narrower than 4. The only way to extend beyond 300mm with the TC and keep autofocus is to use the DA*300.

06-10-2022, 06:46 PM	#32
MikeNArk Loyal Site Supporter Join Date: Sep 2019 Location: Conway, Arkansas Posts: 15,105	Originally posted by zkarj What no-one seems to be mentioning in this thread is the OP's 55-300 PLM will not autofocus on the TC, as its maximum aperture is narrower than 4. The only way to extend beyond 300mm with the TC and keep autofocus is to use the DA*300. I use the Pentax 1.4 HD teleconverter with my 55-300 PLM and KP without problems in good light.

06-10-2022, 08:47 PM	#33
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401	Originally posted by zkarj What no-one seems to be mentioning in this thread is the OP's 55-300 PLM will not autofocus on the TC, as its maximum aperture is narrower than 4. The only way to extend beyond 300mm with the TC and keep autofocus is to use the DA*300. People do it all the time. The limits aren’t “hard and fast” the limits are “a guideline” to expectations. It may be less snappy but it’s likely to work if you have the light.

06-11-2022, 05:23 PM	#34
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by zkarj What no-one seems to be mentioning in this thread is the OP's 55-300 PLM will not autofocus on the TC That's not true, it does, I've used it, so have plenty of other people, doesn't seem like you have, Zkarj. But it's operating outside of the spec, so there are no promises about its performance.