I had a nice home-studio set up with two white shoot-through brollies and a pair of Neewer TT850's. Now the flashes are of no use due to the infamous batteries issue,
First off, Neewer doesn't make flashes, they rebrand them from a half-dozen different Chinese manufacturers. The Neewer TT850 was a rebrand of the Godox V850 I.
Secondly the "infamous battery issue" with the AD180/AD360 and V850 I and V860 I lasted about half a year, until Godox straightened out their supply chain. By the time the AD360 II, V850 II, and V860 II came out, the packs were solid.
Today, the Godox "V" speedlights that run off li-ion packs a pretty universally praised. A lot of folks prefer them to AA-powered flashes, and the packs are replaceable. Granted, the V850 I is a very old model now, manual-only, and doesn't have radio built in, so wanting to upgrade is understandable.
I wanted to revert to a couple of good AA battery powered units. Something affordable, that can be used on remote triggers.
Godox TT600 is the AA analog to the V850 II. It's $65. It's single-pin manual. But as a radio slave to a Godox 2.4 GHz transmitter (other than the FC16 triggers), it can give you remote power, group and HSS control. It's kind of useless on a camera hotshoe, though.
The TT685 is the TTL/HSS-capable speedlight mode ($110) but looks like it may now be discontinued since the
TT685 II ($130) came out around December. The TT685 II only swivels 330º, not 360º, and no longer does "smart" optical wireless for Canon, Nikon, and Sony. But it has a slidelock instead of a screwlock, a slight backwards head tilt, and its UI/feature set has been upgraded to match the V860 III/V1 more closely.
All these 2.4 GHz Godox speedlights come with
built-in radio transceivers (transmitter/receiver unit) in Godox's X system. You can't leave your receiver behind ever again.
Presently I was looking at
this set up (Neewer NW561)...
Then I noticed it was only GN35 unlike the TT850 GN58.
You missed the crucial piece of information, the zoom setting at which the guide number was measured.
On the NW561 the guide number is: 35m, at ISO 100,
zoomed to 35mm.
It's likely your TT850 was GN 58m, at iso 100,
zoomed to 105mm.
The zoom setting is how far back into the head the flash tube is positioned. The farther back, the narrower/more focused the beam (higher zoom) and the more powerful the flash looks.
A Nikon top-of-the-line SB-5000 has a guide number of
35m at
35mm zoom iso 100.
Canon's 580EX, which had a GN of
58m at iso 100,
105mm zoom has identical output to the
60m guide numbered 600EX-RT, at iso 100 and
200mm zoom.
Adorama measure the GN of the Godox V1 at
42m 100 at
105mm zoom. The Godox V860 II is measured at
60mm iso 100 and
200mm zoom.
Most of these speedlights have also had their output measured in identical off-camera lighting setups with a light meter to compare them side-by-side, and they're all pretty much at the same level of light output.
The Nikon looks less powerful because it's measured at a realistic zoom, not the maximum zoom.
The Canon's and Godox fresnel heads look more powerful, because they're measured at maximum zoom.
The V1 looks less powerful, because it zooms less,
and its round head has a more even and wider spread/falloff than a traditional fresnel head.
TL;DR, the 561 is probably around the same power output as your TT850.
Will the 561's still be as good a replacement for my studio? It looked like a good deal, but a shame you can't change the flash units powers like with the remote add-on for the 850s.
I was hoping for a frequency of around 433mhz.
Just FYI. Those triggers that come with the NW561 are probably rebranded
Godox FC16 triggers. They don't allow for groups, remote power control, or HSS, like say, the Cells II/FT16/FTR16s triggers you were probably using with the V850 I.
Personally, I say go with TT685 or TT685 IIs for your camera system (but okay, TT600 if you have to go dirt cheap). And an Godox X2T, XPro, or Flashpoint R2 Pro II transmitter for your camera system.
The Godox 2.4 GHz X system flashes and transmitters allow for group on/off control, remote power control by group in either TTL or M, with HSS, 2nd curtain, MULTI, etc. etc. You even get remote modeling light control on the studio strobes in the system. And that functional support exist not just for Canon and Nikon, but also Sony, Fuji, Olympus/Panasonic, and Pentax.
You get LCD screens so you can see 3-5 group settings all at once, you don't have to use flipping dip switches to set channels, you get TTL with TTL lights, and you're in the current 2.4 GHz system that has cheap AC manual powered strobes (say, the Godox MS300) as well as li-ion powered TTL/HSS strobes in it. You have ten speedlight models to choose from, and you don't have to clip an FTR16s/XTR16s receiver onto the side of the speedlight to trigger it over radio.
You were using first-gen Godox gear. We're at about the 4th generation, now. Take advantage.
And ditch the Neewer branding; there's too much mystery-meat stuff out there you have no idea what it is. That NW651 you're looking at is NOT a Godox flash.
I know, you're all manual-only and you've never needed TTL and only losers use TTL, etc. etc. But chances are you've never used it (since your flashes didn't do it) and you're unaware that TTL can make
any changes to iso, aperture, and flash placement
transparent to the flash exposure. You could shoot at f/5.6 then switch to f/1.4 on the fly and back again to f/5.6 without having to adjust the power on your light.
Godox's "Pro" transmitters also let you use TCM (TTL Convert to Manual) so you can use TTL to set the power level, then switch to M to finesse or lock the level. While TTL sucks for use on all your lights, it can be incredibly convenient for your key, or, if your key/fill are placed at similar distances to your subject, key/fill ratios. And these days, the triggers let you mix TTL and M groups together.
And all the TTL gear also does M. The M-only gear can never do TTL. And in the Godox 2.4 GHz system, the power/group control
Back when David Hobby told people TTL gear was useless for off-camera flash, TTL wireless systems were all OEM, proprietary optical with range/reliability/line of sight issues, and cost about 5x more than manual radio triggering. You couldn't lock the power level in for shot-to-shot consistency, and even in the OEM systems, it was typically only 2 or 3 groups and all-TTL or all-M, not mixed.
But today? The cost difference is minimal (say about $50 between a TT600 and a TT685), it's all radio based, it's five groups (three that can do TTL/M, two that are M only), with mixed TTL/M modes, and TTL-locking (TCM). A
lot has changed in 16 years of flash tech. You may want to see what's out there.
