Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

How to test a filter?
Post new topic   Reply to topic
Home   Adapters and other accessories
View previous topic :: View next topic  


PostPosted: Thu Oct 07, 2010 6:02 pm    Post subject: How to test a filter? Reply with quote
I am not sure if putting a UV filter on an expensive lens
(Zeiss, Leica, ...) is a good idea.

However, I have saved a lens this way.

The question is, can you think of a reasonable test?

A manufacturer "guarantees" 99.999 % light transmission etc.
How can we find out if the specifications are honoured?

Last edited by Nikos on Thu Oct 07, 2010 9:13 pm; edited 1 time in total


PostPosted: Thu Oct 07, 2010 6:06 pm    Post subject: Reply with quote
ask poilu to show you his test files...


PostPosted: Thu Oct 07, 2010 8:03 pm    Post subject: Reply with quote
I just received a b&w and it is a skylight, I thought it was the same like UV but this one is yellow and 1.1, it loose 10% of light
so I am not the best placed to talk about filter Laughing
next time I will order protection filter who don't change colors


PostPosted: Thu Oct 07, 2010 8:24 pm    Post subject: Reply with quote
poilu, wasn't it you to post a thread where you showed the poor IQ of a lens with a UV filter on compared to no filter?

Or is age playing tricks with my memory?


PostPosted: Thu Oct 07, 2010 8:44 pm    Post subject: Reply with quote
yes borders was little better at 100% without filter but I cannot call it poor IQ
what I want to check is colors differences with or without filter
last week I got differences in sea color but it was cloudy, I have to make a controlled test to sort it out


PostPosted: Thu Oct 07, 2010 8:57 pm    Post subject: Reply with quote
Hoods offer lens protection, while increase contrast by reducing flare, even the ever-present flare too dim to plainly see.

UV filter can cut some long distance 'haze' not seen by the eye but recorded by film. Sensors have UV filters, sufficient unless UV is very intense such as at high altitude. Depends on sensor UV filter characteristics, ymmv.

All filters, even clear (multi-coated) glass, reduce light throughput.

A test might be done at very high altitude with telephoto lens, try various
UV filters, see effect on exposure, especially blue channel histogram -- choose the one with cutoff minimizes most long distance 'haze'.


PostPosted: Thu Oct 07, 2010 9:09 pm    Post subject: Reply with quote
poilu wrote:
I just received a b&w and it is a skylight, I thought it was the same like UV but this one is yellow and 1.1, it loose 10% of light
so I am not the best placed to talk about filter Laughing
next time I will order protection filter who don't change colors

Haha, they tried to sell me a skylight instead of a UV last week in a shop. (and it would be an expensive 82mm)

- "You know, you will just tweak the white balance a bit"
- "No thank you, I did not pay Zeiss a truck load of Euros to play with WB"

Cute, huh? Shocked


PostPosted: Thu Oct 07, 2010 11:18 pm    Post subject: Reply with quote
There was an extensive UV filter test at lenstip. While some of the tests were done using special equipment, the tests of individual filters also show flare tests which are quit simple to set up. You may also want to simply pixel-peep resolution with and without filter.


Personally I'd just get a metal lens hood deep enough to protect the front element from impacts (unless you drop it on a spike =). A “protective” filter can theoretically also be risky as it's more prone to shattering (being a fragile flat sheet of glass suspended in a thin ring of soft metal) and filter shards can scratch your lens, especially if the filter breaks between a lens cap and front element due to bumping the camera bag.


PostPosted: Thu Oct 07, 2010 11:58 pm    Post subject: Reply with quote
Arkku wrote:

Personally I'd just get a metal lens hood deep enough to protect the front element from impacts (unless you drop it on a spike =). A “protective” filter can theoretically also be risky as it's more prone to shattering (being a fragile flat sheet of glass suspended in a thin ring of soft metal) and filter shards can scratch your lens, especially if the filter breaks between a lens cap and front element due to bumping the camera bag.


+1


PostPosted: Fri Oct 08, 2010 6:16 am    Post subject: Reply with quote
It angers me to see lens hods not used on normal - tele lenses.


PostPosted: Fri Oct 08, 2010 12:37 pm    Post subject: Reply with quote
poilu wrote:
yes borders was little better at 100% without filter but I cannot call it poor IQ
what I want to check is colors differences with or without filter
last week I got differences in sea color but it was cloudy, I have to make a controlled test to sort it out


Change of colour does not worry me because on digital it is absolutely irrelevant, and on film the use of a UV may actually improve colour more often than damage it.

My concern is about the loss of micro-contrast that a UV filter or any glass surface between my lens and the subject can produce. The fact that the macro contrast does not change does not mean the micro contrast is not affected. If you shoot through a window a landscape outside, the macro contrast will be the same as with no window, but as you go 100% enlargement and check the areas with finer details you will see immediately loss of micro-contast.
I am afraid that this may happen too with UV filters, not as badly as with a window of course, but, to paraphrase Nikos, I did not spend thousands on my Contax lenses to have their performance weakened by a stupid piece of glass in front of them.


PostPosted: Fri Oct 08, 2010 2:25 pm    Post subject: Reply with quote
Arkku wrote:
A “protective” filter can theoretically also be risky as it's more prone to shattering (being a fragile flat sheet of glass suspended in a thin ring of soft metal) and filter shards can scratch your lens, especially if the filter breaks between a lens cap and front element due to bumping the camera bag.


I agree with you, but I guess that depends. Take a look at this. Smile
Post new topic   Reply to topic
Home   Adapters and other accessories
Page 1 of 1