| Author: | | New Member Registered: May, 2020 Posts: 2 | | Review Date: September 11, 2023 | Recommended | Price: $70.00
| Rating: N/A |
| Pros: | Sharpness, bokeh, handling, build quality, low weight | | Cons: | CA wide open | | Sharpness: 8
Aberrations: 7
Bokeh: 8
Handling: 9
Value: 9
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This lens is a surprisingly good performer, with excellent sharpness and bokeh. The build quality, and handling are both superior with wonderfully tactile diamond grips, and smooth well-damped focus of 180 deg. end to end. If you find one at $60-70 bucks you've found an absolute bargain! 
My own copy is the Chinon version with a Canon FD mount and a NINE (9) bladed aperture  (see photo) not (6) as listed at the top of the page. Otherwise it is detail for detail identical to the Chinon version photo above. 
I've uploaded test shots using a Sony Alpha 7 of a fence post comparing it to my Canon FDn 300mm f/4.0 -- a lens that easily costs twice as much on the vintage market and which weighs 1.5x as much -- making the Chinon the go-to choice if you're hoofing it through the wilderness.
Chinon @ f/8
https://www.pentaxforums.com/gallery/photo-chinon-300mm-f-5-6-f-8-62649/
Canon @ f/8
https://www.pentaxforums.com/gallery/photo-canon-fdn-300mm-f8-62647/
Chinon @ f/5.6
https://www.pentaxforums.com/gallery/photo-chinon-300mm-f5-6-62648/
Canon @ f/5.6
https://www.pentaxforums.com/gallery/photo-canon-fdn-300mm-f-4-f-5-6-62650/
As with any (f5.6 or slower) 300mm manual focus lens from the 70's you do not want to shoot wide-open at infinity as it will exhibit significant chromatic aberration. The CA cleans up reasonably at f8, is very good by f/11; particularly if you tend to shoot twigs against a bright sky at infinity (you know who you are birders).
If you're looking for faster and/or apochromatic performance from a manual focus, you should expect to pay significantly more for a 300mm. The Canon FDn 300mm f/4 sells for over twice as much as the Chinon, and the less common manual focus Sigma 300mm f/4 apo can be found from time to time for about 4-5x the cost of this lens.
As you can tell from the consistency of the reviews posted below, there is one statistical outlier whose lens exhibited CA across the full range of aperture settings -- trust and believe that this is an indication someone inexperienced was inside the lens in the past and re-assembled it improperly. You just won't find such a dramatic variation in quality like that from any of the major lens manufacturers from the 70's to the present day.
| | | | | | | New Member Registered: November, 2013 Posts: 14 | | Review Date: July 30, 2019 | Not Recommended | Price: $50.00
| Rating: 4 |
| Pros: | good sharpness, but not extremely sharp | | Cons: | very strong CA's - not suitable for poster shootings | | Sharpness: 6
Aberrations: 2
Bokeh: 8
Handling: 6
Value: 4
Camera Used: k-5 k-x k200d, k-s1 sfx mz5 z20P
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This 4/4 lens construction has absolutely very strong visible CA's. Mines. Perhaps a monday product?
The color fringings are orange-red and green-blue visible still at normal notebook size viewing (12,5%). Stopping down and the CA's will remain. No change at all.
It is the worst tele lens, I ever had used on my pentax cameras
It is a shame lens for Tamron !  They would have better done to include two achromates at least, additionally !
I regret - no recommendation from me because of strong CA's!
PS. maybe there is an earlier or later 6/4 element version - this must be better.
I've bought a TAMRON 23A - this lens is really extremely sharp and because of 15/11 element construction nearly free from CA'S (Sorry - mines - i.e.5.6/300 - has been delivered without achromatic elements = 8 inner reflections against the sunlight instead of 10 reflections of a 6/4 design! It was a 4/4 elements construction as above mentioned.): o | | | | | New Member Registered: April, 2016 Posts: 1 | | Review Date: April 15, 2016 | Recommended | Price: $30.00
| Rating: 8 |
| Pros: | small, light and cheap | | Cons: | slow, purple fringing, sharpness is not very good but acceptable | | Sharpness: 7
Aberrations: 5
Bokeh: 8
Handling: 8
Value: 8
Camera Used: K-500
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I have Chinon version and it's good lens for the price.
Needs to be slower down to f/8 or f/11 which often results in increased ISO. F/5,6 is not acceptable for me. Purple fringing can be a problem sometimes too, but overally it's not bad lens! Some pictures taken with this lens and Pentax K-500:
Moon shot, on the left - SOOC jpeg, on the right - RAW file processed in RawTherappe. F/8, ISO 400
Birds: F/11, RawTherapee
 | | | | | New Member Registered: February, 2012 Posts: 17
2 users found this helpful
| | Review Date: January 31, 2015 | Recommended | Price: $25.00
| Rating: 8 |
| Pros: | Light, sharp, good colour and contrast, good handling | | Cons: | Bit slow. | | Sharpness: 8
Aberrations: 8
Bokeh: 8
Handling: 9
Value: 9
Camera Used: Samsung GX20, Pentax K-x
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I have three Adaptall 300mm f5.6 lenses; the original version, believed to be a remount of the earlier Adaptamatic, the well-regarded SP 54B, and this CT-300.
They are all decent.
I find the original version, which has the longest focus throw, is the easiest to focus.
I find my CT-300 to be the sharpest of my three, and it seems to show less fringing, though since the fringing is most pronounced in the out of focus areas, this may owe something to having nailed the focus on the sharpest shots.
The SP 54B has a close focus ability that the others do not; brilliant for small garden birds in a small garden.
My Tair-3 300mm f4.5 is sharper than any of the Tamrons, and indeed sharper than anything else I have that covers 300mm, leastways I can discern more detail, but the Tair is huge and heavy, and the Tair's contrast out of the camera is inferior; it needs to be boosted in PP to show to advantage. I wouldn't want to sell the Tair short, though. It handles well-enough on the camera. It just takes up an inordinate amount of space in the camera bag.
All the Tamrons autofocus with the Pentax 1.7x AF on a sunny day, but I haven't been able to capture birds in flight; the combination locks on too slowly. The Tair, lacking an aperture lever, does not autofocus with the Pentax 1.7x AF at all, even though I have replaced the M42 with a PK T2 mount.
Wide open, the Tamrons are much superior to the Revuenon (Tele-ennalyt) 300mm f5.6 and an anonymous Optomax 300mm f5.5 that tempted me with the promise of a slightly faster aperture that needless to say wasn't apparent in practice. The Auto Super Travenar 300mm f4.5 is as good, but that's another good-handling but weighty monster, slightly inferior to the Tair, and stuck with an M42 mount.
f5.6 is no faster than a consumer zoom, and ostensibly slower than the Tamron 23A 60-300mm f3.8-5.4. However:
- None of my to-300 zooms actually quite get there; they're 290mm or thereabouts.
- When shooting the AF zooms with AF, the MF Tamrons give sharper results. I don't think it is forward or back focus; I just never know precisely what they've decided to lock on to.
- Tweaking the AF zooms' focus manually, I can get comparable images, but the Tamrons are more easily focused accurately manually than my AF zooms (Pentax F 100-300 f4.5-5.8, Pentax FA 100-300 f4.7-5.8, Sigma 70-300mm f4-5.6 DG (non-APO))
- All these lenses yield subtly different colours. I especially liked the CT-300 on autumn leaves, whilst the 54B excelled at the seaside.
Ramble, ramble. Anyway, recommended!
| | | | | | | Site Supporter Registered: November, 2012 Location: North Wales Posts: 2,869 | | Review Date: May 8, 2014 | Recommended | Price: $50.00
| Rating: 8 |
| Pros: | value, versatility, optically good stopped down | | Cons: | no tripod mount; fringing; 54B better for close up/macro; discriminating TP'ers/birders want faster and better. | | Sharpness: 7
Aberrations: 7
Bokeh: 7
Handling: 9
Value: 9
Camera Used: K-r, K5, Samsung NX20
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The Adaptall f5.6 300's have a particular USP for pentax users: there is no direct equivalent in the Pentax legacy lens lineup. The SMC-M and SMC-A 300*'s are much higher end high spec beasts: f4, larger, ~ twice the weight and up to 10 times the price on the occasions they crop up. The closest equivalents in price are the M42 takumars, again f4 (the 300mm f5.6 tak is the ultra rare "ultra achromat"). This CT300 is actually the second adaptall 300, not the first, the very first version was derived directly from the earlier adaptamatic mount lens, and is readily distinguishable from the CT300 by size, looks and built in tripod mount (and given the performance of the adaptamatic 300mm I have reviewed, might be the preferred version for many... if you can find one!).
But anyway from this standpoint the CT300 is an immediate recommend: its a relatively readily available and great value lens, with the versatility of an M42 style A-M switch, choice of M42, P-KM, or P-KA mount to suit your preferences, pocket and camera.
More discriminatingly, how does this lens compare with the later, well regarded and usually more than twice the price, SP 54B? These are my impressions.
Specification, size and looks wise the lenses are pretty similar, 54B has two more elements and a CFD of 1.4m as opposed to 2.5m. Neither has a tripod mount, both easily fit one round the barrel in front of the aperture ring. There is a legacy tamron TM, that fits the 54B (and other lenses like the 52A) perfectly, but the CT300 needs some packing because the mount is designed for the smooth barrel (focus flush) of the 54B, the focus on the CT300 catches on the foot. I use a cheap one from China modded to fit. The focus travel is a bit longer on CT300, which TBH I find beneficial. But overall construction, mechanics, weight etc. are equal/ equally good.
As far as image sharpness went I felt that my CT300 yielded little to 54B stopped down, they were in the same ballpark for resolution, but was noticeably softer wide open. CT300 has a distinctly cooler colour tone than 54B, and 54B also scores with stronger contrast. Both suffer from fringing/CA under unhelpful conditions, this is reduced by stopping down - typical longitudinal (or bokeh) chromatic aberrations, as you focus fringing changes from green (back focussed) to red (front focussed). 54B did distinctly better for me when used with 014F and 01F TC's (but I wouldn't really recommend the use of tc's with these f5.6 lenses in any case - too slow and base lens resolution isn't quite up to it).
As my remarks suggest, for me this lens was third in line of my tamron 300 f5.6's, behind 54B and my adaptamatic, however I should emphasise only marginally so. Provided your expectations are not unrealistic for a £30/$50 (average ebay UK price) or so lens, I can suggest you will not be disappointed. This 300mm is optically OK, relatively light, portable and user friendly, just the job for covering some TP photo opportunities.
Test pic crops, samsung NX20 (20MPx apsc):
crops f5.6, f8, f11.
 | | | | | Loyal Site Supporter Registered: July, 2012 Location: Toowoomba, Australia Posts: 5,484 | | Review Date: October 13, 2013 | Recommended | Price: $120.00
| Rating: 8 |
| Pros: | Sharp, light, can be hand-held easily | | Cons: | Colours tend to be cool | | Sharpness: 8
Aberrations: 8
Bokeh: 8
Handling: 9
Value: 9
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I bought this lens about ten years ago. It was my first venture past 200mm. There is a lot to like about it - it is sharp and can be used hand-held. This means it can produce good results in situations where opportunity knocks and there is no time for anything else. That was the case with the image below. To get a young rusa and red deer scrapping (in the wild) is a rare thing. The Tamron 300/5.6 is small enough to carry and light enough to use quickly in such situations. The colours tend to be a little too cool for my liking, but that can be addressed in post processing.
 | | | | | Loyal Site Supporter Registered: January, 2008 Location: Paris, TN Posts: 3,349 | | Review Date: November 11, 2012 | Recommended | Price: $38.00
| Rating: 9 |
| Pros: | Excellent performance for its low cost, light weight | | Cons: | Low re-sale value | | Sharpness: 9
Aberrations: 9
Bokeh: 9
Handling: 8
Value: 10
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Many older technology lenses deliver performance well beyond their expectations when used with respect for their era. The CT-300 gives away very little to its newer sibling, the SP 300/5.6 (54B) or the popular consumer 70-300 zooms. I have two of 'em, one converted from an Olympus CF 300 and a CT-300.
As an F5.6, manual focus lens it isn't a great choice for BIF or late day wildlife shots, however, used as a close-up/macro-substitute in the field in normal daylight this lens simply delivers images that are very hard to tell from equivalent images made with my 90mm macros 52B/BB).
CF is minimal and generally limited to narrow easily corrected green/blue margins in over saturated situations from F8 - F16. (See the discussion of this effect in the AD-2 200-500 (06A) review here: http://www.adaptall-2.org/lenses/06A.html ).
I have the 90mm macros and the 180mm macro Adaptalls. These CF/CT 300s fill the desire for a LONG close-up lens far better than the very heavy SP 300/2.8 (360B) and used at F-stops appropriate for close-up DoF serve very well in the field. It's a satisfying and economical substitute for the expensive and hard to find 180mm (63B).
The lens works quite satisfactorily with either a converted AD-2 (25mm) TC or a Pz-AF 1.4x TC when closer distances are in order. Works great with Green Button metering IME.
Note: Failure to use good technique for manual focusing and adequate shutter speed for a 300mm lens can produce disappointing results that have nothing to do with the inherent capability of the lens.
Resale value is low but at the typical cost you can find these today you can afford to keep this one around -- and if LBA isn't too demanding it may even save you from purchasing some much more expensive glass you wouldn't use often anyway!
H2
10" statue shot at 8 ft, K200D, ISO 200, F8. Cropped to format, re-sized 600x800, very light sharpening to compensate.
 | | | | | Senior Member Registered: January, 2008 Location: Ankara, Turkey Posts: 142 | | Review Date: July 11, 2011 | Recommended | Price: $60.00
| Rating: 8 |
| Pros: | compact and light, built in lens hood, sharp, support PKA adapter | | Cons: | slow, no tripod mount | | Sharpness: 8
Aberrations: 7
Bokeh: 8
Handling: 8
Value: 9
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First of all, I can say that it is a steal for 60 USD I paid for it. I have no opportunity to compare it with the newer SP version, but it is sharp enough at wide open (but only 5.6), and also compact and light enough to hand-hold. There is no tripod mount but adapting a third party mount is cheap and easy way to do one. It matched well with my PKA adaptall and 1.4 Pentax TC (see photo bird on the tree). Of course it is slow, but I was not expecting to buy a 2.8 lens for this price  .
All photos were taken with a ist DS, hand-held.
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