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Showing all 3 reviews by marcusBMG

Review of: SMC Pentax-AF 35-70mm F2.8 by marcusBMG on Tue May 9, 2017 | Rating: 8 View more reviews 
SMC_Pentax-AF_35-70mm_F28.jpg

Views: 74755
Reviews: 7
I noticed this lens on ebay and curiosity piqued, bid. I won at a pretty good price judging from those cited in the reviews. http://www.groupoids.org.uk/photography/PostedPics/pentax35-70AF/pentax35-70-2-900.jpg The lens is in decent condition, good optically. I took it out for a spin on my K5, usual haunts - the castle etc. http://www.groupoids.org.uk/photography/PostedPics/pentax35-70AF/IMGP8363xga.jpg http://www.groupoids.org.uk/photography/PostedPics/pentax35-70AF/IMGP8367xga.jpg http://www.groupoids.org.uk/photography/PostedPics/pentax35-70AF/IMGP8368-1xga.jpg On camera it fdoes feel a bit clunky, and the Af style manual focus doesn't offer the same sort of ergonomic feel that a classic MF lens does, however it works pretty well. But good IQ! I'm not sure if its definitely better than the tamron adaptall 17A 35-70mm (or its big brother the 01A), one point on which those adaptall lenses outgun this is close focus. But certainly my pics so far are a firm thumbs-up. Test composite - landscape at 35mm, samsung NX20 (20MPx, apsc). Click on the image to pull up the fullsized 4928x3398 2.5MB image. Image is already good in the centre at f2.8 but exhibits some softness, haloes/coma towards the edges. The edges, even on apsc, remain a bit softer at all f stops, but overall the iq is consistently pretty good. http://www.groupoids.org.uk/photography/PostedPics/pentax35-70AF/Pentax35-70X4-800.jpg

Review of: SMC Pentax-F 100-300mm F4.5-5.6 by marcusBMG on Fri November 27, 2015 | Rating: 7 View more reviews 
SMC_Pentax_F_100-300mm.jpg

Views: 123477
Reviews: 20
I acquired both my DAL 55-300mm and this lens opportunistically cheaply, but this lens was still less than a third of the price of the DAL. So in terms of bang for buck this is already a winner. Previous reviewers have noted most of the obvious points re structure and handling and I don't have much to add. It's no surprise that it is larger and 180g heavier than the DAL being designed for a full frame image circle (reviewer pericombobulation below remarks it's not "crop factor" but crop factor is due to the size of the camera sensor relative to 35mm film, not the lens, these two lenses will have the same field of view at matching focal length on any and every camera they are mounted on!). But for me it's not so big and heavy, I used it on my compact mirrorless NX20 tripod mounted and it was front heavy of course but not so much that I would strongly protest about the absence of a tripod mount (unlike eg the 870g Tamron adaptall 60-300mm 23A fully extended to 300mm - TM essential). I will mention the aperture ring though, that's a plus for me over the DAL, makes the lens more versatile and I can use it on my mirrorless cameras, even if only for testing purposes (yes I can mount the DAL too but only with a diy jamming of the aperture lever can it work at anything other than the entirely unhelpful f22, standard cheap PK-NX adapters don't hold the aperture open). At 300mm the DAL is almost as long as the F 100-300mm, reflecting it's very different design, extending dramatically with zoom, while the F doesn't extend at all. Like pericombobulation I have compared this lens side by side with the DAL 55-300mm. Unlike him however my results clearly favour the DAL. Test pics Samsung NX20, manual focus by eye with 7x evf magnification, jpg's. At 100mm purpling and halo/coma was very evident wide open, where the sunlight was reflecting off eg whitewashed buildings. There was fringing on the skyline as well, in the form of a seepage of purpling into the dark edge. Stopping down ameliorated the CA but it was still discernible at f8 on the skyline at 200% on screen. Resolution was actually broadly quite close to that of the DAL at ~ 90mm f4 (I set at ~100mm but pic is evidently at a slightly shorter focal length, obviously the samsung doesn't record actual focal length) , and pretty consistent, I didn't notice great improvement stopping down. IQ was also consistent across the frame on the APSC cameras used (in fact distinctly more so than the DAL which was a bit softer right edge). Colours and contrast put out by the NX's internal jpg processing were similar. Results at 135mm showed slightly better resolution but were mostly similar, and I wouldn't say the 100-300mm has any significant IQ fall off going right to its 100mm zoom range limit. If it wasn't for the CA issues the F would actually be competitive with the DAL at 100mm. Comparing the crops between the DAL and F is slightly misleading because the sun went behind a cloud, reducing the contrast on the foliage and the glare off the buildings to the detriment of the former and improvement of the latter, but the impression that the F has resolved most things pretty much as well as the DAL is correct. http://www.groupoids.org.uk/photography/ReviewPics/pentaxF100-300/SAM_2540-800.jpg Full size 1:1 crops. 100mm, samsung NX20. http://www.groupoids.org.uk/photography/ReviewPics/pentaxF100-300/SAM_2540_crx5.jpg Results at 300mm showed the F as much softer than the DAL, the F would only start being competitive with the DAL once stopped well down. Some reviewers have suggested that the performance drops noticeably zooming towards 300mm, however I didn't notice that resolution significantly improved backing off from 300mm to ~250mm, maybe a touch. I would simply concur that resolution at the long end just isn't that good; CA however is much improved over the results at 100mm . Wide open was particularly soft, much softer relatively than wide open at the other end of the zoom range. I was only happy with bird test pics results when stopped down, all the wide open shots were disappointing for me. http://www.groupoids.org.uk/photography/ReviewPics/pentaxF100-300/SAM_2549-800.jpg Full size 1:1 crops. 300mm. http://www.groupoids.org.uk/photography/ReviewPics/pentaxF100-300/SAM_2546_crx4.jpg Overall I would have to say the IQ just doesn't quite do it for me, specifically at the 300mm end, not with a DAL 55-300mm in hand. Sharpness 8/10 at 100mm, 6/10 at 300mm. I would like to ask pericombobulation whether he used just AF or checked things with MF and eg live view. It is possible that he has a particularly good F 100-300mm/poor DAL 55-300mm. But in any case if you're looking for a cheap x-300mm zoom option this can do (if you get a good one, reviews of SMC-F series lenses suggest inherent variability). A pigeon at 300mm f10, samsung NX20. http://www.groupoids.org.uk/photography/ReviewPics/pentaxF100-300/SAM_2569-900.jpg And this tit with my K5 @ f8, 1/250. http://www.groupoids.org.uk/photography/ReviewPics/pentaxF100-300/IMGP1768-900.jpg

Review of: SMC Pentax-DA L 50-200mm F4-5.6 ED by marcusBMG on Tue December 10, 2013 | Rating: 7 View more reviews 
SMC_Pentax-DAL_50-200mm_F4-5_6.jpg

Views: 110466
Reviews: 17
I acquired this lens with my K-r as a 2-lens kit. I was unimpressed when I first tried it and it languished in the box. Lately I sold it with another camera but before it went I did these test pics (channel marker is about 1/2km out in the estuary) at 200mm. http://www.tremyfoel.co.uk/photography/DAL50-200-cropx3.jpg First thing I have to say is that the crops are a bit misleading. I was tweaking the focus using live view manually but when I looked at the pics I am fairly sure the camera disobligingly did a little refocus - back focussing in fact on the background. However the general sense is correct: sub par performance at f5.6, still not great at f8. Thats the bad news. The good news is how the IQ jumps as the lens is stopped down to f11. Heres a couple of points of comparison: the same shot taken with a 200mm prime (tamron 4B) and a noted vintage zoom at 210mm (vivitar series one 70-210 komine). I have to say the latter was almost as bad as the DAL wide open! http://www.tremyfoel.co.uk/photography/04B-56-crop.jpghttp://www.tremyfoel.co.uk/photography/VS1-8-crop.jpg The tamron is a classy prime already good at f3.5, however I have to say there's not much between the tamron and the DAL at f11, tha'ts how much it sharpens up. This test pic also at 200mm but of a closer subject - the clock on the church tower - gives a more consistent perspective (no OOF). http://www.tremyfoel.co.uk/photography/DAL50-200-CHcropX3.jpg So I didn't do any investigations at shorter focal lengths and by all accounts it's better at those. If I want to shoot at 200mm, between 04B and this is a no-brainer. And I can't really see any circumstance where AF would override the difference in IQ, not once the difference in shutter speeds between f3.5 and >f8 have been factored in. However, I can say that the lens clearly has some good quality, and bearing in mind there is a steady trickle of these onto ebay and it is obtainable for around fifty quid odd, I think thats a recommend. Just remember to stop down if looking for some TP reach.



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