[ElJamoquio]

I am not talking about the run of the mill consumer grade TC. I am talking about some of the matched ones. For example the adaptall II SP 1.4x or the way Sigma currently does it or the way Pentax used to do it with there manual focus TC. The lens design and tc design are taken into account. That said, 560 is a weird focal length. 400 x 1.4 = 560.

Yup, 560 *is* very odd *AND* the lens looks like the big end can slide backwards so... who knows.

[Chaos_Realm]

In my experience a 400 with a TC is inferior to a 'dedicated' 500/600, even if the 400 is a 'good' lens and the 500/600 is only an 'ok' lens.

The new canon is intriguing to me, though... if the TC/light path is dedicated to a particular lens then the problem should be mitigated.

I think a TC that was optimised for a 400mm F4 would be the best option for pentax at this point. That way they can Kill 3 Birds with the two stones, figuratively speaking. It would provide for a faster end 400mm F4, an acceptable 560mm F5.6 and lastly a 1.4x TC for the K-mount range (although optimised for the 400mm F4) .

I think It would be overall the most cost effective way to cover the super tele range adequately.

[zapp]

Leica sold 560mm lenses for decades. If you call 560 mm odd, what do you call 31, 43, 77, ... mm focal lengths?
If you want to present a long lens, do not present a 400mm lens, but a long lens. 560 maybe short of 600 mm, but really comparable. Most wildlife photographers go for 600 mm these days. A 500x1.4 is not really a replacement for a real 600 lens. The longer the focal length, the more space is available to correct the lens or to keep the price down. I think 560 mm is a fairly good option.

[falconeye]

If you call 560 mm odd

It is a 100mm aperture lens by design. 560mm is a result of their decision to make it a f/5.6 lens.

Personally, I had recommended to do a 500mm f/5.56 lens which has a 90mm aperture and is a lot cheaper to make. But 100mm is a less odd design aka 4".

[Blue]

Leica sold 560mm lenses for decades. If you call 560 mm odd, what do you call 31, 43, 77, ... mm focal lengths?
If you want to present a long lens, do not present a 400mm lens, but a long lens. 560 maybe short of 600 mm, but really comparable. Most wildlife photographers go for 600 mm these days. A 500x1.4 is not really a replacement for a real 600 lens. The longer the focal length, the more space is available to correct the lens or to keep the price down. I think 560 mm is a fairly good option.

We were talking about Pentax lenses. Pentax nor Asahi Optical ever put a 560 lens out before. Plus this Pentax lenses was announced to be 5.6 where as the Telyt-R was available in f4 and f6.8 models. It still makes it a more odd focal length relative to 300, 400, 500 and 600mm lenses given all the major makers have produced those FL. Hirakawa Jun explained the reason behind the 43 and 77 but he didn't design the 31, but yes they are unique to Pentax. The 43 is the diagonal of the full frame 135 film and the 77 is a lucky number between 70-80.

[eurostar]

We were talking about Pentax lenses. Pentax nor Asahi Optical ever put a 560 lens out before. Plus this Pentax lenses was announced to be 5.6 where as the Telyt-R was available in f4 and f6.8 models. It still makes it a more odd focal length relative to 300, 400, 500 and 600mm lenses given all the major makers have produced those FL. Hirakawa Jun explained the reason behind the 43 and 77 but he didn't design the 31, but yes they are unique to Pentax. The 43 is the diagonal of the full frame 135 film and the 77 is a lucky number between 70-80.

Pentax nor Asahi never put a 60-250 lens before, or a 35mm macro, or a 12-24mm, or a 14mm, a 50-135, and many more lenses. Some of those designation are simply old lenght reduce by the crop factor to allow the same file of view, some are due to technical reasons to allow better IQ or to reduce costs... in the end there are not worng of right focal lenght... in a range of xooms you have everyone of them, and use them, at least I don't jump from 85 to 135 to 200 on my 60-250, avoiding the in-between lenght.

By the way, 560/5,6 menas the frontal lens is 10cm in diameter, and probably the choice of the focal lenght was to have not too big and not to expensive glass pieces to produce, to keep down the final cost.

[Blue]

Pentax nor Asahi never put a 60-250 lens before, or a 35mm macro, or a 12-24mm, or a 14mm, a 50-135, and many more lenses. Some of those designation are simply old lenght reduce by the crop factor to allow the same file of view, some are due to technical reasons to allow better IQ or to reduce costs... in the end there are not worng of right focal lenght... in a range of xooms you have everyone of them, and use them, at least I don't jump from 85 to 135 to 200 on my 60-250, avoiding the in-between lenght.

By the way, 560/5,6 menas the frontal lens is 10cm in diameter, and probably the choice of the focal lenght was to have not too big and not to expensive glass pieces to produce, to keep down the final cost.

This discussion wasn't about zoom lenses. It was about prime or unifocal lenses. The point was that 560 is odd and equals 1.4x (400) = 560.

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Last edited by Blue; 05-16-2012 at 09:31 AM.

[ElJamoquio]

It's rather even when you consider 100mm and f/5.6, though.

[Lowell Goudge]

regardless of "odd" or not, I think the real questions should be the following, given that the High ISO performance of the K5 (for example) somewhat negates the need to have a 560mm (or 600 for that matter) F4 lens.

Lets look at this another way, and maybe it will shed some light (pun intended) on the front end diameter issue.

I have a 200-500/5.6 zoom presently. 500 mmat F5.6 is 89mm diameter, and the lens uses a standard (sort of) 95 mm front filter.

I am not aware of a front accessory thread between 95mm and 112 mm which is what is used on the 300/2.8 and 500/4.5 as well as (i believe) the tamron 400/4

So the question is, ASSUMIG pentax wants to maintain the 112mm front filter thread diameter what is the biggest front element that they can mount, considering as well at least some margin between front element and filter ring, that comes out to about 100mm, therefore what is the longest lens that they can put in there, and gaurantee AF will work, if you add a 1.4x TC. remember they really need to be at about F6.9 to make a TC work, therefore you need to really be at below F5.6.

I am willing to bet, that what ever they come up with in terms of final focal length and teleconverter will reliably AF with a K5. if they go to 560mm, then in theory allowing 3 mm all the way aeround the front element and a 106mm element would bring them in at F5.2, and with the 1.4x TC this would probably work

[french_mike]

so, where are the bet its gonna be a DFA and the FF will be annonce in the same time ... ?

[Blue]

I have never bought into the argument that slow lenses are good simply because ISO is better in a given body. For example, the A 50/1.2 can be pushed that much farther on the K-5 than the K20d. Same thing for the FA* 600/4. Plus, these things focus wide open and stop down for the shot. What the real difference is will be the cost. The FA* 600/4 was out of my reach price wise.

regardless of "odd" or not, I think the real questions should be the following, given that the High ISO performance of the K5 (for example) somewhat negates the need to have a 560mm (or 600 for that matter) F4 lens.

Lets look at this another way, and maybe it will shed some light (pun intended) on the front end diameter issue.

I have a 200-500/5.6 zoom presently. 500 mmat F5.6 is 89mm diameter, and the lens uses a standard (sort of) 95 mm front filter.

I am not aware of a front accessory thread between 95mm and 112 mm which is what is used on the 300/2.8 and 500/4.5 as well as (i believe) the tamron 400/4

So the question is, ASSUMIG pentax wants to maintain the 112mm front filter thread diameter what is the biggest front element that they can mount, considering as well at least some margin between front element and filter ring, that comes out to about 100mm, therefore what is the longest lens that they can put in there, and gaurantee AF will work, if you add a 1.4x TC. remember they really need to be at about F6.9 to make a TC work, therefore you need to really be at below F5.6.

I am willing to bet, that what ever they come up with in terms of final focal length and teleconverter will reliably AF with a K5. if they go to 560mm, then in theory allowing 3 mm all the way aeround the front element and a 106mm element would bring them in at F5.2, and with the 1.4x TC this would probably work

[Blue]

so, where are the bet its gonna be a DFA and the FF will be annonce in the same time ... ?

I suspect it may very well be a D FA 560/5.6 WR when released.

[ElJamoquio]

regardless of "odd" or not, I think the real questions should be the following, given that the High ISO performance of the K5 (for example) somewhat negates the need to have a 560mm (or 600 for that matter) F4 lens.

I don't need the (lack of) DOF of a 560 f/4. I do want the autofocus performance of an F4 though, and I would like to be able to AF with a T/C. I don't really agree with your f8.9... sure Pentax will A/F there but really it's a slow and inaccurate process.

The brighter screen is a welcome bonus but not required.

I am not aware of a front accessory thread between 95mm and 112 mm which is what is used on the 300/2.8 and 500/4.5 as well as (i believe) the tamron 400/4

I hope they use an intermediate/rear filter like most other lenses this size do. I'm not sure what 500/f4.5 you're talking about but the sigma 300 f/2.8 and the sigma 500 f/4.5 use rear filters.

I think it's been announced that's it's a 5.6, but I could be mis-remembering.

[ElJamoquio]

so, where are the bet its gonna be a DFA and the FF will be annonce in the same time ... ?

It is a virtual surety that the lens is going to cover a FF circle. My personal thought is that it will be released as a DA*... DFA* (a new designation) seems less likely but perhaps possible with a FF announced soon. Perhaps I'm just being too optimistic, though, both about the FF and the * designation for this lens.

One thing I'm happy about is the stated goal of center sharpness - I really don't care much about what the edges are doing at 560mm.

[Blue]

It is a virtual surety that the lens is going to cover a FF circle. My personal thought is that it will be released as a DA*... DFA* (a new designation) seems less likely but perhaps possible with a FF announced soon. Perhaps I'm just being too optimistic, though, both about the FF and the * designation for this lens.

One thing I'm happy about is the stated goal of center sharpness - I really don't care much about what the edges are doing at 560mm.

D FA WR is not a new designation, however as in the D FA 100/2.8 WR macro. I think it will by either a DA, DA* or D FA WR and don't see the point of D FA*.