jon_savage

Assuming you mean a single shot to crop in you need a very long lens and a sensor with lots of small pixels. I've managed tiny cropped snapshots with a Nikon D7100 and a Sigma 150-600 at 600mm and f6.3. The subjects are in bright sunlight so you can try starting at settings around 1/00th and iso 200 and go from there. No need for very high iso's or very long exposures. Here's a couple of old threads about my related attempts on the ISS and Jupiter that have setting information. Astro Photo Op Photo of Tim Peake! (on International Space Station) Shoot in raw and don't be afraid to tweak it a lot to get something (or probably I just got my exposures wrong!). I took lots of shots at various settings and a few worked out OK so do experiment. I have done Mars, Saturn and Venus but I don't recall the settings. My portfolio here has Saturn in it to give you an idea of what you might expect. There's nothing to lose having a go. :)

I've tried a few times getting images of the odd planet with a DSLR and long lens. I really can't recommend enough at trying to get a view of the planets (well, Jupiter and Saturn are the ones that impress) from your back garden or even just getting a look through a telescope. The first time you see them for real is quite something. Here's an over exposed RAW shot taken with a D7100 and Sigma 150-600S (1/20th!!, 600mm f6.3 ISO 200). I used 1/20th as that was OK on previous attempts. But this has been my clearest one I've ever taken with a DSLR once the image was dialled back in Light Room. Then tweaked within an inch of its life in Light Room until I got something recognisable : Obviously 100% views. I think I just supported the camera on a tripod and followed the bright spot buy hand. I have a motorised tracking mount but I don't recall using it for this but I might have done. So hopefully this can give you an idea what settings to try and what to expect. Next try Saturn and then the ISS. But be warned it could be the slippery slope to astrophotography. Jon

Shun, it’s not my Sigma! I don't mind what the op buys but I obviously do care that he gets exposed to many options and understands their compromises. Otherwise I guess I wouldn’t contribute to the discussion to hopefully help him make the right choice for his situation. Dieter brought up the suggestion “if I wanted a constant fast aperture and superb performance, then I would get the Sigma 18-35/1.8 and Sigma 50-100/1.8” and made the interesting comparison seeing them as a full set of standard primes without the cost and changes. Mike agreed with the suggestion (“spot on”) and suggested cropping may be an acceptable way to get the gaps filled. You said DX couldn’t get the best image quality and suggested it was too heavy and discussed primes on a different system. I was trying to add some factual data to various opinions to put all the pros and cons in some context. Only the op knows what his budget, usage and acceptable compromises are and if they are totally unacceptable to him or not. My choice was a £200 used Tamron 17-50 2.8 non VR for my D7100. Very nearly bought the Sigma but in the end decided to save and upgrade to FX.

Gary, “About FX vs DX in low light. It is the capture area of the pixel. The theory is for a similar sensor capacity, say 24MP, the FX pixel is larger than the DX pixel, thus capturing more light.” That theory is really only applicable if you use the sensor like a solar panel in a field under the sky. Like a camera body with the lens removed. With a camera system there is also a lens to consider. The lens must focus the available light from the field of view onto an image circle the size of the sensor or you obviously can’t get an image! You can choose to spread that amount of light either thinly (dimmer) over a larger area or thicker (brighter) over a smaller area. So if camera systems have different sensor sizes but have the same size* lens and have the same field of view they will in theory perform the same in every aspect when you view the final image. Any differences we see will be in things like manufacturing and technology limitations and not due to the different sensor sizes. A sensor can only collect the light it’s given. What you are taking a picture of doesn’t get any brighter because the sensor the other side of the lens changes size, the amount of light passing through the lens stays the same. Jon * same lens size as in the aperture area that lets the light in

Shun, “I am afraid that is a totally unfair comparison” - I disagree. For someone looking at standard DX zoom options the comparison was intended as useful information to consider in the cost, performance, size and weight trade-offs they might be willing to take. It was especially a fair comparison as it was highlighting all the differences. The comparison is: Two lens DX system covering, “27-150”/”2.7” with a 53-75 gap £2,300 (less if as the op already has a DX body) Two lens FX system covering “24-200” “2.8” with no gap and maybe VR for £3,500-£4,500. “Low light performance”: exactly the same. Weight and size: in the same ballpark. You added a third/forth comparison (that may or may not be considered a totally fair comparison to a zoom kit :)): Multi 1.8 prime lens FX system, lens examples could be some of: 24mm £650, 35mm £435, 50mm £125, 85mm £425, 135mm f2 £1190 180mm f2.8 £750 Multi 1.4 prime lens FX system, lenses like 24mm £1,800, 35mm £1,600, 50mm £390, 58mm £1,500 85mm £1,500, 200mm f2 £5,000, That “very useful focal length range” of 53-75 is hard to fill with a fast prime. Obviously, these FX prime systems have the best light gathering capabilities (biggest diameter glass) but at cost, weight and the lens swapping and missing focal range inconveniences. The point I was picking on was you stating that DX is not going to give you the best low light performance. If you are talking zoom DX then the circumstances described can give DX the best (if best = FX) image quality but only in the above focal ranges. The DX price you pay to equal the FX zoom low light performance is it's only in the limited zoom ranges and also, if it’s important to you, it saves you money. You pays yer money and you takes yer choice. I’m just describing one of the many choices.

Shun, OK, a controversial approach reference the statement “DX is not going to give you the best high ISO results” :) If you are looking for fast, cost effective standard range zooms I don’t think that statement applies. I’m assuming by high ISO results you are talking about the best noise and dynamic range possible in an image for the given available light. D7500, Sigma 18-35 and 50-100 at 1.8 for £2,300 For an FX equivalent of 27-53 and 75-150 at 2.7 I guess you’ll need something like: D750, 24-70 and 70-200 at 2.8. This kit is £3,500-£4,500 depending on lens brand. Across the shared ranges there is no sensor advantage as you are a stop slower on FX (so higher ISO and so increased noise and lower DR). The physics says the photos are exactly the same. System weight and maybe size are similar, again depends on FX lens brands. So if DX Sigmas zooms are too big and heavy I don’t think going FX zooms will change things for either size or quality. For all that extra money spent you do get the 53-75 range filled (is this range that popular “you will be changing lenses very often”?) and the longer 150-200 range and probably VR. Maybe worth the £1,000-£2,000+ (+50%-100%) extra cost? I’ve certainly been drifting to this set up over the years. Fast primes on FX will get you that extra light but at a significant cost, weight, lack of DoF and lens changing compromise. What 1.4 or 1.8 prime can you use for the “pretty big gap” between 35-50 DX (53-75 FX)? The 58mm 1.4 at £1,500 fits nicely in the middle. But if you just want top class standard range zoom photography a DX system is difficult to beat for the price and performance. If you are OK to stop there fine, but in the future if you want big diameter fast glass and the benefits that can bring you will need to ditch DX as FX is where they are. Just food for thought, Jon