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.

Pentax-645 FA300mm/5.6

Pentax-67 M*400m/4

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.

Conclusion

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:

– K-01

– DA14mm

– 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.