Cheetah34 Loc: Virginia Beach

I recently posted a question about scanners. Got lots of great and helpful answers and suggestions. Thanks. I ended up purchasing an Epson FF 680W. Main reason. I have about 1-2,000 old photos to scan plus I really don't need the additional quality of a flat bed.
I have a Sony a7rIV with a 50 mm f1.4 lens and a 34-70 f2.8 (both Sony G master) Thinking about an 85 mm 1.4. I photograph mostly family and, of course, grandkids. Like doing informal portrait work. Sony's 85 1.4 is $1798, the Sigma is $1199. Any suggestions?

camerapapi Loc: Miami, Fl.

Chances are excellent you will do very well with the 50 mm lens.

CHG_CANON Loc: the Windy City

DITTO

The difference between 70mm and 85mm is negligible in terms of focal length. The DOF at f/1.8 is razor thin and likely not wide / deep enough to achieve a sharp focus from nose tip through the ears of your subjects. Rather than experimenting after spending $1000+, try the 50mm and 70mm and see what you can achieve.

BB4A

I can’t recall ANY shoot where I’ve felt I needed something more than 70mm and less than 100mm, to nail my portrait concept. It’s rare these days that I even carry an 85mm lens to a portraiture shoot; I’m very happy to “zoom myself” backwards and forwards with one of my nifty fifty and full frame camera body combos. If I want to get a tight headshot, I use one of my 100-400mm zoom lenses instead. I’m not sure what size sensor (and thereby what the equivalent full frame and 50mm combo is) your camera has, but I’d recommend experimenting with the lenses you have and possibly asking someone you respect to review your work? Be careful about advice and feedback though; they might suggest you sell your 34-70 & buy either the 85 or a 70-200 instead! 😉

repleo Loc: Boston

The GM 85mm 1.4 is supposedly a phenomenal portrait lens. However for more 'informal' or 'candid' type shots I think I would want something a bit longer like the 135mm f1.8 GM or the versatility of the 70-200 f2.8 GM.
Unfortunately, my only experience with any of these lenses has been in my dreams.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

If you do a lot of portrait work, an 85mm F1.4 is a real workhorse. In fact, anything from 85 to 135 is ideal. The advantage of an 85 is that you have tighter composition and this leads to better control of your backgrounds. If you use a 50mm, you generally need to move in a lot closer, and this will often result in an unnatural perspective on the subject ("horse face" narrowed and elongated, and usually unflattering), and lots of background that will distract from the subject. An 85 has less of this.

Zooming with feet changes perspective. This can work in some situations, but again, a 50mm can yield undesirable perspective effects when you get too close.

The 85 lends itself for tight portraits as well as full body shots. Longer focal lengths like 105 and 135 are also flattering, but sometimes the tightness of the composition requires moving back, which again, changes perspective, and faces become flat and wide. Comparing a 50mm to an 85mm you'll find that the illusion of perspective compression is greater in the longer lens, and when combined with skillful use of depth of field to isolate the subject, the results can be stunning.

There is a reason why pros use these focal lengths rather than shorter ones. The difference is a portrait vs a picture. Any lens can take a picture. A "portrait" lens does a better job.

As far as the two lenses you are considering, I have no experience with the Sony, but I've got a friend with the Sigma and I can attest to its awesome image quality, handing, build quality and value. Personally I've used the old Nikkor 85mm F1.4 AF-D and was extremely pleased. The Sigma is MUCH better.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

The Sony 85mm 1.8 is JUST AS SHARP, and with today's high ISO camera's, 1.4 is no longer necessary. The 85 1.8 is a great lens at a great price. Do not over pay for something you really do not need.
I shoot mine off the a9 and a7rIV. Works great.

jerryc41 Loc: Catskill Mts of NY

You live in a very nice area. We've been there quite a few times - relatives nearby. They still have the Christmas display on the beach, right?

Cheetah34 Loc: Virginia Beach

Yes. Lights on the boardwalk. Very popular. I've been here since 1966 after graduating from Navy OCS. Served 4 years active duty and 22 years in the reserves. Love this area even with the increased traffic.

Hsch39 Loc: Northbrook, Illinois

Great explanation. Thank you.

BushDog Loc: San Antonio, TX

Based on the gear you have, I will give you my opinion. I’ve been blessed with the ability to have many camera bodies and lenses over the past 15 years ~ around 20 bodies and 70 lenses. Mostly Canon and Sony but also some Nikon, Fuji & Olympus.

For portraits, I have have used:
~ Canon 85mm f/1.2L Mark ii - was great, gave it to a friend since I mostly use Sony now
~ Canon135mm f/2L - fell in love with the magic of this lens, still have it
~ Zeiss 135mm f/2 Classic - love this lens on both Canon and Sony (w/ adapter on Sony) but don’t use it a lot because of manual focus only. Note: the focus magnification feature on Sony bodies does make it easier to nail focus.
~ Zeiss 135mm f/2 Milvus - successor to the Classic - same comments
~ Sony 85mm f/1.4 GM - just amazing images. But I tend to favor 135mm for portraits - just my preference. I like to back off a little bit from subject. And I can get better candid photos by being at a further distance from the subject.
~ Sigma 105mm f/1.4 DG Art HSM - beautiful images but super heavy and expensive huge filters. I rarely use.
~ Zeiss Batis 135mm f/2.8 - when I ventured into using Sony bodies, I ached for a 135mm f/2 with an FE Mount based on my experience with the Canon 135mm f/2. When this lens was announced, I scoffed at first because it was f/2.8 instead of f/2. I finally lost patience waiting for an f/2 FE Mount 135mm so I bought it. I’m so glad I did. The images this lens gets can be amazing. I haven’t missed f/2 on this lens and it is soooo light!
~ Sony 135mm f/1.8 GM - this lens is absolutely amazing too and I love it. It is heavy in comparison to the Batis.

So, of all these, I mostly use the Zeiss Batis 135 and the Sony 135 GM. When there is reduced available light and I’m not using added light, I will opt for the Sony.

With your Sony a7R Mark IV and its huge sensor (mp), you can capture distant images and crop significantly when necessary and still have quality images. (I have Sony a7Riv, two a7Riii and a9 bodies.)

I didn’t mention the Batis 85mm. That is also a wonderful lens. I considered buying this but opted for the Sony 85mm f/1.4 GM. There is a significant weight difference between these.

I’ll mention again the Zeiss Batis line since they are so light and produce beautiful images. I have the 18mm, 25mm, the 40mm, and the 135mm.

You have lots of great options for 85mm to 135mm. I’m sure you’ll be thrilled with whatever you choose.

imagemeister Loc: mid east Florida

The Sigma. But for informal, 135mm works better IMO on full frame..
.

wireloose

Comparison of these two in today’s Phoblographer, https://www.thephoblographer.com/2020/09/22/sigma-85mm-f14-dg-dn-art-review/ and https://www.thephoblographer.com/2020/09/22/sony-vs-sigma-comparison-battle-of-the-85mm-f1-4-lenses/

Don, the 2nd son Loc: Crowded Florida