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06-26-2013, 10:39 PM   #1
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Lenses for NEX: Pentax or Pen-F Zuiko

I recently bought NEX 5n and planning to use it with manual lenses (yet to receive K & M42 adapters from ebay).

I am trying to make nex+lens combination as small as possible and came across Zuiko Pen-F 40/1.4 & 38/1.8 lenses which complements nex well due to the size (both, lens and the adapter size). I was wondering how they compare with Pentax 50/1.4, 50/1.7 IQ wise. I already have so many Pentax 50's and really looking forward to advice before spending on Zuiko lenses.

Thanks
Yusuf


Last edited by yusuf; 06-27-2013 at 07:44 AM.
06-27-2013, 08:38 AM   #2
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The Pen F 38 is very highly regarded on the NEX camera bodies, as are Pentax lenses. Since you already have the Pentax lenses I would concentrate on those until such time that they prove to be lacking in some way before exploring other options.

And if you're really looking to go small lenses you need to look at rangefinder lenses. Bring money though.

Last edited by bimjo; 06-27-2013 at 08:39 AM. Reason: addition
06-27-2013, 09:04 AM   #3
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QuoteOriginally posted by bimjo Quote
The Pen F 38 is very highly regarded on the NEX camera bodies, as are Pentax lenses. Since you already have the Pentax lenses I would concentrate on those until such time that they prove to be lacking in some way before exploring other options.
I love my Pentax lenses, considering Pen F for the overall size. Pentax lenses with adapter makes the combo little bigger that Pen F.
06-27-2013, 09:06 AM   #4
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My Konica Hexanon 40/1.8 is very small, very good and very cheap. I think Olympus might give you more options, and the Pen-F is about a CM shorter. I went the Contax G route for RF glass. If you decide to use a Lens Turbo or Speedbooster, they do reduce the registration distance a bit, so your K-mount lens setup would be a bit smaller than a glass-less adapter. You wont get anything smaller than an Auto 110 lens, and the prices are trivial, but you'll be stuck at 2.8.


Last edited by kenafein; 06-27-2013 at 09:22 AM.
06-27-2013, 09:24 AM   #5
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QuoteOriginally posted by kenafein Quote
My Konica Hexanon 40/1.8 is very small, very good and very cheap. I think Olympus might give you more options, and the Pen-F is about a CM shorter. I went the Contax G route for RF glass. If you decide to use a Lens Turbo or Speedbooster, they do reduce the registration distance a bit, so your K-mount lens setup would be a bit smaller. You wont get anything smaller than an Auto 110 lens, and the prices are trivial, but you'll be stuck at 2.8.
Hexanon has almost nearly the same flange distance as Pentax so not sure if that will really reduce the overall size. Pen-F lenses have flange distance of 28mm, just 10mm more than nex, hence the adapter is really thin.

Love to get Contax G lenses, but really don't want to spend that much.
06-27-2013, 09:57 AM - 1 Like   #6
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QuoteOriginally posted by yusuf Quote
Hexanon has almost nearly the same flange distance as Pentax so not sure if that will really reduce the overall size. Pen-F lenses have flange distance of 28mm, just 10mm more than nex, hence the adapter is really thin.

Love to get Contax G lenses, but really don't want to spend that much.
I agree, the Pen-F lenses look like a great option, but if you're willing to use the Pentax glass, that you have, you could buy the lens turbo adapter, for the same money. Then you'd basically double your amount of lenses as you'd have the option of 1.09 crop or 1.5 crop. The lens turbo will give you an extra stop of light, a wider angle of view and make it slightly more compact than a glass-less adapter (though heavier).

Also, there doesn't seem to be a lot of lenses in Pen-F mount. The adapter maybe small, but the lens is large. With the Konica, the adapter is large, but the lens is very small(pancake). The combined length might be about the same, and the Konica can be had for 1/3 the price of the Olympus. Just an idea.

It does tend to CA, but I like the lens, for $40.

06-27-2013, 10:04 AM   #7
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QuoteOriginally posted by kenafein Quote
I agree, the Pen-F lenses look like a great option, but if you're willing to use the Pentax glass, that you have, you could buy the lens turbo adapter, for the same money. Then you'd basically double your amount of lenses as you'd have the option of 1.09 crop or 1.5 crop. The lens turbo will give you an extra stop of light, a wider angle of view and make it slightly more compact than a glass-less adapter (though heavier).

Also, there doesn't seem to be a lot of lenses in Pen-F mount. The adapter maybe small, but the lens is large. With the Konica, the adapter is large, but the lens is very small(pancake). The combined length might be about the same, and the Konica can be had for 1/3 the price of the Olympus. Just an idea.
Great post!! thanks Brent!! Lens turbo looks like a nice option, any experience and any quality loss due to glass element?

Is this the one - Focal Reducer Speed Booster Adapter Pentax K PK Mount Lens to Sony NEX E Camera | eBay

06-27-2013, 10:22 AM   #8
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QuoteOriginally posted by yusuf Quote
Great post!! thanks Brent!! Lens turbo looks like a nice option, any experience and any quality loss due to glass element?

Is this the one - Focal Reducer Speed Booster Adapter Pentax K PK Mount Lens to Sony NEX E Camera | eBay
Yes, that is the right one. I cancelled my order, for the FD-mount, because of a reported problem with flaring. I considered waiting for Metabones' adapter. Most people have been very happy with theirs though and I'm about to re-order. Metabones doesn't seem to have a planned release for K-mount, so the Lens Turbo is the only option there. I plan to use the FD version, with an M42 adapter, for my M42 glass. There are a few threads, with examples, on this forum. The adapter is not perfect. There is some softness at the extreme corners and a flaring issue, but the claims are that it makes the images even sharper.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/228831-evaluating-lens-turbo.html

https://www.pentaxforums.com/forums/pentax-price-watch/224280-199-focal-reduc...-sony-nex.html

If you want to search through the NEX thread, there are some excellent images from Christine Tam and others, who have used the Lens Turbo.
https://www.pentaxforums.com/forums/non-pentax-cameras-canon-nikon-etc/159240...es-thread.html

Last edited by kenafein; 06-27-2013 at 10:56 AM.
06-27-2013, 11:10 AM   #9
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The full frame Pentax 50mm F1.4 FA with PK-NEX Lens Turbo is like a 36mm F1.0 APS-C lens.
06-27-2013, 01:00 PM   #10
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QuoteOriginally posted by jogiba Quote
The full frame Pentax 50mm F1.4 FA with PK-NEX Lens Turbo is like a 36mm F1.0 APS-C lens.
Meaning you get a 50mm FF equivalent. What about f-stop? Do you actually get 1 more stop of light at f/1.0? and what happens to DoF? thanks
06-27-2013, 01:00 PM   #11
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I grew up on Pen Zuiko lenses, and I love em, but with the prices today I don't feel the need to go after them... but a few people I respect use these with the NEX and get great results:
Olympus PEN Zuiko 1.8/38 @ NEX-7 | Flickr - Photo Sharing!
Some Olympus Pen-F 38mm f/1.8 love
there are more but these two should show something
06-27-2013, 06:08 PM   #12
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QuoteOriginally posted by carrrlangas Quote
Meaning you get a 50mm FF equivalent. What about f-stop? Do you actually get 1 more stop of light at f/1.0? and what happens to DoF? thanks
It's a .72x focal reducer so it could give you 1 more stop of light unless you get some vignetting. Here is a review of the Metabones Speed booster from DPR :
QuoteQuote:
The Speed Booster is most easily understood as being the opposite of a teleconverter – in that it reduces your focal length. This, then, has a domino effect on the F-number of the lens. Because the F-number is the entrance pupil divided by focal length, reducing the focal length without changing the entrance pupil increases the F-number. So, adding the speed booster to a 50mm F1.4 lens turns it into a 35.5mm F1.0. But, since we’re then going to mount it on an APS-C camera, a comparison of this lens-plus-adapter combination to a full frame camera means we have to multiply these numbers by the camera's 'crop factor'. The end result is a 53.25mm equivalent lens that gives the same depth-of-field as an F1.5 lens would on a full frame camera.
First Impressions: Metabones Speed Booster: Digital Photography Review
06-27-2013, 06:32 PM   #13
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QuoteOriginally posted by jogiba Quote
It's a .72x focal reducer so it could give you 1 more stop of light unless you get some vignetting. Here is a review of the Metabones Speed booster from DPR :
Thanks. Regarding f-stop, say if you mount the 50mm with common mechanical adapter and wide open metering is 1/125 @ f/1.4, when you mount the lens with the lens turbo, is the metering 1/250 @f/1.0 ? I mean, do you really gain a stop?
06-27-2013, 06:50 PM   #14
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QuoteOriginally posted by carrrlangas Quote
Thanks. Regarding f-stop, say if you mount the 50mm with common mechanical adapter and wide open metering is 1/125 @ f/1.4, when you mount the lens with the lens turbo, is the metering 1/250 @f/1.0 ? I mean, do you really gain a stop?
I haven't used it but I doubt. Same light, same opening, so the exposure should remain the same. However, it will let you come closer to the subject and dof will be thinner. Also, the perspective will be different.
06-27-2013, 07:22 PM   #15
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QuoteOriginally posted by yusuf Quote
I haven't used it but I doubt. Same light, same opening, so the exposure should remain the same. However, it will let you come closer to the subject and dof will be thinner. Also, the perspective will be different.
It focuses the full frame's light and compresses it into a smaller image circle, so you do get a faster lens. With a dumb adapter the light is wasted as there is no sensor to read the light at the outer edges.
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