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08-30-2013, 07:32 PM   #1
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Bower 14mm question.

This is a repost of one I made on the Pentax Deals forum.

Today I got to check out my new Bower 14mm f/2.8 lens. I can see this lens will take a learning curve for me to master. Upon testing it seems very slightly soft at 2.8, but sharpens up 3.5. What bothers me is while the center is sharp enough at 2.8 to 4.0, while the upper corners are a little soft, the lower right corner is a little soft but the lower left corner is as sharp as the center. From 4.0 and up it's all about the same. Does anyone know if this is common with this lens?
I did read the "Pentax 14mm F2.8 vs Rokinon 14mm F2.8" reviews here in the forums and it didn't mention this softness in the corners.

The distance scale is not even close. I have to use live view to focus, and outside in bright light my poor old eyes really strain to focus even then. I will have to learn to use the hyperfocal distance and forget about trying to focus on small parts of a scene (like eyes).

I am going to check it out more this weekend, but I might end up returning it to B&H for an exchange to see if I can get a better copy. Unless someone tells me this is normal for the lens.

08-30-2013, 07:57 PM   #2
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I don't have this lens, but it does sound like your copy might be decentered. More about it, and how to test, in this article:

LensRentals.com - Testing for a Decentered Lens: an Old Technique Gets a Makeover
08-30-2013, 09:34 PM   #3
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yup. i think it is pretty common problem with this lens. when i buy a new lens i usually test how well it is centered. I've gone through three different Rokinon 14mm (same exact lens diff brand) and they were all unevenly centered at 2.8. Usually by F4 or F5.6 the problems dissipated. Though i found them all amazingly sharp at the center even at 2.8. It might sound picky/demanding, however I've had a DA 15mm Ltd and a sigma 10-20 and they were both perfectly centered even wide open.
08-30-2013, 10:51 PM   #4
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standard QC

I've been looking at getting one of these lenses to use on a FF Nikon so read a bit about it a while back.
These are not uncommon flaws.

08-31-2013, 03:49 AM   #5
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Yes, I think its a decentering issue. Ultra wide angles are more susceptible to this than regular lenses. And the other problem is the QC, because its such a budget company. You can try getting it exchanged, but there is little guarantee the next one will be perfect. I had my Samyang exchanged once, the next copy is better, but not perfect (the left side is slightly softer, wide open).
The distance scales being off is a common issue. Some say its because the Pentax mount version actually has distance scales made for Canon mount. I don't know, something to that extent, but basically, infinity seems to be around 2m in many cases. There are threads on blog posts on how to fix this issue (you peel back the rubber on the focus ring, unscrew the focus ring, then focus the lens and align it to the distance scales, screw it back, peel the focus ring rubber back. tutorials have photos).

In most situations, what you describe won't ruin your photos, won't even be noticeable. But in some situations (like star photography) it might show up, so do what you must.
08-31-2013, 11:09 AM   #6
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QuoteOriginally posted by Na Horuk Quote
Yes, I think its a decentering issue. Ultra wide angles are more susceptible to this than regular lenses. And the other problem is the QC, because its such a budget company. You can try getting it exchanged, but there is little guarantee the next one will be perfect. I had my Samyang exchanged once, the next copy is better, but not perfect (the left side is slightly softer, wide open).
The distance scales being off is a common issue. Some say its because the Pentax mount version actually has distance scales made for Canon mount. I don't know, something to that extent, but basically, infinity seems to be around 2m in many cases. There are threads on blog posts on how to fix this issue (you peel back the rubber on the focus ring, unscrew the focus ring, then focus the lens and align it to the distance scales, screw it back, peel the focus ring rubber back. tutorials have photos).

In most situations, what you describe won't ruin your photos, won't even be noticeable. But in some situations (like star photography) it might show up, so do what you must.
Thank you all for the replies. I had read about these problems before I ordered the lens, but also read about enough people who had good copies to take a chance with it. The distance scale is not that big of problem, for most situations I would be at F5.6 or smaller. But I hadn't seen much on the performance at F2.8 and decentering issue.

One of the things I was wanting to use it for was star photography mixed with landscapes. After the holiday weekend is over I will return it and try for a better copy. One of the things I like about B&H is their easy return policy.
08-31-2013, 02:46 PM   #7
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Take a photo at f2.8 and minimum focusing distance, of a newspaper at a 45 degree angle to the lens. This way you can see exactly where the DoF is and how sharp the part "in focus" is, and how each of the sides looks like. Just remember that the DoF is not flat
09-01-2013, 06:06 PM   #8
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QuoteOriginally posted by Na Horuk Quote
Take a photo at f2.8 and minimum focusing distance, of a newspaper at a 45 degree angle to the lens. This way you can see exactly where the DoF is and how sharp the part "in focus" is, and how each of the sides looks like. Just remember that the DoF is not flat
I tried this, still not satisfied. I have requested a RMA from B&H, and ordered another Bower 14mm. Hopefully a better copy. If not then I will return it and look for something else.

09-10-2013, 04:20 PM   #9
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Today I received my second Bower 14mm, after returning the first one. This one is a keeper. I tested it with a checkerboard chart at minimum focus distance and it was sharp at F2.8 across the chart. Tried it on distance objects and good there too. I am new to this and amazed at the depth of field this lens gives.
The focus lines on the lens are still way off, but for what I use it for it doesn't matter. I think I will use a white marker to make my own distance marks at 8 feet and another at infinity. Since for landscape use I use the hyperfocal distance method this should give me enough information to obtain a good focus.
09-12-2013, 12:50 PM   #10
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Great that you got it sorted. I would just say that with modern digital cameras, with high MP count, the hyperfocal focusing might not work as well as you hope. At least in my personal experience.
But with a tripod and post processing sharpness increase (up to 40, 50 in LR), it will be super sharp
09-12-2013, 01:00 PM   #11
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I have the Rokinon version of this lens and I love it. Extremely sharp. I've taken pictures directly into the sun with no issues.

It's very hard to focus.

I noticed the scale issue as well.

I haven't pixel level checked my corners and edges, but I haven't seen anything stand out. I hear there's a lot of variation on QC, like others said.


I also have a Samyang 85mm that is amazing. However, it suffers from a common problem of aperture sticking until it gets a fix done on it. I just haven't sent it in yet because it doesn't happen all the time. Probably should sooner than later though.



Took these with the Rokinon 14mm


09-13-2013, 03:00 PM   #12
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The DOF scales and focus distance scales are even worse on the 8mm fisheye, but with an infinite DOF at F4 who really cares. Actually the DOF is so great on ultra wides you cannot distinguish focus accurately through the viewfinder. I use the focus indicator, achieve focus starting at infinity, move through the focus range noting approximate rotation until the hexagon goes out, then move half way back

The 14mm is easier since DOF is not so radical compared to the fisheye
09-13-2013, 10:51 PM   #13
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QuoteOriginally posted by Lowell Goudge Quote
The DOF scales and focus distance scales are even worse on the 8mm fisheye, but with an infinite DOF at F4 who really cares. Actually the DOF is so great on ultra wides you cannot distinguish focus accurately through the viewfinder. I use the focus indicator, achieve focus starting at infinity, move through the focus range noting approximate rotation until the hexagon goes out, then move half way back

The 14mm is easier since DOF is not so radical compared to the fisheye
I keep forgetting about the focus indicator, I will give that a try. Thanks for the tip.
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