richard_driscoll

Wanting to carry a Nikon D7200 with 2 or possibly three of the small, plastic, lightweight consumer lenses when out hiking I've been trying to find a waist pack, bum bag or whatever you call it. IIRC these used to be pretty common but are disappearing. Lowepro seem to only have one, the Inverse 200 which is really too big. Think tank used to have the Speed Demon which might be OK but it's now obsolete. I certainly don't want a backpack where I have to take the thing off to get at the camera. Think Tank want to sell you a belt with loads of separate items hanging off it, but I really don't like that idea at all and the belt looks much less comfortable than the Speed Demon one. Has anyone any ideas?, and many thanks.

That second reference I posted shows how the Biogon suffers from pretty dire cos**4 vignetting which is much the same whatever the stop. The Distagon is a retrofocus design and has the exit pupil further away making the cos**4 vignetting much less. It suffers from optical vignetting wide open but that disappears as the lens is stopped down. If I worked it out right the loss of illumination on the Biogon is about 2.8 stops!! Is it really this bad? I don't know but I've seen colour slide film shot with the 21mm non-retrofocus Leica (Schneider) Super-Angulon that has really dark corners. Some used to say that you could use this creatively - perhaps. In the film days they used to say that if you had a lousy enlarger it made things better in a B&W print because the poor coverage of the enlarger reduced the vignetting due to the camera lens! IIRC Zeiss offered a 16mm Hologon for the relatively recent Contax 35mm film camera. That came with a special ND filter with a dark middle to compensate for the vignetting. We are getting a bit far from discussions about Dandelion chips here. My guess is that it's only with wide angle lenses that there is likely to be a problem. It's probably fortunate that if the chip reports zero (or is it nothing at all) for the exit pupil distance that Nikon probably sets it to be the same as the focal length or otherwise make no compensation for falloff. In principle all bets are off guessing what they might do.....

........ And if you can cope with the errors and the mirror image diagram this shows how much better the illumination of a retrofocus 21mm f/2.8 is than a rangefinder version. Can't say I'm convinced by the explanation though..... http://www.cs.cmu.edu/~sensing-sensors/readings/vignetting.pdf

As the man in the shop said to the unhappy customer, "They are all like that sir." My D40 and D7000 are like it and so are a couple of others I looked at the manuals for. Egg on face it's actually mentioned in the D7200 troubleshooting section which I'd thought just stated the glaringly obvious about most things. More annoyingly the real information about the assist light seems to be only in the "menu guide" not in the manual itself. My S/H D7200 didn't come with the menu guide and I think it may only be available on-line; the manual doesn't mention it in the list of stuff you get with the camera.

It's over 40 years since actually designed any of this stuff and that was a flying spot slide scanner for my PhD project. My book on engineering optics is even older and was not terribly helpful. It must be our lucky day because IOP Publishing have decided to make part of their "Physics of Digital Photography" available as free to read:- https://iopscience.iop.org/book/978-0-7503-1242-4 The section available is the one on fundamental optical formulae. Section 1.4.7 on natural vignetting is relevant to our discussion. It points out that the image space angle version the cos**4 law is modified by the pupil magnification factor which in turn depends on the lens design with telephoto lenses having mp less than 1 and retro-focus lenses greater than 1. As well as that there is a section on focus and recompose and its relation with DOF which I still have to read. I worked out some of this a few years back so it's interesting to see if the conclusions are the same.

Just tried on my D7200. Turned setting a9 on since I usually have it off. No focus lamp!! Turned camera off and on - no joy. Set all 'a' options to their defaults - no joy. Took lens off and replaced - no joy. Lamp is OK since it blinks with self timer. Oh well - two button reset - now it works! However if the focus mode is set to AFS and single focus point the lamp won't work unless the selected point is the centre one and I guess that is what the reset did. Surely the centre 9 (say) should be illuminated OK to work. What's more if you set AFS and auto area it works too! Perhaps the trouble you had? - easy to have the focus point set one off from centre and not notice. Must look in the book. BTW the D7200 is so darned sensitive, things have to get pretty dim before it turns on anyway.

Because all the discussion about the absolute illumination of a multi-element metering sensor is concerned with matrix metering isn't it? In the case of the FA and F4 there is some mechanical communication 'twixt AI or AIS lens and camera I believe but I don't know the details. We all knew that the digital cameras can do C/W metering without extra data, though Nikon say in my manual that it improves if given lens data. IIRC Bjorn used some samples of Nikon's own chips and installed them in some lenses he had but I don't know for sure.

I'd imagined that the lens in front of the metering sensor on the digital cameras is there to form an image of the scene on it's surface. It does this by using the real image in the plane of the screen as its object. The prism system, if well designed, shouldn't have much effect on this. As well as the imaging system we now have to consider the illumination system which is where the exit pupil of the main lens comes in. The cone of light from it is incident on the screen and the condenser, fresnel lens or whatever they are using now ensures that (hopefully) most of the light is not lost, either by the magnifying eyepiece or the metering system. Some of the light goes straight through the screen, some is scattered, it depends on the design of the screen, and I suspect there is a tradeoff between brightness and ease of focussing. In any event my suppositions are all (retrospectively) pretty well confirmed by bjørn rørslett on this site back in 2007:- Nikon DSLR Firmware Updates - Wish List "A final issue is that the Nikon light metering system really needs information on the position of the exit pupil of the lens in order to work reliably, and my guess is that most users haven't a clue what that is not to speak of its position (which, for a zoom lens, does vary along the zooming range as well). All Nikkor CPUs do report the exit pupil position to the camera and I have verified that giving the camera false values of the pupil's position *will* lead to severe errors in the calculated exposure. Hence even inputting the max./min. f-numbers and the focal length of the lens won't guarantee good metering unless the camera finds an exact match for a Nikkor lens in its database and can extract the missing data from there." Of course for the matrix meter to work properly it needs to measure the absolute scene brightness anywhere on the meter sensor surface and any undefined falloff will make this impossible. It needs to do this so that it can classify scenes and also ignore extremely bright areas which are considered to be the light source or bright refection of it. My understanding with wide angle lenses is that the light loss is much reduced when the lens is of retrofocus design since the exit pupil is then further from the focal plane than the focal length. For example, my D7200 reports the exit pupil position of the 35 mm 1.8G DX as something over 100mm IIRC, I don't have any fixed focus wide angle's with ICs in them but at 10mm my new 10-20 zoom has the exit pupil at 70.6 mm (I just looked) so in these cases the focal length doesn't really tell you anything about the illumination falloff.

Sorry Joe but that argument can't possibly hold water. If it were true there would be no difference between metering systems with one element, several hundred elements or several thousand. It can only be that the screen has a partial but not total diffusing effect. In the case of the old Nikon cameras they were all centre weighted and I'll bet the degree of centre weighting varied with the exit pupil position. There were articles in the BJP back in the sixties discussing the effect of exit pupil position on TTL metering. BTW I can't find any statement about what the Dandelion chip does with the the exit pupil position but my guess is that it sets it to be the same as the programmed focal length. Can you confirm that with any of yours? The illumination will fall off as cos**4 and so will be most marked with lenses where the exit pupil is close to the plane of the sensor.

We've had this discussion in the past. About five years back I wrote:- "For stationary subjects isn't it the easiest to just use AF-S, one point focus, locking focus by pressing the shutter button half way down, re-compose as necessary with shutter half way down and shoot when ready. I'm sure we had this discussion a couple of years back and yes, the conclusion was that if you are using AF-S then the two methods are equivalent though perhaps different in convenience. For example using the release to lock you have to keep half pressure on the release to maintain focus lock between shots. In AF-C it is quite different and I think that most of the AF-ON fans above are mostly using that." Anyone know if cameras have changed recently so that things are different now?

I was about to make the same point. If you shoot RAW+jpeg you finish up with an out-of-camera picture you may well like and another with which you can play about for hours on end. The choice is yours. I recently bought a nearly new D7200 and an open box 10-20 Nikon zoom. In terms of bang-per-buck this combination must be pretty nearly unbeatable. Some say that for landscape you need a full-frame camera with zillions of pixels but I don't believe it - a 24MP DX camera like the D7200 is just fine. About all you'd gain in practice is a bigger viewfinder. My advice would be to buy a used D7200. If you decide you don't like it or want something else you can always sell and lose little money. If you do this you'll probably be in a better position to decide what you really do want. By the way, if you buy the cheap Nikon 10-20mm zoom you'll probably be horrified by the plastic construction especially if you are used to the old Nikon MF lenses. Just don't worry about it - the results are what count and if you are an amateur like me you probably don't need ultra-durable equipment. I just remembered. If you use old AI or AIS lenses on a D7200 you can focus using the electronic rangefinder, moving the focus point around the frame. These lenses work on aperture priority and manual. Also the lateral chromatic aberrations are corrected by the camera automatically if you shot JPEG. If you shoot RAW then Nikon's free Capture NX-D can correct for them (as can loads of other application programs). Having said that the modern zooms are so good that there may well be little point in using the older lenses. Stopped down to f/8-11 or so which you probably would for landscape, even the plastic 18-55mm kit zooms are good.

It's my understanding that the matrix meter (and probably the centre-weighted meter to some extent) needs to know the position of the exit pupil to work properly. This information is provided by the Nikon lenses with a "cpu." The implication is that the exit pupil position provided by the Dandelion chip should match that of the lens which is being modified. When you put a non-cpu lens on a digital body and provide the lens focal length (and max. aperture) I've always imagined that the body uses this information to estimate the exit pupil pupil position. It could do this by lookup table except that the combination of maximum aperture and focal length does not uniquely identify a particular lens design so I imagine that most lenses of similar aperture and focal length tend to have the exit pupil in a similar position and that is good enough. I must read up more about this Dandelion chip.....

Up on the moor for a Christmas day hike. It's a 14th century granite cross but you can't see that because it's 90 degrees rotated! Nikon D7200, 10-20mm Nikkor AFP at 10mm. [ATTACH=full]1322713[/ATTACH]

Not many this week so I'm posting a few taken with my new-used D7200 a week or two back. All are Dartmoor, Devon UK in afternoon light. Tamar Estuary Towards Great Mis Tor Towards North Hessary Tor from Great Mis Tor

Strangely enough, for me, it was Thom Hogan's review of the 10-20 that first raised the tripod issue. He seems to differ with Nikon since he says they "equivocate" about the need to turn off VR and says he did need to turn it off!

Having just ordered a Nikon an AFP DX 10-20 zoom with VR I downloaded the manual to see what it says about tripod use with a camera where you can't turn off the VR. I expect to handhold this lens but I was curious. It says that VR is generally recommended when on a tripod! This is in marked contrast to the advice for my most recent AFS lens, the AFS DX 18-55 zoom which says turn the VR off when using a tripod but leave it on if the tripod head is unsecured. Clearly this AFP lens is different. Is the design of the VR system different or does the lens/camera combination have some means of tripod detection? By the way the manual for the replacement for my little midrange zoom, the AFP DX 18-55 VR also tells you to leave the VR on so it's not a focal length issue.

Well, I've finally ordered the Nikon 10-20 AFP VR. In the UK these sell new for £180-£215 but I've found an 'open box' one on offer for £159. It was really between the Nikon 10-20 and the Tamron 10-24 VC which here is well over £300 used, though I did find one at £299. I suspect the optical quality of the two is similar, so it was really a case of the extra zoom range as against weight and price. Many thanks to all for the help.

Thanks Ben. I just found a rather helpful review of this lens here The guy seems pretty impressed and from what I can gather it was OK on a tripod with VR on which surprised me rather. Presumably on your D600 you can switch to manual focus using the lever near the lens mount even though you can't turn off VR?

Thanks for the information. A actually found a review of the Nikon 12-24 on this site (it used to be photozone.de) using a D7000 and it's actually not that bad, though the Nikon 10-24 is probably better. At the moment, however, I probably favour the Nikon 10-20.

Yes I'm sure that this lens is optically one of the best, however in my case the price and weight count against it. Also since this is mainly for outdoor use on a camera with good high ISO performance I don't really need the f/2.8 stop. Top contender at the moment is probably the Nikon 10-20 plastic-fantastic which I'm confident would lose the conkers contest at the first swipe. For the benefit of non-Brits:- Conkers:- Strange game in which a nut from the horse chestnut tree is suspended from a string after boring a hole through it. Taking it in turns, contestants attempt to destroy their opponent's conker by hitting it with their own. Performance enhancements include pickling in vinegar and oven baking the nut, though benefits from this treatment are largely unproven.

Sorry my typo. it's a D7200. I passed on the D7100 and the D7500 is no better with non-CPU lenses than my D40, so the D7200 is kind of last of it's kind and hopefully My Last Camera as I'm now almost 72!

Thanks for that Dieter. I had read your earlier post but discounted the Tamron because it looked as if the price looked too high used. I now find that the advert. was a rogue and it seems I can buy one for around the same price as the Nikon 10-24, or a little less. Perhaps I'll go with the Tamron as it's about the same weight as the Nikon and the VC is a bonus.The idea is that I can switch to a 35mm f/1.8 DX after 24mm and then pick up on a 55-200 zoom. Maybe even leave the 35 mm at home sometimes. D7200 seems great. Many small tweaks that make it much nicer to use than the D7000 and the low light high ISO JPEGs are pretty impressive. I know you hate the D7xxx v. the D200/300/500 but for my purposes the size and weight really matter!

I'm finally getting a slightly used D7200 to replace my D7000 and also decided to have a go with a wide zoom - something wider than the 18-xxx kit zooms. I've decided to buy used and would appreciate some advice from people who've used some of the contenders on my short list. This lens is mainly for landscape and weight is an issue since I'll be carrying the equipment along with hiking kit. I don't necessarily need anything that will exploit all the 24 mp of the camera - one more appropriate for, say, 10-15 mp would probably do. I think that I'd prefer a lens that went out to 24 or 28 mm and started at 12mm rather than one starting at 10mm and finishing at 20mm. Not sure about VR. Do you really need it outdoors on a wide lens? Mind you as I've got older I find it less easy to hold the camera really still! Anyway so far I've come up with:- Nikon 10-24 f/3.5-4.5 460g about £290 Not much wrong with this one I think, though more expensive than the others. Nikon 12-24 f/4 460g about £200 This is a very old design. Is it optically up to the job? If so it's a contender. Probably the best mechanically. Nikon 10-20 f/4.5-5.6 230g- !!! about £170 Has VR which on the D7200 you can't turn off. I did know in advance of buying the camera! Reports seem mixed, some say it's good, others say only good for the price. Shame it doesn't go a bit longer. Has a plastic mount which I'm happy with on a zoom at £70, less so on one at this price. Still I love the low weight. Sigma 10-20 f/3.5 530g about £220 Same as above about the zoom range. 100g more than the Nikon offerings. Reports seem a bit mixed and maybe it suffers from the variability that plagued the older slower version. Tokina 12-28 f/4 540g about £175-£200 This was a hot favourite despite the weight until I saw the review on lenstip which pointed out that Tokina still have a problem with flare. Just how bad is this? Has anybody got one of these? Tokina 12-24 f/4 540g Mk1 £150 Mk2 £200 On the Mk2, flare seems better than the 12-28 above. I'd be inclined to go for the Nikon 12-24 at 100g less and better flare resistance. Is the lower price of the newer 12-28 on mpb.com here in the UK telling me anything? Any thoughts and other suggestions appreciated. The postman has just delivered my Black Friday 1300 clicks as new D7100 so it's time to open the box!

There are a couple aspects to why the old cameras seem old. One is the sensor; another is the JPEG engine. You can't improve on the first but you can on the second if you shoot NEF. For example I can open an old picture taken with my D40 using Capture NX-D and get access to all the latest picture controls Neutral, Flat, Standard and even the Clarity slider. I can even use the latest noise reduction, 'better quality' and 'better quality 2013'. Mind you with those huge photosites (only 6 Mp) there is no noise to be seen at low ISO and the default is not to apply any.

My £2.25 one from Hong-Kong arrived yesterday. Clearly a different plastic moulding from the old one being a little thicker, though both say "for Nikon" and look similar. I took the old one apart and it looks as if the problem may be that the battery contact spring has lost it's set so contact is intermittent. It's possible to peel off the self adhesive front panel (giving access to the screws) and replace it; so repairs are possible if one has the inclination!