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09-03-2013, 06:36 AM   #1
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K-30 viewfinder darker than K-5?

I compared my friend's K-5 with my K-30 and its viewfinder is definitely brighter.

Anyone else notice this? If this is true then it's another plus point in favor of the K-5 for those choosing between the two.

It would also mean that even if the OVF specs are the same, they are not equal.

Effect of selling a product at a lower price point?

09-03-2013, 06:45 AM   #2
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Was the lens on the K-5 a faster lens? A lens with a larger aperture will let more light through the OVF...
09-03-2013, 06:47 AM   #3
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QuoteOriginally posted by boriscleto Quote
Was the lens on the K-5 a faster lens? A lens with a larger aperture will let more light through the OVF...
Even if they were both the 18-55mm, the zoom would have to be at the same place, it will be darker at 55 than 18.
09-03-2013, 06:59 AM   #4
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Thanks for the replies. Come to think of it, the lens on the K-5 was a 18-50 Tamron with 2.8 max aperture if I remember correctly.

Although I can't remember what lens I was using as I was constantly switching between an 18-55 kit, 50-200, and a DAL 35.

Shows how scientific my test methods are :-D.

Let's assume I was using the 18-55 kit. Would the difference between 3.5 and 2.8 apertures be that noticable?

09-03-2013, 07:11 AM   #5
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A full stop cuts the light in half, the difference between f2.8 and f3.5 is 2/3 of a stop, so it should be noticeable side by side. If the 18-55mm happened to be at 55mm, which is f5.6, then it is 2 full stops darker.

If I take my 35mm f2.8 and set it to f3.5, then pull the DOF preview, there is definitely a noticeable difference.
09-03-2013, 10:10 AM   #6
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Also the T-stop is likely lower(better) on the Tamron. This is the Total amount of light getting trough all the glass and is effected by number of elements, quality of glass, coatings, reflections, etc. People forget about that but it is significant light loss.
09-03-2013, 10:28 AM   #7
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QuoteOriginally posted by ToyTank Quote
Also the T-stop is likely lower(better) on the Tamron. This is the Total amount of light getting trough all the glass and is effected by number of elements, quality of glass, coatings, reflections, etc. People forget about that but it is significant light loss.
Modern zooms are fairly equal if they are around the same focal length range, you shouldn't see a significant difference in most cases. Primes will usually have a noticeably lower T-stop than zooms at equal focal length though.
09-03-2013, 10:44 AM   #8
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Yeah pretty close 3.4 t stop to 4.6 so basically one stop total difference at 18mm. 2/3 stop to aperture size, 1/3 stop for better transmittance. I call that significant.

09-03-2013, 03:46 PM   #9
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Thanks for the info! Next time I have to check with similar lenses :-)
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