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02-18-2012, 10:01 PM   #1
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Questions about 50mm lenses

First off, thanks to everyone who has written lens reviews - the database here is a real treasure trove.

I have a number of questions about 50mm lenses or other relatively inexpensive fast prime lenses and I open to hearing any and all thoughts. A bit of background. I have a K-5 with the WR 18-55 kit lens. I recently managed to purchase three SMC-A lenses: a 28 f2.8 (which I'm expecting to use a lot), a 70-210 f4 and a 35-105 f3.5. The latter I haven't picked up yet, but based on a number of comments from users here looked like a good buy. It is coming from the same source as the first two, and those were in mint condition. Overall I ended up paying about $180 for the three.

The one thing that I've been thinking about adding is a fast 50mm or something in that range. Prior to the recent announcement of the new lenses from Pentax, I had the DA 35mm f2.4 on my radar, but I think the 50mm f1.8 now looks more interesting, at least as far as autofocus lenses go. For times when I am taking snapshots of people etc., I can see the autofocus being a huge plus.

On the manual focus front, the 50mm f1.7 seems to be the most useful possibility. The overall comments indicate that is better than the 1.4 at aperatures below about f4, and it certainly costs a lot less. The 1.7 also seems to be a lot better than the f2 when wide open. Since my interest in getting this sort of lens is to use it when the kit lens is too slow, performance wide open is an issue. I'd be interested to hear more from folks who use these lenses in tough lighting situations where you need to keep the lens as open as possible.

So the questions I'm trying to resolve are whether I should wait for the autofocus version to come out, or whether I should aggressively hunt for a 50mm 1.7 now. I'm limiting the hunt to A mounts, because it better meshes with the way I use a camera. Or are there other lenses, that don't cost a huge amount, that I should keep on my shortlist.

Many thanks,
Marc

02-18-2012, 11:06 PM   #2
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I love the 50mm in M mount - compact, solid, sharp & cheap. The only drawback is no A setting on aperture. F/1.4 is more for ease of focus, as anyone who used 35/1.4, 50/1.4 or 85/1.4 will tell you. The DOV is so shallow at F/1.4 that you could hardly include any area which is your interest. So a F/1.7 not only save you money but also more practical. Check the M50s out. You will not be disappointed!

Last edited by MJL; 02-18-2012 at 11:14 PM.
02-18-2012, 11:18 PM   #3
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QuoteOriginally posted by MSL Quote
Overall I ended up paying about $180 for the three.
And that was an a very good deal by the way. I have and use the Pentax-A 28mm f/2.8 and the 50mm f/1.4. If manual focus is OK there is nothing wrong with either A 50mm f/1.4 or f/1.7. The 1.4 goes a 1/2 stop wider but the 1.7 is a little cheaper. On the other hand you see a lot more 1.4's that 1.7's on the market. If you are going to go that route take whichever one comes by at the right price first.

If you need auto-focus then waiting for the new lens might be a good option as the price will likely be very attractive. The FA 50mm f/1.4 is still available new for about $350us and the assumption is that the new f/1.8 will be much less. If it comes in at maybe $250 it will be a big hit in my opinion.
02-19-2012, 03:17 AM   #4
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Slower lenses tend to be sharper wide-open than faster lenses. My Meyer Primotar-E 50/3.5 is indeed sharper wide-open than any of my f/1.2-1.4-1.7 Fifties. But I think my K50/1.2, and FA and SuperTak 50/1.4s, beat my M50/1.7 or SuperTak 55/1.8 by the time they're stopped-down to f/2-2.8.

We don't use superfast lenses for wide-open edge-to-edge flatfield sharpness. We use them to grab shots that would otherwise be impossible. For super-sharp, try the MacroTak 50/4 (but it can be tricky to focus beyond 1m). The M50/1.7 and SuperTak 55/1.8 are very very good lenses. But the FA50/1.4, my gotta-get-the-shot lens, is ALWAYS in my carry bag. There are reasons that 50-55-58mm f/1.2-1.4 lenses are prized. They produce images that slower lenses just can't.

They needn't be horribly expensive. I got really good deals on a planar Yashica ML 50/1.4 (US$10) and Tomioka 55/1.4s (US$2 and US$25), and decent deals on the SuperTak 50/1.4 and MacroTak 50/4(1x) (US$55 each). All those should be generally available for under US$100. I paid market price last year for the K50/1.2 (US$250), widely regarded as about the best Fifty ever except maybe for the A version. And my FA50/1.4 was only US$200 when I bought it new 3 years back. With some careful hunting and a bit of luck, f/1.4s can be found for under US$50.

02-19-2012, 03:21 AM   #5
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In my experience, I have found that slower manual-focus lenses are harder to focus acccurately than faster ones of good quality.
02-19-2012, 07:18 AM   #6
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QuoteOriginally posted by RioRico Quote

We don't use superfast lenses for wide-open edge-to-edge flatfield sharpness. We use them to grab shots that would otherwise be impossible. For super-sharp, try the MacroTak 50/4 (but it can be tricky to focus beyond 1m). The M50/1.7 and SuperTak 55/1.8 are very very good lenses. But the FA50/1.4, my gotta-get-the-shot lens, is ALWAYS in my carry bag. There are reasons that 50-55-58mm f/1.2-1.4 lenses are prized. They produce images that slower lenses just can't.

.
Thanks for replying - I had hoped to get your insight here given all the lenses you have played with.

Is there really that much difference in getting a shot between a 50 1.4 and 1.7? Maybe I already know the answer to that from my film days, in that my 70-210 f2.8-3.5 could get shots a similar range f4 lens could not, especially if I held it to the 2.8 end of the zoom. But on a camera like a K-5, will the difference between the two 50s matter that much? I certainly appreciate the need for a fast lens - one reason I don't want the 28 f2.8 to be the fastest lens in the kit.
02-19-2012, 07:30 AM   #7
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QuoteOriginally posted by MSL Quote
Is there really that much difference in getting a shot between a 50 1.4 and 1.7?
As I mentioned above, one essential difference may lie in the ease and accuracy of manual focusing.
A 50/1.4 that's sharp in the central focus zone at f/1.4
will help you do better than with a cheapo f/1.7
that doesn't have central sharpness and contrast wide open.
02-19-2012, 07:52 AM   #8
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My experience:
I have the F 50mm 1.4, the FA 50mm 1.4 and had the A 50mm 1.4. All very good, and I could never see any difference in image quality between the three. I also had the F 50mm 1.7, and in spite of it's fine reputation my copy was remarkedly softer at 1.7 than my f1.4 lenses wide open. At 2.8 the difference was gone. I guess my copy was a lemon, but lesson learnt was that you need to examine the very lens you want to use.

Second experience: It's a very discouraging exercise to manually focus an f1.4 lens with the original Pentax matte focusing screen. I thought something was wrong with my otherwise stellar A* 85mm 1.4 lens, so many shots were slightly out of focus. When I read this thread and bought another screen from Taiwan it brought new life to the fast lenses. So if you go the fast lenses lane, consider getting the Canon EE-s screen too.

Kjell

02-19-2012, 08:05 AM   #9
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QuoteOriginally posted by bilybianca Quote
Second experience: It's a very discouraging exercise to manually focus an f1.4 lens with the original Pentax matte focusing screen. I thought something was wrong with my otherwise stellar A* 85mm 1.4 lens, so many shots were slightly out of focus. When I read this thread and bought another screen from Taiwan it brought new life to the fast lenses. So if you go the fast lenses lane, consider getting the Canon EE-s screen too.
Changing screens may mess with the metering, and may make slow lenses hard to handle.
Like so much in photography, it's a tradeoff.

I don't have the A* 85/1.4, but do have the cheaper (!) Zeiss ZK 85/1.4, as well as a Voigtlaender 58/1.4.
Personally, I'm able to focus them both
with a mixture of focus confirmation/CIF, stock viewfinder screen interpretation, and live view.
It does depend on practice, eyesight, and so on.
Strangely enough, I find to easier to focus this way with the APS-C K-x
than I ever did with the microprism screen in the FF film Spotmatic.
02-19-2012, 08:26 AM   #10
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QuoteOriginally posted by lytrytyr Quote
Changing screens may mess with the metering, and may make slow lenses hard to handle.
Like so much in photography, it's a tradeoff.
I haven't done any tests myself, but according to others in the thread I linked to, metering actually improves with the Canon screen. I cannot confirm this from my own experience, but neither have I had any problems with it. As I understand it, the metering problems occur with certain split prism screens. The Canon screen has no split prism, it's a uniform matte sceen that shows the true DOF down to at least f1.4, while the stock screen can't show any difference in DOF below f2 and hardly below f2.8.


QuoteQuote:
I don't have the A* 85/1.4, but do have the cheaper (!) Zeiss ZK 85/1.4, as well as a Voigtlaender 58/1.4.
Personally, I'm able to focus them both
with a mixture of focus confirmation/CIF, stock viewfinder screen interpretation, and live view.
It does depend on practice, eyesight, and so on.
Strangely enough, I find to easier to focus this way with the APS-C K-x
than I ever did with the microprism screen in the FF film Spotmatic.
After changing the screen, I don't have to rely on screen interpretation or live view. Focus confirmation isn't precise enough for fast lenses. Now I see in the viewfinder when focus is spot on and press the shutter button. My hit rate with the 85mm lens has gone up from 30-40% to 100%. To each his own.

Kjell
02-19-2012, 08:41 AM   #11
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QuoteOriginally posted by bilybianca Quote
My hit rate with the 85mm lens has gone up from 30-40% to 100%.
Sounds good! Does the A* 85/1.4 exhibit focus shift?
02-19-2012, 08:44 AM   #12
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QuoteOriginally posted by bilybianca Quote
Focus confirmation isn't precise enough for fast lenses.
Well, you have to be aware of how it works, with each particular lens and direction of focus change.
02-19-2012, 09:18 AM   #13
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QuoteOriginally posted by lytrytyr Quote
Sounds good! Does the A* 85/1.4 exhibit focus shift?
What is focus shift? Do you mean QuickShift? The A* lenses are manually focused, like all A-series lenses.

Kjell
02-19-2012, 09:22 AM   #14
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QuoteOriginally posted by bilybianca Quote
What is focus shift?
That's where it may look sharp at f/1.4,
but if you stop down to f/2,
then it's no longer in focus.
02-19-2012, 10:21 AM   #15
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QuoteOriginally posted by lytrytyr Quote
That's where it may look sharp at f/1.4,
but if you stop down to f/2,
then it's no longer in focus.
I haven't got a doctor's degree in physics, but how on earth can stopping down make it harder to get things in focus? Stopping down means an increased DOF.

Do you mean that "focus shift" is something inherent to some lenses, so that you'd have to stop down with DOF preview before focusing? I've never heard of or experienced that. And I have done pretty much shooting with Pentax gear the last 27 years.

I'm not trying to convince you to get an EE-s screen, just trying to share my experience with OP.

Kjell
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