Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-04-2021, 11:09 AM   #136
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 40,442
QuoteOriginally posted by thibs Quote
Agreed. A 300/2.8 with converters would morph into a 450/4 and 600/5.6.
420 ƒ/4 with a 1.4. 600 ƒ5.6 doesn't work well with APS-c, maybe for FF at least with my 300 2.8.


Last edited by normhead; 10-04-2021 at 11:28 AM.
10-04-2021, 12:53 PM   #137
Pentaxian
reh321's Avatar

Join Date: Nov 2014
Location: South Bend, IN, USA
Photos: Gallery | Albums
Posts: 23,126
QuoteOriginally posted by normhead Quote
420 ƒ/4 with a 1.4. 600 ƒ5.6 doesn't work well with APS-c, maybe for FF at least with my 300 2.8.
Then I guess you need to get a modern “APS-C” camera.
All the latest Pentax cameras seem to focus just fine.
10-04-2021, 01:55 PM   #138
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 40,442
QuoteOriginally posted by reh321 Quote
Then I guess you need to get a modern “APS-C” camera.
All the latest Pentax cameras seem to focus just fine.
Oh, the focus isn't the issue. It's the 2x degrading the image past the point where you get the same detail with the 1.7x. The larger K-1 pixels do just fine with the 2x.
10-04-2021, 01:58 PM   #139
Pentaxian
MMVIII's Avatar

Join Date: Mar 2008
Location: EU
Posts: 1,121
QuoteOriginally posted by thibs Quote
Agreed. A 300/2.8 with converters would morph into a 450/4 and 600/5.6.
I'm not a tele guy, but this seems to be a very clever and effective option. One lens, two (optimized dedicated) converters to cover three tele focal lengths with faster aperture and in the 2x option more reach than the zoom, which this way would also not be cannibalized. They should definitely do that. Could this be made cheaper than the 560 has been?


Last edited by MMVIII; 10-04-2021 at 02:04 PM.
10-04-2021, 02:23 PM   #140
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 40,442
QuoteOriginally posted by MMVIII Quote
I'm not a tele guy, but this seems to be a very clever and effective option. One lens, two (optimized dedicated) converters to cover three tele focal lengths with faster aperture and in the 2x option more reach than the zoom, which this way would also not be cannibalized. They should definitely do that. Could this be made cheaper than the 560 has been?
The level of sharpness you'd have to build into the original lens to be able to handle a 2x converter might make the cost prohibitive. I know people do it, but usually with lenses like 70-200s which can be made incredibly sharp for a reasonable price. It's hard to imagine the price of a 300 or 400 made to that level of sharpness.
10-04-2021, 02:38 PM - 1 Like   #141
Moderator
Loyal Site Supporter
Wheatfield's Avatar

Join Date: Apr 2008
Location: The wheatfields of Canada
Posts: 15,903
QuoteOriginally posted by MMVIII Quote
I'm not a tele guy, but this seems to be a very clever and effective option. One lens, two (optimized dedicated) converters to cover three tele focal lengths with faster aperture and in the 2x option more reach than the zoom, which this way would also not be cannibalized. They should definitely do that. Could this be made cheaper than the 560 has been?
What is old is new again. Back in the 70s, I believe, Nikon made just that very thing. IIRC, it was a rear lens group that had the focusing and aperture mechanisms, and 2 or 3 interchangeable front groups that gave different telephoto lengths.
There isn't a snowball's chance in hell that anything similar will happen from Pentax, but it is nice to dream.
10-04-2021, 02:49 PM   #142
Pentaxian
KiloHotelphoto's Avatar

Join Date: Jan 2015
Location: Glen Mills, PA
Photos: Albums
Posts: 1,027
QuoteOriginally posted by normhead Quote
The level of sharpness you'd have to build into the original lens to be able to handle a 2x converter might make the cost prohibitive. I know people do it, but usually with lenses like 70-200s which can be made incredibly sharp for a reasonable price. It's hard to imagine the price of a 300 or 400 made to that level of sharpness.
Exactly, and with higher pixel density cameras it makes it harder to develop.

I rarely use my 2x only when it's not safe to get closer to something or if I'm just bored and want to mess around. I've got some shots that have turned out sharp with it, mostly small birds that are pretty close and just trying to fill the frame. But when putting it on the 600 and then being 1200mm F8 and shooting something further away you also deal with more atmospheric distortions with heat haze and shots aren't sharp.

10-04-2021, 10:43 PM - 1 Like   #143
Pentaxian
MMVIII's Avatar

Join Date: Mar 2008
Location: EU
Posts: 1,121
QuoteOriginally posted by thibs Quote
Agreed. A 300/2.8 with converters would morph into a 450/4 and 600/5.6.
QuoteOriginally posted by normhead Quote
The level of sharpness you'd have to build into the original lens to be able to handle a 2x converter might make the cost prohibitive. I know people do it, but usually with lenses like 70-200s which can be made incredibly sharp for a reasonable price. It's hard to imagine the price of a 300 or 400 made to that level of sharpness.
QuoteOriginally posted by Wheatfield Quote
What is old is new again. Back in the 70s, I believe, Nikon made just that very thing. IIRC, it was a rear lens group that had the focusing and aperture mechanisms, and 2 or 3 interchangeable front groups that gave different telephoto lengths.
There isn't a snowball's chance in hell that anything similar will happen from Pentax, but it is nice to dream.
Fair points, while I still think that this is not an unsolveable technical problem today. Sure - at which price point. On the other hand, if the 560 was a 5+k lens then there is some room to start with.
But, at the end of the day, as clever as it would be, I also don't see it coming.
10-05-2021, 03:59 PM   #144
Loyal Site Supporter
Loyal Site Supporter




Join Date: Nov 2015
Photos: Albums
Posts: 4,186
QuoteOriginally posted by Wheatfield Quote
What is old is new again. Back in the 70s, I believe, Nikon made just that very thing. IIRC, it was a rear lens group that had the focusing and aperture mechanisms, and 2 or 3 interchangeable front groups that gave different telephoto lengths.
There isn't a snowball's chance in hell that anything similar will happen from Pentax, but it is nice to dream.
My Kodak Retina has a 50mm lens that turns into a 35mm or 85mm with a swap of the front elements.
And loads of rangefinders had similar (but simpler) wide angle and telephoto converters that screwed or clipped on the front.

The Lomography folks are selling the same thing for SLRs now... (and have been for a few years, I guess).

I even sold a $30 clip-on plastic wide angle lens (designed for camcorders) to real estate agents buying Kodak DC40 digital cameras in the 1990s... Interchangeable lens mirrorless in 1995

In telephoto land was it Novoflex that had a lens with swappable elements? To me that always seemed better than the simple, cheap telephotos with even cheaper 2x converters...

-Eric
10-05-2021, 04:10 PM   #145
Moderator
Loyal Site Supporter
Wheatfield's Avatar

Join Date: Apr 2008
Location: The wheatfields of Canada
Posts: 15,903
QuoteOriginally posted by TwoUptons Quote
My Kodak Retina has a 50mm lens that turns into a 35mm or 85mm with a swap of the front elements.
And loads of rangefinders had similar (but simpler) wide angle and telephoto converters that screwed or clipped on the front.

The Lomography folks are selling the same thing for SLRs now... (and have been for a few years, I guess).

I even sold a $30 clip-on plastic wide angle lens (designed for camcorders) to real estate agents buying Kodak DC40 digital cameras in the 1990s... Interchangeable lens mirrorless in 1995

In telephoto land was it Novoflex that had a lens with swappable elements? To me that always seemed better than the simple, cheap telephotos with even cheaper 2x converters...

-Eric
That's ki d of the reverse of my point. To do it today with anything better than cheap kit zoom quality, it's going to be expensive. For Pentax to do it based on how many they can expect to sell, it will rival buying a seat on Jeff Bezos' rocket ship.
10-05-2021, 04:33 PM - 1 Like   #146
Loyal Site Supporter
Loyal Site Supporter




Join Date: Nov 2015
Photos: Albums
Posts: 4,186
QuoteOriginally posted by Wheatfield Quote
That's ki d of the reverse of my point. To do it today with anything better than cheap kit zoom quality, it's going to be expensive. For Pentax to do it based on how many they can expect to sell, it will rival buying a seat on Jeff Bezos' rocket ship.
If it would cost the same as a trip on one of Bezo's rockets, we just need to convince William Shatner to fund it

I tend to agree. Unless they do something wacky, like Canon's new inexpensive telephotos, but SLR viewfinders don't like those slow apertures, so Pentax can't play the same trick...

And I don't think Ricoh has the expertise to do something like the old 400-600 mirror lens in a modern form... and it would have the same problem as above...

Unless something completely unexpected materializes, I think we're stuck with the 150-450 as the longest lens for the foreseeable future...

-Eric
10-05-2021, 11:38 PM   #147
Pentaxian
thibs's Avatar

Join Date: Jun 2007
Location: Belgium
Photos: Albums
Posts: 7,001
QuoteOriginally posted by TwoUptons Quote
If it would cost the same as a trip on one of Bezo's rockets, we just need to convince William Shatner to fund it

I tend to agree. Unless they do something wacky, like Canon's new inexpensive telephotos, but SLR viewfinders don't like those slow apertures, so Pentax can't play the same trick...

And I don't think Ricoh has the expertise to do something like the old 400-600 mirror lens in a modern form... and it would have the same problem as above...

Unless something completely unexpected materializes, I think we're stuck with the 150-450 as the longest lens for the foreseeable future...

-Eric
Yep, could be stuck with worse though
10-06-2021, 12:21 AM   #148
Veteran Member




Join Date: Jun 2010
Location: Genf
Posts: 1,138
QuoteOriginally posted by MMVIII Quote
I'm not a tele guy, but this seems to be a very clever and effective option. One lens, two (optimized dedicated) converters to cover three tele focal lengths with faster aperture and in the 2x option more reach than the zoom, which this way would also not be cannibalized. They should definitely do that. Could this be made cheaper than the 560 has been?
I wonder how AF will behave with a 600/5.6 reached with a converter
Not too optimistic about the result
10-06-2021, 02:26 AM   #149
Pentaxian
MMVIII's Avatar

Join Date: Mar 2008
Location: EU
Posts: 1,121
QuoteOriginally posted by fsge Quote
I wonder how AF will behave with a 600/5.6 reached with a converter
Not too optimistic about the result
I can understand that this question comes up, but my curious mind is asking "why?".
Let's assume the sharpness and contrast are not a problem, at regular focal length they are amazing and the converter does not decrease it too much. Definitely not beyond the level of a zoom at such a focal length. The effective aperture is still at 5,6, not worse than the 560 has been. Why should the phase detection AF function any different from a regularly attached lens, if the AF-motor is in the lens and the focus group to move is physically the same? Of course there are other practical challenges to AF at these focal lengths like keeping a subject in the image frame etc.
Again, not claiming this will be produced at any time, just curious about the physical background of automatically assumed "restrictions"...
10-06-2021, 10:06 AM   #150
Pentaxian
thibs's Avatar

Join Date: Jun 2007
Location: Belgium
Photos: Albums
Posts: 7,001
Because it the past Pentax AF reacted badly to converters.
Of course now that they do offer one (although only APS), they mostly fixed the issue. At least with their own converter.
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!
560mm, 600mm, camera, da, da 55-300 plm, da560, diameter, front, image, kg, length, lens, lenses, pentax, pentax news, pentax rumors, plm, post, pound, price, range, shutter, subject, sync, telephoto lens design, tripod, weight
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
New half mirror OVF&EVF Hybrid Viewfinder patent OoKU Pentax News and Rumors 45 01-08-2021 12:43 PM
Is the D FA* 50/1.4 a Pentax/ Ricoh design or a Tokina design? Wheatfield Pentax SLR Lens Discussion 60 06-28-2020 03:15 PM
ricoh files patent on 2 Q lens designs and on 4/3 design! shaolen Pentax News and Rumors 20 08-21-2014 12:03 AM
Fuji files a new patent for sensor design...... Eric Auer Canon, Nikon, Sony, and Other Camera Brands 1 01-30-2014 03:43 AM
FA Limited lens series won the 2010 Good Design Long Life Design Award Patriot Pentax SLR Lens Discussion 26 11-29-2010 06:16 AM



All times are GMT -7. The time now is 04:24 PM. | 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