Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-31-2011, 07:17 AM   #1
Veteran Member
Deiberson's Avatar

Join Date: Dec 2009
Photos: Albums
Posts: 734
My Manuals IQ vs Newer AF VErsions

I started shooting Pentax when my grandfather passed away and I inherited his old film bodies and several (10-15) lenses.
I later came to find out that I could use these lenses on modern dslr's. In the bag was a
SMC A 50 1.4, SMC 55 1.8, SMC A 28 2.8 among others.

When I have everything dialed, the 50 is great. SHARP SHARP SHARP. I get lucky with the other lenses too but the manual focus is killing me. For every 15 shots, I get one that I like.

So my question is, would I be better off with 2-3 auto focus primes? I know the answer to this, but what I don't know is the IQ of these lenses compared to my manual's. The 50 is pretty good and I love the heavy build. I've only seen pics of the AF 50 1.4 but it looks a little plasticky. Does it produce images that are as sharp?

My other lens that I would be interested in would be something like the Sigma 30mm, but I know that's the real deal. These options though are much more expensive, but I figured I could find the 50 relatively inexpensive on the marketplace.

Thanks

01-31-2011, 07:28 AM   #2
Loyal Site Supporter
eddie1960's Avatar

Join Date: Aug 2010
Location: Toronto
Photos: Gallery | Albums
Posts: 12,165
New primes will benefit from rear coatings if they were designed for digital. Not sure if the fa50 1.4 ever got this upgrade, AFAIK the A50 1.4 and the FA 50 1.4 share the same optical formula but the A is better built though lacks the AF
You could also probably benefit from some accessories that would help you raise the number of keepers
first would be a split image prism, combined with catch in focus on the camera you should have a higher success rate
second may be a magnifying eyepiece or if you wear reading glasses an eyepiece for your specific prescription (I picked up one of these recently combined with a split image and it has made life far easier)

reviews on viewfinder accessories can be found at the link below. there are also numerous threads on replacing the focusing screen

Viewfinders and Screens - Pentax Accessory Review Database - Flashes, Grips, Camera Bags
01-31-2011, 07:51 AM   #3
Pentaxian
8540tomg's Avatar

Join Date: Feb 2008
Location: Waterloo, Ontario
Photos: Gallery
Posts: 4,444
QuoteOriginally posted by Deiberson Quote
I started shooting Pentax when my grandfather passed away and I inherited his old film bodies and several (10-15) lenses.
I later came to find out that I could use these lenses on modern dslr's. In the bag was a
SMC A 50 1.4, SMC 55 1.8, SMC A 28 2.8 among others.

When I have everything dialed, the 50 is great. SHARP SHARP SHARP. I get lucky with the other lenses too but the manual focus is killing me. For every 15 shots, I get one that I like.

So my question is, would I be better off with 2-3 auto focus primes? I know the answer to this, but what I don't know is the IQ of these lenses compared to my manual's. The 50 is pretty good and I love the heavy build. I've only seen pics of the AF 50 1.4 but it looks a little plasticky. Does it produce images that are as sharp?

My other lens that I would be interested in would be something like the Sigma 30mm, but I know that's the real deal. These options though are much more expensive, but I figured I could find the 50 relatively inexpensive on the marketplace.

Thanks
Deiberson,

I'll just support what Eddie said above.

Only you can answer this question about upgrading to AF lenses. The older MF glass you inherited is capable of producing great images. It will, however, take a lot of time and practice to get used to it. If your camera permits it you might want to swap out the original focusing screen for a KatzEye or other aftermarket screen. These micro prism screens will be similar to those found in your grandfather’s gear and will make manual focusing much easier. Even with a new screen you must accept the fact you are going to have a lot of out-of-focus and missed with MF. The good news is in digital it doesn’t cost anything. The fact you got these lenses free is just an added bonus.

The AF 50/1.4 is by all accounts a great lens. If you don’t have the patience for manual focusing by all means get one. It won't be as well built as your old gear but will be much easier to use.

I'm sure you will be able to sell the old lenses if you decide to go totally AF. Take some time to get used to the old glass before you make such a move. You might regret it later if you don't.

Tom G

Last edited by 8540tomg; 01-31-2011 at 08:25 AM.
01-31-2011, 07:58 AM   #4
Loyal Site Supporter
eddie1960's Avatar

Join Date: Aug 2010
Location: Toronto
Photos: Gallery | Albums
Posts: 12,165
I did take a quick look at what is in your albums. Action shots like the cycling and the dog running towards you are particularly difficult with manual focus, but AF also misses these types of shots sometimes.
for anything like this I would stop down the lens as far as i could while maintaining a good shutter speed (and likely bump my iso up to allow it, the kx should produce excellent images at anything 800 iso and below, and with a little post is capable of much higher)

shooting at f8-f11 will give you a much wider in focus area and you will have less missed shots. any fast lens AF or not will be tough to nail the focus on if you shoot wide open (1.4 to even f2.8) starting at f4 and above will increase the number of keepers and reserve the wider apertures for when the light demands it or you need the shallower DOF (IE posed portraits etc)

01-31-2011, 08:33 AM   #5
Veteran Member
Deiberson's Avatar

Join Date: Dec 2009
Photos: Albums
Posts: 734
Original Poster
a lot of those pics in the albums were probably shot with my sigma 17-70 AF. Imagine how bad my MF pics look.
01-31-2011, 08:47 AM   #6
Veteran Member
paperbag846's Avatar

Join Date: Jul 2010
Photos: Gallery
Posts: 2,396
IMHO, the 50 1.4 is a hard lens to manually focus.

When you are manually focusing it, you are looking at the world "wide open". and that lens is a little soft wide open. It's hard to tell when you are in perfect focus.

For action, you want to stop the thing down past f4 if you can... but you also want to try other things as well.

A) Turn on catch-in-focus in the custom settings.
B) Buy a split prism focus screen for your camera.
or C) Shoot as you focus. You are more likely to end up with 1 in focus if you take 3 alternatives.

In general, I find the SMC 55 easier to manually focus than the A 50 1.4.... for whatever reason.

Keep the 28mm though, the DOF on that lens is rather forgiving and it's a great lens in general.

Also, don't "upgrade" to the FA 50 1.4. The IQ is identical, and the AF is not particularly snappy. You could easily learn to autofocus that quickly. Go for something different...

I might suggest something like the Tamron 17-50 f2.8 as an autofocus lens. It's snappy, fast, super sharp, flexible, and a great deal. You might find your primes don't get much use after you pick it up.

If you want primes, consider the DA 70 2.4, which is a snappy focuser, and a focal length you don't have yet. It's a reasonable price on the used market.
01-31-2011, 08:58 AM   #7
Loyal Site Supporter
eddie1960's Avatar

Join Date: Aug 2010
Location: Toronto
Photos: Gallery | Albums
Posts: 12,165
QuoteOriginally posted by Deiberson Quote
a lot of those pics in the albums were probably shot with my sigma 17-70 AF. Imagine how bad my MF pics look.
It was more in reference to subject matter as the exif wasn't there for me to see what lens it was

the 17-70 isn't the snappiest lens for focus that being said (neither is my 24-70 2.8)
some of the newer designs like the mentioned tamron are pretty quick by comparison

I wouldn't give up on the manual lenses though, practice and some additional tools will raise your success level. Also there are various focusing exercises you can do to improve your technique

there are some good tips in the article below, and more threads than you can shake a stick at here (search focusing technique)

Mastering manual focus on Pentax DSLRs « robertsdonovan.com

Another alternative some use is Live view for focusing but i find that useful only for tripod mounted shots myself, and most of those for me will be at or near infinity so it's not so useful to me.
01-31-2011, 10:56 AM   #8
Veteran Member
Deiberson's Avatar

Join Date: Dec 2009
Photos: Albums
Posts: 734
Original Poster
I have a question regarding the focus trap. I have my settings set AF and my menu #2 option set to AF-S. Why is my camera still taking an OOF shot when the shutter is fully depressed?
I can't get the trap to work on my k-x.

01-31-2011, 11:10 AM   #9
Loyal Site Supporter
eddie1960's Avatar

Join Date: Aug 2010
Location: Toronto
Photos: Gallery | Albums
Posts: 12,165
i don't have a kx so i can't say where it is in the kx menu but on the k7 its called Catch In focus and is in the custom settings turn it on and when using prefocus in the area you want depress the shutter and fine focus it will release when it's in focus (probably works best at smaller apertures like f4+
01-31-2011, 11:16 AM   #10
Veteran Member
Deiberson's Avatar

Join Date: Dec 2009
Photos: Albums
Posts: 734
Original Poster
found it, thanks
01-31-2011, 11:19 AM   #11
Veteran Member
Deiberson's Avatar

Join Date: Dec 2009
Photos: Albums
Posts: 734
Original Poster
one more thing regarding this technique. if i'm fine tuning the focus and the shutter releases when i have a longer shutter speed, say 1/4.....can i get motion blur by focusing through the trap?
01-31-2011, 11:25 AM   #12
Loyal Site Supporter
eddie1960's Avatar

Join Date: Aug 2010
Location: Toronto
Photos: Gallery | Albums
Posts: 12,165
if you are shooting at 1/4 you can get blur no matter what
with the sr on it will minimize it but subject blur can still occur. if you are shooting on a tripod then you don't want to use this technique or sr, but use the 2 sec self timer after focusing (on a tripod most times you will be shooting f8-11 in any case with the exception of macro.)
I actually had CIF disabled but with the split prism I can focus pretty accurately except in really low light (CIF is useful for concerts)
01-31-2011, 11:27 AM   #13
Veteran Member
Deiberson's Avatar

Join Date: Dec 2009
Photos: Albums
Posts: 734
Original Poster
how exactly will the split prism increase the accuracy of the manual focus? i'm under the impression that it is just a replacement screen that is easier to see through. but i'm not familiar with the system at all
01-31-2011, 11:36 AM   #14
Loyal Site Supporter
eddie1960's Avatar

Join Date: Aug 2010
Location: Toronto
Photos: Gallery | Albums
Posts: 12,165
go to Focusing Screen

it will show you all the variants available for the kx

they also have a helpful section that will show what the image looks like through the viewfinder.

your old film cameras likely have a microprism collar (like a circle of diamond shapes) that wil disappear when the subject is in focus. a split prism will split the image and when it comes together in focus the 2 halves will match up
I bought the K3 nikon type screen as it also has a rule of thirds grid which is quite a useful composition tool and helps with getting level horizons as well
they come with tools there is an easy onscreen installation guide, you may need to shim it (it will come with a shim) I didn't need the shim but YMMV
combined with the +3 viewfinder (my reading glass prescription is +3) I'm getting mostly in focus shots. they aren't all good shots but the screen and camera have nothing to do with that.
pentax also makes a 1.3 magnifying eyepiece for people who Manual focus
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
af, focus, iq, k-mount, lenses, pentax lens, slr lens, smc
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pentax K-x or Newer K-r? InStitches49 Pentax K-r 20 10-21-2010 04:21 PM
Looking for newer camera gsr9987 Troubleshooting and Beginner Help 3 07-20-2010 12:00 PM
Old flashes and newer bodies Steve Beswick Pentax Film SLR Discussion 7 02-16-2010 03:21 AM
Help me choose, is newer better? CWyatt Pentax SLR Lens Discussion 10 07-18-2009 06:13 PM
Newer lenses on *ist D K1000_Ron Troubleshooting and Beginner Help 4 06-15-2009 09:03 AM



All times are GMT -7. The time now is 01:12 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top