Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-03-2015, 06:14 AM   #16
Pentaxian
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 10,331
QuoteOriginally posted by canteaus Quote
Is my split screen seeing what my lens sees?
Yeah, it is possible. There are some threads about adding shims to custom focusing screens in DSLRs, but I dunno about the MX specifically. It should be okay out of the factory, but the camera is old and might have been serviced poorly or just got loose over the years.
Can you run some tests wide open and at near focusing distances? Also, can you try the lens on a DSLR? That way testing the lens would be easier, so you can see if it has a major fault preventing infinity focus.

Edit: Also, the tip about UV filter and lens hood is good. Particularly on bright days and landscape photos

07-03-2015, 06:15 AM   #17
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,873
Are you able to determine if there is no back or front focus issue with manual focus lens on the camera (assuming you test it with an object closer to you)?
07-03-2015, 08:41 AM   #18
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 26,231
QuoteOriginally posted by canteaus Quote
Is there anyway that my split screen might not be properly calibrated to my lens?
The question is whether it is properly calibrated to your camera. Does your split screen see what the film sees? A good shop can test whether your screen is properly shimmed and seated in its retainer.

I am still curious as to how you are assessing sharpness and why you feel that what you have is substandard. Is your lens focus and sharpness acceptable at moderate distance, say 10 meters using the split image for focus?

Since you are shooting film, there are a number of variables affecting sharpness:
  • Focus accuracy
  • Quality of lens
  • Your choice of film
  • Processing
  • How viewed
The first two points are the same as for digital. The last is the most telling. If you assess sharpness by examining the negative directly, that is the gold standard. If you are working from a scan or optical print, the quality of that process is important. Here are a few bullet points regarding film and scans:
  • Most color films have rather poor resolution when compared to digital sensors or B&W films
  • Minilab scan quality is highly variable and prone to artifact. This true regardless of the file size or number of pixels.
  • Low end scanners for personal use are usually worse than a minilab scan
  • It takes practice and a decent scanner to extract the full sharpness from a 35mm negative or slide.


Steve

Last edited by stevebrot; 07-03-2015 at 08:54 AM.
07-04-2015, 01:59 AM   #19
Pentaxian




Join Date: Mar 2010
Location: Frankfurt am Main
Posts: 1,045
You should carefully read what stevebrot tells. He listed a couple possble causes (if there is an issue at all).

And: forget about the split screen.
If you focus on items in a distance of 1-3 m and they are sharp or even slightly out of focus, anything at infinite should be sharp, too. The only exception could be if then lens is focussing beyond infinity AND you are using the scale instead of the VF to set distance. And, of course, if the lens itself is miscalibrated, the split screen may fool you without being the cause of the problem.

And I want to add to the possibility of UV interference:
It's long ago, but now I remember that on cloudless summer days I did not use an UV, but a "Skylight" filter (R3 I think, at that time nicknamed "anti-haze" filter). It does not only filter the UV rays, but supresses the increased blue light of such situations. The skylight filter does what your brain is doing for you automatically, but film does not. With DSLRs, WB cares for it (not always perfectly). Landscape pictures will get a slightly warmer touch, which - in most cases - will be an improvement anyway.


Last edited by RKKS08; 07-04-2015 at 02:04 AM. Reason: typing
07-04-2015, 07:28 PM   #20
Pentaxian
ChristianRock's Avatar

Join Date: Jul 2013
Location: Marietta, GA
Photos: Gallery | Albums
Posts: 4,048
The focusing screen is to check the infinity focus position. I think people who never had manual lenses that focus past infinity, would not know why this is important...
07-05-2015, 12:45 PM   #21
Pentaxian




Join Date: Mar 2010
Location: Frankfurt am Main
Posts: 1,045
Not only manual lenses , also many AF lenses - specially longer ones - CAN also focus past infinity.
You will find users complaining their new AF lens does not focus to infinity all over the web. In many cases the reason is, that the lens can JUST focus to infinity.
Depending on the (body) brand, the possibility to focus beyond infinity may be needed for the AF system to make the short "hunting" to get precise focus.
And the ability to focus beyond will enable the lens to focus at all temperatures.

And, the remark in my last post referred to a possible wrongly shimmed focusing screen. The MX has user changable screens and should not need any modification in shimming, if original Asahi parts are used. And wrong shimming as well as misaligned/shifted mirror would show effects for all distances. Using the distance scale instead the screen for focusing is never a good idea. Sadly, scales are not always correct, not only for infinity.
08-21-2015, 01:57 PM   #22
Senior Member
bygp's Avatar

Join Date: Aug 2015
Location: Toulon, South of France
Photos: Albums
Posts: 282
QuoteOriginally posted by Na Horuk Quote
Are you sure the camera stopped down the lens correctly? Because a photo can look soft if its f1.4 focused at infinity. The other problem might be actual infinity focus - the lens' focus ring might be miscalibrated, or the lens mount might be a little off, thus preventing the lens from reaching infinity. One other possibility with a miscalibated focus ring is that the lens might focus past infinity.
The other thing is the film and developing itself, which might not be as "sharp" as you expect if you used modern DSLRs with digital sharpening. Especially if there was some atmospheric haze or something.
I have the same trouble, easy to see on a K200D camera, using a Chinon MC 50mm f/1.7, I can't get a sharp landscape while focusing on infinity... I think the "or the lens mount might be a little off, thus preventing the lens from reaching infinity." option is the good one, I'm sure I don't reach infinity, did many tests to find that.

But if this is the reason, how to correct mount lens "little off" problem ?
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!
camera, f8, f8 and infinity, focus, images, images at f8, infinity, lens, pentax, pentax help, photography, photos, troubleshooting
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pentax HD da 20-40mm Ldt sharpness at 2.8 and infinity?? focus ring position cake Pentax SLR Lens Discussion 8 05-20-2015 11:09 PM
The Soft Place: Post Your Soft Focus Images jeffkpotter Mini-Challenges, Games, and Photo Stories 64 04-22-2014 05:39 PM
K1 wont focus at infinity Frieght train Visitors' Center 3 09-04-2013 03:26 AM
Modify old 500mm f8 to infinity focus? andybrown33 Pentax SLR Lens Discussion 2 11-28-2012 05:48 AM
The Soft Place: Post Your Soft Focus Images jeffkpotter Post Your Photos! 22 04-23-2009 09:04 PM



All times are GMT -7. The time now is 08:36 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