LBA: M 400mm f5.6 (lost thread updated)

MightyMike said:

Perhaps i mis-read... but why on earth would you post a comparison
where the one side had focus errors,

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Because it was a summary/reprise of a thread lost in the crash, where I posted the first six-way picture and didn't know at first that it was a focus error. It was written for anyone who had seen that thread and was interested in an update.

stewartpratt said:

Correct me if I'm wrong here, but if your first six pictures are
invalid and there's no point in anyone looking at them (thinks: why
post them?)

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See reply to mighty mike

stewartpratt said:

then all we have to go on is one picture from the Pentax
(with no indication of aperture) and no pictures from the Sigma.

How are we supposed to draw any comparative conclusion from one image
from one lens?

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The COMPARISON is invalid, not ALL SIX PICTURES... the ones for the Sigma are still legitimate.

Just1moreDave said:

The focus ring sounds like it should be better. I'd try exercising it
a bit, if you haven't already.

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Doesn't seem to be helping, so far. I'll be taking it outside today. At least that's the plan... but, there are a coupla football games that could prove distracting.

Just1moreDave said:

Can you post some details about your indoor test? I'm curious to see
what results I could get from my Tokina SD 400/5.6.

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I used a dollar bill draped over a fluorescent light bulb at 15 or 16 feet (5m), with tripod, 2 second MLU, and homemade remote release. The bill was the first thing I could think of with detail tiny enough to really challenge the lenses.

--

K10D, Sig 17-70, FA 50/1.4, DA 50-200, Sig 135-400... next up: gotta get something wiiiiiide.

cseiler said:

Thanks for posting - very interesting l wonder if the first picture
was bad due to an unstable tripod, maybe even the Sigma can perform
better?

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This Sigma has always been a frustrating lens; I think what we're seeing here is about as good as it can get.

cseiler said:

It would also be interesting if the Pentax has more chromeric
aberrations in high contrast situations.

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I would expect so but I haven't managed to check that yet.

--

K10D, Sig 17-70, FA 50/1.4, DA 50-200, Sig 135-400, M 400/5.6... gotta get something wiiiiiide.

--

K10D, Sig 17-70, FA 50/1.4, DA 50-200, Sig 135-400, M 400/5.6... gotta get something wiiiiiide.

Sigma 135-400 @ "400", f5.6 (wide open):



( that's a larger crop from the same shot used at the top of the six-way thing)

SMC M 400 f5.6 (wide open):



--

K10D, Sig 17-70, FA 50/1.4, DA 50-200, Sig 135-400, M 400/5.6... gotta get something wiiiiiide.

I yeild the M400 F5.6 does give a better result however for this to be fair did you focus bracket the Sigma also? AF lenses can be off focus sometimes not noticable in real life but on a close range test front focus or back focus issues may be magnified, my first 100-300 F4 at close range front focused by 2.5cm (1inch) this would totally make the result in such a test look much worse unless i focus bracketed.
--
Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote '



http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=121&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=

Sigma 135-400 at 400, f5.6 (wide open), ISO 560, tripod with MLU, range about 100m, 100% crop from about midway between center and corner:



SMC M 400 at f5.6 (wide open), same conditions but a bit overexposed:



... in some areas one seems sharper, in some areas the other does. A pretty even match. I think maybe I like the M better overall, but you could argue the other way based on things like the tiny white spots near the middle.

--

K10D, Sig 17-70, FA 50/1.4, DA 50-200, Sig 135-400, M 400/5.6... gotta get something wiiiiiide.

I've tried focus-bracketing in other situations, like when I was taking moon shots with it, and the fact is, this is as sharp as that lens ever gets.

--

K10D, Sig 17-70, FA 50/1.4, DA 50-200, Sig 135-400, M 400/5.6... gotta get something wiiiiiide.

Here are two shots where I first focused on sparkly reflections on the water, and then on a fence in front of the water. As you can see, the white spots that are in focus are white, but the ones in front, which are back-focused, have big major purple fringes. In the second shot, where the sparklies are front-focused, the bokeh has green edges and purple centers.





--

K10D, Sig 17-70, FA 50/1.4, DA 50-200, Sig 135-400, M 400/5.6... gotta get something wiiiiiide.

--

K10D, Sig 17-70, FA 50/1.4, DA 50-200, Sig 135-400, M 400/5.6... gotta get something wiiiiiide.

--

K10D, Sig 17-70, FA 50/1.4, DA 50-200, Sig 135-400, M 400/5.6... gotta get something wiiiiiide.

MightyMike said:

the thing is the
M400mm F5.6 is a very primative and simple design which can be good
and bad but if it were made today i can assure you that it would not
be just 5 element 5 group... even if it were to be made as a consumer
grade lens.

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For long focus lenses, "primitive" designs deliver great results. A top quality 400mm long focus lens can be made with only an achromatic doublet -- yes, that's 2 elements in one group. The highly regarded Leica Telyt 400mm was of this type.

The ever increasing number of elements in modern telephotos is required in order to make lenses more compact. An achromatic doublet of 400mm focal length needs to be positioned 400mm from the focal plane at infinity. That means a very long lens. In order to shorten the lens, a negative element has to be inserted in the light path, that's a telephoto lens. The stronger the negative element, the shorter the lens and the worse the aberrations.

To obtain good correction of the aberrations (mainly chromatic) resulting from the telephoto design, more elements need to be added and special glasses need to be used. Usually, modern telephoto lenses are faster; they also feature internal focusing and autofocus, all these refinements requiring additional elements. That doesn't make a multi-element telephoto better than an achromatic doublet long focus lens. Of course, the long focus is longer and heavier, while the modern telephoto is lighter and faster, but that doesn't tell anything about image quality.

The Pentax M is not a strong telephoto design -- that is why the lens is rather long -- so it doesn't need so many corrective elements as most recent lenses, which are more compact. For example, the M 400/5.6 is 277mm long and has 5 elements in 5 groups, while the FA 400/5.6 has 9 elements in 8 groups and measures only 199mm.

MightyMike said:

as for the 40mm F2.8 which is a beautiful lens well lets
just say that even though its a 5 element 5 group design ecah element
has been chosen very carefully to work the best with each other and
in that regard it can almost but not accurately be considered 5
element 1 group.

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I am not sure to understand. The DA 40 has 5 elements in 4 groups. It's a good lens, compact, but not very fast compared to most lenses of similar focal length. That doesn't make it a 5 element 1 group lens.

Cheers!

Abbazz
Fujica G690 online resource: http://artbig.com/

Abbazz said:

For long focus lenses, "primitive" designs deliver great results. A
top quality 400mm long focus lens can be made with only an achromatic
doublet -- yes, that's 2 elements in one group. The highly regarded
Leica Telyt 400mm was of this type.

Click to expand...

Interesting and yet the Pentax 85mm F2 that is just an achromatic doublet is a soft focus lens unless you stop down 3 stops, i'm not saying it isn't possible, in fact i have made my own lens experiments with high quality achromatic doublets... My result was also a telephoto lens at approx. 300mm and it was soft focus. however i hadn't added any aperture control.

Abbazz said:

The ever increasing number of elements in modern telephotos is
required in order to make lenses more compact. An achromatic doublet
of 400mm focal length needs to be positioned 400mm from the focal
plane at infinity. That means a very long lens. In order to shorten
the lens, a negative element has to be inserted in the light path,
that's a telephoto lens. The stronger the negative element, the
shorter the lens and the worse the aberrations.

Click to expand...

Yes i have done this very thing, both with positive and negative diopters

Abbazz said:

To obtain good correction of the aberrations (mainly chromatic)
resulting from the telephoto design, more elements need to be added
and special glasses need to be used. Usually, modern telephoto lenses
are faster; they also feature internal focusing and autofocus, all
these refinements requiring additional elements. That doesn't make a
multi-element telephoto better than an achromatic doublet long focus
lens. Of course, the long focus is longer and heavier, while the
modern telephoto is lighter and faster, but that doesn't tell
anything about image quality.

Click to expand...

Fair enough

Abbazz said:

I am not sure to understand. The DA 40 has 5 elements in 4 groups.
It's a good lens, compact, but not very fast compared to most lenses
of similar focal length. That doesn't make it a 5 element 1 group
lens.

Click to expand...

I'm sorry, i was told that it was 5 elements in a previous post, i didn't look it up so i assumed it to be 5E 5G

--
Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote '



http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=121&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=

Nice comparrison, it looks to me that the sigma crop is slightly underexposed as it shows more grain noise, i highly doubt the lens is at fault, both are decent and each seems to have sharper and softer areas for whatever reason... perhaps in-camera NR?
--
Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote '



http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=121&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=

paulkienitz said:

Why on Earth are three or four different people all completely
ignoring the second, larger test picture at the bottom of the
post??????

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Just commenting on what I see. If you don't want us commenting on what you post, then don't post it! Or at least post something you WANT us to comment on. I was just going by what my eyes showed me.

I just bought an old Vivitar TX 400mm 5.6. I hope mine is somewhere in the neighborhood of there. My Sigma has turned out to be rather disappointing as to CA.

(Actually, I was more after the TX adapter. Now I can use my favorite 135mm from my Olympus kit! A better Tokina-made 400mm would just be icing on the cake.)

MightyMike said:

it looks to me that the sigma crop is slightly
underexposed

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It was the M shot that was overexposed. This happened to be a shadowy section of the image.

(shakes head) And I did say so. You seem not to want to believe anything I say...

yes but i never saw the whole image... so based on the part shown the exposure looks better on the M... i'm not saying i don't believe you i'm just pointing out an observation thats all, nothing personal... i like to see comparrisons between lenses it increases my knowledge and adjusts my opinion accordingly
--
Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote '



http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=121&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=