Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-18-2016, 04:52 PM   #1
Senior Member




Join Date: Feb 2015
Location: Troisdorf
Posts: 298
special focusing screen for manual focusing?

Hey guys

is there a "special" focusing screen which comes in handy for focusing manual?
Does it make sense to get one when using mf lenses?
I have got an acquaintance who told me after buying a new focusing screen his "problems" focusing manual are solved...

regards Sascha

05-18-2016, 05:01 PM   #2
Veteran Member
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 11,183
Hey there! There are plenty of threads on this topic already.
Pentax advises against this modification on DSLRs, but you can easily find focusing screens for your camera online. KatzEye, FocusingScreens com, JinFinance, and others sell them. Note that the screen has to fit into your camera, as cameras are not all the same. Installing it is not super difficult, but it requires a bit of dexterity, and there is a chance you fumble it up, even ruin the focusing screen (mostly by leaving a finger print on it, as these focusing screens are really difficult to clean and should be touched only with special tools).

The stock focusing screen is optimized for relatively slow zoom lenses and is not great for lenses with f-number below f2.8. If you use lenses faster than f2.8, then you might want to exchange focusing screen. Note that focusing screens made for fast lenses will work less well with really slow lenses. This is why some people have two DSLRs, one with stock focusing screen for zoom lenses, and one with exchanged focusing screen for fast manual primes.
05-18-2016, 05:25 PM   #3
Senior Member




Join Date: Feb 2015
Location: Troisdorf
Posts: 298
Original Poster
you got me...
...asking without any kind of research beforehand

Thank you for replying with all that information!
I will search the other threads

maybe one last question without research?
if I use fast mf lenses and slow af zooms is there so much negative impact when shooting with the af ones?
05-18-2016, 05:47 PM   #4
Tas
Site Supporter
Site Supporter




Join Date: Aug 2013
Location: Brisbane, QLD
Photos: Gallery | Albums
Posts: 2,178
QuoteOriginally posted by NoobOnTour Quote
you got me...
...asking without any kind of research beforehand

Thank you for replying with all that information!
I will search the other threads

maybe one last question without research?
if I use fast mf lenses and slow af zooms is there so much negative impact when shooting with the af ones?
I don't know which camera you're using as there is some reluctance in the forum on changing the screen in the K-1. Anything else though is achievable.

I replaced the stock focusing screen in my K5 as I found it hard to manually focus, particularly the fast lenses (I have f1.4-f2.8 in manual focus lenses). I installed an S type screen sourced from focusingscreen.com. This was simple to do by following the instructions and using the supplied equipment. Note though I had a back focus issue so had to swap the standard shims out for those supplied with the replacement screen. All of this takes about 5 mins to do and the s type screen made a huge improvement in my success rate for manual focussing.

I have heard that it is harder to focus with the replacement screens but to be honest I didn't swap the original back in to compare. My preference was focussing with the fast aperture lenses so if there was a problem with slower glass I didn't really care. The S type maybe worse, but unlike a split screen the S type won't black out as you stop down. So manual focus is still achievable with slower lenses and the S type screen.

I now use a K-1 and as it's new I'm reluctant to worry about a screen replacement, particularly with the effectiveness of focus confirmation when using the viewfinder and live view. I will consider an S type replacement if one becomes available otherwise I will leave it as is.

There's lots of focusing screen discussions here as mentioned so you can add the above to what you find. Good luck with whatever direction you go with for a focusing screen.

Tas

05-18-2016, 08:36 PM   #5
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 41,532
QuoteOriginally posted by Na Horuk Quote
Pentax advises against this modification on DSLRs
???? Pentax currently sells three screens as alternative to the stock MF-60 AF that comes with their APS-C cameras. They also list interchangeable screens as a feature for all current model dSLRs with the exception of the K-1.

What Pentax discourages is installation of screens with potential to affect meter function. This would include all screens with split image or microprism at the center where spot metering becomes unreliable. Also of concern are screens which are designed specifically for use with lenses f/2.8 and faster where the screen brightness may dim excessively with slower lenses or when vintage lenses are stopped down for metering. The Canon S-type screens fall into that category.

Another reason why installing a third-party screen may be problematic is the matter that there is no standard thickness for focusing screens. When a cut-down Nikon screen is inserted into a Pentax camera, the potential exists that the factory calibration shims may no longer be appropriate for the new screen. Assessing the need to re-shim is not difficult, though finding appropriate replacement shims may be. Some vendors supply plastic shims with their screens and some users on this site have had good success crafting shims from paper or thin metal stock.

QuoteOriginally posted by Na Horuk Quote
The stock focusing screen is optimized for relatively slow zoom lenses and is not great for lenses with f-number below f2.8.
You are being generous with the f/2.8 number.

As with the stock screens for all AF dSLRs (all brands), Pentax-brand screens are optimized for brightness at the expense of apparent depth-of-field (DOF).* A side-effect is that the viewfinder DOF is never narrower than what you would expect at f/3.5-f/4. As a result, fine focus is hit-or-miss regardless of the maximum aperture of the lens mounted. When using a fast lens at or near maximum aperture, the chances of missed focus are high.

When working on tripod, use of magnified live view is a very good option for accurate and precise manual focus, particularly with fast lenses. Some users have had good results with live view hoods that feature a magnifying eyepiece (e.g. Hoodman).

As noted above, manual focus with slower lenses is problematic regardless of screen used. The prisms in split-image focus aides will "black out" as the lens aperture becomes more narrow. This is due to the physics of the device and is true for both bright and dim light. The aperture at which this happens varies by design with most split image focus aides being usable to somewhere between f/5.6 and f/8. Some screens will resist blackout to between f/11 and f/13. Microsprism focus aids are also aperture sensitive with most being unusable at f/5.6 and narrower. S-type screens become less effective at about f/4.

Despite the inconvenience and cautions, I am a strong advocate of screens with focus aides for manual focus lenses. I shot with a KatzEye screen for almost seven years on my K10D and have used both S-type and KatzEye (currently) screens on my K-3.


Steve

* The need for extra brightness is a result of light diverted from the partially-silvered main mirror for use by the auto-focus system. Unfortunately, accommodating the AF system is at odds with a well-functioning optical focus path.
05-19-2016, 04:28 AM   #6
Veteran Member
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 11,183
QuoteOriginally posted by NoobOnTour Quote
if I use fast mf lenses and slow af zooms is there so much negative impact when shooting with the af ones?
It can cause the viewfinder to go darker than with the stock screen, which can be problematic in low light. As mentioned above, some screens can affect metering.
The kit lenses will be darker at some focal lengths.
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!
screen, tripod
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Manual focus - Focusing screen Storm Chaser Pentax DSLR Discussion 15 01-20-2016 04:42 AM
How I replaced my focusing screen with a high-end SLR focusing screen... bygp Pentax DSLR Discussion 18 12-01-2015 07:00 PM
Manual Focusing Screen for K-30 - Help please infocus Pentax DSLR Discussion 4 10-13-2014 06:00 AM
Manual Lens focusing issues (focusing screen) Akarak Troubleshooting and Beginner Help 15 01-25-2013 06:56 PM
Focusing manual lens with OEM focusing screen, is a split screen really needed? skid2964 Pentax Camera and Field Accessories 16 09-17-2010 02:54 PM



All times are GMT -7. The time now is 06:33 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