Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-20-2013, 01:48 AM   #1
Pentaxian
littledrawe's Avatar

Join Date: Jan 2010
Location: Red Rock
Photos: Gallery | Albums
Posts: 2,434
Let's Talk About Teleconverter Bokeh...

I would like to see samples of other converters to see what they produce. This shot is the Tamron Adaptall 2 1.4X TC and it got me thinking about how bokeh is affected by the TC. I don't like the background of the shot and I know there are things that I can do to change it in PP but I would rather not have to if I can avoid it. Does anyone have any unprocessed TC bokeh images to give us an idea of which ones may be better than others.



10-20-2013, 06:03 AM   #2
Senior Member
Powerstroke 7.3's Avatar

Join Date: Jan 2013
Location: Crestview Fl
Photos: Albums
Posts: 100
I have the Rokunar 1.7 tele convertor and if you look at this post
https://www.pentaxforums.com/forums/post-your-photos/237062-nature-quick-trip-zoo.html#post2509461
, the third and forth shots have some nice bokeh. I am using it with my DAL 55-300. Also here are some more. The 1st is equivalent to 323mm, 2nd is 442mm and the 3rd is 510mm.
Attached Images
View Picture EXIF
PENTAX K-30  Photo 
View Picture EXIF
PENTAX K-30  Photo 
View Picture EXIF
PENTAX K-30  Photo 
10-20-2013, 07:13 AM   #3
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
You need to remember that the teleconverter just doubles the image, so I would expect you are seeing the same bokeh as your lens
10-20-2013, 09:23 AM   #4
Site Supporter




Join Date: Jan 2013
Location: Northern Wisconsin
Posts: 691
QuoteOriginally posted by littledrawe Quote
I would like to see samples of other converters to see what they produce. This shot is the Tamron Adaptall 2 1.4X TC and it got me thinking about how bokeh is affected by the TC. I don't like the background of the shot and I know there are things that I can do to change it in PP but I would rather not have to if I can avoid it. Does anyone have any unprocessed TC bokeh images to give us an idea of which ones may be better than others.
WOW! what a fantastic shot... I'm not sure that the bokeh is all that bad but rather that it is distracting the eye away from the hawk.... might not make much difference which convertor you use? Great picture though...

10-20-2013, 11:45 AM   #5
Site Supporter




Join Date: Mar 2012
Location: Minnesota
Photos: Gallery
Posts: 20
Teleconverter bokeh

Here is one from my film days.
lens 55mm Mamiya-Sekor f/1.4 2X screw mount teleconverter Vivitar I think.
f stop unrecorded. Distance from back seat to front seat of a canoe.
The corner & maybe edges have the teleconverter swirl even for things in focus, the ojects in the center are so out of focus
that bokeh may not apply. There are mid distance brush limbs to check for bokeh.
I had to reduce by file to less than 900 MB to upload it, my scanned file was 7.42MB, I hope there is still enough detail yo
show the teleconverter effects.

dean45
Attached Images
 
10-20-2013, 12:37 PM   #6
Loyal Site Supporter
RollsUp's Avatar

Join Date: Apr 2008
Location: AK USA
Photos: Gallery
Posts: 1,389
Here's few taken with my DA* 300 with an AFA 1.7 TC





10-22-2013, 12:47 AM   #7
Pentaxian
littledrawe's Avatar

Join Date: Jan 2010
Location: Red Rock
Photos: Gallery | Albums
Posts: 2,434
Original Poster
QuoteOriginally posted by Lowell Goudge Quote
You need to remember that the teleconverter just doubles the image, so I would expect you are seeing the same bokeh as your lens
Lowell, is this really true? Each lens produces a different bokeh depending on the optical elements and construction so wouldn't adding extra glass change the "look"?

QuoteOriginally posted by woodywesty Quote
WOW! what a fantastic shot... I'm not sure that the bokeh is all that bad but rather that it is distracting the eye away from the hawk.... might not make much difference which convertor you use? Great picture though...
Thank you for the compliment. I will eventually try to make the background more pleasing in PP but I just wanted an example of what I think may be happening.

QuoteOriginally posted by dean45 Quote
Here is one from my film days.
Thanks for the shot, I love that it was taken when that life jacket was probably top of the line product.

QuoteOriginally posted by RollsUp Quote
Here's few taken with my DA* 300 with an AFA 1.7 TC
Great subjects! Since you happen to have what many consider the cream of the crop out of current telephoto lenses and a great converter, how about some shots w/out the converter and the the same shots with it for comparison??
10-22-2013, 03:08 PM   #8
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
QuoteOriginally posted by littledrawe Quote
Lowell, is this really true? Each lens produces a different bokeh depending on the optical elements and construction so wouldn't adding extra glass change the "look"?
Remember though the TC function is to take a focused image and make it twice as big. It is added to an already complete lens, as opposed to being part of the complete lens

Maybe try an experiment. Take a shot with a lens, then sake a shot with the same lens, at the same focal length if it is a zoom, and from the same spot take a shit with the lens plus TC. Then crop the lens image to the same field of view and tell me what you see.

I'll bet that the images are the same.

10-22-2013, 06:51 PM   #9
Pentaxian
panoguy's Avatar

Join Date: Sep 2007
Location: Washington, D.C.
Photos: Gallery | Albums
Posts: 3,279
QuoteOriginally posted by Lowell Goudge Quote
and from the same spot take a shit with the lens plus TC.
I'll tell you what I see, but it won't be pretty...
10-22-2013, 07:05 PM   #10
Site Supporter
G_Money's Avatar

Join Date: Jul 2007
Location: London, Ontario, Canada
Posts: 593


Here's a crop of an image with an A*600mm + 1.4X-L converter. I think it looks a little like the donut bokeh from a mirror lens. I'm guessing it's because of the way the tc extends its optics into the body of the host lens. I'm pretty sure that if the tc was removed, the oof highlights would look different.
10-22-2013, 07:53 PM - 1 Like   #11
Veteran Member
borno's Avatar

Join Date: Nov 2006
Location: md-usa
Photos: Gallery | Albums
Posts: 2,580
It seems to me, and I use TC's frequently, they can do some strange things to the OOF highlights and foliage when they are at a particular distance from the in focus area. Even a lens with good results with no TC can get crazy. I still usually get good results, but here are a couple with a canon 300mm and a 2x.





same combo with different conditions:


10-23-2013, 05:49 AM   #12
Senior Member




Join Date: Feb 2011
Location: Brooklyn, New York
Posts: 108
QuoteOriginally posted by panoguy Quote
I'll tell you what I see, but it won't be pretty...

That's one of the funniest typo-response combinations I've ever read on here, I nearly spit water everywhere
10-23-2013, 11:47 AM   #13
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
QuoteOriginally posted by G_Money Quote

Here's a crop of an image with an A*600mm + 1.4X-L converter. I think it looks a little like the donut bokeh from a mirror lens. I'm guessing it's because of the way the tc extends its optics into the body of the host lens. I'm pretty sure that if the tc was removed, the oof highlights would look different.
I shoot a lot with either the sigma TCs which extend just a little into lenses, or with the SMC-F 1.7x converter but I have to admit I never see artifacts like what you show

Mostly, what is see really is only perhaps slightly increased lateral CA. And not much longitudinal CA. I think however, that may be because I never seem to have hot spots or out of focus point sources in the background. What has made your bokeh so bad is really the very small but out of focus bright spots
10-23-2013, 12:48 PM   #14
Site Supporter
G_Money's Avatar

Join Date: Jul 2007
Location: London, Ontario, Canada
Posts: 593
QuoteOriginally posted by Lowell Goudge Quote
What has made your bokeh so bad is really the very small but out of focus bright spots
Yes, it's quite noticeable in the specular highlights on some shots, otherwise I think the bokeh is usually normal. But I think it's safe to say that it's a result of the tc.
10-23-2013, 02:45 PM   #15
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,312
QuoteOriginally posted by G_Money Quote
Yes, it's quite noticeable in the specular highlights on some shots, otherwise I think the bokeh is usually normal. But I think it's safe to say that it's a result of the tc.
What about diffraction patterns from the cusps in the aperture? Just a thought
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!
bokeh, k-mount, pentax lens, shot, slr lens, tc
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Getting started with film... let's talk about the film film! KeithM2 Pentax Film SLR Discussion 18 02-26-2012 09:22 PM
Let's Talk Turkey.... magkelly General Talk 20 11-25-2011 03:08 PM
Let's talk about Sigma 24 1.8 EX Asph Macro mauriziolippa Pentax SLR Lens Discussion 12 03-05-2011 07:30 PM
Let's talk about the Maine GOP's new party platform for a moment... deadwolfbones General Talk 49 05-13-2010 07:17 PM
Poll: Let's talk about bokeh Syb Photographic Technique 21 11-01-2007 12:49 AM



All times are GMT -7. The time now is 07:09 PM. | See also: NikonForums.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