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10-02-2010, 06:58 AM   #1
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2ndhand FA35mm/2 - a dud? (with pictures!)

I found a FA35/2 in the local classifieds last night. I'm somewhat disappointed. The images are not at all what I expected. I was hoping for something at the level of my M50/1.4, which I like a lot.

So, I put my K-x on a tripod and photographed my bookshelf. It looks like this, for reference.


Then I autofocused the FA35 and shot wide open at f2. 100% center crop (attachment no.1):


I tried manual focus with LiveView too and got this (attachment no.2):

Slightly better, but not great.

I put on the M50/1.4 and shot at f2 (attachment no.3):

That's more like it.

Lastly, I tried the FA35 at f4, which is better than at f2. Naturally (attachment no.4).


I know that the M50 magnifies more and that makes it look better in the same crop size, but still.

Do I have a broken lens here? Or is this just the way the FA35/2 is supposed to look at f2?

Hope to hear from some FA35 experts.

And I hope the pictures are there as attachments this time.

Sincerely,
--Anders.

Attached Images
View Picture EXIF
PENTAX K-x  Photo 
View Picture EXIF
PENTAX K-x  Photo 
View Picture EXIF
PENTAX K-x  Photo 
View Picture EXIF
PENTAX K-x  Photo 

Last edited by asp1880; 10-02-2010 at 10:16 AM. Reason: fixed pictures
10-02-2010, 07:09 AM   #2
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No pictures...
10-02-2010, 07:16 AM   #3
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Anders I don't see any images!

I have used the FA35, mostly on a K10D and then a K20D. On the K10 I ended up going into the DeBug menu for AF correction and it seemed better. And of course K20 has AF correction in its menu- does the KX have that feature?

The AF did seem to miss focus every once in a while, if the point of focus didn't clearly stand out from the background or have a lot of contrast- but that is more because of the camera's focus system I thought; the little red focus point that I'd see in the VF is waaay smaller than the actual focus zone. So for me I'd say it was operator error and just getting to know the camera.

That said, I thought the FA35 was extremely sharp, even at F2, as long as I did my part to ensure it was focused correctly. If you can get your images up maybe we can diagnose it better for you. FA35 is a good lens.
10-02-2010, 08:27 AM   #4
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QuoteOriginally posted by NeverSatisfied Quote
Anders I don't see any images!
Maybe that's the problem
In which case I'd say YES it is definitely defective

10-02-2010, 12:33 PM   #5
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I don't know, I've never had much luck testing focus on something like a bookshelf. Try a solitary object with a good deal of distance and contrast from the background. Or, dare I say it, maybe a focus chart?
10-02-2010, 12:55 PM   #6
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Well, maybe the bookshelf sends an amateurish message. Duly noted. :-)
But I'm not concerned with focus, but sharpness. E.g. looking at the lettering on
the red book, I think it's obvious that the IQ is sub par.

Sincerely,
--Anders.
10-02-2010, 01:42 PM   #7
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Have you tried taking some real pictures with it?

K7 FA35 f2

http://www.rolleiman.com/Photos/k7js6156mFA35f2.jpg



http://www.rolleiman.com/Photos/k7js6157mFA35f2.jpg



K7 FA35 f11

http://www.rolleiman.com/Photos/k7js6159mFA35f11.jpg



http://www.rolleiman.com/Photos/k7js6160mFA35f11.jpg



10-02-2010, 03:17 PM   #8
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QuoteOriginally posted by asp1880 Quote
I found a FA35/2 in the local classifieds last night. I'm somewhat disappointed. The images are not at all what I expected. I was hoping for something at the level of my M50/1.4, which I like a lot.

So, I put my K-x on a tripod and photographed my bookshelf. It looks like this, for reference.


Then I autofocused the FA35 and shot wide open at f2. 100% center crop (attachment no.1):


I tried manual focus with LiveView too and got this (attachment no.2):

Slightly better, but not great.

I put on the M50/1.4 and shot at f2 (attachment no.3):

That's more like it.

Lastly, I tried the FA35 at f4, which is better than at f2. Naturally (attachment no.4).


I know that the M50 magnifies more and that makes it look better in the same crop size, but still.

Do I have a broken lens here? Or is this just the way the FA35/2 is supposed to look at f2?

Hope to hear from some FA35 experts.

And I hope the pictures are there as attachments this time.

Sincerely,
--Anders.

Hi Anders, there are things to consider when doing some test shots inorder to give or see a fair side by side comparison between lenses.

* were the compared images shot at infinity, mid-range or close-up?
* were the images cropped out at magnified level?
* make sure to compensate the focal distance when using both lenses inorder to show atleast similar size or magnification of the subject. not necessarily relying the lens' minimum focusing distance but illustrating the other lens' image size/magnification. the 35mm is a shorter lens, so it would be necessary to adjust the 50mm a bit further away if the 35mm is shooting at minimum focal distance already.
* remember that 35/2 is shot wide open and 50/1.4 at f2 is closed down by a stop. shooting wide open usually display a shallow DOF especially fast lenses with such focal lengths. this has big influence since stopping down would make images sharper and more in focus, which is the case with the 50/1.4 at f2 appears sharper.


some things I noticed with the test images:

1.> the first 2 images don't looked properly focused or it looks blurry.
did you turn off the SR while using the tripod? or atleast shot it above 1/250 shutterspeed?

2.> a very good lighting or flash would had helped to see the differences between the images.

3.> from what it looks like, the AF and the LV focusing aren't that spot on IMO.

10-03-2010, 11:02 AM   #9
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The second (manual focus with live view) image looks out of focus: the blur around high contrast lines takes on chromatic aberration. The first image may also be out of focus, or it may just be soft with high-contrast scenes at that aperture. I don't know the lens well enough to say. The f/4 image is very sharp, and appears as if it could give the 50/1.4 a run for its money even when cropped, at least comparing f/4 to f/2.

My only concern is that the blur at f/2 seems to trend down more than it trends up. Another way of saying that is that at a high contrast edge, there is more blur below the line than above the line. You may want to re-orient the lens and see if that remains consistent regardless of camera orientation.

A few other things I would try: focus on an angled subject with lots of high-contrast edges, like text on a page. This way you can see the focal plane and evaluate that, rather than whether the camera is focusing properly. Also, take a picture of a low-contrast yet detailed subject, like a dry leaf, and see how much detail is rendered as compared to these high-contrast, low-detail subjects. Another thing is to take a picture of a very flat subject, like a wall, and see whether the focus plane remains flat or if it is tilted; looking at center crops here won't tell us whether there is a tilt to the focus plane that runs near at one edge and far at the other, but that info could be relevant to what you're seeing. Last, take images at different aperture--preferably third-stops--and see where it sharpens enough for your needs.

Finally, depending on how much you paid, and from what I see, I don't think you got a dud. This lens may not do well at rendering extreme contrast wide-open, but it does very well stopped down to f/4. These sort of tests helps you understand the limitations of the lens--no lens is perfect--which will help you in the field.
10-03-2010, 09:39 PM   #10
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possibly a case of back or front focusing. Google for charts that you can use to test this.
10-04-2010, 03:23 PM   #11
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Thanks for all your suggestions. Great input all around, appreciated.

@Pentaxor: I use my Manfrotto tabletop tripod and I have tried various shutter times. The original shots were at 0.5 sec shutter using the 2 sec MLU self timer, which also disables SR.
Tonight I tried with the popup flash, per your suggestion. I must say that the images sharpen up considerably that way compared to the 0.5 sec exposure.

The focus test:
I did the focus test with the newspaper page, you know the one. My lens seems to do well there, no apparent FF or BF.
I did notice though, that even when the screwdrive is engaged, there is enough play in the focus ring to wiggle the focus one newspaper text line back and forth. This is at close range, 0.5 meter. Is that excessive play?

The portrait-orientation test:
@JohnPB: You noticed that the blur seems to trend down predominantly. I could easily reproduce the phenomenon again tonight, so I tried to flip the camera into portrait orientation and shoot again. And the blur direction stays constant relative to the lens and camera. Does that point at shutter shake?

Observation 1: the blur direction is constant re. the camera.
Observation 2: the images are less blurry when using flash.
Possible conclusion: the blur was caused by shutter induced camera shake.
Critique: But I used 0.5 sec shutter, tripod and MLU!

The lenstip.com review:
I found the lenstip.com FA35/2 review today. They have a resolution versus aperture plot that shows the f2 center res to be only 65% of the f4 res. Maybe that's what I'm seeing and that's just how the FA35/2 is.

It's late now and this post is too long and makes too little sense. Tomorrow I'll try to photograph my daughter and see if I can capture her eyebrows and eyelashes the way I can with the M50/1.4.

Sincerely,
--Anders.
10-04-2010, 05:34 PM   #12
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OP, the Manfrotto table top tripod is not very steady imo. Use a proper tripod that has proper isolation. I say this because the K-x shutter is pretty loud and can be felt, so if you just have it on a table, there is every chance for vibration to affect the shot. Secondly, looking at the exif of your images, the shutter speed is way too slow and I'm inclined to believe that there is camera shake in your images. Do a focus test with bright sunlight, not indoor incandescent lighting for better accuracy. Images shot with flash will appear sharper because the very short duration of the flash will freeze any movement.

JeffJS, fyi your images are just too large in size and slow down loading of the page considerably...
10-04-2010, 05:48 PM   #13
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QuoteOriginally posted by asp1880 Quote
Thanks for all your suggestions. Great input all around, appreciated.

@Pentaxor: I use my Manfrotto tabletop tripod and I have tried various shutter times. The original shots were at 0.5 sec shutter using the 2 sec MLU self timer, which also disables SR.
Tonight I tried with the popup flash, per your suggestion. I must say that the images sharpen up considerably that way compared to the 0.5 sec exposure.

The focus test:
I did the focus test with the newspaper page, you know the one. My lens seems to do well there, no apparent FF or BF.
I did notice though, that even when the screwdrive is engaged, there is enough play in the focus ring to wiggle the focus one newspaper text line back and forth. This is at close range, 0.5 meter. Is that excessive play?

The portrait-orientation test:
@JohnPB: You noticed that the blur seems to trend down predominantly. I could easily reproduce the phenomenon again tonight, so I tried to flip the camera into portrait orientation and shoot again. And the blur direction stays constant relative to the lens and camera. Does that point at shutter shake?

Observation 1: the blur direction is constant re. the camera.
Observation 2: the images are less blurry when using flash.
Possible conclusion: the blur was caused by shutter induced camera shake.
Critique: But I used 0.5 sec shutter, tripod and MLU!

The lenstip.com review:
I found the lenstip.com FA35/2 review today. They have a resolution versus aperture plot that shows the f2 center res to be only 65% of the f4 res. Maybe that's what I'm seeing and that's just how the FA35/2 is.

It's late now and this post is too long and makes too little sense. Tomorrow I'll try to photograph my daughter and see if I can capture her eyebrows and eyelashes the way I can with the M50/1.4.

Sincerely,
--Anders.
Hi Anders, glad to know that you saw some differences. usually shooting with a flash brings out the optimal performance of the lens due to better metering, and exposure ( better lighting and faster shutter speed). actually you can have great results even without using the flash as long as you got good lighting and shooting at faster shutter speeds. shooting at 0.5 shutter speed is just too slow especially for testing and as you say, is much more susceptible to camera shake.

I think that the lenstip resolution test is understandable and pretty consistent with any lens lpmm at wide open which is around 30lpmm. then an improvement after stopping down, e.g. FA35 from f2 to f2.8 and FA50 from 1.4 to f2 lpmm. you cannot really fairly compare an f2 lens with faster lens stopped down at f2. this is the advantage mostly of some faster lenses. and the slower lenses have to adjust DOF only after stopping down. although there might be some exceptions as well.

so basically, what you are seeing is what you have just stated.

anyway, since you have somehow already resolved the blur or soft rendering issue caused by shooting at slow shutterspeed, I guess you are pretty much content with the sharp images that you saw when you used a flash?

so basically there is nothing wrong with the lens but just a case of camera shake. things to consider when using this lens is to use a flash, shoot at faster shutterspeed, and boost the ISO to avoid the camera blur.
10-04-2010, 07:16 PM   #14
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Is there a filter on the lens? If yes, take it off and try again.

John
10-04-2010, 07:32 PM   #15
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Sounds like the problem is for the most part solved, though for the record my impression of my FA 35/2 is that it is on a par (if not better) wide open with my K 55/1.8 at f/2 and may well be the sharpest lens I own.

BTW...I would suggest using something other that a bookcase for testing lenses at maximum aperture. The DOF may be less than the bow in the spines of the books depending on lens and shooting distance. A setup that I have seen used is:
  • Classified ad section of the newspaper glued to a piece of hardboard as target
  • Camera at 20x the lens focal length from the target. Target should be large enough to fill the frame at this distance. Target must be at right angles to the lens axis.
  • Focused using a split image screen (Live view may be a good substitute, though I cannot say. My camera lacks that feature)
  • Best of 5 attempts
This setup will show center vs. edge sharpness as well as allow detection of centering defect.

Steve


(Yes, sharper than the 77/1.8 Limited and my Sigma Macro...)
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