After Paul's comment about using the 2x on the 150-450 I looked into them a bit. It seems as if the Pentax 2x will crop on FF, but that Tamron has one that won't. Also, after looking at some posts by folks who pixel peep, that when it comes to fine detail, the teleconverter doesn't actually gain you anything in detail in the final image over cropping. In short, when the sensor is outresolving the lens, a 2x TC will give you four times as many pixels, but each pixel is only 1/4 as good. It seems to me, that if you are shooting professionally, where post processing time is of the essence, then if the detail in the final image is about the same, then the TC is definitely worth it, particularly if you aren't shooting wide open anyways, and the loss of a stop or two doesn't matter. My only real experience with this was many years ago, I did some tests, photographing the moon, and the final images, cropped to the size of the moon and processed to the same number of pixels, if anything the TC images were degraded over the cropped images. Back in the days of film, where film, particularly tri-X, didn't out resolve the lens, then the TCs would make a significant improvement. So, do TCs help? If so when? Thoughts? Experience? If so, which ones do the best? I can definitely understand that even if a TC isn't a full 24x36, when I actually would use one, I'd go to a crop sensor first, so that doesn't really matter. -- Larry Colen LRC@red4est.com http://red4est.com/lrc

I don't recall where this was much discussed, but wherever, it was between people who know far more than I about the finer things in photography. The general consensus was that most teleconverters do degrade the image somewhat, 2x converters being quite a bit worse than 1.4 converters, and that one is better off to shoot without one and crop the image as part of processing it. This was prior to the vast improvements we've seen in AI driven image resizing, so my own opinion, which is probably not worth much, is to forget about the 2x converter and if you have enough pixels to crop, do it, and if you have to use an AI resizing tool to give you enough pixels to crop with, resize and then crop. Obviously this gives some limitations. For example, with the 2x converter you will bring a very distant subject close enough that resizing will give a more usable image, and this is a consideration that must be accounted for.  Matched multipliers seem to be the exception to this as do the higher end units. I have the Rear Converter A 1.4X-L which I use from time to time with my A*600/5.6 and it seems fine. It is well matched to the lens though. When I went on my Fuji buying spree a couple of years back I purchased their 1.4 teleconverter to stretch out my 50-140/2.8 and it also seems quite good, but when I was researching it I was told to definitely stay away from their 2x converter. Apparently it isn't up to the red badge Fuji lenses and degrades them quite a bit. HTH bill On 6/26/2025 1:39 PM, Larry Colen wrote: > After Paul's comment about using the 2x on the 150-450 I looked into > them a bit. > > It seems as if the Pentax 2x will crop on FF, but that Tamron has one > that won't. > > Also, after looking at some posts by folks who pixel peep, that when > it comes to fine detail, the teleconverter doesn't actually gain you > anything in detail in the final image over cropping.  In short, when > the sensor is outresolving the lens, a 2x TC will give you four times > as many pixels, but each pixel is only 1/4 as good. > > It seems to me, that if you are shooting professionally, where post > processing time is of the essence, then if the detail in the final > image is about the same, then the TC is definitely worth it, > particularly if you aren't shooting wide open anyways, and the loss of > a stop or two doesn't matter. > > My only real experience with this was many years ago, I did some > tests, photographing the moon, and the final images, cropped to the > size of the moon and processed to the same number of pixels, if > anything the TC images were degraded over the cropped images. Back in > the days of film, where film, particularly tri-X, didn't out resolve > the lens, then the TCs would make a significant improvement. > > So, do TCs help? If so when?  Thoughts? Experience? > > If so, which ones do the best? > > I can definitely understand that even if a TC isn't a full 24x36, when > I actually would use one, I'd go to a crop sensor first, so that > doesn't really matter. >

LRC

Thanks Bill, That pretty much confirms my thoughts. LRC On 2025-06-26 13:53, Bill wrote: > I don't recall where this was much discussed, but wherever, it was > between people who know far more than I about the finer things in > photography. > > The general consensus was that most teleconverters do degrade the > image somewhat, 2x converters being quite a bit worse than 1.4 > converters, and that one is better off to shoot without one and crop > the image as part of processing it. > > This was prior to the vast improvements we've seen in AI driven image > resizing, so my own opinion, which is probably not worth much, is to > forget about the 2x converter and if you have enough pixels to crop, > do it, and if you have to use an AI resizing tool to give you enough > pixels to crop with, resize and then crop. > > Obviously this gives some limitations. For example, with the 2x > converter you will bring a very distant subject close enough that > resizing will give a more usable image, and this is a consideration > that must be accounted for. > >  Matched multipliers seem to be the exception to this as do the higher > end units. I have the Rear Converter A 1.4X-L which I use from time to > time with my A*600/5.6 and it seems fine. It is well matched to the > lens though. > > When I went on my Fuji buying spree a couple of years back I purchased > their 1.4 teleconverter to stretch out my 50-140/2.8 and it also seems > quite good, but when I was researching it I was told to definitely > stay away from their 2x converter. Apparently it isn't up to the red > badge Fuji lenses and degrades them quite a bit. > > HTH > > bill > > On 6/26/2025 1:39 PM, Larry Colen wrote: >> After Paul's comment about using the 2x on the 150-450 I looked into >> them a bit. >> >> It seems as if the Pentax 2x will crop on FF, but that Tamron has one >> that won't. >> >> Also, after looking at some posts by folks who pixel peep, that when >> it comes to fine detail, the teleconverter doesn't actually gain you >> anything in detail in the final image over cropping.  In short, when >> the sensor is outresolving the lens, a 2x TC will give you four times >> as many pixels, but each pixel is only 1/4 as good. >> >> It seems to me, that if you are shooting professionally, where post >> processing time is of the essence, then if the detail in the final >> image is about the same, then the TC is definitely worth it, >> particularly if you aren't shooting wide open anyways, and the loss of >> a stop or two doesn't matter. >> >> My only real experience with this was many years ago, I did some >> tests, photographing the moon, and the final images, cropped to the >> size of the moon and processed to the same number of pixels, if >> anything the TC images were degraded over the cropped images. Back in >> the days of film, where film, particularly tri-X, didn't out resolve >> the lens, then the TCs would make a significant improvement. >> >> So, do TCs help? If so when?  Thoughts? Experience? >> >> If so, which ones do the best? >> >> I can definitely understand that even if a TC isn't a full 24x36, when >> I actually would use one, I'd go to a crop sensor first, so that >> doesn't really matter. >> > -- > %(real_name)s Pentax-Discuss Mail List > To unsubscribe send an email to pdml-leave@pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions. -- Larry Colen LRC@red4est.com http://red4est.com/lrc