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06-09-2009, 07:14 AM   #16
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QuoteOriginally posted by axl Quote
thanks woof.
very informative. I for one have always thought that Pentax 50s - both 1.4 and 1.7 - share the same optical design.
Thanks again for your post.
Peter... welcome... I know it was a bit of a left turn, but this kind of information always helps me. It figured into my decision to get an F 50mm f/1.7, and it may indicate to you that having a 1.8 or 1.7, you might prefer the other non-Takumar/Pentax lens more to add a little variety to your stable.

I too always thought the fast 50's were the same but wondered what the point was with the difference in speed. Pentax has sometimes sold downmarket lenses that were nothing more than the upmarket lens with an f/stop or so removed from the aperture ring. The Super Takumar 55mm f/1.8 and the Super Takumar 55 f/2.0 are just such a pair. Sell more units by selling the same basic lens for less to the downmarket folks who have a pricepoint below the upmarket goods. The SV/H1a are essentially the same camera with the H1a being slightly defeatured for the downmarket.

When I originally started looking at the 50mm lenses, I thought this might be what I'd find. Doing the research, the lineages became clear.

QuoteOriginally posted by séamuis Quote
I certainly hope not. I dont think I will be counting lineage. if I do I fear my collection will spiral even further out of financial control. I just bought a fish-eye-takumar 1:11/18mm :ugh:
Séamuis - sorry, couldn't help myself. Just kidding of course. I personally have this issue. For example, I have every version of the 135 f/3.5 ever made. After a while a 135mm is a 135 is a 135. Except when it is a 105mm ... there was a point at which Pentax actually swapped the optical formulas for these lenses. Heh.

On the fisheye... Congrats! Very, very nice. Well worth the crimp it will cause for a short time.

QuoteOriginally posted by richard64 Quote
I take back what I said about the A50/1.7
I've just taken some pictures and found that it had far more "pop" than I thought it had:
Richard... that is a very beautiful photo. Same basic lens formula of course... In fact it seems that it was the M/A lenses that made the transition from 55mm to 50mm in the evolution of the F/FA lenses from the old 55mm lenses.

Here is the formula for that lens:



FWIW, here is the formula for the M 50 1.7



That sort of completes the analysis of the lineage. I had not added that to the original post, but now that we are past that, this sort of confirms the whole thing.

It's a beautiful thing actually knowing where those fast 50's came from.

woof

06-09-2009, 07:17 AM   #17
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QuoteQuote:
On the fisheye... Congrats! Very, very nice. Well worth the crimp it will cause for a short time.
thanks Seaain, it cost a pretty penny, but still cheaper than the DA 10-17. I would still like to get the 17mm f/4 version. but the 18 is just so unique, I really cant wait to try it out.
06-11-2009, 05:34 AM   #18
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QuoteOriginally posted by woof Quote

The F and Fa 50mm F/1.7 seems to be a direct descendant of the 55mm f/1.8.

The 55mm f/1.8 has Six elements in five groups. So does the F/Fa 50mm.
The 55 has a minimum focusing distance of .45 meters. So does the F/FA 50.
55mm aperture blades 6, 50mm aperture blades 6
55mm filter diameter 49mm, 50mm filter diameter 49mm
55mm angle of view is 43 degrees, the 50mm 47 degrees (difference expected)


It is tempting to think that the F/FA 50mm f/1.7 would have more in common with the F/FA 50mm f/1.4 or perhaps going back to the Super Takumar 50mm f/1.4. The latter was a 7 elements in 6 groups as was the former. I believe that those lenses each have 8 aperture blades. I know the F/FA does.
I think the number of apperture blades goes like this:

5 blades: all 50/4 macros
6 blades: A50/2.8 macro, all 50/1.7's, all 55/1.8 or 2.0
8 blades: all other 50/2.8 macros, all K-mount 50/1.4 (don't know about the Tak 50/1.4, I don't have my copy here), K50/1.2
9 blades: A50/1.2 and DA*55/1.4



QuoteOriginally posted by richard64 Quote
I take back what I said about the A50/1.7

I've just taken some pictures and found that it had far more "pop" than I thought it had:


Richard
I didn't say that it had less "pop", just that one was slightly warmer and the other slightly sharper.

Now, even with the similarities in optical design that Woof point out, there is still the gradual improvement of the coating formulas. All 55/1.8/2.0 lenses (Takumars and K generations) are older than all 50/1.7 lenses (M, A, F, and FA generations), and hence have older coatings. That itself may be enough to explain at least the appearance of better sharpness in my A50/1.7 than my K55/1.8 and 2.0 due to better contrast, and probably also a difference in colour tone. Non the less, I find it usefull to have both to choose between.
06-11-2009, 05:41 AM   #19
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QuoteQuote:
I didn't say that it had less "pop", just that one was slightly warmer and the other slightly sharper.

Now, even with the similarities in optical design that Woof point out, there is still the gradual improvement of the coating formulas. All 55/1.8/2.0 lenses (Takumars and K generations) are older than all 50/1.7 lenses (M, A, F, and FA generations), and hence have older coatings. That itself may be enough to explain at least the appearance of better sharpness in my A50/1.7 than my K55/1.8 and 2.0 due to better contrast, and probably also a difference in colour tone. Non the less, I find it usefull to have both to choose between.
its really a non issue. unless of course you do no post processing. the difference in colour can easily be changed in a matter of seconds in a photo/graphics program. of course, I personally don't find the colours of the 55 lacking in any way. but I agree, most of the differences can likely be credited to the older coatings. except of course the bokeh, for which I still think the 55 does better than the 43, and better than any of the normal 50's.

06-11-2009, 05:48 AM   #20
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Seamuis, I used to think what you say abot color... BUT... as I discovered, the auto white balance does not correct for lens tonality, not all the way. Neither does a simple color correction in PS. The reason for this is that the spectral response of a lens is not linear; you'd have to mess with curves in the different channels etc. to attempt to tailor a look.

And that look is part of why we cherish our lenses.

The coatings thing - again from my pov - there are flavors to be had, and so-called defects can be accepted, loved, and made useful. From a technical standpoint, multi coating does remove a lot of veiling flare, which is the enemy of contrast and saturation.

I've found that in situations where this veiling is minimized the differences between older and newer lenses becomes much smaller, one might say 'insignificant'.
06-11-2009, 06:08 AM   #21
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QuoteOriginally posted by séamuis Quote
its really a non issue. unless of course you do no post processing. the difference in colour can easily be changed in a matter of seconds in a photo/graphics program. of course, I personally don't find the colours of the 55 lacking in any way. but I agree, most of the differences can likely be credited to the older coatings. except of course the bokeh, for which I still think the 55 does better than the 43, and better than any of the normal 50's.
Well, I suppose I'm old fashioned who want the picture as close to what I intended already at the raw version. And I did not complain on my 55's colors, for portrait I actually prefere them. The 50/1.4/1.7 can be too cold and too sharp.

If you bring your argument a bit further: get me a future DSLR with enourmous amount of pixels and all post processing abilities: tone, sharpening, distorsion removal etc...the only lens you need is one wide angle lens and you can do anything from landscape to portrait to birds with the same lens, just crop and post process!
06-11-2009, 06:14 AM   #22
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QuoteOriginally posted by Douglas_of_Sweden Quote
Well, I suppose I'm old fashioned who want the picture as close to what I intended already at the raw version. And I did not complain on my 55's colors, for portrait I actually prefere them. The 50/1.4/1.7 can be too cold and too sharp.

If you bring your argument a bit further: get me a future DSLR with enourmous amount of pixels and all post processing abilities: tone, sharpening, distorsion removal etc...the only lens you need is one wide angle lens and you can do anything from landscape to portrait to birds with the same lens, just crop and post process!
im not sure id want such a camera to be honest.
06-11-2009, 06:18 AM   #23
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QuoteOriginally posted by séamuis Quote
im not sure id want such a camera to be honest.
Me neither! Would take all the fun away.

06-11-2009, 06:32 AM   #24
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QuoteOriginally posted by Douglas_of_Sweden Quote
Me neither! Would take all the fun away.
absolutely.
06-11-2009, 07:27 AM   #25
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QuoteQuote:
I certainly hope not. I dont think I will be counting lineage. if I do I fear my collection will spiral even further out of financial control. I just bought a fish-eye-takumar 1:11/18mm
Check out this "mint" 50mm Takumar macro:

http://cgi.ebay.ca/RARE-ASAHI-Pentax-MACRO-TAKUMAR-50mm-f-4-LENS-New-w-box_W...3A1%7C294%3A50


QuoteQuote:
The F and Fa 50mm F/1.7 seems to be a direct descendant of the 55mm f/1.8.

The 55mm f/1.8 has Six elements in five groups. So does the F/Fa 50mm.
The 55 has a minimum focusing distance of .45 meters. So does the F/FA 50.
55mm aperture blades 6, 50mm aperture blades 6
55mm filter diameter 49mm, 50mm filter diameter 49mm
55mm angle of view is 43 degrees, the 50mm 47 degrees (difference expected)

One thing to note about the K55/1.8 & K55/2, they have a 52mm filter thread.

Last edited by gofour3; 06-11-2009 at 07:34 AM.
06-11-2009, 07:31 AM   #26
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I put in a best offer on that lens... thanks for spreading the word.

if I hadn't just bought a Takumar 18mm fish-eye I would buy that without hesitation. I currently have three 'mint' in box Takumars. and this 50 is the really desirable preset version. the only one that will do 1:1. and if im lucky will be my fourth.
06-11-2009, 07:39 AM   #27
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Good luck, hope you get it. It looks like a gem!
06-11-2009, 07:46 AM   #28
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QuoteOriginally posted by gofour3 Quote
Good luck, hope you get it. It looks like a gem!
im still kicking myself for buying the fish-eye. as much as ive wanted one, I would love to have this more. it would also be more useful. we shall see what happens. im still waiting on a reply to my offer.
06-11-2009, 09:00 AM   #29
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QuoteOriginally posted by gofour3 Quote
One thing to note about the K55/1.8 & K55/2, they have a 52mm filter thread.
This 52mm filter size is a peculiarity of the K lenses. Even when the optical design was unchanged from Takumar to K to M (such as the 50/4 and 100/4 macros), the K versions were the only ones with 52mm filter threads.
06-11-2009, 09:02 AM   #30
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QuoteOriginally posted by Just1MoreDave Quote
This 52mm filter size is a peculiarity of the K lenses. Even when the optical design was unchanged from Takumar to K to M (such as the 50/4 and 100/4 macros), the K versions were the only ones with 52mm filter threads.

I always hated this about my K 55. nearly all of my lenses (excepting a few takumars) have 49mm filter threads, so I have a stockpile of filters and hoods in 49mm, and of course none will fit the dang thing.
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