50mm vs 55mm DA

manually focusing with my current 50mm A lense means i am missing shots so it's time to upgrade...

does anyone have experience using both of these lenses?

i'm sure both are very sharp - is there much of a difference in how quickly they auto focus?

Do you mean the FA 50mm f/1.4 v. the DA* 55mm?

yes i think so.

although to be honest, i mean the 55mm DA* compared with any available 50mm autofocus lense, at whatever price each is currently selling for.

what i'm trying to ask is - what advice can anyone offer me for bang for my buck on a fast 50mm autofocus lense? anything under f2 will do me at this point.

Well if you can pick up a FA 50 f/1.4 new or used, there's your bang for buck. It's a great little lens

Edit: Quick search finds one on eBay

FA or F 50mm f1.7 if you can find one.
FA on Ebay
F on Ebay

DA*:
Sharper and better contrast wide open
Quick Shift (ie you can still use the focus ring in AF mode)
Designed specifically as a 'portrait lens' (the typical use of a 50 on digital) - so more aperture blades for better bokeh for example
Weather sealed (I think)

FA:
Cheaper
Lighter?
Doesn't rely on Pentax's (dodgy) SDM motor for focusing
Can be used on film cameras (if you have one ofc)
Presumably less vignetting at larger apertures since it's a film/FF lens

Another option, if you're feeling lucky, is the Sigma 50. It is cheaper than both the FA and DA* (the former could be had for £300 at SRS until recently, but they're gone) and has much better sharpness/contrast wide open than the FA (it is also designed as a wide-open portrait lens like the DA*). However there are two major caveats to this: the first is that it's (relatively) quite heavy at about 500g, the second is that it is notorious for front/back-focusing.

Now the first problem is down to your opinion: do you want to have a prime that can be pocketed or taken around in a small bag, without weighing you down, or do you want better wide-open quality in a less-portable package?

The second is a flaw rather than a mere downside, and has not been 'fixed in later batches' as reported in some places (I bought one from SRS in January which suffered badly). The solution to this is to buy from a dealer which pays for return postage on faulty items (IIRC both SRS and Park do this - though best to email them before ordering to confirm).

thank you very much for all your excellent input. particularly those ebay links.

greytop / mike p - how do you find the autofocus on the F and FA lesnes, compared to, for example, the recent WR kit lenses?

mr cynical - brilliant breakdown of pros and cons, thank you. portability is less of a priority for me than sharpness and focusing.

sounds like none are too bad, so much will depend on price i think.

this forum really is handy for getting quick answers to technical questions

The AF speed of the FA 50mm F1.4 is so similar to the DA 18-55mm WR's that I can't decide which is quickest.

I don't know about the DA* 55mm (apart from what you can read on photozone.de). I can only afford to buy the hood! ...that I use with a DA L 55-300mm.

I'm sure the 55 is superior, and it really should be for the money it costs, but anyway the FA 50 is a great lens from f2. At f1.4 you get a vaseline-style soft-focus effect.

My FA 50 f/1.4 is a very snappy focuser on the K-7, no complaints at all. Like Pete I can't say I've done back comparison between the FA 50 and my 18-55 WR lens but I would guestimate that they're similar. I'm pretty sure the DA* 55 will be a little lethargic in comparison, if my DA* 16-50 and 60-250 lenses are anything to go by.

Here's an image from my FA 50

[IMG]http://img21.imageshack.us/img21/7753/pinkandgreen800.jpg[/IMG]

AF is very slow on the 55mm but if Im honest I'm not sure its any worse than the FA 50mm .. maybe it just seems so because you cant hear it focusing. I must admit that 9/10 times I put the FA 50mm f1.7 in my kit bag because its a lot smaller and it means I can fit something else in.

Edit : cant here it focusing???? ... at least spell it right even if no one takes any notice.

You almost got it perfect

The DA*55 also has a bigger "view" then APS-C it will work on film as well.
Also the Number of blades has indeed something to do with Bokeh but it's only 10% of the whole story the optics of the lens are far more important with rendering a good bokeh.

From all the lenses the Sigma is the sharpest wide open but at f/2 all the lenses preforms equal.
The FA is softer in the corners then the DA* and Sigma and at later apertures, around f/5.6 the DA* is also more constant across the frame where the sigma peaks more in the centre with the sharpness and the corner are then softer as well.

I don't know how the speed is with AF with all the lenses.

Basicly if you want to use the lens wide open and want sharpness there Sigma is the choice.

For overall preformance the DA* is the better lens.

On a budget the FA50 is of course super as well and can play with the big boys.

Btw DPreview have all the 3 the lenses reviewed http://www.dpreview.com/

Is the DA* 55 officially full frame?

No, only the DFA are that of the digital lenses but we all know that for example the DA*200 is so good as the same as the FA*200 for example and it works very well on film.
They did some tests one the pentaxforum.com site and most of the DA* lenses work on full frame only the wide angle and the very budget lenses give a problem.

Will try to look it up.

ps. here it is.
http://www.pentaxforums.com/forums/pentax-slr-lens-discussion/31629-da-lens-full...

Nothing about the DA*55 but the DPreview says that it works.

I was wondering what the hood is designed for and if it provides as much shading as the DA 55-300mm hood?

Tough question Pete, the design of the hood is different because the one for the DA55-300 is a chopped tulip type where the DA*55 is a simple circular hood type.

I would say the one for the DA55-300 would be more effective but the DA*55 is good enough.

Here is a read that might interest you.
http://toothwalker.org/optics/lenshood.html