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Forum: Pentax Medium Format
09-23-2020, 04:43 AM
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Forum: Pentax Medium Format
08-02-2020, 05:22 PM
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Hello Richard L.,
You can get a Pentax 645 lens plate for the Cambo Actus. It has a manual lever for controlling the aperture that uses a 0-10 scale. It also works on the Pentax 645 lenses that do not have a manual aperture ring.
Actus Lensplate with Pentax 645 Lens Bayonet – Digital Back
You can use the 1-10 scale on the lens plate to set your aperture although it's not ideal because the numbers don't correspond to a specific aperture. I do understand why they did it that way since every lens has a different range.
If you want to use the aperture ring to set the f/stop then you can put the lens on auto before mounting it to the lens plate then move the lever on the lens plate to 10. Doing this closes the lens to the smallest aperture. Then using the aperture ring on the lens, you can open the f/stop to the setting you want for shooting.
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Forum: Pentax Medium Format
08-02-2020, 02:04 PM
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The Actus is a pleasure to work with. It is incredibly well made, not too big, and offers a lot of versatility. I'm using it with the Fuji GFX 50s. I'm not sure if the Actus will work with the K.
The difficulty for me has been finding the right lenses. Fortunately, Pentax 645 and 67 w/adapter lenses offer a wide variety of great choices. The 645 DFA 35mm, the 67 55mm latest and 75mm 2.8 are working very well for architectural photography…which is what I got the Actus for. I'm wanting to try out the 67 105mm f/2.4 as well.
What I like about using the Pentax lenses is that I can also use them on my 645z for handheld photography like environmental portraits. Focusing on the fly with an EVF is awkward to me. While the quality of the Fuji GFX is fantastic, it doesn't really feel like a camera to me. It feels more like a digital capturing device. When the Pentax 645z is in my hands, it definitely feels like a camera.
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Forum: Pentax Medium Format
07-29-2020, 05:02 AM
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Thank you!
For those that are interested, I added small images and screenshots to the post so people can see the images without having to click the links. The links to the full-sized images and RAW files are still included. Also, the first test was taken on the 645z and the second test was originally taken on the Fuji GFX 50s with a Cambo Actus. This seemed to add extra variables so I retook the images for the second test using the 645z and edited the post accordingly. Hopefully the results will help.
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Forum: Pentax Medium Format
07-25-2020, 05:22 AM
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Since I mainly use my cameras for work, I like to have backups as well. I'll probably end out keeping them both 35s. My plan, as of now, is to use the HD D-FA on the Cambo Actus for architectural/interiors and use the A on the 645z for on location action shots. I really like the quality of the 28-45 as well, and the 28mm focal length, but it is a beast and doesn't seem to have a very big image circle at 28mm so I haven't had much luck with it when a shift is needed. The image circle does seem to get bigger and give more room for shifting in the mid range though.
Hey 672 - I also noticed right away that the A version of the lens is slightly wider, wasn't expecting that. That little bit of extra view could be just what you need when your back is against the wall.
Coming from FF 35mm, I'm so enamored with most all of the Pentax lenses I've tried on the 645z. Such a step up.
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Forum: Pentax Medium Format
07-23-2020, 09:11 AM
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Thank you for the clarification! Even though I've been doing this for a while I still get the terms mixed up…it seems there is a bit of both in the images I've uploaded, but I was trying to describe the distortion.
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Forum: Pentax Medium Format
07-23-2020, 08:59 AM
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Gorgeous shots Richard!
The 35mm A is a great lens. Also consider Pentax 67 lenses with the 645 adapter. I'm really liking the 55mm and have a 75mm 2.8 on the way, which I hear is superb on the 645z.
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Forum: Welcomes and Introductions
07-23-2020, 08:04 AM
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Forum: Pentax Medium Format
07-23-2020, 07:55 AM
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Here is another test. Both of the images were shot on a tripod using Pentax 645z with a shutter release and the mirror up. The images from both lenses were shot at f/13 which I determined was the best overall sharpness.
From earlier tests, I found f/11 and f/13 to be the sharpest for both lenses. For this test I took three images at each f-stop, refocused between each one, then chose the sharpest. The difference between f/11 and f/13 was very very close, I've included links to ACR screenshots, full-sized images, and RAW files from each lens for those that would like to take a really close look.
This building has vertical and horizontal architectural lines to help determine lens distortion. I'm about 40 feet from the building.
Here is the ACR screenshot of the D-FA without any lens correction:
Link to full sized image:
01-35mm-DFA-nocorrection.png | Diggles Creative
Here is the ACR screenshot of the A without any lens correction:
Link to full sized image:
02-35mm-A-nocorrection.png | Diggles Creative
You can see that both lenses have noticeable distortion at this distance.
Here is the ACR screenshot of the D-FA with Adobe's lens profile applied:
Link to the full sized image:
03-35mm-DFA-acr-lensprofile.png | Diggles Creative
Just a couple clicks to add the Adobe profile for this lens does a pretty good job of fixing the distortion and slight vignetting.
Here is the ACR screenshot of the A with my attempt at fixing it using custom lens profile settings:
Link to the full sized image:
04-35mm-A-acr-manual.png | Diggles Creative
It's ok but not quite as good as the Adobe profile for the D-FA included with ACR. I was having difficulty getting the horizontal lines straight while keeping the vertical lines from becoming concave. Someone that is experienced at creating lens profiles would do a better job I'm sure.
Here is a link to the ACR screenshot of the A using Adobe's 645 FA 35mm lens profile:
Link to the full sized image:
05-35mm-A-acr-smcfaprofile.png | Diggles Creative
I tried a few different Pentax 645 lens profiles and this one did really good job. On other shots I've taken with the A lens when closer to the building, not included in this test, this lens correction profile didn't work quite as well, but it was still the best after a little tweaking.
Here is the final A image:
Link to the full sized image:
_PXZ1822-SMC-Pentax-A-645-35mm.jpg | Diggles Creative
Here is the final D-FA image:
Link to the full sized image:
_PXZ1817-HD-PENTAX-D-FA645-35mm.jpg | Diggles Creative
If you look closely at the full-sized images you will see that the A lens ever so slightly sharper in the center, but the D-FA is noticeably better around the edges.
I don't think you can go wrong with either of these lenses, they are both really nice. If I didn't have both to compare to each other, I'd be thrilled the A. Since my business plans for the 35mm focal length are to use it for architecture/interiors the D-FA is the better choice of these lenses for me. It seems to be slightly sharper all the way around and the distortion will be much quicker for me to fix.
Here is a link to a gallery that includes all the images from this test including RAW files:
2020-07 645 35mm A vs D-FA - Images | Diggles Creative |
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Forum: Pentax Medium Format
07-23-2020, 06:36 AM
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The 28-45 is a great lens as well. I'm having a love/hate relationship with it. The glass is so good, but I'm wanting shift capabilities and it only gives me about 2mm. I've put it on and taken it off ebay 3 times in the last few weeks.
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Forum: Pentax Medium Format
07-22-2020, 03:32 PM
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I'm working on keeping the DFA, if I do enough tests I'll prove to myself it's better :lol:
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Forum: Pentax Medium Format
07-22-2020, 03:30 PM
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Thank you for the info. I was wondering if I was missing something, but it doesn't look like I did.
In addition to the 645z, I'm using these lenses on a Cambo Actus. My goal is to use the manual aperture on the lens instead of the lever of the lens board. The lever on the actus lens board uses a 0-10 scale so it doesn't directly relate to the f stops on the camera.
I did figure out a workaround though. If I put the lens on auto before mounting it to the lens board then move the lever on the lens board to 10 it closes the lens to it's smallest aperture. Then I can open the f stop to the setting I want for shooting, which is usually f11 for this setup.
With the 67 lenses I don't have to do the extra step.
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Forum: Pentax Medium Format
07-22-2020, 03:14 PM
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Thank you Adam!
---------- Post added 07-22-20 at 04:20 PM ----------
Based on this first test the images are definitely not 4 times better! I'll see if I can justify the new one with my second test.
My plans are to get closer to a more modern building with vertical and horizontal architectural lines to see if how they compare under that circumstance.
---------- Post added 07-22-20 at 04:20 PM ----------
Which one did you keep?
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Forum: Pentax Medium Format
07-22-2020, 10:54 AM
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Hello,
Many of the reviews I've read here and other forums online have stated that while the A version of the lens is excellent, the HD version is much better. Just many other photographers, I'm always striving for the best image quality which led me to purchase the HD even though I already bought an A just a couple weeks ago. My plan is to keep the best one and sell or return the other.
Here is the SMC Pentax-A image:
Link to full sized image:
https://digglescreative.photoshelter.com/gallery-image/2020-07-645-35mm-A-vs...000nBNZzqCAk2Y
Here is the HD Pentax-D FA image:
Link to full sized image:
https://digglescreative.photoshelter.com/gallery-image/2020-07-645-35mm-A-vs...000nBNZzqCAk2Y
Both of the images were shot on a tripod with the mirror lock up using a shutter release. I shot a series of images with both lenses from f/5.6 to f/16 so I could evaluate which aperture led to the best results–f/11 at 1/90 was the best for both. I made minor adjustments to the exposure settings in ACR to account for the brightness difference between the two shots. No optic corrections were made in ACR. They were taken 2 minutes apart.
Based on this single test, the differences seem minor. The HD version is barely sharper in the center. On the right and left edges, the A version may even be a bit better. The corners are sharper on the HD version but not a whole lot.
When toggling between the two images I can see that the profile of each lens looks different. The HD seems a bit more correct, I'm not sure the A is bad though.
My goal is to use this lens for architecture and interiors. So I have a couple of questions about these two lenses for anyone that has experience with testing both lenses:
- Is the difference between these two lenses seen in example images what I should expect? or should it be more dramatic?
- Are there any other tests you can recommend to help me further evaluate them?
Thank you in advance for any help you can provide.
Warren
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Forum: Pentax Medium Format
07-22-2020, 06:49 AM
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Hello,
When the 67 55mm (latest model) lens is unmounted and the aperture ring is turned I can see the aperture diaphragm opening and closing. With the 645 lenses the diaphragm stays wide open when rotating the aperture ring.
There are two different levers on the back of each of these lenses. One seems to control 'auto' aperture settings and the other 'manual' aperture settings. When either lens is set to manual, moving the aperture ring moves the 'manual' lever.
So when I set the aperture on a 645 lens manually the diaphragm stays wide open. If I then move the 'auto' lever with my finger it stops based on where the aperture was set. Is this a function of the depth of field preview? So the aperture is always wide open for focusing, but when a picture is taken the camera moves the 'auto' lever prior to exposure?
Is this just a difference in the way the lenses work mechanically? So the 'manual' aperture ring works on 645 lenses but only if they are mounted to the 645 body?
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Forum: Welcomes and Introductions
07-22-2020, 06:42 AM
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Hello,
About a month ago I purchased a 645z and am really enjoying it. It brings back a lot of memories of the 645 film camera I used to have.
Over the last few weeks I've been discovering how great of a resource this forum is. There is so much detailed help provided by the users. The information provided on lenses has influenced my choices greatly and I have not been disappointed. My hope is to contribute when I can to help others with their decisions.
Warren
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