Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-14-2014, 08:44 AM - 2 Likes   #16
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 24,390
To me there are a couple of issues,

- the price will come down.

-Whether you buy one or not, it's there. For years people have been whining about no SDM AF capable TC for Pentax. Now there is one.

-I've watched my Canon shooting buddy shoot with a 70-200 and 2x converter for his Canon for years with great results. Yet the consensus on this site was that there wasn't a TC available for Pentax that didn't degrade the IQ. I've found no indication that this TC degrades IQ used on a good lens. This TC puts me on par with what he's shooting, with better resolution and approx. the same reach and ƒ-stop.

-The other great use of TC's is macro work, if you have a 1:1 macro lens (we have two in the family) the TC enlarges the image even further. Either Pentax TC is a great addition to any macro-shooter.

-We have no primes over 90mm... but we have two excellent ƒ2.8 telephoto primes (also our macros), Use of the 1.4 gives us a 98mm ƒ4 prime and and a 126mm prime.

-We haven't had the purple fringing issues with the A-400 we have with the 1.7 TC yet. And limiting the loss of Aperture to one F stop make a difference focusing the A-400 TC combo. I'm much more confident using the A-400 with the 1.4 TC.

-My A-400 isn't weather sealed. The DA* 60-250 plus 1.4 at 350mm is.

I'll be the first to admit, for a lot of shooters, none of those things is very important, I'd be the last to say it should be a part of everyone's kit... but for what it does for us, the $600 doesn't seem that bad. My only regret is that because we bought it, there's no money in the lens account and my Rokinon tilt shift, which I've craved for years, will now have to wait. ( It's just recently become available in Pentax mount.) For any given shooter, there could be a lot of pieces of equipment out there that would be more useful to you. That's a decision each of us makes on his/her own, but the decision shouldn't be based on some kind of feeling that the TC isn't up to scratch. If you want a TC, there are lots of reason why this should be it.

03-14-2014, 09:57 AM   #17
Pentaxian
Barry Pearson's Avatar

Join Date: Jul 2013
Location: Stockport
Posts: 870
QuoteOriginally posted by normhead Quote
-The other great use of TC's is macro work, if you have a 1:1 macro lens (we have two in the family) the TC enlarges the image even further. Either Pentax TC is a great addition to any macro-shooter.
Or, of course, keep the image the same size but get further from the subject. Reduces the risk of spooking the subject and/or casting shadows on the subject.

(The Pentax 1.4x Teleconverter on the DA* 300mm f/4 isn't strictly a Macro lens, but focusing down to 4.6 feet from the sensor - is that bigger than 1/3rd size on the sensor? - makes it very good for some wildlife).
03-14-2014, 10:40 AM   #18
Veteran Member
enoxatnep's Avatar

Join Date: Nov 2008
Location: The edge of nowhere, Alberta, Canada
Photos: Gallery | Albums
Posts: 467
Original Poster
QuoteOriginally posted by normhead Quote
-The other great use of TC's is macro work, if you have a 1:1 macro lens (we have two in the family) the TC enlarges the image even further. Either Pentax TC is a great addition to any macro-shooter.
Hmmm, another compelling argument in favor of this TC.
03-14-2014, 11:30 AM   #19
Pentaxian
Barry Pearson's Avatar

Join Date: Jul 2013
Location: Stockport
Posts: 870
QuoteOriginally posted by Stone G. Quote
Oh, but that's what a 1.4X TC does: It magnifies the viewing angle by a factor of 1.4 and thus, also the diameter of the image circle. You can test that with any 1.4X teleconverter on a film- or (CaNikon) DSLR body.
Yes, a Teleconverter expands the image circle. And if it is designed for an FF camera, the resultant image circle will typically be at least FF size.

But a Teleconverter designed for APSC-sensor cameras could be designed in a more limited way. In principle it could expand just the centre portion, not the whole, of the APSC image, until it covers an APSC-sensor but not necessarily much more. In other words, it might vignette and/or have bad image quality on an FF camera, as long as it still covers an APSC-sensor.

My tests of a few of my lenses tell me that the new Pentax Teleconverter doesn't vignette on a film camera. So far so good. I hope that the image quality of the expanded image will be good to the corners too. Sooner or later, I expect to test this by shooting a film, and I will publish the results.

I am impressed at the number of Pentax lenses that are compatible with the new Teleconverter. I guess that inside Ricoh this Teleconverter has been considered as part of the release road-map of a potential FF camera. It would enable some people to adopt such a camera before there has been time to produce a complete set of FF lenses.

03-14-2014, 01:26 PM   #20
Pentaxian




Join Date: Sep 2009
Location: Southern California
Photos: Gallery | Albums
Posts: 3,181
QuoteOriginally posted by Gray Quote
Tamron 1.4x PZ converter.
QuoteOriginally posted by Gray Quote
My experience with the Tamron has been great, especially with the DA* 60-250. I agree that the Sigma does tend to hunt when light is not good. But here are two examples at extreme focal lengths of SDM/HSM lenses that I quickly dug out which I know were taken with the Tamron 1.4x.
These images illustrate exactly why I sold my Tamron 1.4x PZ converter. The colors and overall IQ were noticeably degraded when using it on my quality glass. So far, from comments and images posted here, this doesn't appear to be the case with the new Pentax HD TC. That's why I'm actually considering shelling out $600 for one, expensive as it may be.

The DA*60-250 takes overall nicer images on its own than that 2nd example. There's nothing wrong with your photo - it was a nice catch - but optically it's degraded. I also see "the look" of the Tamron TC being imposed on the first image (though I'm not as familiar with that lens).
03-14-2014, 02:44 PM   #21
Veteran Member
stormtech's Avatar

Join Date: Jan 2011
Location: In the boonies (NW Penna)
Photos: Gallery | Albums
Posts: 5,670
Ok folks - I need some help here. Brain fog is settling in as usual and trying to figure this out. I want to see what the magnification difference would be with this TC on my DA* 300.

The 1.4x should make an approximately 40% larger image. So I took a look at recent image from my DA* 300 on my K-5IIs. The original image size is 4928x3264. If I crop this image by 40% I would have an image of 2957x1958. I don't know if I am way off base here or not....

So I did above said crop on this image, then of course downsized them to view on the web. Here is my result. First is the native image - the second cropped by 40%:

Is this a true life example of what I would get using the TC?
03-14-2014, 02:50 PM   #22
Senior Moderator
Loyal Site Supporter
Parallax's Avatar

Join Date: Apr 2008
Location: South Dakota
Photos: Gallery
Posts: 15,312
If you've enlarged 40%, reducing that enlargement 40% doesn't get you back to the start. 100 enlarged 40% is 140. reducing 140 by 40% (.4*140=56) leaves 84.
By pixel measurement on my monitor the larger bird is about 60% larger than the smaller, and that's consistent with the math you used. I believe the second picture needs to be 3520 pixels wide

Last edited by Parallax; 03-14-2014 at 03:15 PM.
03-14-2014, 02:54 PM   #23
Veteran Member
stormtech's Avatar

Join Date: Jan 2011
Location: In the boonies (NW Penna)
Photos: Gallery | Albums
Posts: 5,670
QuoteOriginally posted by Parallax Quote
If you've enlarged 40%, reducing that enlargement 40% doesn't get you back to the start. 100 enlarged 40% is 140. reducing 140 by 40% (.4*140=56) leaves 84.
100 * 1.4 is 140. 140 divided by 1.4 is 100.
Oh boy......that is all going way over my fogged head right now.......

So if you could help me with this, what would I crop the original 4928x3264 image to so I could get an idea of what the TC would do for me?

03-14-2014, 03:05 PM   #24
Senior Moderator
Loyal Site Supporter
Parallax's Avatar

Join Date: Apr 2008
Location: South Dakota
Photos: Gallery
Posts: 15,312
I've updated my post. I think the second picture needs to be cropped to 3520 pixels wide, not 2957. (4928/1.4)
03-14-2014, 03:18 PM   #25
Veteran Member
stormtech's Avatar

Join Date: Jan 2011
Location: In the boonies (NW Penna)
Photos: Gallery | Albums
Posts: 5,670
QuoteOriginally posted by Parallax Quote
I've updated my post. I think the second picture needs to be cropped to 3520 pixels wide, not 2957. (4928/1.4)
Ok - makes some sense to me now.....here is my try with the second image @ 3520:

Thanks for helping me out Paralax!
03-14-2014, 03:20 PM   #26
Senior Moderator
Loyal Site Supporter
Parallax's Avatar

Join Date: Apr 2008
Location: South Dakota
Photos: Gallery
Posts: 15,312
That's it! It measures 40% bigger.
03-14-2014, 04:08 PM   #27
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 24,390
OK here's the best way to explain it. Say your sensor is 5000 pixels across and 3000 deep. You take the first picture. With that image you crop it 40% to 4000 pixels wide. Your resolution is probably about 2200, lw/ph before you crop. You have to reduce your resolution by 40% because you've cropped it. So now your resolution is about 1400to 1600, because you've cropped 40% of what your image resolved.
Assuming a high quality lens... you put your TC on and take the picture that is about the same as your cropped version of the TC less image.
You now have the full 2200 lw/ph your camera is capable of, you you have an image with 2200 lw/ph instead of 1400-1500. You've increased the subject resolution about 40%.

Depending on the lens, you may not get the whole 40%, but you will see an improvement, with this TC. I've heard others say that with their TCs you could actually get a better image just enlarging the image taken with the same lens and no TC. But with both the Pentax 1.4 and 1.7 that's not the case. The trick is the lens has to be good enough to remain sharp after magnification, and the TC has to be good enough to magnify without loss of resolution. If you use a less capable lens, or a less capable TC you could get negative results. With a capable lens and a good TC, you can increase your resolution within the confines of the copped area.
03-14-2014, 05:01 PM   #28
Veteran Member
stormtech's Avatar

Join Date: Jan 2011
Location: In the boonies (NW Penna)
Photos: Gallery | Albums
Posts: 5,670
Thanks for that Norm - makes sense.

I'm not really trying to beat this to death - I really want the new TC and firmly believe in it. But financial situations have now made me really have to justify every purchase. This is why I needed to do a good comparison to see what magnification result that $600 would buy me. Being I am using a DA* 300 and DA* 60-250 for most of my shooting, I feel it is a close call when I compare cropping a native image taken with those lenses vs. not cropping with the TC.

And while 1.4x or 40% more magnification is substantial, for me having to shoot from a stationary position, it doesn't look like it would make enough difference. I would still have to crop a lot of the images taken with the TC.

Thanks to Paralax for straightening me out quickly. With my first pair of examples I was ready to get my credit card out!
03-14-2014, 06:29 PM   #29
Banned




Join Date: Feb 2014
Location: Perth, Australia
Posts: 120
QuoteOriginally posted by Gray Quote
"Very well" means I press the AF button and the lens focuses + resulting image quality is excellent. You do need good light for AF, but as I live in sunny South Africa where there is plenty of light I usually don't have a problem.

My experience with the Tamron has been great, especially with the DA* 60-250. I agree that the Sigma does tend to hunt when light is not good. But here are two examples at extreme focal lengths of SDM/HSM lenses that I quickly dug out which I know were taken with the Tamron 1.4x.


Sigma 50-500 at 500mm with Tamron 1.4x PZ converter.


DA* 60-250 at 250 with Tamron 1.4x PZ converter.
Great photo's Gray well done. Looks like the new teleconverter is working well.

Last edited by Parallax; 03-14-2014 at 06:47 PM.
03-14-2014, 06:34 PM   #30
Pentaxian
Gray's Avatar

Join Date: Oct 2011
Location: Cape Town
Photos: Gallery
Posts: 384
QuoteOriginally posted by DSims Quote
The colors and overall IQ were noticeably degraded when using it on my quality glass
DSims, you're making work for me, digging up the originals. If anything the photos above show my poor PP skills : but they are 22 MB raw files downscaled twice over to 250 KB 72 ppi jpegs.

I can't upload the original raw files, but here are untouched jpegs of the originals.





Both these are taken handheld at the maximum focal lengths of both lenses, where IQ does tend to degrade, and of small objects (one in shade, the other sunlit) which would otherwise have been even smaller. I posted these here for people to make up their own minds about the Tamron and show that it does work with SDM/HSM, nothing more. Now back to the Pentax converter...

Last edited by Gray; 03-14-2014 at 06:56 PM.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
1.4x, af, converter, cost, da*, euros, justify, k-mount, length, lenses, light, mm, pentax, pentax 1.4x, pentax lens, price, pz, rear, ricoh, sigma, slr lens, tamron, teleconverter, users
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Wanted - Acquired: Pentax Rear Converter-A 1.4X-L Weevil Sold Items 8 02-10-2014 02:32 PM
Pentax 67 1.4X rear converter gurtch Pentax Medium Format 10 10-24-2013 12:00 AM
For Sale - Sold: Pentax SMC A 1.4x-L Rear Converter littledrawe Sold Items 4 03-21-2013 11:18 PM
Wanted - Acquired: 6x7 1.4X teleconverter (rear converter) littledrawe Sold Items 2 01-22-2012 08:01 PM



All times are GMT -7. The time now is 12:19 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top