Originally posted by normhead You left out a macro lens which I consider essential, you included no 1.4 lenses, and you didn't include the weight of the 2X TC. As well you have to only two lenses less than 70mm.
OK, here's my kit I used after my shoulder surgery.
K-3 800gms
DA 21 ltd.-134 gms
40 XS 45 grams.
DA 55-300 PLM 445 gm
1424 gms.
One body 3 lenses, two primes and 100-300 covered. See if you can beat 1324 gms? Because that's a very functional kit with a K-P at 700gms (with battery.) Trade the 21 and 40 for the DA 20-40 li. and you have an excellent, light 2 lens package.
Seriously, cutting weight and sticking with FF doesn't make any sense with a bad shoulder.
I find it pointlessly offensive that you just make up kit you haven't used for the sake of argument. I post my kit. You post cherry picked nonsense just to make a point.
It wasn't meant as an offensive comment. I was speaking about differences between the 2 tele lenses, one of them being f2.8 while the other being f4.5-f6.3 (reach vs. aperture). We discussed in other topics about the actual use of gear and I told you more than once that when comes to performance, I talk only about the lenses or cameras I used. This was not such a case and that's why I spoke about the difference in terms of aperture between the Pentax and Tamron lens, as you mentioned above for example KP or 20-40mm which as far as you said in other topics you haven't use.
I also learned something which I didn't knew about the Tamron, that it doesn't have a TC available. I don't use TCs on lenses with little reach (70-180mm, 70-200mm) and this is the reason I didn't knew about the use of TC, if this is your concern.
If I would have to choose a light APS-C combo right now, between all the camera brands available I would pick the following:
1. Sony A6600 at 503g (with battery and memory card inserted)
2. Tamron 17-70mm f2.8 at 525g
3. Tamron 70-180mm f2.8 at 810g
Total package weight = 1838g. This kit would be 414g heavier than your kit, but I would have constant f2.8 from 17mm to 180mm. Replacing the 70-180mm lens with a 70-300mm f4.5-f6.3 lens and the kit would be similar in weight with yours, but with a big advantage from 17 to 70mm due to constant f2.8 aperture. The main reason for this choice of mine would be the two f2.8 Tamron lenses.
If you go out and shoot with K3 and 21mm f3.2 lens (good lens, I had it), you'll have a total weight of 934g and you will be limited by the focal length. Going out with Sony and 17-70mm f2.8 you'll have a total weight of 1028g, but way more flexibility for extra weight of 94g. Now, if you keep the same focal length for Sony, you can replace the 17-70mm f2.8 with Sony 20mm f1.8 at 373g and the difference between K3 with DA 21mm lens and A6600 with 20mm f1.8 will be exactly 58g in favor of Sony with the benefit of having f1.8 instead of f3.2.
Then, K3 with 40mm f2.8 will have 851g, while A6600 with Zeiss 40mm f2 will have 864g. Again, 13g advantage of Pentax with a little more advantage in terms of aperture for Sony (f2 vs. f2.8).
If you go out and shoot with K3 and 55-300mm, your total weight will be 1245g. Going out with Sony and Tamron 70-180mm f2.8 your total weight will be 1313g. You loose 120mm but you gain 2 stops in terms of aperture for extra weight of 68g. Replacing the 70-180mm f2.8 with Tamron 70-300mm f4.5-6.3 and the total weight will be 1048g, which is 197g lighter than your kit. Both 70-180mm and 70-300mm are full frame lenses, while 55-300mm PLM is an APS-C lens.
As I said, it all depends on what you plan shooting. Me, I would trade the extra 120mm reach on the tele lens for constant f2.8 from 17mm to 180mm. But that being said, I can't find any reason to go back to APS-C. The best lenses available are the full frame ones anyway (new Pentax lenses like 50mm f1.4, 85mm f1.4, etc.) so for me a full frame makes much more sense... In this regard, a Tamron 28-75mm f2.8 at 550g with a Tamron 70-180mm at 810g would make a nice and light 28-180mm f2.8 kit with A7R IV at less than 2kg.
With:
1. Tamron 17-28mm f2.8 at 420g
2. Tamron 28-75mm f2.8 at 550g
3. Tamron 70-180mm f2.8 at 810g
you have a
17-180mm f2.8 full frame combo or a
25-270mm f2.8 APS-C combo from 3 lenses at the weight of Pentax 70-200mm f2.8 alone (1780g for 3 f2.8 lenses vs. 1755g for Pentax lens).
As for price and weight comparation:
1. K-1 II with Pentax 15-30mm f2.8, Pentax 24-70mm f2.8 and Pentax 70-200mm f2.8 cost at B&H today 6020$ and the total weight of this combo is 4507g.
2. A7R III (released 3-4 months before K-1 II) with Tamron 17-28mm f2.8, Tamron 28-75mm f2.8 and Tamron 70-180mm f2.8 cost at B&H today 5275$ and the total weight of this combo is 2437g.
There is a
745$ price advantage for Sony combo with a
2070g weight advantage for Sony also. Even if you replace A7R III with A7R IV and you will still have a 45$ cheaper combo than Pentax with a full frame 61mp sensor or with a 26mp APS-C option included. I don't know about you, but I call this portability for the ones looking at both full frame and APS-C while having fast f2.8 aperture lenses in the bag.
That's why I hope to see Tamron lenses in RF and Z mount, because they bring portability at quite good performance and price.