Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-28-2019, 06:59 PM   #1
Junior Member




Join Date: Aug 2015
Posts: 46
The Pentax 645 45s -- just how meh are they?

I really need a 45mm medium format lens for a digital view camera outfit...


I need to cover a 33mm x 44mm Fuji GFX sensor, and I need a bit of room for movement. I'll settle for 5mm of shift. Technically the image circle of a 645 lens easily meets these requirements. Case in point: my SMC Pentax-A 645 35mm f/3.5 is serving me well. I get a good 5mm of shift, and a usable 10mm as long as I don't need the far-shifted edges to be spectacular.


I've already built the custom mount and lens board I need to use Pentax 645 lenses on my camera, so the logical lens to buy is the SMC Pentax-A 645 45mm f/2.8, or the FA version (but I prefer the A lenses). However, reviews and online evaluations that I've found of both P645 45mm lenses describe them as just OK . I could go with the Pentax 67 45mm lens, but then I have to build another custom mount, which I'd prefer not to do (and it's not without its flaws either apparently).


So... I'd appreciate some insights into the P645 45mm lenses from people who have used either or both a lot. For example, is the problem that they're strong in the centre but weak at the edges over their intended image areas (i.e., 645 film)? If that's the case, are they actually good in the central portion covered by a 33mm x 44mm sensor? Or are they just much weaker overall than other Pentax 645 lenses like the SMC Pentax-A 645 35mm f/3.5?

Thanks, Rob

08-28-2019, 07:34 PM   #2
Pentaxian
mikeSF's Avatar

Join Date: Jan 2009
Location: East Bay Area, CA
Photos: Gallery
Posts: 6,273
I don't have much to share, as I only owned it for a short while, but during that time I found it to be a reasonable lens. Here is one sample:
The Gold Coast (Explore #86) | Returning to a familiar favor? | Flickr
08-28-2019, 10:56 PM   #3
New Member




Join Date: Oct 2017
Posts: 18
45mm lens

Ive got the the Pentax A 645 45mm lens and well stopped down its not a bad lens but just not as spectacular as the 35mm. They are pretty cheap and readily available so worth a try if you can find one really cheap. I did compare it to my FA 45-85 AF zoom and the zoom was noticebly sharper at the 45mm end. Another low cost option is the A45-85 zoom which I think is the same optical formula as the AF version and is much cheaper and probably preferable for your needs, just bigger and heavier than the 45.Cheers.
08-29-2019, 06:17 AM - 1 Like   #4
Loyal Site Supporter
Loyal Site Supporter
blackcloudbrew's Avatar

Join Date: Mar 2009
Location: Cotati, California USA
Photos: Gallery | Albums
Posts: 4,337
I have an A 645 45 and used it as my wide angle lens for my 645 and 645n very successfully. No, it's not the 35mm - which I wanted for my 645 and 645n - but it was a very serviceable lens and gave me a lot of lovely images. Oh, and it was considerably cheaper than the A or FA 35mm lenses.





I will say that now with my 645z, I own the considerably more expensive DA 645 28-45 zoom and it replaces all of my wide angle 645 lenses, however, with your rig, that wouldn't work for you. Basically I suggest you get a 645 A 45.

08-29-2019, 08:45 AM   #5
Forum Member




Join Date: Aug 2018
Posts: 53
I have the 45 A for my 645, and find the field of view useful. I wanted the 35 A, but couldnít justify the going-rate prices. My copy of the 45 is not as sharp as my 75 f2.8 A, for certain, but I havenít played around with finding the ideal stopped down aperature with it, either.
Attached Images
View Picture EXIF
EZ Controller  Photo 
08-29-2019, 10:18 AM   #6
Moderator
Loyal Site Supporter




Join Date: Apr 2014
Location: Baltimore
Photos: Albums
Posts: 1,818
QuoteOriginally posted by Kmier Quote
I have the 45 A for my 645, and find the field of view useful. I wanted the 35 A, but couldnít justify the going-rate prices. My copy of the 45 is not as sharp as my 75 f2.8 A, for certain, but I havenít played around with finding the ideal stopped down aperature with it, either.
I have a 35A, and a 35FA that I've been too lazy to sell. But now I have the DFA 35, so I'm ready to part with both....
08-29-2019, 10:21 AM   #7
Moderator
Loyal Site Supporter




Join Date: Apr 2014
Location: Baltimore
Photos: Albums
Posts: 1,818
I have a bunch of 645 lenses

The 45 is an incredibly useful FL, but it's definitely not the same caliber as pretty much all of my other lenses. It requires more careful use. I wouldn't hesitate to use it for certain things, but for anything that has masses of detail, you'll have some work cut out for you both in the field and in post.
08-29-2019, 06:35 PM   #8
Junior Member




Join Date: Aug 2015
Posts: 46
Original Poster
Thanks for sharing opinions and pictures folks. You're confirming what I've been reading everywhere else. These are inexpensive, so I could try one out. The catch is there's no resale potential so I'd be stuck with what, by most accounts, is at best an "OK" lens.

08-30-2019, 04:56 AM   #9
Moderator
Loyal Site Supporter




Join Date: Apr 2014
Location: Baltimore
Photos: Albums
Posts: 1,818
QuoteOriginally posted by rdeloe Quote
Thanks for sharing opinions and pictures folks. You're confirming what I've been reading everywhere else. These are inexpensive, so I could try one out. The catch is there's no resale potential so I'd be stuck with what, by most accounts, is at best an "OK" lens.
You could also rent one, possibly. But I also picked one up cheap, and have no regrets. It's just important to "understand" this lens, but that can be said of more than a few lenses everywhere, even the good ones.
11-21-2019, 10:11 AM   #10
Site Supporter
Site Supporter




Join Date: Nov 2008
Location: Washington DC, USA
Photos: Albums
Posts: 596
If you already have a custom mount for 645 lenses, could you get the 67 45mm f/4 and use the 645-67 adapter with it on your current board?

Failing that, have you considered the 645 A (or FA) 45-85mm f/4.5 zoom? They get better reviews than the primes.

QuoteOriginally posted by rdeloe Quote
I really need a 45mm medium format lens for a digital view camera outfit...


I need to cover a 33mm x 44mm Fuji GFX sensor, and I need a bit of room for movement. I'll settle for 5mm of shift. Technically the image circle of a 645 lens easily meets these requirements. Case in point: my SMC Pentax-A 645 35mm f/3.5 is serving me well. I get a good 5mm of shift, and a usable 10mm as long as I don't need the far-shifted edges to be spectacular.


I've already built the custom mount and lens board I need to use Pentax 645 lenses on my camera, so the logical lens to buy is the SMC Pentax-A 645 45mm f/2.8, or the FA version (but I prefer the A lenses). However, reviews and online evaluations that I've found of both P645 45mm lenses describe them as just OK . I could go with the Pentax 67 45mm lens, but then I have to build another custom mount, which I'd prefer not to do (and it's not without its flaws either apparently).


So... I'd appreciate some insights into the P645 45mm lenses from people who have used either or both a lot. For example, is the problem that they're strong in the centre but weak at the edges over their intended image areas (i.e., 645 film)? If that's the case, are they actually good in the central portion covered by a 33mm x 44mm sensor? Or are they just much weaker overall than other Pentax 645 lenses like the SMC Pentax-A 645 35mm f/3.5?

Thanks, Rob
11-21-2019, 06:37 PM - 1 Like   #11
Junior Member




Join Date: Aug 2015
Posts: 46
Original Poster
Thanks for the suggestions. Since making this post, I bought a P67 45mm lens and have it up and running. It's a really nice lens -- great big image circle (perfect for shifting on a GFX 50R), and pleasant to use because it's not as huge as some of the other P67 lenses. Pixel peepers will notice that it's not as sharp as the P645 35mm, but it meets my needs, and I really like the angle of view it provides on a GFX sensor.

My first instinct was to use a P67 to P645 adapter, so I bought one to do that. Unfortunately, it doesn't work on my custom P645 mount because the P645 mount is set in a deeply-recessed Toyo board, and there's just no room to get the big adapter into the space. However, I have a solution I'm happy with. I pulled out the six M1.7 screws in the mount of the P67 45mm lens, fitted a custom 110mm x 110mm custom lens board over the mount, and screwed it down nice and tight with M1.7x8 screws. With this setup, I can't use it off my Toyo VX23D camera anymore, but that's OK because I have another camera for hand-held work. Currently I only use my GFX 50R on the Toyo digital view camera.

Here's what the lens looks like on its mount board: https://drive.google.com/open?id=1qW0PT-a0CwJ_n9yaQqU8xFxU4lm6Xp44
The board is 3D printed out of plastic. This was the easiest, most cost effective way to make a board because I needed a very large hole to fit snugly around the lens mount. It's extra thick in the middle (just under 6mm). When the lens is screwed to the board, it's flat and extremely stiff (which is important).

And here is the lens mounted on the Toyo VX23D with the Fuji GFX 50R, ready to shoot: https://drive.google.com/open?id=161uDqvqrJqEwY3Ldh1ykbjpoB0megYlU
In this picture you might notice a strange white thing under the Auto/Manual switch on the lens... I have no use for that switch on this setup, and it won't stay in the right position for long. My solution here is a wedge made out of a soft white pencil eraser! The switch is held permanently in the active position, with no pressure on it to damage the mechanism.

Rob


QuoteOriginally posted by yurihuta Quote
If you already have a custom mount for 645 lenses, could you get the 67 45mm f/4 and use the 645-67 adapter with it on your current board?

Failing that, have you considered the 645 A (or FA) 45-85mm f/4.5 zoom? They get better reviews than the primes.

Last edited by rdeloe; 11-21-2019 at 06:42 PM.
11-22-2019, 03:32 PM   #12
Loyal Site Supporter
Loyal Site Supporter




Join Date: Oct 2018
Location: Quebec City, Quebec
Posts: 1,990


I purchased a used in like-new condition 645 A 45 mm f/2.8 very cheap 3 or 4 years ago and I find it very satisfying for landscape use. I always use an f/11 aperture and I found the lens has very good contrast and nice colors. This focal length is one of the most useful in landscape photography.

Last edited by RICHARD L.; 11-25-2019 at 08:52 AM.
12-24-2019, 04:10 PM   #13
Junior Member




Join Date: Aug 2015
Posts: 46
Original Poster
Just a quick note to finish the story on my search for a 45mm lens. A couple posts up I described the solution I made with a P67 45mm f/4. On my camera (Toyo VX23D) this is very easy to use because the aperture ring is accessible on the flat mount board. It also has a nice big image circle, so there's lots of room for shift.


I would have been happy with this lens for the long haul... but I had the opportunity to try the Pentax-A 645 45-85mm f/4.5 lens. That is a very fine optic indeed. The 45mm end of the P645 zoom is considerably sharper than the P67 45mm. If you're working for the web, or you don't make huge prints, you probably won't notice the difference. However, I was looking for a solution that would allow for larger prints with the files from my Fuji GFX 50R (which rides on the back of the Toyo).


The P645 45-85mm lens has much less shift-ability at 45mm (maximum 10mm before it hard vignettes on something inside the lens). I can live with that. Interestingly, the image circle increases considerably from 45mm to 63mm, and then decreases again from 63mm to 85mm. At 85mm I can shift around 15mm, but at 63mm in portrait orientation a 20mm shift is very good, and a 25mm shift is still entirely usable if the far shifted 10% of the image is in something like clouds or darkness.
12-31-2019, 02:08 PM   #14
Pentaxian




Join Date: Jan 2013
Location: Near Vienna, Austria
Photos: Gallery
Posts: 1,153
QuoteOriginally posted by rdeloe Quote
Just a quick note to finish the story on my search for a 45mm lens. A couple posts up I described the solution I made with a P67 45mm f/4. On my camera (Toyo VX23D) this is very easy to use because the aperture ring is accessible on the flat mount board. It also has a nice big image circle, so there's lots of room for shift.


I would have been happy with this lens for the long haul... but I had the opportunity to try the Pentax-A 645 45-85mm f/4.5 lens. That is a very fine optic indeed. The 45mm end of the P645 zoom is considerably sharper than the P67 45mm. If you're working for the web, or you don't make huge prints, you probably won't notice the difference. However, I was looking for a solution that would allow for larger prints with the files from my Fuji GFX 50R (which rides on the back of the Toyo).


The P645 45-85mm lens has much less shift-ability at 45mm (maximum 10mm before it hard vignettes on something inside the lens). I can live with that. Interestingly, the image circle increases considerably from 45mm to 63mm, and then decreases again from 63mm to 85mm. At 85mm I can shift around 15mm, but at 63mm in portrait orientation a 20mm shift is very good, and a 25mm shift is still entirely usable if the far shifted 10% of the image is in something like clouds or darkness.
Thank you for keeping us informed about your experience!
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!
45mm, 645d, 645z, camera, custom, f/3.5, lens, lenses, medium format, p645, pentax, pentax 645 45s, pentax-a, smc
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Landscape Is this good or meh? MossyRocks Photo Critique 15 01-22-2019 07:02 AM
Machinery They don't make them like they used to. MrKodak Post Your Photos! 5 08-30-2018 12:15 PM
35mm Takumar...Meh Colors jawats Pentax SLR Lens Discussion 19 06-16-2018 07:43 PM
Pentax D 150-450mm f/4.5-5.6 @ Lensauthority for $1000 - "meh" condition luftfluss Pentax Price Watch 4 11-03-2017 11:11 AM
Snow? Rain? Fog? Meh... ve2vfd Pentax DSLR Discussion 1 01-18-2013 09:26 PM



All times are GMT -7. The time now is 03:52 PM. | See also: NikonForums.com, CanonForums.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