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12-06-2011, 11:01 PM - 1 Like   #1
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FA* 300 2.8 vs A*300 f/2.8

LBA has placed me in the prediciment of having both a FA* 300 f2.8 and a classic Pentax A* f2.8.. (I did have a A* f4 and a DA*F4 also, but they went down the road to help finance this adventure. The A* f/2.8 has been a part of me in its nice little silver trunk for so long, that I couldn't bare to part with it until I have convinced myself that the FA*300 will do anything as well at the A*.

I just got the FA* today, so only have first impressions and so far have only been able to try it out indoors. For those who haven't seen them
here are a couple pictures.
<these are thumbnails--- Click to expand>


Mechanically and optically the lenses are quite dissimlar although both are internal focusing. the A* is a little shorter and fatter, the latter mostly
because of a built in sliding lens hood. The FA* has a screw on. the FA* like other FA* has a sliding collar mf/af clutch. Both take 112mm filters on the front and drop ins in a holder in the back. The FA* is almost half a kilo lighter than the A* making it a lot more user friendly if the idea of hand holding has crossed your mind.

I'm not aware of anyone who has optically compared these, and my excuse for holding on to the A* for the moment was to see if they were IQ comparable. Oh yes, both are compatible with the Converter-A n.nx-L <long> converter, although unfortunately these converters are, well, converter-A's and don't auto focus.

While I haven't had a chance to use the lens in the daylight I did a quick test with the two tonight indoors at 18 feet.--but taking a set of indoors
photos at f/2.8 at a 1/13th of a second.---and longer exposures as I stopped down----result--- couldn't find a difference. likewise with wide
open shots with the Converter-A 1.4-L---I couldn't verify any difference.

what I'm looking for----have others attempted to figure out if there is meaningful IQ difference in these two lenses. It will be hard even with LBA for me to dream up a reason to keep both of them if there isn't something significant that the Pentax A will do that the FA* won't....

12-07-2011, 10:29 AM   #2
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Generally the optical formulas are improved in newer lenses, but as both lenses are superb, I doubt you'll see much of a difference. The presence of AF is a big deal for the FA*, though- I couldn't live without it on an expensive tele like this.

Adam
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12-07-2011, 11:41 AM   #3
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QuoteOriginally posted by Adam Quote
Generally the optical formulas are improved in newer lenses, but as both lenses are superb, I doubt you'll see much of a difference. The presence of AF is a big deal for the FA*, though- I couldn't live without it on an expensive tele like this.
The AF is why I broke my piggy bank to make the change, but alas, Pentax
forgot to put AF in their converters so there are the delightful 1.4x-L and 2.0x-L converters that will produce magnificant results with this piece of glass, but......

I've been a loyal pentax user since I manged to save up enough $$$ to buy
a Spotomatic shortly after the came out.

There hasn't been an updated converter since the Pentax-F AF adapter was introduced in 1987 some 24 years ago. While I have expressed my own concerns that theusefulness of optical cropping was diminishing as thequality
of sensors was increasing (effectively making photoshop cropping as good as optical cropping)

I really think I'm going to like the FA*300--- turns out that I bought it from a member of the forum here..... I am sortof saddened though that the long end of things is seemingly orphaned. These FA*300's seem as rare as hens teeth.
Indeed I don't ever recall seeing one for sale before though I suppose I have
slept through some....

Indeed I had planned onslogging through life with 2 300's, the SDM f4 model
and the Old Pentax-A model----and pulling one or the other out of my quill depending on the circumstances, but my first pass suggests little reason
for carrying around both.... where the FA* will provide the speed of the A* and the auto focus present in the DA*, although I suppose one has to wonder
how you put a value on one more f stop of speed in a lens when auto ISO exists.

I guess to sort of answer my own question, I see a Lot of value in the extra F stops even though I avoid actually taking photos using them if I can. It comes from increased ability to get the focus right. For almost as long as I've done photography, I've understood "open it up, focus, shut it down, and take"

the slower the lens, the less well this works.
12-08-2011, 01:19 AM   #4
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You can try the Sigma APO converters (1.4x or 2x).
On my DA*300, the Sigma 1.4x is better then the Pentax-A 1.4x, but without SDM-AF and LiveView.

12-08-2011, 03:09 AM   #5
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Looking forward to your tests.
12-08-2011, 03:33 AM   #6
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I'm looking forward to you deciding to keep the Pentax-FA* 300mm F2.8 ED [IF] and sell me the Pentax-A* 300mm F2.8 ED [IF] for 50 delivered.
12-08-2011, 03:48 AM   #7
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so excited for the results!
12-08-2011, 07:01 AM   #8
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Congratulations. I'm looking forward to seeing some side-by-side results!

12-23-2011, 01:56 AM   #9
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This thread seems to have died all of a sudden. What happened to the test pic's?
01-08-2012, 01:48 PM   #10
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QuoteOriginally posted by bossa Quote
This thread seems to have died all of a sudden. What happened to the test pic's?
the weather has been bad. Hard to do interesting 300 mm photos when it's foggy.
01-08-2012, 02:24 PM   #11
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@rvannatta, I suggest you do some AF tests as well. It seems that most of these lenses need at least some AF adjustment (ours needs +9 or +10). It'll have a profound difference on the results of your tests, unless you shoot in live view.
01-08-2012, 07:47 PM   #12
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QuoteOriginally posted by Clinton Quote
@rvannatta, I suggest you do some AF tests as well. It seems that most of these lenses need at least some AF adjustment (ours needs +9 or +10). It'll have a profound difference on the results of your tests, unless you shoot in live view.
I need to investigate the focus some. Had a sunny afternoon right after I complained about the fog and I hauled a carload of equipment
out in the field and took 50 shots. The distance was far enough to be 'almost infinity' and the subject was very deep in depth.
As we will see in the next message the focus was OK. I used the green setting for 'average distance' and dthat is pretty much what I got.

a couple of weeks ago, I took some 'close up' photos --- about 50 feet out, and was getting better results hand focused than auto focused, but
by target was less than full frame by a country mile so even with the 'spot focus' setting I wasn't convinced that extraneous items weren't causing
the problem. One of the things that one has to understand about AF is that it doesn't think like we do. When we manually focus we always focus on what interests us and the rest is brokeh, but the computer has to guess what interests us and when it guesses wrong........

This has a lot to do with all the bad press about the DA*16-50 not getting it right.... Two features of this lens the people don't fully understand
cause most of the problem IMHO. First, people are used to the kit lens or other really slow lenses.---- Slow wide angles have amazing depth
of field, and you really have to try hard to 'get it wrong'. At f/2.8 the story is different. the second issue is related. When the 16-50 came out
the pentax cameras all had a view finder that showed about 80% of the actual image. As nearly as I can tell, things in the invisible 20%
are seen by the Focus control. so if you stand beside an large object and just try to 'crop' the near large object out of the picture, expecting
the lens to focus on more distance subjects, it may outsmart you. When I first got the 16-50 this was a fairly common issue, but either I have trained myself to avoid those conditions, or pentax has tuned that out of the AF algorithm because I don't see it now like I used to.

anyhow I'm still investigating the AF300 focus accuracy as close range, but at near infinity, it looks pretty good.
01-08-2012, 08:21 PM   #13
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QuoteOriginally posted by bossa Quote
This thread seems to have died all of a sudden. What happened to the test pic's?
weather improved today and here are some. Had some very contrasty winter sun and took about 50 shots all with
a remote timer on tripod.

it begins with a shot at 50mm just to show the area.

I'll give the conclusions first.... The I took the photos with the FA*300 f/2.8 first and on getting back to my house they were mostly over
exposed by a stop or so. My inclination is that I was likely initially sloppy in covering the viewfinder and when I started the shoot
I had some direct sun on the camera, but by the time I fininshed 30 minutes later I didn't. Consequently I tweeked the exposure in photo
shop and believe the exposure issue was operator error.

Bottom line is I don't see a material difference in IQ between the fa*300 f/2.8 and the A*300 f/2.8

This is a DA* 16-50 shot at 50mm of the 'shoot area'---note windmill and buildings in Center.
<Click to expand thumb nail>


This is the FA*300 f/2.8 taken at f2.8 (click to expand)


This is the FA*300 f/2.8 taken with stacked converters (1.4x-L stacked with 1.7x AF adapter (click to expand)




This is the A*300 f/2.8 taken at f2.8 (click to expand)


This is the A*300 f/2.8 taken at f2.8 --with stacked 1.4x-L and 1.7x af converter (click to expand) AF adapter allowed to focus




This is the DA* 60-250 taken at f5.6 and 250mm (click to expand)


This is the DA* 60-250 taken at f5.6 with AF 1.7x adapter/converter(click to expand)




This is the Pentax A* 600 f/5.6 with a 2x-L converter wide open(click to expand)


This is the Pentax A* 600 f/5.6 with a 2x-L converter wide open(click to expand)
(note background out of focus)


It's interesting---all these pictures have some problems. Probably the best one is the one taken with the DA*250. -- it's at least
all in focus. telephotos, the stronger they get the less depth of field they have. Interestingly though, it appears that a converter
doesn't change the DOF characteristics of the underlying lens, so a short lens with a converter provides more depth than
the long lens eventhough the effiective field of view is the same. In the scene there is a lot of distance between
the gate post in the front and the trees in the back----probably 500 feet. the DA*250 shot was taken in the program mode
which happened out at f5.6... it has the gate post and the trees both in focus. those with the longer lenses
have something in focus, but I purposely took them wide open and the DOF wasn't adequate for the subject.

the 600 shot is focused on the gatepost (holding the aluminum gate) and there are focus issues with the buildings and beyond.

what I really need to do is to get aroundn to install the Katzeye that I have but haven't installed.

Last edited by rvannatta; 01-09-2012 at 08:15 AM.
01-09-2012, 08:28 AM   #14
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for those early birds that already looked through thephotos, Ihad some uploading issues, and slipped some more in the list showing various lenses with
aggressive converter useage. the most remarkable observation to me is that the DA*60-250 with an AF 1.7x converter held its own particularly by providing
the most depth of field.
01-09-2012, 08:59 AM   #15
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QuoteOriginally posted by rvannatta Quote
for those early birds that already looked through thephotos, Ihad some uploading issues, and slipped some more in the list showing various lenses with
aggressive converter useage. the most remarkable observation to me is that the DA*60-250 with an AF 1.7x converter held its own particularly by providing
the most depth of field.
Your experience with autofocus on the F2.8 class of 300mm telephoto lenses is the same as mine. That depth of field can be razor thin. I found that sometimes its easier to just switch to manual focus. And manual focus is really easy with both "A" and "FA" lenses because that shallow DOF makes an in-focus image just pop out.

I find the hood for the FA*300/2.8 to be a pain to use. I seem to be always fighting it. Lens take real nice pics, though.

What I've experienced is the "A" series lenses are a touch cooler than the "FA" series. But in normal everyday use this isn't really noticeable.

The little one in the middle is an A50/1.7.

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