Pentax-645 FA 300mm/5.6 review
I was looking for a smaller lens to use when i don’t want to take my big and heavy Pentax-67 M*400mm/4. Sure, i could have bought one of the 300mm lenses available in K-mount but i was curious about that lens and how it would perform on my K20D and K-01. There is not much info or reviews on that lens, from what i’ve found it’s said to be a good lens, so i think it’s worth writing a small review on the image quality and my impressions of how it feels to use it in the field.
Lens specifications and first impressions
This lens is not marked as a “*” lens but the build quality is very good as usual with Pentax lenses. The focusing ring is large and smooth just how i like them on a lens. You can switch to AF by pushing it forward to the front of the lens and then pull it back toward the camera to switch to MF, like the FA* K-mount lenses.
– Weight: 775 gr
– 7 elements in 7 groups
– Filter size: 67mm (same as my FA20mm/2.8 and DA*50-135mm/2.8 certainly an advantage for me)
– Min. focusing distance: 2.20 Meter
– Number of aperture blades: 9 (nearly rounded)
– Range of F-stop: f/5.6 to f/45 (two position between f/5.6 and f/11, after that 1/2 f/stop between f/11 up to f/32 and full stop between f/32 and f/45).
Here is a size comparison with my Pentax DA*50-135mm/2.8:
The lens hood have a small part on the bottom that you can remove so that you can turn your polarizer filter that is attached to the lens, i like that feature (the DA*50-135 also have it). There is no tripod collar on that lens, i would have liked to have one on such a long lens but since it’s not that heavy in handles quite well.
The nights during the week were cold, between 0C to -6C, good conditions for ice formation around rivers and ponds. On that morning i tried different ISO and shutter speeds to see the effects and selected my favorite later.
K-01, 1/15 sec. at f/11, ISO 500, tripod.
What about the image quality of that lens ?
I didn’t shoot brick wall or other set-up for this lens, instead i decided to evaluate it’s IQ only from photos in the field since long lenses can be affected by the environnement like wind and haze. Keep in mind that the comments apply to the lens used on APS-C cameras and that the IQ can differ if you use that lens on a 645D.
As for sharpness i tried it at every apetures, my conclusion is that it’s good at f/5.6 and it’s at it’s best from f/6.3 to f/11. At f/16 the diffraction already shows it’s nose and from f/22 to f/45 i call it soft and unusable.
This photo was taken near the minimum focusing distance of the FA300mm/5.6. The lens was stopped down at f/8 and i found the sharpness to be very good. As usual the camera was attached to a solid tripod.
My goal when i bought that 300mm was to replace my big and heavy Pentax-67 M*400mm/4 (weighing 3700 gr.) so i could take a smaller camera bag for my photo outing when wildlife is not my primary interest. So i wanted to know how the sharpness of the FA300mm/5.6 would compare to the M*400mm/4. My guess before taking some shots was that the 400mm would be sharper at f/5.6 since it will already be stopped down 1 stop and the 300mm will be W/O. My guess was right, not a big guess since it is logical and predictable.
Most of the time i use my 400mm at f/5.6 but i also stop it 1/2 stop more when i can, so i tested both lenses stopped 1/2 stop more than f/5.6 and it’s probably at that setting that i will use the FA300mm most of the time.
OK, i said i wouldn’t take photos of brick wall …. well i cheated just a little here !
Here is a 100% crop of a photo i took in the field to see how those 2 compares, this shot was taken stopped down 1/2 stop from f/5.6. Both shots were taken with my K-01 in RAW with no PP and i did use the 2 second delay with the help of a solid tripod.
But a photo taken in RAW needs some PP so i did that in the photo below to show how the final photo would looks like.
Same shot of the FA300mm/5.6 with some PP, amount 100 and radius at 1.0. This is a 100% crop.
Now a more interesting subject, a Golden Eagle portrait taken in a Zoo and a 50% crop after PP in Photoshop.
K20D at ISO 640 lens set at f/6.3, on a tripod (no cropping).
Here is the 50% crop of the photo above.
Aberrations and flare control
Older lenses can suffer of aberrations and flare because they were not designed for digital sensors, the coating on the rear lens elements can cause reflections on the sensor. I came across some Pigeons on a roof with strong backlit around sunrise. I took some shots to see if i could produce some CA, in that shot below taken with my K-01 and the FA300 at around f/8 we can see some CA but it’s not that bad at all.
It’s a 100% crop from a shot taken at f/8.0 with no correction of the CA, not bad for an older MF lens. In most situations i couldn’t see any CA in my photos.
In most of the situation i didn’t encounter any problem with flare, but while i was taking photos of the Golden Eagle at the Zoo i did had problem with flare. I don’t know if it’s due to the lens (probably sensor flare due to the older coating) or reflections inside the K-mount adapter. My Pentax-67 M*400mm/4 also have flare problems in that kind of light, subject against a white sky are when the lens is pointing in the direction of that sky.
The flare i encountered with the P-645 FA300/5.6 on my K20D.
In the field
Even if it’s a Medium format lens it’s not heavy and handles well with my K20D and even my K-01. The biggest difference between the FA300mm/5.6 and my M*400mm/4 is that to focus from the minimum distance to infinity the FA300mm needs only 1/3 of a turn of the focusing ring where the M*400mm needs a full 360 turn! So the M*400mm is more precise and easier to obtain critical focus but with time i will get the hang of it like all my others AF lenses.
So how a lens handles in the field can have a negative effect on the sharpness also. Since this lens doesn’t come with a tripod collar it’s important to have a good technique. A tripod collar is probably not needed on a 645 camera since the lens is light enough to be supported and with the weight of the camera the handling may not be as good if a tripod collar was included.
After some practice in the field i now find it easy to use on a tripod with my K20D or K-01 and i’m getting sharp results without any problem.
Did i do the right thing when i bought that lens ?
The more i use it the more i like it and i’m getting to know how to use it to get the best out of it. I’m taking it with me everyday when i’m going to work, my kit is:
– DA35 mm Macro Ltd
– DFA100mm Macro WR
– Super Takumar 150mm
– Pentax-645 FA300mm/5.6
A lot less weight than my regular camera bag and it feels so light, i think i will use that lens a lot and will take it with me for our yearly vacation instead of my Big M*400mm/4 and knowing that i will not loose any IQ! The DA*300mm/4 would certainly be sharper W/O and at f/5.6 but the price is higher also, if a 300mm would be my main long lens the DA*300 would be my choice but for more occasional use the Pentax-645 FA300mm/5.6 is a great choice.
Some photos taken with that lens:
A cold morning with frost and fog makes for great photo opportunities.
K-01, FA300mm at f/11, tripod.
Snowy Owl taken in a Zoo through a fence.
K20D at f/6.3, tripod.
Sigma 19mm/2.8 vs Pentax FA 20mm/2.8.
Two lenses with the same focal lenght and speed but with different purpose since the Pentax was made during 35mm SLR era and the Sigma is a brand new design optimized for APS-C MLC (and M 4/3 cameras). I bought my Pentax FA20 around 1995-1997 for about 850$ CDN (Canadian) and the Sigma just cost 240$ (CDN with shipping and taxes). The most evident physical difference is the diameter of the front of the lens, the Pentax takes 67mm filters and the Sigma takes 46mm filters ! The Sigma have 7 aperture blades and the Pentax have 6, they are more rounded on the Sigma so it should produce a better Bokeh.
The build quality is better on the Pentax , which is not a surprise, the Sigma comes with a lens hood and i had to buy it separately for my Pentax…. now, the Pentax lenses always comes with a lens hood. The minimum focusing distance of the Pentax is 0.25 meter and for the Sigma it’s 0.20 meter.
I will test both of them on my Sony NEX-3 to see how they compares to each others.
Here is a photo taken in the field with both lenses on my NEX-3 from the same place, you can see that the Sigma’s 1mm advantage is evident here, the plant is not cut in the upper part of the frame.:
– Pentax FA20mm/2.8:
– Sigma 19mm:
Now, here is my test set-up inside my house for sharpness and CA. My tripod was set to it’s lowest position and at 0.7 meter from “Fraisinette” . I use a bubble level to be sure that the camera was leveled side to side and that it was not tilted down in the front.
All the photos were taken in RAW at ISO 200 with the 2 second delay, manual focus was used with the help of the focus peaking. The photos were developed in Lightroom where i turned the sharpening to zero and nothing else was done in PP after that, only resized and saved them in Jpeg for the web.
Now the results:
Sigma at f/2.8.
Pentax at f/2.8.
We can see that the Sigma is sharper and have better contrast than the Pentax at f/2.8. After that the Pentax is always sharper than the Sigma all the way up to f/11, from f/16 diffraction kick in and they are very similar in performance.
Sigma at f/8.
Pentax at f/8.
The Sigma 19mm is knowned for it’s CA, but what about the Pentax ?
Well the Sigma showed CA at all apertures while the Pentax is free of CA from f/5.6. The CA is not that visible here but easier to see while zooming in Photoshop. You can see it along the white dress on the right side of the photo.
Sigma CA at f/2.8.
Sigma CA at f/11.
Pentax CA at f/2.8.
If you need to shoot often at f/2.8 then the Sigma 19mm is the one to buy, Pentax lenses are not always the sharpest W/O but sharpens nicely when stopped down and the FA20 is no exception here. The corners in the Pentax shots are better since this is a FF lens but the Sigma is still very good when stopped down.
They are both very good lenses, the Pentax is a tad sharper and shows more details when viewed at 100% but in normal use and when printed you may have difficulties setting them apart. The Sigma have AF on an NEX camera and is smaller since the Pentax needs an adapter. So for the price the Sigma is a no brainer.
The Sigma is a modern lens and the Pentax is a legacy lens, i will continue using my Pentax FA20mm on my K-01 and my Sigma 19mm on my NEX-3.
Some shots taken with both lenses:
Sigma 19mm at f/5.6.
Sigma at f/11.
Pentax FA20mm at f/13 with Polarizer.