Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-30-2010, 07:56 AM   #16
1,000,000th Poster!




Join Date: Apr 2010
Location: Montreal, QC
Photos: Gallery | Albums
Posts: 172
Original Poster
QuoteOriginally posted by paperbag846 Quote
How to do a lens test:

1) Set up your tripod with a far away background and some stationary object close by.
2) Focus and shoot lens A on the stationary object wide open, at f4, and at f8.
3) Focus and shoot lens B on the stationary object wide open, at f4, and at f8.
4) Remember to keep white balance fixed (do not use AWB).
5) Use a proper hood.

Now you are done! Compare each lens at each aperture and see what you like best.

EDIT: No guarantee that this will help you much... I tried to figure out if I should sell the K 55 1.8 or the A 50 1.7, and i simply could not pick a favorite because they are both different enough! Gah!
I'll follow your instructions during the weekend. I might be able to tell if there's a difference. Thank you for the WB tip. I might set everything on manual in order to make sure that everything remains the same.

09-30-2010, 08:08 AM   #17
Pentaxian
audiobomber's Avatar

Join Date: May 2008
Location: Sudbury, Ontario
Photos: Albums
Posts: 6,631
QuoteOriginally posted by Flickeroo Quote
I'll follow your instructions during the weekend. I might be able to tell if there's a difference. Thank you for the WB tip. I might set everything on manual in order to make sure that everything remains the same.
I would leave the WB on auto, assuming that's how you intend to use the lens. I prefer to let the camera set the exposure too, since different lenses may expose differently. I like to make my test mimic reality as much as I can. For resolution testing though, always a tripod and 2s MLU.

If you decide to post your results, which is always welcome around here, be prepared for a lot of critique. No matter what settings you use, someone will think you should have done something different.
09-30-2010, 09:27 AM   #18
Veteran Member
paperbag846's Avatar

Join Date: Jul 2010
Photos: Gallery
Posts: 2,396
QuoteOriginally posted by audiobomber Quote
I would leave the WB on auto, assuming that's how you intend to use the lens.
I suggest to keep the WB fixed so that you can see any differences in how the lens' render colours. While it might be further away from "real" shooting, the trick here is to control variables to elucidate any differences between the two lenses.
10-01-2010, 04:59 AM   #19
Pentaxian
bdery's Avatar

Join Date: Mar 2008
Location: Quebec city, Canada
Photos: Gallery
Posts: 5,661
QuoteQuote:
Some on this board say the 1.7 is sharper at 1.8, but the only objective test I've seen found otherwise. Nifty 50 Shootout ERPhotoReview Maybe the people who preferred the 1.7 didn't use a hood, maybe they confused contrast with resolution, or quite possibly their copy was sharper. Most who say the 1.7 is sharper are just parroting someone else. In a test dgaies posted showing the two, most thought the 1.7 sharper and some (like me) found the opposite. One thing for sure, they are both great lenses, so you can't lose.
I fully agree with the last sentence.

However, I disagree with the rest. It's nickpicking, since indeed both lenses are great, but being an optical designer I know some stuff about contrast, sharpness, MTF, and all those other buzzwords we love On my K20D, my f1,4 was clearly less sharp AND less contrasty at f1,8 than my f1,7 wide open. Could it be anecdotal? Sure. But I think considering the sheer number of people observing the same thing, it's more than parrotting.

I still have sample shots even though I don't own the f1,4 anymore, I could show them to you if you'd like.

10-01-2010, 06:06 AM   #20
Veteran Member
dgaies's Avatar

Join Date: Oct 2009
Location: Maryland / Washington DC
Posts: 3,917
QuoteOriginally posted by audiobomber Quote
Some on this board say the 1.7 is sharper at 1.8, but the only objective test I've seen found otherwise. Nifty 50 Shootout ERPhotoReview Maybe the people who preferred the 1.7 didn't use a hood, maybe they confused contrast with resolution, or quite possibly their copy was sharper. Most who say the 1.7 is sharper are just parroting someone else. In a test dgaies posted showing the two, most thought the 1.7 sharper and some (like me) found the opposite. One thing for sure, they are both great lenses, so you can't lose.
QuoteOriginally posted by bdery Quote
I fully agree with the last sentence.

However, I disagree with the rest. It's nickpicking, since indeed both lenses are great, but being an optical designer I know some stuff about contrast, sharpness, MTF, and all those other buzzwords we love On my K20D, my f1,4 was clearly less sharp AND less contrasty at f1,8 than my f1,7 wide open. Could it be anecdotal? Sure. But I think considering the sheer number of people observing the same thing, it's more than parrotting.

I still have sample shots even though I don't own the f1,4 anymore, I could show them to you if you'd like.
Here's a link to the sample shots (100% crops) of the FA50/1.4 and FA50/1.7. If I could do it over again (I don't have either lens at the moment), I would have taken more test shots under different conditions to try and answer the question more completely. However, at the time I was just trying to figure out which lens I wanted to keep (like the OP ).

The botton line is they are both fantastic lenses, and as many people have said, you really can't go wrong with either. My personal opinion (not just based on this particular test, but on real world shots too), is that the 50/1.7 is slightly sharper than the 50/1.4 at larger apertures. However, there are other factors (bokeh, color, the extra half-stop of speed, cost) that would be important to consider when choosing between the two lenses.
10-01-2010, 08:16 PM   #21
Veteran Member
mysticcowboy's Avatar

Join Date: Apr 2009
Location: port townsend, wa
Photos: Albums
Posts: 968
I've used both lenses and don't find any appreciable difference in in IQ. The half stop speed increase in the 1.4 isn't that valuable as the lens is very soft at that f-stop. You'll get at least a third more from the FA lens. On the other hand the FA is better built and has a metal filter thread.
10-01-2010, 08:17 PM   #22
Veteran Member
mysticcowboy's Avatar

Join Date: Apr 2009
Location: port townsend, wa
Photos: Albums
Posts: 968
I've used both lenses and don't find any appreciable difference in in IQ. The half stop speed increase in the 1.4 isn't that valuable as the lens is very soft at that f-stop. You'll get at least a third more from the FA lens. On the other hand the FA is better built and has a metal filter thread. I kept the F.
10-03-2010, 05:19 AM   #23
Pentaxian
bdery's Avatar

Join Date: Mar 2008
Location: Quebec city, Canada
Photos: Gallery
Posts: 5,661
QuoteOriginally posted by dgaies Quote
The botton line is they are both fantastic lenses, and as many people have said, you really can't go wrong with either. My personal opinion (not just based on this particular test, but on real world shots too), is that the 50/1.7 is slightly sharper than the 50/1.4 at larger apertures. However, there are other factors (bokeh, color, the extra half-stop of speed, cost) that would be important to consider when choosing between the two lenses.
My opinion exactly.

10-03-2010, 10:49 AM   #24
Pentaxian
Ratmagiclady's Avatar

Join Date: Nov 2008
Location: GA
Photos: Gallery | Albums
Posts: 13,464
Oh, why didn't I realize, you have your copies of both lenses in hand. Yes, a test!

I'd also suggest adding a test of people shots or any other favored subjects at those wider apertures, and see which you may like better subjectively.
10-03-2010, 11:49 AM   #25
1,000,000th Poster!




Join Date: Apr 2010
Location: Montreal, QC
Photos: Gallery | Albums
Posts: 172
Original Poster
QuoteOriginally posted by Ratmagiclady Quote
Oh, why didn't I realize, you have your copies of both lenses in hand. Yes, a test!

I'd also suggest adding a test of people shots or any other favored subjects at those wider apertures, and see which you may like better subjectively.
I had just a few minutes to set up a test, but I didn't choose my subject properly and the timing was wrong. The lighting wasn't constant (cloudy with sunny breaks) and it was quite windy. So a flower bush with trees in the background wasn't a good idea.

With what I did get it's really hard to tell them apart. But I need to set up something in my living room with constant lighting and no wind!
10-03-2010, 12:47 PM   #26
Pentaxian
audiobomber's Avatar

Join Date: May 2008
Location: Sudbury, Ontario
Photos: Albums
Posts: 6,631
QuoteOriginally posted by Flickeroo Quote
I need to set up something in my living room with constant lighting and no wind!
I suggest you do the test in daylight, since your K-x AF will misfocus at wide apertures under tungsten light. I usually shoot a cereal box indoors or outside in full shade, from about 6-8 feet. I like cereal boxes because they're colourful, they have printing that shows resolution very well (100% crop), they don't move in a breeze and they're small enough in the frame that you can get a good look at bokeh. Definitely use a tripod or solid stand and 2s timer.
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!
50mm, camera, f1.4, f1.7, fa, fa 50mm f1.4, flexibility, kit, lens, pentax help, photography, trade
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: SMC Takumar 50mm 1.4 / Pentax-A 50mm 1.7 / Pentax-M 50mm 1.4 (US) JP_Seattle Sold Items 3 09-02-2010 06:17 PM
For Sale - Sold: K10D + grip + 18-55mm, DA 12-24mm, FA 50mm/1.7, D FA 50mm/2.8 macro (Worldwide dgaies Sold Items 6 07-17-2010 03:46 PM
For Sale - Sold: Pentax *ist DL, FA 50mm f/1.4, DFA 100mm f/2.8 macro, DA 18-55mm, A 50mm f/2.0 chemxaj Sold Items 14 05-31-2010 09:34 AM
For Sale - Sold: F 24-50mm 4, A 24-50mm 4, M 35mm 2, M 50mm 1.4, A 35-105mm 3.5, A 70-210mm 4 raybird Sold Items 7 08-29-2008 01:06 PM



All times are GMT -7. The time now is 08:29 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