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12-04-2015, 10:52 AM   #1
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FA 645 300mm f5.6 alternative

Hi all-

I am new the the forum and Pentax. I have been shooting with the 645Z this past year and have been building up my lens collection. I have used the lens reviews on this site to guide my decisions and in general have been very pleased with the performance of the Pentax 645 lenses. I do seem to have found a weak point though in the 300mm range. I purchased a copy of the 300mm f5.6 as it seems to be a pretty well regarded lens and it is relatively small and light which is important for me since I do landscape photography and would like to minimize weight if possible.

The first copy of the lens didn't seem to be sharp at all, to the point that I honestly couldn't use any of the images made from it. Since the lens has been reviewed so favorably I figured that I just got a bad copy and purchased another copy. It does not seem to perform much better. I thought it might be camera shake, but I shoot exclusively off a tripod with MLU, remote and delayed shutter trigger. I have also tested it at higher ISO's so that my shutter speed was fast and should eliminate shake. Nothing seems to have worked, but I figure I have to be doing something wrong since the images that are made are unusable. Has anyone else here run into similar issues or have any advise on what might be going wrong? I have contemplated buying a Really Right Stuff long lens support but I don't want to invest any more money before I know the lens is worth it. Any thoughts or suggestions are appreciated.

Thanks,
andy

12-04-2015, 11:56 AM   #2
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There are several 645Z and D shooters using the 67 300EDIF with good results. I use it on the 67 and it is sharp with no CA wide open. It is heavy though and requires an adapter for the D/Z.
12-04-2015, 03:11 PM   #3
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Well, 645 FA*300/4 is also a (yes, more expensive...) good and pretty riskless alternative.
12-04-2015, 03:23 PM   #4
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Are you using manual with live view or auto focus?

I find that using 200fa +1.4tc gives excellent results and is cheaper and lighter than the 300...

12-04-2015, 04:42 PM   #5
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can you share some pictures? at this point, we don't know for sure if the issue is with equipment or technique.
I am astounded by the 67 M*300/4 but that does not meet your weight criteria.
12-04-2015, 11:41 PM   #6
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Well, I just know for the D, not for the Z. I am using the 300/4* A and the 150-300 FA.

The 300/4* is much stronger at f/5.6 an 300mm, the 150-300 is quite soft wide open beyond 220 or 240mm. But this changes quickly stopping down. f/7.1 is good as long as you are not counting pixels in 100% view. And starting from f/9, there is nothing to complain at all.

The 300/4* is the better if you plan to use the lens at larger appertures or in combination with a converter.

There is another lens that is quite good on the 645D and has 300mm, at lower costs. It is the 300/4 6x7 non ED. Is sharpness is good from wide open on. The drawbacks of the low prive are: It is quite heavy and big, but has no tripod collar, so it can blur easily if the tripod is not really good (Gitzo Systematic series 3 or better). And up to f/5.6, contrasts are very low, so post processing is needed to increase the contrasts.
12-05-2015, 01:04 AM   #7
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QuoteOriginally posted by Zygonyx Quote
645 FA*300/4 is also a (yes, more expensive...) good and pretty riskless alternative.
+1 for the FA*300mm f/4 ED [IF] - it handles the 1.4X RTC surprisingly well, 2X is really pushing it IMO - bokeh seems to get harsher.
12-05-2015, 06:31 AM   #8
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well, my question would be, can you get it sharp at all, when focussing manually ? optical viewfinder and/or LV ?
if that is the case, it is worth checking if the AF needs compensating in the menu.
Mine is tacksharp, center to rim from f8,
but supersensitive to vibration, but then you have probably already taken any care, that one could take.
so yes, there are sharp ones, this is actually the first time I am hearing any neg. feedback on this lens.
cheers
Z

12-05-2015, 08:13 AM   #9
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QuoteOriginally posted by zobeleye Quote
well, my question would be, can you get it sharp at all, when focussing manually ? optical viewfinder and/or LV ?
if that is the case, it is worth checking if the AF needs compensating in the menu.
Mine is tacksharp, center to rim from f8,
but supersensitive to vibration, but then you have probably already taken any care, that one could take.
so yes, there are sharp ones, this is actually the first time I am hearing any neg. feedback on this lens.
cheers
Z
That is what I heard. I am on the blink of purchasing the FA 300/5.6. Can't beleieve it is so bad. Must be vibration or AF calibration.
I want it because it is light.
12-05-2015, 11:17 AM   #10
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The FA300/5.6 is useless mounted on a tripod by the body for 2 reasons.

First the shutter vibration at crucial speeds say from 1/10 through 1/500 just shake it too much on the Z. Second is that the lens sticks out too far and moves very easily.

I have the FA 5.6 300 and purchased specifically the ReallyRightStuff long lens support package including clamps, rail and front lens support and guess what, I can now get wonderful sharp images from it.

If I wanted to be critical I would say that ultimately the Z is only good with lenses up to 150mm and for anything else you are better off with an A7rII and some long lens using the electronic first shutter.

If the Z had EFC then we would have a perfect camera.
12-05-2015, 06:07 PM   #11
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Original Poster
Thank you everyone for your responses! As for stopping down, I really don't shoot anything less than f/11 so its not a wide open issue. As others have mentioned I am suspicious that it is vibration from the lens sticking out so far in front of the camera, but I have done some unscientific tests of very fast shutter speeds (>1/1000s) to see if that helps at all. Unfortunately it didn't seem to help that much, but I also had to mess with ISO in this particular situation to get that shutter speed so maybe that had something to do with it.

I have attached two images to show what I am talking about. The first is the whole image and the second is a 100% crop of the tree in the lower right. When compared to my other lenses the 300 f 5.6 just docent come close. Recently I have resorted to using the A 150 and cropping but I prefer not to do that as I throw away too much data.

2351HD, it sounds like you have had similar issues with this lens. I too have thought about purchasing the RRS long lens support but I didn't want to spend more money without knowing if the lens was worth it and could produce critically sharp images, but it sounds like you are saying it works pretty well? As others have mentioned, I am primarily interested in this lens not only for the focal length but also the size and weight. By purchasing a RRS lens support that increases the weight similar to the 150-300 so would I just be better off getting that instead?

Thanks again!
Andy

Last edited by abrehm; 02-29-2016 at 09:03 PM.
12-05-2015, 06:09 PM   #12
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QuoteOriginally posted by 2351HD Quote
If I wanted to be critical I would say that ultimately the Z is only good with lenses up to 150mm..
With proper support and correct long lens technique anything up to 800mm should be fine.
12-05-2015, 09:09 PM   #13
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QuoteOriginally posted by Digitalis Quote
With proper support and correct long lens technique anything up to 800mm should be fine.
How could I improve my technique to get better results? For the image above I used a Gitzo 3 series tripod with MLU, remote and delayed shutter and it still seems that I have vibration or bad technique issues. Any suggestions?
12-06-2015, 02:11 AM   #14
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You won't be better off with the 150-300, it will suffer the same problems.

To get it to work well you need the long lens support.

Also for the record, I had a mint FA300 f4 and its tripod foot sucks, offers no stability so even it should be used with the long lens support. That's why I sold it and got the 5.6, why bother with the extra weight of the f4.
12-06-2015, 02:47 AM   #15
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QuoteOriginally posted by 2351HD Quote



If I wanted to be critical I would say that ultimately the Z is only good with lenses up to 150mm and for anything else you are better off with an A7rII and some long lens using the electronic first shutter.
That's quite a statement. I don't find that's the case at all. The 200 with 1.4 is fantastic.
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