Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-15-2009, 08:27 PM   #1
Veteran Member
VaughnA's Avatar

Join Date: Feb 2009
Location: Virginia
Photos: Gallery | Albums
Posts: 1,363
Wide AF Vs Manual vs Cost

I'm looking for something wider than my current 50 1.7 as a prime as I really like the improved sharpness of the prime. I'd like auto focus since my eyes aren't the greatest but the cost is pretty prohibitive with my current situation. It looks like getting an AF prime < 50mm is about 4-500 bucks. Since DOF is greater with wides I'm considering just going on and getting manual focus lenses and seeing how that goes since there may be a little more room for error. But I'm wondering if I'll be able to focus the thing as sharp as my kit lens does automatically in most cases. Good Idea? What would you folks recommend for cheap wides? I prefer bayonet and Auto if possible.

Thanks

12-15-2009, 09:09 PM   #2
Veteran Member
Steinback's Avatar

Join Date: Jan 2008
Location: GTA, ON, Canada
Photos: Gallery | Albums
Posts: 1,672
If you're patient it should be possible to find a used F 28mm f/2.8 or FA 28mm f/2.8 AL for $250 or less. Both are autofocus and should outperform the kit lens.
12-15-2009, 10:58 PM   #3
Pentaxian
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
Photos: Gallery | Albums
Posts: 4,838
It's true that the margin for error is greater. I have used a 16mm fisheye at f8 and forgotten to refocus, still getting usable results due to its enormous DOF. But if you really can't focus that well, you will not see the improved sharpness of a prime over the kit lens. You'll have to stop down to increase DOF so you won't be able to use the wider apertures. So it really comes down to your focus ability.

If you want to try it, consider a Pentax-M or Pentax-A 28mm f2.8. My reasoning is, Pentax lenses will be easier to resell without loss if it doesn't work, these two lenses are inexpensive, and f2.8 is about as fast as you are likely to find anyway.

An alternative is looking for a deal on a DA 16-45/4, which you might get for as low as $250. On paper, it doesn't look that great of an improvement. It's not really faster anywhere. But you get 16mm, better IQ all around, and AF. It is going to be really hard to find any primes below 24mm that match this lens, and to be fair, you should include at least two lenses because you're comparing to a zoom.
12-16-2009, 04:28 AM   #4
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,342
while there may be more room for error, it is also harder to focus spot on because the depth of field is so great that you can't really tell.

Even with a split image viewfinder, I find certain circumstances with my 28mm F2.5 that I am not as sharp as I would like because of this.

Note that the faster the lens the easier it should be to focus due to the narrower DOF

12-16-2009, 05:25 AM   #5
axl
Veteran Member




Join Date: Mar 2007
Location: Nove Zamky, Slovakia
Photos: Gallery | Albums
Posts: 7,181
QuoteOriginally posted by Lowell Goudge Quote
while there may be more room for error, it is also harder to focus spot on because the depth of field is so great that you can't really tell.

Even with a split image viewfinder, I find certain circumstances with my 28mm F2.5 that I am not as sharp as I would like because of this.

Note that the faster the lens the easier it should be to focus due to the narrower DOF
Exactly my point!
I was trying MF24/2.8 but I found the fousing much harder than I thought!
12-16-2009, 06:10 AM   #6
Inactive Account




Join Date: Dec 2008
Location: Ames, Iowa, USA
Photos: Albums
Posts: 2,965
If you use the green hexagon in the viewfinder as the indication that focus has been achieved you will be duplicating what the camera does.

Using manual focusing with focus trapping is exactly the same as autofocusing except your fingers replace the camera's motor (the camera decides when focus is achieved & activates the shutter).

Go for a manual lens methinks.

Dave
12-16-2009, 07:21 AM   #7
Pentaxian
8540tomg's Avatar

Join Date: Feb 2008
Location: Waterloo, Ontario
Photos: Gallery
Posts: 4,446
You are not likely to find many bargains in MF lenses below 24mm. My widest lens at the moment is the K 24/2.8. I guess this equates to roughly 30 or 31mm in the digital format. As I donít shoot a lot of wide angle stuff I find this old lens is more than adequate for my needs. If you donít require anything much wider this may suffice for your needs as well. Older lenses, 20mm and wider get very expensive as a quick scan on Ebay will confirm.

I donít find focusing an issue as I have installed a KatzEye focusing screen in my K10. KatzEye is expensive but has made manually focusing much easier with all my older lenses. There are several threads dealing with focusing screens in the forum and I would submit the standard screen provided by Pentax just isnít up to the manual focus job. There are cheaper Chinese screens out there which many forum members are using and are pleased with.

Good and cheap are terms which donít go together very often when looking for used lenses. Good luck with your search.

Tom G
12-16-2009, 09:49 AM   #8
Pentaxian
reeftool's Avatar

Join Date: Dec 2007
Location: Upstate New York
Photos: Gallery | Albums
Posts: 8,043
QuoteOriginally posted by 8540tomg Quote
Good and cheap are terms which donít go together very often when looking for used lenses. Good luck with your search.

Tom G
Very true but there are some great bargains to be had. It does require patience however. There are several lenses I would like to have and I browse through the Marketplace and Ebay on a regular basis. If I find what I want at the price I can afford I go for it. If I can't, I wait. I see a lot of 28mm manual focus lenses listed often on Ebay for very good prices.

12-16-2009, 10:14 AM   #9
Veteran Member
kevinschoenmakers's Avatar

Join Date: Mar 2009
Location: Shanghai
Photos: Gallery
Posts: 1,513
You could try getting an A28F2.8 (I have one, I love it) and see how you do with manual focussing. Remember that pentax dSLRs give a beep and a visual blink of the center focuspoint when focus has been achieved, so even with bad eyesight you should be able to focus relatively easily. And if it doesn't work out for you, these lenses will only cost you about $40, and they can be resold for the same amount.
12-16-2009, 11:53 AM   #10
Veteran Member
VaughnA's Avatar

Join Date: Feb 2009
Location: Virginia
Photos: Gallery | Albums
Posts: 1,363
Original Poster
Good answers all. A lot to think about. I've been considering the 16-45 and I might go that route to start on getting something wide with better quality than my kit 18-55WR. I'm also going to keep an eye out for one of the F28's. I think I'll stick to the AF lenses.
12-16-2009, 01:05 PM   #11
Pentaxian
philbaum's Avatar

Join Date: Oct 2007
Location: Port Townsend, Washington State, USA
Posts: 3,659
QuoteOriginally posted by VaughnA Quote
Good answers all. A lot to think about. I've been considering the 16-45 and I might go that route to start on getting something wide with better quality than my kit 18-55WR. I'm also going to keep an eye out for one of the F28's. I think I'll stick to the AF lenses.
I think you made the right decision. I probably AF 90% of the time, and MF when necessary in problem situations, like night exposures. at 61 i can still MF in a pinch, but think of AF as more reliable and faster where the situation is right for it.

If you look at Pentax F 28 f2.8 lens in the database, the folks rave about them. Bought one and am very happy with it. Pretty small lens and it snaps to focus quickly. The downside is when i bought 2 months ago, there were 3 of them on ebay, and they all went for about $250. You might also look at that lineup of fast sigma's in this range. i think they made a 24, 28, and 30, seem to get good reports, heavier but faster. I didn't look in them in any detail because i wanted a smaller size.
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, af vs, auto, cost, focus, k-mount, pentax lens, slr lens, vs, wides
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Decent Fast-ish Manual Wide shiestmiester Pentax SLR Lens Discussion 9 06-28-2010 05:34 AM
Wide-Angle Manual Focus Lens hangu Pentax SLR Lens Discussion 41 04-22-2010 04:11 PM
Manual wide angle prime lens? Olypentax Pentax SLR Lens Discussion 4 02-06-2010 10:46 PM
Why does one cost more than another? Mallee Boy Pentax Camera and Field Accessories 12 10-06-2008 05:42 PM



All times are GMT -7. The time now is 10:36 AM. | See also: NikonForums.com, CanonForums.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